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Prof. Dr. Elena G. Biosca
Departamento de Microbiología y Ecología, Universitat de València, Valencia, Spain

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0 Phage therapy
0 Bacteriophages
0 biotechnological applications
0 Plant Pathogenic Bacteria

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Microbiology
Published: 16 November 2020 in Frontiers in Microbiology
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Antibiotic misuse is a public health problem due to the appearance of resistant strains in almost all human pathogens, making infectious diseases more difficult to treat. The search for solutions requires the development of new antimicrobials as well as novel strategies, including increasing social awareness of the problem. The Small World Initiative (SWI) and the Tiny Earth (TE) network are citizen science programs pursuing the discovery of new antibiotics from soil samples and the promotion of scientific culture. Both programs aim to bring scientific culture and microbiological research closer to pre-university students through a crowdsourcing strategy and a Service Learning (SL) educational approach, with a 2-fold objective: to encourage students to pursue careers in science and to involve them in the discovery of soil microorganisms producing new antimicrobials. SWI and TE projects were put into practice in Spain under the common name MicroMundo. [email protected] was implemented at the Universitat de València (UV) during the academic years 2017–2018 and 2018–2019. It trained 140 university students to disseminate this initiative into 23 high/secondary schools, and one primary school, involving about 900 people (teachers and students) as researchers. A total of 7,002 bacterial isolates were obtained from 366 soil samples and tested for antibiosis at UV and high/secondary school centers. About 1 or 7% of them produced inhibition halos for the Escherichia coli or Bacillus cereus target strains, respectively. Geolocation of sampling sites by an application developed ad hoc and Kriging analysis also allowed detection of soil foci of antibiotic-producing bacteria. Evaluation of the project by university, high/secondary, and primary school students revealed their strong positive perception and their increased interest in science, as a consequence of acquiring new scientific and pedagogical concepts and skills that they were able to pass on to other classmates, younger students, or relatives. To further expand the dissemination of the project in the Valencian Community, diverse extramural activities deemed to include a gender perspective and aimed at different age groups, were also carried out, obtaining very satisfactory results, increasing sensitivity and awareness to the global antibiotic crisis.

ACS Style

Sergi Maicas; Belén Fouz; Àngela Figàs-Segura; Jesús Zueco; Hortensia Rico; Alfonso Navarro; Ester Carbó; Jaume Segura-García; Elena G. Biosca. Implementation of Antibiotic Discovery by Student Crowdsourcing in the Valencian Community Through a Service Learning Strategy. Frontiers in Microbiology 2020, 11, 1 .

AMA Style

Sergi Maicas, Belén Fouz, Àngela Figàs-Segura, Jesús Zueco, Hortensia Rico, Alfonso Navarro, Ester Carbó, Jaume Segura-García, Elena G. Biosca. Implementation of Antibiotic Discovery by Student Crowdsourcing in the Valencian Community Through a Service Learning Strategy. Frontiers in Microbiology. 2020; 11 ():1.

Chicago/Turabian Style

Sergi Maicas; Belén Fouz; Àngela Figàs-Segura; Jesús Zueco; Hortensia Rico; Alfonso Navarro; Ester Carbó; Jaume Segura-García; Elena G. Biosca. 2020. "Implementation of Antibiotic Discovery by Student Crowdsourcing in the Valencian Community Through a Service Learning Strategy." Frontiers in Microbiology 11, no. : 1.

Journal article
Published: 10 October 2020 in FEMS Microbiology Ecology
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Fire blight caused by Erwinia amylovora affects pome fruit worldwide, generating serious economic losses. Despite the abundant literature on E. amylovora infection mechanisms of aerial plant organs, root infection routes remain virtually unexplored. Assessing these infection pathways is necessary for a full understanding of the pathogen's ecology. Using the pathosystem Pyrus communis–E. amylovora and different experimental approaches including a green fluorescent protein transformant (GFP1) and epifluorescence microscopy (EFM) and laser confocal scanning microscopy (LCSM), we demonstrated the pathogen's ability to infect, colonize and invade pear roots and cause characteristic fire blight symptoms both in the aerial part and in the root system. Plant infections after soil irrigation with E. amylovora-contaminated water were favored by root damage, which agreed with EFM and LCSM observations. E. amylovora GFP1 cells formed aggregates/biofilms on root surfaces and invaded the cortex through wounds and sites of lateral root emergence. Sugars, sugar-alcohols and amino acids typically secreted by roots, favored the in vitro biofilm development by E. amylovora. Migration of E. amylovora cells to aerial tissues mainly occurred after xylem penetration. Overall, our findings revealed, for the first time, common root infection patterns between E. amylovora and well-known soil borne plant pathogens and endophytes.

ACS Style

Ricardo D Santander; José F Català-Senent; Àngela Figàs-Segura; Elena G Biosca. From the roots to the stem: unveiling pear root colonization and infection pathways by Erwinia amylovora. FEMS Microbiology Ecology 2020, 96, 1 .

