Monday, June 17, 2013

Mycolytic enzymes produced by Streptomyces violaceusniger and their role in antagonism of wood-rotting fungi

Anand Nagpure, Bharti and Rajinder K. Gupta. 2013
Journal of Basic Microbiology. DOI 10.1002/jobm.201200474

An extracellular mycolytic enzyme cocktail produced by antagonist Streptomyces violaceusniger MTCC 3959 under submerged fermentation was characterized. The strain MTCC 3959 produced higher amounts of extracellular chitinase and protease during late exponential phase whereas β-1,3-glucanase production was at peak in mid stationary phase. Cell-free culture filtrate exhibited a broad range of antifungal activity against both white and brown rot fungi. The inhibitory activity was completely lost after the treatment with proteinase K and temperature, indicating that extracellular antifungal metabolites are heat labile and proteinaceous in nature. Optimum pH and temperature for chitinase was 9.0 and 60°C, for β-1,3-glucanase 6.0 and 60°C and for protease 9.0 and 70°C. Mycolytic enzymes were moderately thermostable with a wide pH stability range from pH 5.0 to 10.0. The zymogram analysis of cell-free culture filtrate revealed five chitinase and four protease isoenzymes with approximate molecular weight of 20.8-114.8 and 22.8-120.5 kDa, respectively whereas β-1,3-glucanase appeared as a single band of 131.8 kDa. S. violaceusniger MTCC 3959 produced mycolytic enzyme cocktail that can be effectively used for suppression of phytopathogenic basidiomycetes and can also evolve as a potential biofungicide.