Biocontrol efficiency and potential mechanism of streptomyces distatochromogenes XT34 against postharvest anthracnose caused by colletotrichum musae on banana fruit

Banana anthracnose caused by Colletotrichum musae is a serious postharvest disease. Use of fungicides has potential adverse effects on the environment safety and human health. Application of biological control agents (BCA) is a promising strategy for managing postharvest fruit diseases. In this study, Streptomyces sp. XT34 was isolated from the banana rhizosphere soil and exhibited a strong antifungal activity against C. musae. Combining the phenotypic and whole-genomic alignment, strain XT34 was identified as Streptomyces diastatochromogenes. Strain XT34 extracts reduced the disease incidence of anthracnose and maintained the fruit quality of banana. Treatment of extracts reduced the colonization of C. musae on fruit surface. The activity inhibition of cell wall-degrading enzymes maintained the cell-wall strength of fruit. The activity increase of defense enzymes contributed to the low disease symptom. It was supported by the differentially expressed genes (DEGs) related to supramolecular fiber organization and flavonoid biosynthesis. In addition, spore germination of C. musae was effectively inhibited by extracts. The morphology of mycelia and spore become wrinkled and ruptured. The treatment of extracts increased the optical density of A260 and soluble sugar and protein contents of C. musae. The integrity of cell membrane was also destroyed, reflecting on an increase in electrical conductivity and malondialdehyde. Several metabolites were found in the genome of strain XT34 using antiSMASH. Eleven volatile compounds were identified by gas chromatography-mass spectrometer (GC-MS). Notably, strain XT34 and extracts exhibited a broad-spectrum antifungal activity against eight phytopathogenic fungi. Hence, S. diastatochromogenes XT34 provides a potential BCA to control banana anthracnose. •Streptomyces XT34 exhibits strong antifungal activity against banana anthracnose.•Strain XT34 inhibits fruit decay and maintained quality in postharvest banana.•Strain XT34 extracts maintain cell-wall strength of fruit.•Extracts induce the biosynthesis of supramolecular fiber organization and flavonoid.•Strain XT34 extract inhibit pathogenic spore germination and caused cell rupture.