AMA Style

Ricardo D Santander, José F Català-Senent, Àngela Figàs-Segura, Elena G Biosca. From the roots to the stem: unveiling pear root colonization and infection pathways by Erwinia amylovora. FEMS Microbiology Ecology. 2020; 96 (12):1.

Chicago/Turabian Style

Ricardo D Santander; José F Català-Senent; Àngela Figàs-Segura; Elena G Biosca. 2020. "From the roots to the stem: unveiling pear root colonization and infection pathways by Erwinia amylovora." FEMS Microbiology Ecology 96, no. 12: 1.

Original research article
Published: 06 December 2019 in Frontiers in Microbiology
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Three new lytic bacteriophages were found to effectively control the pathogen Ralstonia solanacearum, a quarantine bacterium in many countries, and causative agent of bacterial wilt, one of the most important vascular plant diseases. Bacterial wilt management has been carried out with fluctuating effects, suggesting the need to find alternative treatments. In this work, three lytic phages were isolated from environmental water from geographically distant regions in Spain. They proved to specifically infect a collection of R. solanacearum strains, and some of the closely related pathogenic species Ralstonia pseudosolanacearum, without affecting non-target environmental bacteria, and were able to lyze the pathogen populations within a wide range of conditions comprising environmental values of water temperatures, pH, salinity, and lack of aeration found in storage tanks. The three bacteriophages displayed high efficiency in controlling R. solanacearum, with reductions of the bacterial populations of several orders of magnitude in just a few hours, and proved to be able to survive in freshwater for months at environmental temperatures keeping activity on R. solanacearum, pointing out their suitability for field application through irrigation. Concerning their biocontrol potential, they were effective in reducing high populations of the pathogen in environmental water, and bacterial wilt incidence in planta by watering with either one phage or their combinations in assays with more than 300 plants. This is the first report on effective R. solanacearum biocontrol by applying single or combined bacteriophages through irrigation water in conditions mimicking those of the natural settings. The three phages belong to the Podoviridae family and are members of the T7likevirus genus. They are the first isolated phages from river water with activity against R. solanacearum, showing the longest persistence in natural water reported until now for phages with biocontrol potential, and consistently being able to control the disease in the host plant under environmental conditions. Consequently, the use of these bacteriophages for the prevention and/or biocontrol of the bacterial wilt disease caused by R. solanacearum has been patented. Evidence provided reveals the suitability of these waterborne phages to be effectively considered as a valuable strategy within the frame of sustainable integrated management programs.

ACS Style

Belén Álvarez; María M. López; Elena G. Biosca. Biocontrol of the Major Plant Pathogen Ralstonia solanacearum in Irrigation Water and Host Plants by Novel Waterborne Lytic Bacteriophages. Frontiers in Microbiology 2019, 10, 2813 .

AMA Style

Belén Álvarez, María M. López, Elena G. Biosca. Biocontrol of the Major Plant Pathogen Ralstonia solanacearum in Irrigation Water and Host Plants by Novel Waterborne Lytic Bacteriophages. Frontiers in Microbiology. 2019; 10 ():2813.

Chicago/Turabian Style

Belén Álvarez; María M. López; Elena G. Biosca. 2019. "Biocontrol of the Major Plant Pathogen Ralstonia solanacearum in Irrigation Water and Host Plants by Novel Waterborne Lytic Bacteriophages." Frontiers in Microbiology 10, no. : 2813.

Journal article
Published: 26 October 2017 in PeerJ
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The fire blight pathogenErwinia amylovoracan be considered a psychrotrophic bacterial species since it can grow at temperatures ranging from 4 °C to 37 °C, with an optimum of 28 °C. In many plant pathogens the expression of virulence determinants is restricted to a certain range of temperatures. In the case ofE. amylovora,temperatures above 18 °C are required for blossom blight epidemics under field conditions. Moreover, this bacterium is able to infect a variety of host tissues/organs apart from flowers, but it is still unknown how environmental temperatures, especially those below 18 °C, affect the pathogen ability to cause fire blight disease symptoms in such tissues/organs. There is also scarce information on how temperatures below 18 °C affect theE. amylovorastarvation-survival responses, which might determine its persistence in the environment and probably contribute to the seasonal development of fire blight disease, as occurs in other pathogens. To characterize the virulence and survival ofE. amylovoraat temperate and low temperatures, we evaluated the effect of three temperatures (4 °C, 14 °C, 28 °C) on symptom development, and on different parameters linked to starvation and virulence.E. amylovorawas pathogenic at the three assayed temperatures, with a slow-down of symptom development correlating with colder temperatures and slower growth rates. Siderophore secretion and motility also decreased in parallel to incubation temperatures. However, production of the exopolysaccharides amylovoran and levan was enhanced at 4 °C and 14 °C, respectively. Similarly, biofilm formation, and oxidative stress resistance were improved at 14 °C, with this temperature also favoring the maintenance of culturability, together with a reduction in cell size and the acquisition of rounded shapes inE. amylovoracells subjected to long-term starvation. However, starvation at 28 °C and 4 °C induced an enhanced viable but nonculturable (VBNC) response (to a lesser extent at 4 °C). This work revealsE. amylovoraas a highly adaptable pathogen that retains its pathogenic potential even at the minimal growth temperatures, with an improved exopolysaccharide synthesis, biofilm formation or oxidative stress resistance at 14 °C, with respect to the optimal growth temperature (28 °C). Finally, our results also demonstrate the thermal modulation of starvation responses inE. amylovora,suggesting that the starvation-survival and the VBNC states are part of its life cycle. These results confirm the particular psychrotrophic adaptations ofE. amylovora, revealing its pathogenic potential and survival at temperate and low environmental temperatures, which have probably contributed to its successful spread to countries with different climates. This knowledge might improve integrated control measures against fire blight.

