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

• Main Authors: Fang, Y. (Author), Gao, D.-Y (Author), He, B. (Author), Liu, J.-X (Author), Sun, X.-B (Author), Wang, J.-H (Author), Wang, J.-K (Author), Wang, Q. (Author)
• Format: Article
• Language: English
• Published: Springer Science and Business Media B.V. 2022
• Subjects: Acid-stable; Additives; Agriculture; amino acid sequence; Amino Acid Sequence; animal; Animals; beta glucan; beta-Glucans; enzyme specificity; Feed additives; Genes; Glucanase; Glucans; glycosidase; Glycoside Hydrolases; Heterologous expression; Hydrolases; Hydrolysis; Icelandics; metabolism; Microbiota; Microbiotas; microflora; Plants (botany); recombinant protein; Recombinant Proteins; rumen; Rumen; Rumen microbe; sheep; Sheep; Substrate hydrolysis; Substrate Specificity; Sugars; β-glucanase
• Online Access: View Fulltext in Publisher

 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 Icelandic moss lichenan and konjac gum, IDSGLUC5-26 releasing cellobiose (G2; occupying 17.37% of total reducing sugars), cellotriose (G3; 23.97%), and cellotetraose (G4; 30.93%) from barley β-glucan and Icelandic moss 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 barley β-glucan or Icelandic moss 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-stable IDSGLUC5-26, will be of interest for potential application in food-/feed-additive development. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.