Molecular cloning of a gene coding for thermostable beta‐glucanase from Bacillus macerans

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Abstract
The bg/M gene DNA coding for a thermostable beta‐1.3,1.4‐glucanase of Bacillus macerans E138 was isolated by direct shot‐gun cloning into Escherichia coli using plasmid pBR322 as a vector. By deletion analysis the bg/M coding region was located within a 1.0 kb region of the cloned Bacillus DNA fragment. In E. coli, plasmid pBGLM12/2 containing the B. macerans bg/M gene gave rise to a beta‐glucanase expression 40 times higher than that of the B. macerans gene donor. The molecular weight of beta‐glucanase, isolated either from E. coli cells or from the culture filtrate of B. macerans, was in the range of 24 kD. The enzymes purified from E. coli or from the culture filtrate of B. macerans, had a halflife of about 40 min at 65 °C. This indicated an increased temperature stability of the B. macerans enzyme in comparison to other Bacillus‐beta‐glucanases.