ACS Style

Ricardo Delgado Santander; Elena G. Biosca. Erwinia amylovorapsychrotrophic adaptations: evidence of pathogenic potential and survival at temperate and low environmental temperatures. PeerJ 2017, 5, e3931 .

AMA Style

Ricardo Delgado Santander, Elena G. Biosca. Erwinia amylovorapsychrotrophic adaptations: evidence of pathogenic potential and survival at temperate and low environmental temperatures. PeerJ. 2017; 5 ():e3931.

Chicago/Turabian Style

Ricardo Delgado Santander; Elena G. Biosca. 2017. "Erwinia amylovorapsychrotrophic adaptations: evidence of pathogenic potential and survival at temperate and low environmental temperatures." PeerJ 5, no. : e3931.

Journal article
Published: 20 September 2017 in Molecular Plant Pathology
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The life cycle of the plant pathogen Erwinia amylovora comprises periods inside and outside the host in which it faces oxidative stress caused by hydrogen peroxide (H2O2) and other compounds. The sources of this stress are plant defences, other microorganisms and/or exposure to starvation or other environmental challenges. However, the functional roles of H2O2-neutralizing enzymes, such as catalases, during plant–pathogen interactions and/or under starvation conditions in phytopathogens of the family Erwiniaceae or closely related families have not yet been investigated. In this work, the contribution of E. amylovora catalases KatA and KatG to virulence and survival in non-host environments was determined using catalase gene mutants and expression, as well as catalase activity analyses. The participation of E. amylovora exopolysaccharides (EPSs) in oxidative stress protection was also investigated. Our study revealed the following: (i) a different growth phase regulation of each catalase, with an induction by H2O2 and host tissues; (ii) the significant role of E. amylovora catalases as virulence and survival factors during plant–pathogen interactions; (iii) the induction of EPSs by H2O2 despite the fact that apparently they do not contribute to protection against this compound; and (iv) the participation of both catalases in the detoxification of the starvation-induced intracellular oxidative stress, favouring the maintenance of culturability, and hence delaying the development of the viable but non-culturable (VBNC) response.

ACS Style

Ricardo Delgado Santander; Àngela Figàs-Segura; Elena G. Biosca. Erwinia amylovoracatalases KatA and KatG are virulence factors and delay the starvation-induced viable but non-culturable (VBNC) response. Molecular Plant Pathology 2017, 19, 922 -934.

AMA Style

Ricardo Delgado Santander, Àngela Figàs-Segura, Elena G. Biosca. Erwinia amylovoracatalases KatA and KatG are virulence factors and delay the starvation-induced viable but non-culturable (VBNC) response. Molecular Plant Pathology. 2017; 19 (4):922-934.

Chicago/Turabian Style

Ricardo Delgado Santander; Àngela Figàs-Segura; Elena G. Biosca. 2017. "Erwinia amylovoracatalases KatA and KatG are virulence factors and delay the starvation-induced viable but non-culturable (VBNC) response." Molecular Plant Pathology 19, no. 4: 922-934.

Mini review article
Published: 14 July 2017 in Frontiers in Plant Science
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Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management programme to effectively fight bacterial wilt in the field.

ACS Style

Belén Álvarez; Elena González Biosca. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture. Frontiers in Plant Science 2017, 8, 1 .

AMA Style

Belén Álvarez, Elena González Biosca. Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture. Frontiers in Plant Science. 2017; 8 ():1.

Chicago/Turabian Style

Belén Álvarez; Elena González Biosca. 2017. "Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture." Frontiers in Plant Science 8, no. : 1.

