Background: A wide variety of microorganisms, including bacteria, live in the rhizosphere zone of plants and have an impact on plant development both favorably and adversely. The beneficial outcome is due to the presence of rhizobacteria that promote plant growth (PGPR). Results: In this study, a bacterial strain was isolated from lupin rhizosphere and identified genetically as Serratia marcescens (OK482790). Several biochemically and genetically characteristics were confirmed in vitro and in vivo to determine the OK482790 strain ability to be PGPR. The in vitro results revealed production of different lytic enzymes (protease, lipase, cellulase, and catalase), antimicrobial compounds (hydrogen cyanide, and siderophores), ammonia, nitrite, and nitrate and its ability to reduce nitrate to nitrite. In silico and in vitro screening proposed possible denitrification-DNRA-nitrification pathway for OK482790 strain. The genome screening indicated the presence of nitrite and nitrate genes encoding Nar membrane bound sensor proteins (NarK, NarQ and NarX). Nitrate and nitrite reductase encoding genes (NarI, NarJ, NarH, NarG and NapC/NirT) and (NirB, NirC, and NirD) are also found in addition to nitroreductases (NTR) and several oxidoreductases. In vivo results on wheat seedlings confirmed that seedlings growth was significantly improved by soil inoculation of OK482790 strain. Conclusions: This study provides evidence for participation of S. marcescens OK482790 in nitrogen cycling via the denitrification-DNRA-nitrification pathway and for its ability to produce several enzymes and compounds that support the beneficial role of plant-microbe interactions to sustain plant growth and development for a safer environment.

Salvadora persica is an endangered medicinal plant due to difficulties in its traditional propagation. It is rich in bioactive compounds that possess many pharmaceutical, antimicrobial activities and widely used in folk medicine. The current study aims at in vitro propagation of Salvadora persica and the application of different nanoparticles (NPs) to induce the synthesis of bioactive and secondary metabolites within the plant. The cellular and genetic responses to the application of different NPs were evaluated. The impact of nanoparticles NPs (ZnO, SiO2, and Fe3O4) on callus growth of Salvadora persica and the production of its active constituent benzyl isothiocyanate was examined, regarding some oxidative stress markers, antioxidant enzymes, and genetic variabilities. An encouraging impact of 0.5 mg/l ZnO NPs on benzyl isothiocyanate production was shown reaching up to 0.905 mg/g callus fresh weight in comparison to 0.539 mg/g in control callus. This was associated with decreasing hydrogen peroxide content and increasing superoxide dismutase and peroxidase activities. The deposition of the NPs on cellular organelles was detected using a transmission microscope. Fifteen Inter-Simple Sequence Repeats (ISSR) primers detected an overall, 79.1% polymorphism among different treatments. A reduction in genomic DNA template stability (GTS) was made and was more pronounced in higher doses of different NPs. This study is a stepping stone in developing a productive protocol for in vitro production of benzyl isothiocyanate from Salvadora persica using NPs as a valuable anticancer compound.

COVID-19 is a pandemic disease caused by the SARS-CoV-2, which continues to cause global health and economic problems since emerging in China in late 2019. Until now, there are no standard antiviral treatments. Thus, several strategies were adopted to minimize virus transmission, such as social distancing, face covering protection and hand hygiene. Rhamnolipids are glycolipids produced formally by Pseudomonas aeruginosa and as biosurfactants, they were shown to have broad antimicrobial activity. In this study, we investigated the antimicrobial activity of rhamnolipids against selected multidrug resistant bacteria and SARS-CoV-2. Rhamnolipids were produced by growing Pseudomonas aeruginosa strain LeS3 in a new medium formulated from chicken carcass soup. The isolated rhamnolipids were characterized for their molecular composition, formulated into nano-micelles, and the antibacterial activity of the nano-micelles was demonstrated in vitro against both Gram-negative and Gram-positive drug resistant bacteria. In silico studies docking rhamnolipids to structural and non-structural proteins of SARS-CoV-2 was also performed. We demonstrated the efficient and specific interaction of rhamnolipids with the active sites of these proteins. Additionally, the computational studies suggested that rhamnolipids have membrane permeability activity. Thus, the obtained results indicate that SARS-CoV-2 could be another target of rhamnolipids and could find utility in the fight against COVID-19, a future perspective to be considered.

