Expression and biochemical characterization of a novel thermostable alkaline β-1,3-1,4-glucanase (lichenase) from an alkaliphilic Bacillus lehensis G1.

New thermostable β-1,3-1,4-glucanase (lichenase) designated as Blg29 was expressed and purified from a locally isolated alkaliphilic bacteria Bacillus lehensis G1. The genome sequence of B. lehensis predicted an open reading frame of Blg29 with a deduced of 249 amino acids and a molecular weight of 28.99 kDa. The gene encoding for Blg29 was successfully amplified via PCR and subsequently expressed as a recombinant protein using the E. coli expression system. Recombinant Blg29 was produced as a soluble form and further purified via immobilized metal ion affinity chromatography (IMAC). Based on biochemical characterization, recombinant Blg29 showed optimal activity at pH9 and temperature 60 °C respectively. This enzyme was stable for more than 2 h, incubated at 50 °C, and could withstand ∼50 % of its activity at 70 °C for an hour and a half. No significant effect on Blg29 was observed when incubated with metal ions except for a small increase with ion Ca ²⁺ . Blg29 showed high substrate activity towards lichenan where V _m , K _m , K _cat, and k _cat /K _m values were 2040.82 μmolmin ^‾1 mg ^‾1 , 4.69 mg/mL, and 986.39 s‾ ¹ and 210.32 mLs ^‾1 mg‾ ¹ respectively. The high thermostability and activity make this enzyme useable for a broad prospect in industry applications.
Competing Interests: Declaration of competing interest The authors declare that they have no competing interests.
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