Research article
Published: 05 August 2016 in PLOS ONE
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Lichens, self-supporting mutualistic associations between a fungal partner and one or more photosynthetic partners, also harbor non-photosynthetic bacteria. The diversity and contribution of these bacteria to the functioning of lichen symbiosis have recently begun to be studied, often by culture-independent techniques due to difficulties in their isolation and culture. However, culturing as yet unculturable lichenic bacteria is critical to unravel their potential functional roles in lichen symbiogenesis, to explore and exploit their biotechnological potential and for the description of new taxa. Our objective was to improve the recovery of lichen associated bacteria by developing novel isolation and culture approaches, initially using the lichen Pseudevernia furfuracea. We evaluated the effect of newly developed media enriched with novel lichen extracts, as well as the influence of thalli washing time and different disinfection and processing protocols of thalli. The developed methodology included: i) the use of lichen enriched media to mimic lichen nutrients, supplemented with the fungicide natamycin; ii) an extended washing of thalli to increase the recovery of ectolichenic bacteria, thus allowing the disinfection of thalli to be discarded, hence enhancing endolichenic bacteria recovery; and iii) the use of an antioxidant buffer to prevent or reduce oxidative stress during thalli disruption. The optimized methodology allowed significant increases in the number and diversity of culturable bacteria associated with P. furfuracea, and it was also successfully applied to the lichens Ramalina farinacea and Parmotrema pseudotinctorum. Furthermore, we provide, for the first time, data on the abundance of culturable ecto- and endolichenic bacteria that naturally colonize P. furfuracea, R. farinacea and P. pseudotinctorum, some of which were only able to grow on lichen enriched media. This innovative methodology is also applicable to other microorganisms inhabiting these and other lichen species.

ACS Style

Elena G. Biosca; Raquel Flores; Ricardo Delgado Santander; José Luis Díez-Gil; Eva Barreno. Innovative Approaches Using Lichen Enriched Media to Improve Isolation and Culturability of Lichen Associated Bacteria. PLOS ONE 2016, 11, e0160328 .

AMA Style

Elena G. Biosca, Raquel Flores, Ricardo Delgado Santander, José Luis Díez-Gil, Eva Barreno. Innovative Approaches Using Lichen Enriched Media to Improve Isolation and Culturability of Lichen Associated Bacteria. PLOS ONE. 2016; 11 (8):e0160328.

Chicago/Turabian Style

Elena G. Biosca; Raquel Flores; Ricardo Delgado Santander; José Luis Díez-Gil; Eva Barreno. 2016. "Innovative Approaches Using Lichen Enriched Media to Improve Isolation and Culturability of Lichen Associated Bacteria." PLOS ONE 11, no. 8: e0160328.

Research article
Published: 15 May 2015 in PLOS ONE
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Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle.

ACS Style

Mónica Ordax; Jaime E. Piquer-Salcedo; Ricardo Delgado Santander; Beatriz Sabater-Muñoz; Elena González Biosca; María M. López; Ester Marco-Noales. Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission. PLOS ONE 2015, 10, e0127560 -e0127560.

AMA Style

Mónica Ordax, Jaime E. Piquer-Salcedo, Ricardo Delgado Santander, Beatriz Sabater-Muñoz, Elena González Biosca, María M. López, Ester Marco-Noales. Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission. PLOS ONE. 2015; 10 (5):e0127560-e0127560.

Chicago/Turabian Style

Mónica Ordax; Jaime E. Piquer-Salcedo; Ricardo Delgado Santander; Beatriz Sabater-Muñoz; Elena González Biosca; María M. López; Ester Marco-Noales. 2015. "Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission." PLOS ONE 10, no. 5: e0127560-e0127560.

Journal article
Published: 04 November 2014 in FEMS Microbiology Ecology
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Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-protection against oxidative, osmotic, and acid stresses and was essential for cross-protection against heat shock, but nonessential against acid shock. RpoS also mediated regulation of motility, exopolysaccharide synthesis, and virulence in immature loquats, but not in pear plantlets, and contributed to E. amylovora survival in nonhost tissues during incompatible interactions. Our results reveal some unique roles for the rpoS gene in E. amylovora and provide new knowledge on the regulation of different processes related to its ecology, including survival in different environments and virulence in immature fruits.

ACS Style

Ricardo Delgado Santander; Mercedes Monte-Serrano; Jose Juan Rodriguez Herva; Emilia Antonia Lopez Solanilla; Pablo Rodríguez-Palenzuela; Elena G. Biosca. Exploring new roles for therpoSgene in the survival and virulence of the fire blight pathogenErwinia amylovora. FEMS Microbiology Ecology 2014, 90, 895 -907.

AMA Style

Ricardo Delgado Santander, Mercedes Monte-Serrano, Jose Juan Rodriguez Herva, Emilia Antonia Lopez Solanilla, Pablo Rodríguez-Palenzuela, Elena G. Biosca. Exploring new roles for therpoSgene in the survival and virulence of the fire blight pathogenErwinia amylovora. FEMS Microbiology Ecology. 2014; 90 (3):895-907.

Chicago/Turabian Style

Ricardo Delgado Santander; Mercedes Monte-Serrano; Jose Juan Rodriguez Herva; Emilia Antonia Lopez Solanilla; Pablo Rodríguez-Palenzuela; Elena G. Biosca. 2014. "Exploring new roles for therpoSgene in the survival and virulence of the fire blight pathogenErwinia amylovora." FEMS Microbiology Ecology 90, no. 3: 895-907.

