Isolation, Screening and Identification of Mannanase Producing Microorganisms

Abstract

Mannan is used in many industries and known to be the major polysaccharides of legume seeds, coconut kernel and tubers of konjac. Several bacteria and fungi have been reported to produce mannanase. In this paper, 19 bacteria and 4 fungi showing mannanase production were isolated from twenty-three soil samples. Isolate NT 6.7 showed high mannanase activity (0.306 unit/ml), displayed broad inhibition to pathogens; Salmonella serovar Enteritidis S003 and Escherichia coli E010, and could promote growth of probiotic Lactobacillus reuteriAC5. The strain was identified by morphological, physiological, biochemical (API 50 CHB, 99.5%identity) and 16 S rDNA sequence (99%identity) tests as Bacillus circulans. The mannanase activity from this strain had optimum pH of 7.0-9.0, optimum temperature at 50 ^oC and high stability at 50 ^oC. The results suggested mannanase produced from B. circulans NT 6.7 had interesting properties and could be applied in prebiotic preparation.