Extracellular Cellulase-free Xylanase Production by Alkaliphilic Bacillus firmus K-1 in Fermentor Using Corn Hull as a Carbon Source

Abstract

In our previous work, we found that an extracellular cellulase-free xylanase produced by alkaliphilicBacillus firmus K-1 in 250 ml shake flasks with 20 ml working volume had a potential for using in pulpprebleaching process. In this work, to scale up the production of xylanase, the cultivation of Bacillus firmus K-1 using500 ml working volume in a liter commercial fermentor was optimized using 1.0% corn hull as a carbon sourceand 0.4% urea as a nitrogen source under non sterile condition. The results showed that the production ofxylanase was found to increase along with dissolved oxygen, the cell growth and protein content. The optimalconditions were at initial pH at 10.5 and temperature at 37 ÌC with agitation speed at 400 rpm and aeration rateat 1 vvm for 24 h. Xylanase production was in a yield of 0.96 U/ml of culture supernatant.

Keywords : alkaliphilic Bacillus firmus K-1 / cellulase-free xylanase / corn hull / fermentor