Biological characteristics and antibacterial activity against gram-positive bacteria of Microbacterium sp. C21 isolated from soil

Most commercial antibiotics are derived from Streptomyces. The search for new potential microbial sources (non-Streptomyces) antibacterial activity is proposed to prevent drug resistance by current pathogenic microbes. Strain C21 was isolated soil, with small colonies (0.8-1.2 mm in size) on an intensive soil extract medium (ISEM). Sequence analysis of the 16S rRNA gene revealed strain belongs group bacteria that difficult cultivate, and considered a candidate novel species genus Microbacterium. Except R2A medium, only able grow nutrient-poor media such as NB/3, TSB/10, R4/10. N-acetylglucosamine, maltose, D-glucose, L-proline, L-rhamnose, inositol, sodium acetate 3-hydroxybutyric acid were suitable carbon growth C21. Crude fermentation liquid can inhibit Enterococcus faecalis CCARM 5168 at concentration 16 μg/ml, 8 μg/ml E. 5171, 32 5024, 64 faeciumCCARM 5025, Streptococcus agalactiaeCCARM 4504, S. pyogenes 4520. Results this study established basis future studies finding compounds difficult-to-culture bacteria.