Screening of Thermotololant Bacteria for Cellulase, Xylanase, and Protease Production

With environmental concern, green and sustainable management of waste biomass, including lignocellulosic material (e.g., agricultural waste and plant residue) and by-products from the food industry (e.g., feather and residues from poultry industry), has gained considerable attention. This is because good removal practices can reduce carbon dioxide emissions and air pollution resulting from waste burning. Microbial and enzymatic degradation is an alternative to converting lignocellulose and feather-containing waste to other bioproducts with increased value. This study aims to isolate and identify potential bacteria that produce cellulase, xylanase, and protease. These enzymatic activities are essential for degrading carbohydrates or protein in the waste, typically present as a mixture. Out of 120 isolated bacteria collected from the hot spring in Krabi province, we found one potential isolate, strain 46-2, with good cellulase, xylanase, and protease production. The 16s rRNA gene analysis indicated that strain 46-2 belonged to Bacillus species, whose closest relatives are Bacillus paralicheniformis and B. licheniformis. When strain 46-2 was grown on an agar plate containing carboxymethyl cellulose (CMC), beechwood xylan (BWX), and casein, halo zones occurred around the colonies. This qualitative analysis indicated that strain 46-2 secreted extracellular enzymes, including endoglucanase, xylanase, and protease, to degrade CMC, BWX, and casein, respectively. In addition, the growth of strain 46-2 on chicken feathers was tested, as the feather has a complicated protein structure. The result showed that strain 46-2 grew well on the feather. Therefore, strain 46-2 shows promise as cellulase, xylanase, and protease producer with the potential to be applied in waste degradation.