Abstract: A Streptomyces sp. LS1-128 (closely related to S. sindenensis) isolated from the sediments of Loktak Lake, the largest freshwater lake in Eastern India, shows broad spectrum antimicrobial activity with significant inhibition zones against B. pumilus MTCC 1607 (25 mm), E. coli MTCC 739 (20 mm), B. sphaericus MTCC 2303 (19 mm), B. subtilis MTCC 121 (14 mm) and C. albicans MTCC 227 (11 mm). LS1-128 is an aerobic, gram-positive actinomycete with off-white to brown substrate mycelium with no diffusible pigment. Spores are arranged in rectiflexible chains in the aerial mycelium. It grows well in ISP2, ISP3, ISP4, ISP5, ISP6, ISP7, Streptomyces Agar and Actinomycete Isolation Agar. It can degrade starch, casein and urea and has good growth on almost all carbon sources tested including L-Arabinose, D-Fructose, D-Galactose, D-Glucose, D-Mannitol, D-Rhamnose, Salicin and D-Xylose. Based on the phenotypic and genotypic characteristics, LS1-128 was found to be most closely related to Streptomyces sindenensis (99.927% homology). The other close relatives are S. parvus, S. badius and S. globisporus). LS1-128 with promising antimicrobial activities obtained from Loktak Lake sediment has been putatively designated as Streptomyces sindenensis strain LS1-128.