Potential of Crude Extract of Streptomyces sp. nov., Strain TRM76147 for Control of A. gaisen

Abstract

Pear black spot, caused by A. gaisen during fruit growth, is a disease that significantly reduces pear yield. Biological control using antagonistic microorganisms is regarded as a viable alternative to chemical agents. The discovery of TRM76147, a novel species of Streptomyces isolated from the Taklamakan Desert, has demonstrated promising potential in addressing this issue. This study was conducted to determine the potential of crude extract of Streptomyces sp. nov., strain TRM76147, for control of A. gaisen. TRM76147 is closely related to Streptomyces griseoviridis NBRC 12874T, exhibiting an average nucleotide identity (ANI) value of 82.13%. Combined with the polyphasic taxonomic identification, this suggests that TRM76147 is a potentially new species. Through analyses using BigSCAPE and antiSMASH, it was determined that the TRM76147 genome contains 19 gene clusters. The ethyl acetate extract of this strain demonstrates antifungal activity, with the active substance remaining stable at temperatures up to 70 °C, achieving an activity level of 16.23 ± 0.22 mm. Furthermore, the crude extract maintains its antifungal efficacy across a pH range of 2 to 12. Notably, the antifungal diameter was recorded at 16.53 ± 0.12 mm following 80 min of UV irradiation. Under different treatment conditions, TRM76147 fermentation crude extract caused A. gaisen spore crumpling and spore number reduction. In addition, this study also found that the TRM76147 fermentation broth could control the production of pear black spot disease, which initially revealed the inhibition mechanism. The abundant actinomycete resources in this study have good application and development value in the discovery of new species and the study of bioactive substances and biological control.