Isolation, identification and evaluation of the Actinobacteria derived from wheat farms to perform biological control of fungal diseases

Nowadays pesticides are extensively used to protect food security worldwide. Due to their undesirable effects, they are considered as important environmental pollutants. Methods for pest biological control are enumerated as an alternative for chemical pesticide. This study was performed to isolate and identify the antifungal-compound-producing Actinobacteria againstAspergillus nigerfungi (stored product pest)and Bipolaris sp.(responsible for root and crown rot disease) from wheat farms of Hajiabad region, Hormozgan province. Three farming sites were sampled in this study. Actinobacteria were isolated by soil extract agar and starch casein agar media. Antifungal activities were evaluated by well diffusion agar method. Potent isolates were identified through morphological, physiological, biochemical, and genetic analysis. Findings: Approximately a total number of 207 Actinobacteria isolates were isolated. From two isolation media, the soil extract agar yielded 125 isolates and exhibited more efficacy. Results of physical treatments showed that heat treatment could isolate 85 colonies and followed by desiccation and UV treatments by 57 and 46 colonies respectively. Evaluation of the antifungal activities of 100 morphologically distinct isolates revealed that only two isolates exhibited antifungal activity against Aspergillus niger and Bipolaris sp. Identification of potent isolates according to morphological, biochemical and physiological properties showed that these isolates belong to Streptomyces genus. Genetically, identification and phylogenetic analysis based on16srRNA gene revealed a high similarity between Streptomyces sp.MG-11and Streptomyces albus (similarity: 99%) and between Streptomyces sp.MG-21 and Streptomyces griseus (similarity: 99%). Discussion and Conclusions: Results of this study suggest that Streptomyces sp. MG-11 and Streptomyces sp.MG-21can be considered as appropriate candidates for biological control studies against the selected fungal diseases in wheat farms.