Screening, isolation, taxonomy and fermentation of an antibiotic producer Streptomyces xinghaiensis from soil capable of acting against linezolid resistant strains.

Linezolid resistant cultures are emerging in hospitals. In the present study 3 soil actinomycetes were isolated in a screening programme having potential to produce antibiotic against linezolid resistant cases. One culture was coded as RK-46 and further studied. The micromorphology, biochemical tests and 16S ribosomal DNA gene sequence analysis were conducted to know the identity of the culture and was found as a strain of Streptomyces xinghaiensis. The culture produced antibiotic active against five clinical resistant strains. The antibiotic production was tested by cultivating in eleven different media. The fermentation profile was studied in YEME medium supplemented with calcium carbonate. The maximum activity was noticed at 72 h. Antibiotic activity was extracted into ethyl acetate and was subjected to activity guided purification by column chromatography, TLC and HPLC methods. The pure compound was eluted with retention time of 6.8 min and subjected to 1H, 13C NMR and Mass spectral analysis. The acquired data was compared with that in natural products data base, and was found to be a known antibiotic, reductiomycin. The purified compound showed activity against 5 linezolid resistant cultures and on Mycobacterium tuberculosis. This compound is also showing mild anti cancer activity and is biologically permeable as per Lipinksi's rule.