Journal article
Published: 20 February 2014 in FEMS Microbiology Ecology
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Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants distributed worldwide. This bacterium is a nonobligate pathogen able to survive outside the host under starvation conditions, allowing its spread by various means such as rainwater. We studied E. amylovora responses to starvation using water microcosms to mimic natural oligotrophy. Initially, survivability under optimal (28 °C) and suboptimal (20 °C) growth temperatures was compared. Starvation induced a loss of culturability much more pronounced at 28 °C than at 20 °C. Natural water microcosms at 20 °C were then used to characterize cellular, physiological, and molecular starvation responses of E. amylovora. Challenged cells developed starvation-survival and viable but nonculturable responses, reduced their size, acquired rounded shapes and developed surface vesicles. Starved cells lost motility in a few days, but a fraction retained flagella. The expression of genes related to starvation, oxidative stress, motility, pathogenicity, and virulence was detected during the entire experimental period with different regulation patterns observed during the first 24 h. Further, starved cells remained as virulent as nonstressed cells. Overall, these results provide new knowledge on the biology of E. amylovora under conditions prevailing in nature, which could contribute to a better understanding of the life cycle of this pathogen.

ACS Style

Ricardo Delgado Santander; James D. Oliver; Elena G. Biosca. Cellular, physiological, and molecular adaptive responses ofErwinia amylovorato starvation. FEMS Microbiology Ecology 2014, 88, 258 -271.

AMA Style

Ricardo Delgado Santander, James D. Oliver, Elena G. Biosca. Cellular, physiological, and molecular adaptive responses ofErwinia amylovorato starvation. FEMS Microbiology Ecology. 2014; 88 (2):258-271.

Chicago/Turabian Style

Ricardo Delgado Santander; James D. Oliver; Elena G. Biosca. 2014. "Cellular, physiological, and molecular adaptive responses ofErwinia amylovorato starvation." FEMS Microbiology Ecology 88, no. 2: 258-271.

Conference paper
Published: 27 June 2012 in Microbes in Applied Research
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Erwinia amylovora is a pathogenic bacterium affecting economically important rosaceous plants worldwide. It causes fire blight, one of the most difficult-to-control diseases of pome fruit trees, which has been related to the ability of the pathogen to respond to changes in the environment. Bacteria can respond to environmental stresses by activating the expression of rpoS gene, encoding the alternative sigma factor RpoS, involved in cell protection against environmental challenges, such as nutrient limitation. We aimed to study the possible involvement of the sigma factor RpoS on the short-term survival of the fire blight pathogen under natural conditions of nutrient scarcity in water. Then, a mutant in the rpoS gene was obtained from E. amylovora and the survival of this mutant and its wild type parent strain was monitored along one week in water microcosms. Initial results have shown that the rpoS mutant exhibited a reduction in culturability and viability over time not observed in the wild type parent strain, suggesting that rpoS gene may help E. amylovora to survive under natural nutrient limitation conditions.

ACS Style

R. D. Santander; M. Monte-Serrano; J. F. Català-Senent; J. J. Rodriguez-Herva; E. López-Solanilla; P. Rodriguez-Palenzuela; E. G. Biosca; A Mendez-Vilas. Effect of rpoS mutation on short-term survival of Erwinia amylovora under nutrient-limited conditions. Microbes in Applied Research 2012, 110 -114.

AMA Style

R. D. Santander, M. Monte-Serrano, J. F. Català-Senent, J. J. Rodriguez-Herva, E. López-Solanilla, P. Rodriguez-Palenzuela, E. G. Biosca, A Mendez-Vilas. Effect of rpoS mutation on short-term survival of Erwinia amylovora under nutrient-limited conditions. Microbes in Applied Research. 2012; ():110-114.

Chicago/Turabian Style

R. D. Santander; M. Monte-Serrano; J. F. Català-Senent; J. J. Rodriguez-Herva; E. López-Solanilla; P. Rodriguez-Palenzuela; E. G. Biosca; A Mendez-Vilas. 2012. "Effect of rpoS mutation on short-term survival of Erwinia amylovora under nutrient-limited conditions." Microbes in Applied Research , no. : 110-114.

Conference paper
Published: 27 June 2012 in Microbes in Applied Research
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The plant pathogen Erwinia amylovora is responsible for fire blight disease, causing serious losses in pome fruitgrowing areas around the world. Difficulties in controlling fire blight have been related to the survival abilities of this pathogen in nature under different environmental conditions. One such survival strategy is the adoption of the viable but nonculturable (VBNC) state, where the cells remain viable but unable to grow on routine solid media. Because loss of culturability by VBNC cells has been related to oxidative stress, we have studied the expression of selected oxidative stress-related genes (katA, katG, and oxyR) in E. amylovora cells exposed to VBNC-inducing conditions. Gene expression was determined by reverse transcriptase polymerase chain reaction (RT-PCR), using the 16S rRNA gene as control. Initial results have shown down regulation of katA, katG and oxyR genes during the entry of E. amylovora cells into the VBNC state. However, the expression of the housekeeping 16S rRNA gene was maintained during entry and within the VBNC state.

