Engineered Alcaligenes sp. by chemical mutagen produces thermostable and acido-alkalophilic endo-1,4-β-mannanases for improved industrial biocatalyst

This study reported physicochemical properties of purified endo-1,4-beta-mannanase from the wild type, Alcaligenes sp. and its most promising chemical mutant. The crude enzymes from fermentation of wild and mutant bacteria were purified by ammonium sulfate precipitation, ion exchange and gel-filtration chromatography followed by an investigation of the physicochemical properties of purified wild and mutant enzymes. beta-mannanase from wild and mutant Alcaligenes sp. exhibited 1.75 and 1.6 purification-folds with percentage recoveries of 2.6 and 2.5% and molecular weights of 61.6 and 80 kDa respectively. The wild and mutant beta-mannanase were most active at 40 and 50? with optimum pH 6.0 for both and were thermostable with very high percentage activity but the wild-type beta-mannanase showed better stability over a broad pH activity. The beta-mannanase activity from the parent strain was stimulated in the presence of Mn2+, Co2+, Zn2+, Mg2+ and Na+. V-max and K-m for the wild type and its mutant were found to be 0.747 U//mL/min and 5.2 x 10(-4 )mg/mL, and 0.247 U/mL/min and 2.47 x 10(-4 )mg/mL, respectively. Changes that occurred in the nucleotide sequences of the most improved mutant may be attributed to its thermo-stability, thermo-tolerant and high substrate affinity- desired properties for improved bioprocesses.

Automated summary

This study investigated the physicochemical properties of purified endo-1,4-beta-mannanase from the wild type, Alcaligenes sp. and its most promising chemical mutant. The wild and mutant enzymes were purified and analyzed for their molecular weights, optimal temperature and pH, stability, and substrate affinity. The results showed that the mutant enzyme had improved thermo-stability, thermo-tolerant, and high substrate affinity compared to the wild-type enzyme. These findings have important implications for enhancing bioprocesses.