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

Abstract

This study reported physicochemical properties of purified endo-1,4-β-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. β-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 β-mannanase were most active at 40 and 50 °C with optimum pH 6.0 for both and were thermostable with very high percentage activity but the wild-type β-mannanase showed better stability over a broad pH activity. The β-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 × 10⁻⁴mg/mL, and 0.247 U/mL/min and 2.47 × 10⁻⁴mg/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.

Keywords:

• β-mannanase
• chemical mutagenesis
• kinetic parameters
• metal ion tolerance
• purification and characterization
• pH and thermostability

Acknowledgments

The authors sincerely acknowledge the provision of laboratory space and equipment, and technical support by the technical arms of the Departments of Biochemistry and Microbiology, Federal University of Technology, Akure, Nigeria.

Author contributions

Ademole Ajulo, Olusola Tosin Lawal and Victoria Kehinde Olatunji contributed reagents and materials, and carried out the experiment, Olusola Tosin Lawal and Oladipo Oladiti Olaniyi analyzed and interpreted the data, Oladipo Oladiti Olaniyi conceived and designed the experiments and wrote the paper, while Olusola Tosin Lawal edited the manuscript. All the authors approved the final version of the manuscript and agreed to be accountable for all the findings from this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was not financially supported by any funding agency.