Background: Drought stress is a catastrophic abiotic stressor that impedes the worldwide output of commodities and the development of plants. The Utilizing biological antioxidant stimulators, Arbuscular mycorrhizal fungi (AMF) are one example increased the plants' ability to withstand the effects of drought. The symbiotic response of soybean (Glycine max L.) to AMF inoculation was assessed in the experiment presented herewith at different watering regimes (field capacity of 25, 50, and 90%). The vegetative, physio-biochemical traits, and regulation of genes involved in polyamine synthesis in G. max plants were evaluated. Results: The results obtained suggested that AMF inoculation has an advantage over plants that were non-inoculated in terms of their growth and all assessed criteria, which responded to drought stress by showing slower development. It is evident that the gas exchange parameters of the soybean plant were substantially reduced by 36.79 (photosynthetic rate; A), 60.59 (transpiration rate; E), and 53.50% (stomatal conductance gs), respectively, under severe stress of drought in comparison to control; non-stressed treatment. However, the AMF inoculation resulted in a 40.87, 29.89, and 33.65% increase in A, E, and gs levels, respectively, in extremely drought-stressful circumstances, when in contrast to non-AMF one that was grown under well-watered conditions. The drought level was inversely proportional to mycorrhizal colonization. The total antioxidant capacity, protein, and proline contents were all enhanced by AMF inoculation, while the malondialdehyde and hydrogen peroxide contents were decreased. Polyamine biosynthesis genes expression; Ornithine decarboxylase (ODC2), Spermidine synthase (SPDS) and Spermine synthase (SpS) were upregulated in drought and to even higher level in AMF’s mild drought inoculated plants’ shoots. This implies that AMF plays apart in the enhanced survival of soybean plants stressed by drought and reduced plant membranes damage by limiting the excessive production of oxidative stress generators; ROS. Conclusions: In summary, the present investigation demonstrates that inoculation of AMF may be a supportable and environmentally advantageous method for improving the physio-biochemical traits, plant growth, and polyamine biosynthesis genes of soybean plants in the incident of limited water availability.

Background: Enhancing crops’ drought resilience is necessary to maintain productivity levels. Plants interact synergistically with microorganisms like Beauveria bassiana to improve drought tolerance. Therefore, the current study investigates the effects of biopriming with B. bassiana on drought tolerance in Malva parviflora plants grown under regular irrigation (90% water holding capacity (WHC)), mild (60% WHC), and severe drought stress (30% WHC). Results: The results showed that drought stress reduced the growth and physiological attributes of M. parviflora. However, those bioprimed with B. bassiana showed higher drought tolerance and enhanced growth, physiological, and biochemical parameters: drought stress enriched malondialdehyde and H₂O₂ contents. Conversely, exposure to B. bassiana reduced stress markers and significantly increased proline and ascorbic acid content under severe drought stress; it enhanced gibberellic acid and reduced ethylene. Bioprimed M. parviflora, under drought conditions, improved antioxidant enzymatic activity and the plant’s nutritional status. Besides, ten Inter-Simple Sequence Repeat primers detected a 25% genetic variation between treatments. Genomic DNA template stability (GTS) decreased slightly and was more noticeable in response to drought stress; however, for drought-stressed plants, biopriming with B. bassiana retained the GTS. Conclusion: Under drought conditions, biopriming with B. bassiana enhanced Malva’s growth and nutritional value. This could attenuate photosynthetic alterations, up-regulate secondary metabolites, activate the antioxidant system, and maintain genome integrity.