Genome Mining Revealed a High Biosynthetic Potential for Antifungal Streptomyces sp. S-2 Isolated from Black Soot

The increasing resistance of fungal pathogens has heightened the necessity of searching for new organisms and compounds to combat their spread. Streptomyces are bacteria that are well-known for the production of many antibiotics. To find novel antibiotic agents, researchers have turned to previously neglected and extreme environments. Here, we isolated a new strain, Streptomyces sp. S-2, for the first time, from black soot after hard coal combustion (collected from an in-use household chimney). We examined its antifungal properties against plant pathogens and against fungi that potentially pose threat to human health (Fusarium avenaceum, Aspergillus niger and the environmental isolates Trichoderma citrinoviridae Cin-9, Nigrospora oryzae sp. roseF7, and Curvularia coatesieae sp. junF9). Furthermore, we obtained the genome sequence of S-2 and examined its potential for secondary metabolites production using anti-SMASH software. The S-2 strain shows activity against all of the tested fungi. Genome mining elucidated a vast number of biosynthetic gene clusters (55), which distinguish this strain from closely related strains. The majority of the predicted clusters were assigned to non-ribosomal peptide synthetases or type 1 polyketide synthetases, groups known to produce compounds with antimicrobial activity. A high number of the gene clusters showed no, or low similarity to those in the database, raising the possibility that S-2 could be a producer of novel antibiotics. Future studies on Streptomyces sp. S-2 will elucidate its full biotechnological potential.