Isolation of cellulose-degrading bacterium I2 and functional verification of related degradation genes
Cellulose is the most abundant renewable energy material on the Earth,and the exploration of highly efficient cellulose-de-grading bacteria and cellulose enzymes has been a focal point of research.In this study,a cellulose-degrading Bacillus strain,designated as I2,was isolated and the functionality of its cellulose genes was validated.I2 was isolated from the accumulated wheat straw in the Bao-tianman Nature Reserve in Nanyang,Henan Province,with a genome size of 4.2 Mbp containing 4 635 genes,capable of degrading a sig-nificant portion of filter paper within 48 hours.Through predictions from the Carbohydrate-Active enZymes(CAZy)carbohydrate database and enzyme activity assays,182 genes detected in the database were analyzed,andit was established that four proteins in I2 exhibit cellu-lose enzyme activity.Among them,G2269 displayed the highest cellulase endoglucanase activity,reaching 49.02 U/mL under pH 5.0 and 55 ℃ conditions.Metal ions Ca2+and Zn2+had a significant enhancing effect on the activity of G2269,while Mn2+and Cu2+signifi-cantly inhibited the activity of G2269.Mg2+,Co2+,K+,Ni2+,and NH4+had no significant effect on the activity of G2269.Further-more,G2269 demonstrated good thermal stability and acid-alkali stability,retaining 70％of its activity after 30 minutes at 65 ℃,presen-ting promising application prospects,particularly in the fields of food processing and feed production.
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