Heterologous expression and characterization of two novel glucanases derived from sheep rumen microbiota

Abstract

β-Glucanases are a suite of glycoside hydrolases that depolymerize β-glucan into cellooligosaccharides and/or monosaccharides and have been widely used as feed additives in livestock. In this study, two novel glucanase genes, IDSGluc5-26 and IDSGluc5-37, derived from sheep rumen microbiota, were expressed and functionally characterized. The optimal temperatures/pH of recombinant IDSGLUC5-26 and IDSGLUC5-37 were 50°C/5.0 and 40°C/6.0, respectively. Notably, IDSGLUC5-26 showed considerable stability under acidic conditions. Both IDSGLUC5-26 and IDSGLUC5-37 showed the highest activities toward barley β-glucan, with V max values of 89.96 ± 9.19 µmol/min/mg and 459.50 ± 25.02 µmol/min/mg, respectively. Additionally, these two glucanases demonstrated hydrolysis of barley βglucan and Icelandic moss lichenan, IDSGLUC5-26 releasing cellobiose (G2; occupying 17.37% of total reducing sugars), cellotriose (G3; 23.97%), and cellotetraose (G4; 30.93%) from β-glucan and lichenan after 10 min and suggestive of a typical endo-β-1,4-glucanase (EC.3.2.1.4). In contrast, IDSGLUC5-37 was capable of liberating dominant G3 (64.11% or 67.55%) from β-glucan or lichenan, suggesting that the enzyme was likely an endo-β-1,3-1,4-glucanases/lichenase (EC3.2.1.73). These ndings describe the expression and characterization of two novel glucanase genes from sheep rumen microbiota. The two recombinant enzymes, particularly the acid-adapted IDSGLUC5-26, will be of interest for potential application in food-/feed-additive development.

Heterologous expression and characterization of an endoglucanase from Lactobacillus plantarum dy-1

“…Glucanases are a group of glycoside hydrolases that depolymerize β-glucan into cello-oligosaccharides and monosaccharides. 7 Consequently, we hypothesized that the structural and functional changes of glucan may be caused by β-glucan hydrolysis in barley by KN812-14265 secreted during fermentation.…”

“…Glucanases are a group of glycoside hydrolases that depolymerize β-glucan into cello-oligosaccharides and monosaccharides. 7 Consequently, we hypothesized that the structural and functional changes of glucan may be caused by β-glucan hydrolysis in barley by KN812-14265 secreted during fermentation. In this study, we conducted a heterologous expression of an endoglucanase gene called Lpeg14265 in E. coli that we previously identified in L. plantarum dy-1.…”