Abstract
A novel endo-β-1,4-mannanase gene was cloned from a novel actinomycetes, Nonomuraea jabiensis ID06-379, isolated from soil, overexpressed as an extracellular protein (47.8 kDa) in Streptomyces lividans 1326. This new endo-1,4-β-mannanase gene (manNj6-379) is encoded by 445-amino acids. The ManNj6-379 consists of a 28-residue signal peptide and a carbohydrate-binding module of family 2 belonging to the glycoside hydrolase (GH) family 5, with 59–77% identity to GH5 mannan endo-1,4-β-mannanase. The recombinant ManNj6-379 displayed an optimal pH of 6.5 with pH stability ranging between 5.5 and 7.0 and was stable for 120 min at 50 °C and lower temperatures. The optimal temperature for activity was 70 °C. An enzymatic hydrolysis assay revealed that ManNj6-379 could hydrolyze commercial β-mannan and biomass containing mannan.
Highlights
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This paper described the cloning and sequence analysis of the gene encoding ManNj6379, an endo-1,4 β-mannanase secreted by the N. jabiensis ID06-379 strain isolated from soil
E. coli was grown in Luria Bertani (LB) medium at 37 ◦C for 18–24 h, and S. lividans 1326 recombinant was grown in Trypticase Soy Broth (TSB) medium supplemented with 1% (w/v) tryptone, 3% (w/v) glucose and 5 μg/mL of thiostrepton at 28 ◦C for 72 h with shaking at 180 rpm
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Introduction β-mannanase is the common name for mannan endo-1,4-β-mannosidase, endo-1,4-βmannanase, or 1,4-β-D-mannan mannanohydrolase (E.C. 3.2.1.78) This enzyme catalyzes the random hydrolysis of β-1,4-mannosidic linkages in the main chain of β-mannans and hetero-mannan, which consists of a β-(1-4)-linked backbone of glucose (Glc) and mannose (Man) units [1], and is valuable in various biotechnological applications, those related to renewable resource utilization. Β-mannanases have drawn much interest in degrading mannan-containing polysaccharides because of their important roles. Various applications in the feed, food, pulp/paper, and detergent industries have been reported [2]. The mannan-degrading enzyme system occurs in many bacteria and fungi species. Mannan hydrolysis is carried out by free-living soil microorganisms that include several types of thermophilic bacteria, fungi, and actinomycetes in numerous species of the genus Streptomyces [15]. Endo 1,4-β-mannanases have been isolated from plants, fungi, and bacteria, and many other genes encoding the enzymes have been cloned and sequenced, there have been no reports of β-mannanases derived from Nonomuraea sp
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