A thermostable β-mannanase from Paenibacillus thiaminolyticus: purification, characterization and its application

Mannans and heteromannans are ubiquitous in nature as part of the hemicellulose fraction in hardwoods and softwoods. Endo-1, 4- β- D-mannanase (EC 3.2.1.78) is a hydrolytic enzyme which catalyzes the random cleavage of β-1, 4- D-manno-pyranosyl linkages within heteromannans and releases linear or branched  oligosaccharides of various lengths. A thermotolerant bacterium Paenibacillus thiaminolyticus with an ability to produce extracellular β-mannanase was isolated from soil sample, produced significant levels of endo-mannanase when grown on agro-wastes viz. oat bran and wheat bran. Enzyme was purified to homogeneity with specific activity of 8812 U mg⁻¹ protein. The purified β-mannanase was an extracellular monomeric protein with a molecular mass of 38 kDa on SDS–PAGE. A band of clearance was observed on zymogram. The optimal temperature and pH for enzyme were 60°C and 6.0 respectively. It was completely stable at 55°C for 24 h and retained 50 % activity at 60°C up to 3 h. The β-mannanase was highly stable between pH 5.0-8.0. The enzyme remained stable after 1 h of pre-incubation with most of the tested organic solvents. The enzyme demonstrated high specific activity towards glucomannan and galactomannan.  These unique properties make this enzyme attractive for biotechnological applications. The compatibility of β-mannanase with various detergent additives along with wash performance test confirmed its potential applicability for detergent industry.