ACS Style

R. D. Santander; J. D. Oliver; E. G. Biosca; A Mendez-Vilas. Expression analyses of oxidative stress katA, katG and oxyR genes in Erwinia amylovora in the viable but nonculturable state. Microbes in Applied Research 2012, 1 .

AMA Style

R. D. Santander, J. D. Oliver, E. G. Biosca, A Mendez-Vilas. Expression analyses of oxidative stress katA, katG and oxyR genes in Erwinia amylovora in the viable but nonculturable state. Microbes in Applied Research. 2012; ():1.

Chicago/Turabian Style

R. D. Santander; J. D. Oliver; E. G. Biosca; A Mendez-Vilas. 2012. "Expression analyses of oxidative stress katA, katG and oxyR genes in Erwinia amylovora in the viable but nonculturable state." Microbes in Applied Research , no. : 1.

Journal article
Published: 23 November 2011 in Trees
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Little is known about the survival mechanisms of Erwinia amylovora outside its hosts. It has been demonstrated that it enters the viable but nonculturable state (VBNC) when exposed to different types of stress. In the VBNC state, bacterial cells remain viable but unable to grow on the solid general media where they usually do, and are thus undetectable by conventional culture-dependent methods. In this work, we have evaluated the recovery of E. amylovora VBNC cells by passage through pear plantlets, in comparison with other recovery methods commonly used for this pathogen: incubation in KB broth and inoculation of immature fruits. VBNC cells were obtained by exposure of bacterial cells to different types of stress (oligotrophy, nutrient deprivation and chlorine), and recovery assays were performed at 26°C. In all cases, the recovery of VBNC cells was more effective in plantlets than in liquid KB or immature fruits. In fact, when cells were exposed to chlorine for more than 30 min, only passage through host plant gave positive result, enabling recovery of E. amylovora cells few days after inoculation of plants. These results suggest a higher effectiveness of in planta recovery than those performed with liquid KB or detached fruits. Our results support the hypothesis of the VBNC state being part of the E. amylovora life cycle. The potential existence of this physiological state in nature should be taken in consideration in epidemiological studies of fire blight, with the aim to optimize the management and control of this disease.

ACS Style

Ricardo Delgado Santander; José Francisco Català Senent; Ester Marco-Noales; E. G. Biosca. In planta recovery of Erwinia amylovora viable but nonculturable cells. Trees 2011, 26, 75 -82.

AMA Style

Ricardo Delgado Santander, José Francisco Català Senent, Ester Marco-Noales, E. G. Biosca. In planta recovery of Erwinia amylovora viable but nonculturable cells. Trees. 2011; 26 (1):75-82.

Chicago/Turabian Style

Ricardo Delgado Santander; José Francisco Català Senent; Ester Marco-Noales; E. G. Biosca. 2011. "In planta recovery of Erwinia amylovora viable but nonculturable cells." Trees 26, no. 1: 75-82.

Journal article
Published: 14 September 2011 in Trees
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The bacterium Erwinia amylovora causes fire blight, a serious and widespread disease of several pome fruit and ornamental plants. The use of suitable detection tools is essential for preventing its dissemination and, according to the protocol of the European and Mediterranean Plant Protection Organization, the isolation and further identification of E. amylovora is the only conclusive test of its presence. However, bacterial growth on solid media can be hampered when the pathogen is suffering stressful conditions in pome fruit or in other habitats. Since copper is an essential micronutrient that, in E. amylovora, also increases the exopolysaccharide production in rich-nutrient media, we have designed a non-selective differential medium containing 1.5 mM CuSO4 to improve the recovery of E. amylovora from plants under unfavorable conditions. In this new medium named Recovery Erwinia amylovora-Stressed Cells (RESC), its colonies were easily distinguished by a light yellow color and a high mucus production. The plating recovery of several E. amylovora strains in vitro and from naturally infected samples was significantly improved with respect to other media routinely employed, particularly when the pathogen was suffering stressful conditions. Thus, the recovery of stressed E. amylovora cells (after UV irradiation, nutrient deprivation, or the presence of copper ions in non-copper-complexing media) was significantly enhanced on RESC medium, and their culturability period extended. Therefore, RESC is a useful and valuable medium for the isolation of E. amylovora when adverse conditions in the natural environment are expected.

ACS Style

Mónica Ordax; Elena González Biosca; María M. López; Ester Marco-Noales. Improved recovery of Erwinia amylovora-stressed cells from pome fruit on RESC, a simple, rapid and differential medium. Trees 2011, 26, 83 -93.

AMA Style

Mónica Ordax, Elena González Biosca, María M. López, Ester Marco-Noales. Improved recovery of Erwinia amylovora-stressed cells from pome fruit on RESC, a simple, rapid and differential medium. Trees. 2011; 26 (1):83-93.

