Biochemical characterization of a novel bifunctional chitosanase from Paenibacillus barengoltzii for chitooligosaccharide production

A novel chitosanase gene, designated as PbCsn8, was cloned from Paenibacillus barengoltzii. It shared the highest identity of 73% with the glycoside hydrolase (GH) family 8 chitosanase from Bacillus thuringiensis JAM-GG01. The gene was heterologously expressed in Bacillus subtilis as an extracellular protein, and the highest chitosanase yield of 1, 108 U/mL was obtained by high-cell density fermentation in a 5-L fermentor. The recombinant chitosanase (PbCsn8) was purified to homogeneity and biochemically characterized. PbCsn8 was most active at pH 5.5 and 70 degrees C, respectively. It was stable in a wide pH range of 5.0-11.0 and up to 55 degrees C. PbCsn8 was a bifunctional enzyme, exhibiting both chitosanase and glucanase activities, with the highest specificity towards chitosan (360 U/mg), followed by barley beta-glucan (72 U/mg) and lichenan (13 U/mg). It hydrolyzed chitosan to release mainly chitooligosaccharides (COSs) with degree of polymerization (DP) 2-3, while hydrolyzed barley beta-glucan to yield mainly glucooligosaccharides with DP > 5. PbCsn8 was further applied in COS production, and the highest COS yield of 79.3% (w/w) was obtained. This is the first report on a GH family 8 chitosanase from P. barengoltzii. The high yield and remarkable hydrolysis properties may make PbCsn8 a good candidate in industrial application.

Automated summary

A novel chitosanase gene, PbCsn8, was cloned and expressed in Bacillus subtilis with the highest activity at 70 degrees Celsius and pH 5.5. It showed specificity towards chitosan and glucan, making it a potential candidate for industrial applications. High yield and remarkable hydrolysis properties suggest PbCsn8 could be valuable in industrial settings.