Partitioning and purification of extracellular beta-1,3-1,4-glucanase in aqueous two-phase systems

The partition behaviors of beta-1,3-1,4-glucanase, alpha-amylase and neutral proteases from clarified and whole fermentation broths of Bacillus subtilis ZJF-1A5 were investigated. An aqueous two-phase system (polyethylene glycol (PEG)/MgSO(4)) was examined with regard to the effects of PEG molecular weight (MW) and concentration, MgSO(4) concentration, pH and NaCl concentration on enzyme partition and extraction. The MW and concentration of PEG were found to have significant effects on enzyme partition and extraction with low MW PEG showing the greatest benefit in the partition and extraction of beta-glucanase with the PEG/MgSO(4) system. MgSO(4) concentration influenced the partition and extraction of beta-glucanase significantly. pH had little effect on beta-glucanase or proteases partition but affected alpha-amylase partition when pH was over 7.0. The addition of NaCl had little effect on the partition behavior of beta-glucanase but had very significant effects on the partitioning of alpha-amylase and on the neutral proteases. The partition behaviors of beta-glucanase, alpha-amylase and proteases in whole broth were also investigated and results were similar to those obtained with clarified fermentation broth. A two-step process for purifying beta-glucanase was developed, which achieved beta-glucanase recovery of 65.3% and specific activity of 14027 U/mg, 6.6 times improvement over the whole broth.