Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from hypersaline ecosystems and evaluate the abilities of antifungal bacteria to secrete extracellular hydrolytic enzymes, anti-Botrytis metabolites and volatiles. Methods and Results: Grey mould was reduced in strawberry fruits treated with halophilic antagonists and artificially inoculated with B. cinerea. Thirty strains (20·2%) were active against the pathogen and reduced the percentage of fruits infected after 3 days of storage at 20°C, from 50% to 91·66%. The antagonists were characterized by phenotypic tests and 16S rDNA sequencing. They were identified as belonging to one of the species: Virgibacillus marismortui, B. subtilis, B. pumilus, B. licheniformis, Terribacillus halophilus, Halomonas elongata, Planococcus rifietoensis, Staphylococcus equorum and Staphylococcus sp. The effective isolates were tested for antifungal secondary metabolites. Conclusions: Moderately halophilic bacteria may be useful in biological control against this pathogen during postharvest storage of strawberries. Significance and Impact of the study: The use of such bacteria may constitute an important alternative to synthetic fungicides. These moderate halophiles can be exploited in commercial production and application of the effective strains under storage and greenhouse conditions.

Overall, 180 yeasts and bacteria isolated from the peel of citrus fruits were screened for their in vitro antagonistic activity against Penicillium digitatum and P. italicum, causative agents of green and blue mold of citrus fruits, respectively. Two yeast and three bacterial isolates were selected for their inhibitory activity on mycelium growth. Based on the phylogenetic analysis of 16S rDNA and ITS rDNA sequences, the yeast isolates were identified as Candida oleophila and Debaryomyces hansenii while the bacterial isolates were identified as Bacillus amyloliquefaciens, B. pumilus and B. subtilis. All five selected isolates significantly reduced the incidence of decay incited by P. digitatum and P. italicum on ‘Valencia’ orange and ‘Eureka’ lemon fruits. Moreover, they were effective in preventing natural infections of green and blue mold of fruits stored at 4 °C. Treatments with antagonistic yeasts and bacteria did not negatively affect the quality and shelf life of fruits. The antagonistic efficacy of the five isolates depended on multiple modes of action, including the ability to form biofilms and produce antifungal lipopeptides, lytic enzymes and volatile compounds. The selected isolates are promising as biocontrol agents of postharvest green and blue molds of citrus fruits.

Introduction.Opuntia ficus indica L. inermis(OFI) is used in traditional medicine pharmacopeia for its richness in natural bioactive compounds. It has been proven to be effective in the improvement of the healing of laser-induced skin burns. The aim of the present study was to investigate the wound healing effect of OFI extracted oil on full-thickness skin wound.Materials and Methods. The OFI seeds were firstly isolated from mature prickly pears, washed, dried, and then cold-pressed. The antimicrobial activities of OFI seed oil were estimatedin vitroagainst bacteria, yeast, and fungi. Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) were calculated. Skin wound healing was investigated using an excisional wound healing model in rats. The skin wounds of three experimental groups of rats were topically treated once/day with saline solution (control group), 0.15 mg/mm²of a reference drug Esth’Elle Pharma Cicaplaie cream (reference group), and 0.6 μl/mm²of OFI seed oil (OFI oil group). The healing process was monitored daily and the percentage of wound contraction was calculated. A histological study was carried on skin biopsies.Results. The extracted oil has shown an interesting antimicrobial effect onEnterobacter cloacae, antiyeast effect againstCandida parapsilosisandCandida sake, and antifungal activity against three opportunistic cutaneous molds (Penicillium, Aspergillus, and Fusarium). Moreover, OFI oil has shown a good wound healing effect. It prevents cutaneous infections and reduces the reepithelialization phase.Conclusion. OFI extracted oil hasin vitroantimicrobial/fungal properties andin vivowound healing activity. It seems to be efficient in the treatment of cutaneous infections and the promoting of the scarring process.

Bacterial and archaeal aerobic communities were recovered from sediments from the shallow El-Djerid salt lake in Tunisia, and their salinity gradient distribution was established. Six samples for physicochemical and microbiological analyses were obtained from 6 saline sites in the lake for physico-chemical and microbiological analyses. All samples studied were considered hypersaline with NaCl concentration ranging from 150 to 260 g/L. A specific halophilic microbial community was recovered from each site, and characterization of isolated microorganisms was performed via both phenotypic and phylogenetic approaches. Only one extreme halophilic organism, domainArchaea, was isolated from site 4 only, whereas organisms in the domainBacteriawere recovered from the five remaining sampling sites that contained up to 250 g/L NaCl. Members of the domainBacteriabelonged to generaSalicola, Pontibacillus, Halomonas, Marinococcus, andHalobacillus, whereas the only member of domainArchaeaisolated belonged to the genusHalorubrum. The results of this study are discussed in terms of the ecological significance of these microorganisms in the breakdown of organic matter in Lake El-Djerid and their potential for industry applications.

Trichoderma strains were sampled in 4 different bioclimatic zones of Tunisia, a Mediterranean North African country with strong climatic and edaphic variability from north to south, to assess the genetic diversity of endemic species of Trichoderma and their relationship to the bioclimatic zones. In all, 53 strains were isolated and identified at the species level by analysis of their internal transcribed spacers regions 1 and 2 (ITS1 and ITS2) of the rDNA cluster and (or) a fragment of the translation elongation factor 1 (tef1) gene, using an online interactive key for species identification in Trichoderma and ex-type strains and taxonomically established isolates of Trichoderma as references. At least 2 different species were observed in each ecosystem. Trichoderma harzianum clade VI and Trichoderma longibrachiatum were present in forest soils in north Tunisia; Trichoderma atroviride and Trichoderma hamatum were found in cultivated fields in northeast Tunisia; T. harzianum clade VI, a Trichoderma sp. close to the T. harzianum complex, and Trichoderma saturnisporum were isolated from forest soils in central Tunisia; and T. harzianum clade II and T. hamatum were present in oasis soils in south Tunisia.