Chicago/Turabian Style

Mónica Ordax; Elena González Biosca; María M. López; Ester Marco-Noales. 2011. "Improved recovery of Erwinia amylovora-stressed cells from pome fruit on RESC, a simple, rapid and differential medium." Trees 26, no. 1: 83-93.

Journal article
Published: 01 May 2011 in Acta Horticulturae
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R.D. Santander; J.F. Català-Senent; E.G. Biosca; E. Marco-Noales. RECOVERY OF ERWINIA AMYLOVORA VIABLE BUT NON-CULTURABLE CELLS IN PEAR PLANTLETS. Acta Horticulturae 2011, 283 -287.

AMA Style

R.D. Santander, J.F. Català-Senent, E.G. Biosca, E. Marco-Noales. RECOVERY OF ERWINIA AMYLOVORA VIABLE BUT NON-CULTURABLE CELLS IN PEAR PLANTLETS. Acta Horticulturae. 2011; (896):283-287.

Chicago/Turabian Style

R.D. Santander; J.F. Català-Senent; E.G. Biosca; E. Marco-Noales. 2011. "RECOVERY OF ERWINIA AMYLOVORA VIABLE BUT NON-CULTURABLE CELLS IN PEAR PLANTLETS." Acta Horticulturae , no. 896: 283-287.

Journal article
Published: 01 May 2011 in Acta Horticulturae
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R.D. Santander; J.F. Català-Senent; E.G. Biosca; M. Ordax; E. Marco-Noales. COLONIZATION OF PEAR PLANTLETS INOCULATED WITH ERWINIA AMYLOVORA BY SOIL IRRIGATION. Acta Horticulturae 2011, 301 -305.

AMA Style

R.D. Santander, J.F. Català-Senent, E.G. Biosca, M. Ordax, E. Marco-Noales. COLONIZATION OF PEAR PLANTLETS INOCULATED WITH ERWINIA AMYLOVORA BY SOIL IRRIGATION. Acta Horticulturae. 2011; (896):301-305.

Chicago/Turabian Style

R.D. Santander; J.F. Català-Senent; E.G. Biosca; M. Ordax; E. Marco-Noales. 2011. "COLONIZATION OF PEAR PLANTLETS INOCULATED WITH ERWINIA AMYLOVORA BY SOIL IRRIGATION." Acta Horticulturae , no. 896: 301-305.

Journal article
Published: 30 September 2010 in Research in Microbiology
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Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants very difficult to control. We demonstrated that copper, employed to control plant diseases, induces the “viable-but-nonculturable” (VBNC) state in E. amylovora. Moreover, it was previously reported that copper increases production of its main exopolysaccharide (EPS), amylovoran. In this work, the copper-complexing ability of amylovoran and levan, other major EPS of E. amylovora, was demonstrated. Following this, EPS-deficient mutants were used to determine the role of these EPSs in survival of this bacterium in AB mineral medium with copper, compared to their wild type strain and AB without copper. Total, viable and culturable counts of all strains were monitored for six months. With copper, a larger fraction of the viable population of EPS mutants entered into the VBNC state, and earlier than their wild type strain, showing the contribution of both EPSs to long-term survival in a culturable state. Further, we demonstrated that both EPSs can be used as carbon source by E. amylovora under deprivation conditions. Overall, these previously unreported functions of amylovoran and levan provide survival advantages for E. amylovora, which could contribute to its enhanced persistence in nature.

ACS Style

Mónica Ordax; Ester Marco-Noales; María M. López; Elena G. Biosca. Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies. Research in Microbiology 2010, 161, 549 -555.

AMA Style

Mónica Ordax, Ester Marco-Noales, María M. López, Elena G. Biosca. Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies. Research in Microbiology. 2010; 161 (7):549-555.

Chicago/Turabian Style

Mónica Ordax; Ester Marco-Noales; María M. López; Elena G. Biosca. 2010. "Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies." Research in Microbiology 161, no. 7: 549-555.

Journal article
Published: 05 June 2009 in Journal of Applied Microbiology
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Aims: Survival of Erwinia amylovora, causal agent of fire blight in pome fruits and other rosaceous plants, was monitored inside mature apples calyces under some storage conditions utilized in fruit. Methods and Results: Apple fruit calyces inoculated with two E. amylovora strains and their respective GFP‐marked strains were maintained at 26° and 5°C, and the effect of copper treatment was assayed at 0·01 and 0·1 mmol l−1 CuSO4. In nontreated apples at 26°C, part of the population of E. amylovora survived in the ‘viable but nonculturable’ (VBNC) state, whereas at 5°C the majority of the population retained culturability. In copper‐treated apples, the whole population adopted the VBNC state irrespective of temperature. Regardless of temperature, copper and inoculum dose, VBNC cells recovered culturability and pathogenicity in King’s B broth or by host plant passage. Conclusions: Erwinia amylovora survived for at least 35 days in mature apple calyces. Besides, the ability of the pathogen in the VBNC state to regain culturability and pathogenicity suggests that the apple fruit could be a potential carrier of E. amylovora contributing to the spreading of fire blight disease. Significance and Impact of the Study: The risk of E. amylovora dissemination through mature fruit transport, although low, has been demonstrated, and should be considered in pest risk assessments.

