Streptomyces violaceusniger as Bioactive Agent against Wood Rotting Fungi

Abstract

Wood protection by impregnation with synthetic chemicals in wood and timber newlineindustries is often harmful to the human health and environment at large. Excessive newlineuse of chemical fungicides has led to deteriorating human health, environmental newlinepollution, adverse effects on beneficial microflora of ecological importance and newlinedevelopment of pathogen resistance to fungicides. However, the ever-increasing newlinepublic concern and the new environmental regulations on the use of chemicals have newlinecreated a need for the development and use of alternative methods for wood newlineprotection. Biological wood protection by antagonistic microbes alone or in newlinecombination with biochemicals, is one of the most promising ways for the newlineenvironmentally sound wood protection. newlineThe present study reveals the antifungal potential of Streptomyces newlineviolaceusniger MTCC 3959 and its extracellular metabolites, making it an attractive newlinecandidate for biocontrol studies on a wide range of wood-rotting fungi. In vitro newlineantagonism of cell-free culture filtrate (CCF) indicated that extracellular, antifungal newlinemetabolites secreted by S. violaceusniger MTCC 3959 are heat-sensitive proteins that newlinecontribute to the growth inhibition of tested fungi. Strong chitinolytic, glucanolytic newlineand proteolytic ability of S. violaceusniger MTCC 3959 and its thermostable and pHtolerant newlinemycolytic enzymes can be applied in the field for biocontrol of wood-rotting newlinefungi. newlineAs the filamentous fungal cell-wall contains chitin, glucans and proteins, it is newlineexpected that chitinases, and#946;-1,3-glucanases, and proteases would hydrolyze these newlinecomponents and play a significant role in cell-wall lysis of the pathogen. An newlineextracellular chitinase, produced by antagonistic S. violaceusniger MTCC 3959, was newlinepurified to homogeneity, with an estimated molecular weight of 56.5 kDa. The newlinepurified chitinase showed high temperature optima and thermal stability in newlinecombination with wide range of pH tolerance (pH 3.0-10.0), which could be useful in newlinebio-degradation of chitinous waste.