Heterologous Expression and Characterization of Two Novel Glucanases Derived from Sheep Rumen Microbiota

• Published in: World Journal Of Microbiology And Biotechnology
• Main Authors: De-ying, Gao, Xiao-bao, Sun, Fang, Ying, He, Bo, Jun-hong, Wang, Liu, Jian-xin, Jia-kun, Wang, Wang, Qian
• Format: Web Resource
• Language: English
• Published: Durham Research Square 31.01.2022
• Subjects: Microbiota; Sheep
• DOI: 10.21203/rs.3.rs-1278060/v1

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 Vmax 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 β-glucan 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 findings 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.