ACS Style

M. Ordax; E.G. Biosca; S.C. Wimalajeewa; M.M. Lopez; E. Marco‐Noales. Survival ofErwinia amylovorain mature apple fruit calyces through the viable but nonculturable (VBNC) state. Journal of Applied Microbiology 2009, 107, 106 -116.

AMA Style

M. Ordax, E.G. Biosca, S.C. Wimalajeewa, M.M. Lopez, E. Marco‐Noales. Survival ofErwinia amylovorain mature apple fruit calyces through the viable but nonculturable (VBNC) state. Journal of Applied Microbiology. 2009; 107 (1):106-116.

Chicago/Turabian Style

M. Ordax; E.G. Biosca; S.C. Wimalajeewa; M.M. Lopez; E. Marco‐Noales. 2009. "Survival ofErwinia amylovorain mature apple fruit calyces through the viable but nonculturable (VBNC) state." Journal of Applied Microbiology 107, no. 1: 106-116.

Conference paper
Published: 26 January 2009 in Current Research Topics in Applied Microbiology and Microbial Biotechnology
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Copper is an essential micronutrient that at relatively high concentrations can increase bacterial growth on rich-nutrient media. In some bacteria copper also increases the exopolysaccharide production, like in Erwinia amylovora, causal agent of fire blight, a very serious and widespread disease of pome fruits and ornamental plants. The isolation and further identification of E. amylovora is the conclusive test for its presence in a vegetal sample. However, bacterial growth on solid media can be hampered by several factors. In oreder to optimize the recovery process we have modified a common nonselective medium, the King's B (KB), by adding copper. In the copper-modified KB medium, E. amylovora colonies were early and easily differentiated by a yellow colour and high mucoid. The new medium was tested in vitro and in vivo, showing a recovery efficiency of E. amylovora higher than on the other media routinely employed, and resulting a useful tool to isolate this pathogen from the plant material.

ACS Style

M. Ordax; E. G. Biosca; M. M. López; E. Marco-Noales; Antonio Mendez-Vilas. The addition of copper sulphate to a non-selective medium improves the recovery of plant associated bacteria: Erwinia amylovora as a model. Current Research Topics in Applied Microbiology and Microbial Biotechnology 2009, 92 -96.

AMA Style

M. Ordax, E. G. Biosca, M. M. López, E. Marco-Noales, Antonio Mendez-Vilas. The addition of copper sulphate to a non-selective medium improves the recovery of plant associated bacteria: Erwinia amylovora as a model. Current Research Topics in Applied Microbiology and Microbial Biotechnology. 2009; ():92-96.

Chicago/Turabian Style

M. Ordax; E. G. Biosca; M. M. López; E. Marco-Noales; Antonio Mendez-Vilas. 2009. "The addition of copper sulphate to a non-selective medium improves the recovery of plant associated bacteria: Erwinia amylovora as a model." Current Research Topics in Applied Microbiology and Microbial Biotechnology , no. : 92-96.

Conference paper
Published: 26 January 2009 in Current Research Topics in Applied Microbiology and Microbial Biotechnology
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Ralstonia solanacearum biovar (bv) 2 causes bacterial wilt and potato brown rot in solanaceous plants in temperate areas. The pathogen is able to persist in the environment, where it is frequently disseminated by watercourses. In these habitats, the effect of long-term oligotrophy on its survival remains to be ascertained. On that purpose river water microcosms were inoculated with R. solanacearum bv 2, incubated at 24°C and monitored for total, viable and culturable bacterial cell numbers up to four years. Within the first year, R. solanacearum bv 2 populations remained roughly constant in the initial levels. Then and until the fourth year, total counts slowly increased, while viability slightly declined and culturability decreased to a greater extent, pointing out a proportion of the bacterial populations entering the viable but non-culturable state. As cells in this state are not detected by cultivation-based methods, they represent a new challenge in designing strategies for control of the bacterial wilt disease.

ACS Style

Belén Álvarez; M. M. López; E. G. Biosca; Antonio Mendez-Vilas. Extended nutrient limitation influences Ralstonia solanacearum survival in natural water microcosms. Current Research Topics in Applied Microbiology and Microbial Biotechnology 2009, 38 -41.

AMA Style

Belén Álvarez, M. M. López, E. G. Biosca, Antonio Mendez-Vilas. Extended nutrient limitation influences Ralstonia solanacearum survival in natural water microcosms. Current Research Topics in Applied Microbiology and Microbial Biotechnology. 2009; ():38-41.

Chicago/Turabian Style

Belén Álvarez; M. M. López; E. G. Biosca; Antonio Mendez-Vilas. 2009. "Extended nutrient limitation influences Ralstonia solanacearum survival in natural water microcosms." Current Research Topics in Applied Microbiology and Microbial Biotechnology , no. : 38-41.