Isolation and Characterization of Two Streptomyces Spp. from Saw Dust for Their Cellulase Production and Cellulolytic Activity

Abstract

Two highly cellulolytic actinomycetes, namely SD1 and SD2, were locally isolated from saw dust and provisionally identified as Streptomyces cirratus (SD1) and Streptomyces cellulosae (SD2) respectively. These isolates were capable of producing cellulolytic enzymes during growth on different cellulosic substrates. They were grown under different conditions and showed that carboxymethyl cellulose (CMC) was the best cellulosic substrate for inducing the synthesis of extracellular cellulolytic enzymes. In addition, both the isolates showed goodgrowth at different pHs, temperature, period, carbon and nitrogen sources when grown in liquid Winstead's media having 1.2% CMC as cellulosic substrate. However, the optimum growth was at pH 6.5-8.5, temperature 30-40°C and 8-14 days of incubation period using CMC as carbon source. The cellulose hydrolysis by both the isolates was also optimum under these conditions with the maximum level of reducing sugar produced due to carboxymethyl cellulase (CMCase) activity of SD1 and SD2 391.76 U/mL and 328.09 U/mL, respectively. The effects of various metal ions (Na⁺, K⁺, Ca⁺, Mg⁺, Ag⁺, Hg²⁺, Mn ²⁺, Li⁺ andFe³⁺) on the two cellulases were also investigated and some metal ions were found to inhibitcellulase reversibly. 

The Chittagong Univ. J. B. Sci. 9(1&2):01-18,2019