Improvement of cellulose degradation by cloning of endo-β-1, 3-1, 4 glucanase (bgls) gene from Bacillus subtilis BTN7A strain

The aim of this study is to construct a new recombinant strain able to degrade cellulose efficiently. The endo-β-1, 3-1, 4 glucanase (bgls) gene was cloned from Bacillus subtilis BTN7A strain by using PCR technique. The specific primers of bgls gene were deduced. Optimization of PCR mixture and program were identified. The nucleotide sequence of bgls was placed in the public domain (GenBank accession number KM009051.1). The obtained bgls DNA was cloned with pGEM®-T Easy Vector. The recombinant plasmid designated as Bgls-NRC-1 was transformed into E. coli DH5α. The successful cloning of the bgls gene was tested either by PCR or by evaluating its expression in its new bacterial host. The bgls gene was expressed efficiently in E. coli and the enzyme activity of the transformant was compared to the enzyme activity of the donor bacterial strain. The new constructs produce much higher enzyme yields than the donor bacterial strain, they produce about 29% and about 57% higher cellulase specific activity at 37 °C and 55 °C respectively. Optimization of cellulolytic activity of the new recombinant strain were described. The effect of minimal medium supplemented with CMC or cellulose, or complete medium (LB) on bgls expression were tested, the order of cellulase activity production was CMC27.2 > cellulose 21.9 > LB 19.8 U/mg protein, respectively at 24 h. CMC was proved to be the best medium for cellulase production. Results also showed that double the initial inoculum resulted in more cellulase activities in all media.