First report of a tropical Lysobacter enzymogenes producing bifunctional endoglucanase activity towards carboxymethylcellulose and chitosan

Abstract

In the past, Lysobacter spp. were found only in temperate and sub-tropical zones. In order to assess the existence of Lysobacter spp. in tropical environments, samples were collected from grass-covered soil in Thailand. Among several bacteria obtained, isolate 521 (NCCB 100553) was identified as Lysobacter enzymogenes based on morphology and physiological tests along with 16S rRNA gene sequence analysis. Phenotypic characteristic variations of L. enzymogenes 521 with respect to the most studied strain from temperate regions, L. enzymogenes C3, were observed. The growth rate, carboxymethylcellulase (CMCase) and chitosanase activity of L. enzymogenes 521 were clearly higher than those of L. enzymogenes C3. Nucleotide and predicted amino acid sequences of the endoglucanase derived were deduced from draft genome sequencing. Phylogenetic analysis of the endoglucanase gene and multiple alignment of the deduced amino acid sequence illustrated that the endoglucanase (Cel8A) from L. enzymogenes 521 displayed homology to family 8 glycoside hydrolases (GHF-8), and was found to be similar to the bifunctional endoglucanase (Cel8A) from Lysobacter sp. IB-9374. Bifunctional CMCase and chitosanase activities of a purified endoglucanase with a mass of 41 kDa from L. enzymogenes 521 were revealed by zymogram analysis. This is the first report on the phenotypical characteristics, the endoglucanase with bifunctional CMCase and chitosanase activities, and the endoglucanase gene, from L. enzymogenes from a tropical environment.