High temperature acclimation and enzymatic properties of a lignin-degrading strain

Abstract:

[Background] High temperature decreases microbial activity, thus limiting the lignin degradation in garden waste composting. [Objective] To acclimatize a lignin-degrading strain—Bacillus sp. NO.2, improve its activity at high temperature, and observe its growth status and enzymatic properties. [Methods] The temperature gradient method was used to domesticate the strain, and the growth curve, enzyme activity, and lignin degradation rate were compared before and after the domestication. Moreover, the temperature range and pH range for the enzymatic reaction of lignin-degrading enzymes generated by the strain were determined. [Results] The maximum biomass was insignificantly different between the original strain and the domesticated strain at 60 ℃. However, the activity of laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) was 30.75%, 35.98%, and 29.62% higher, and the lignin degradation rate was 60.52% higher than those of the original strain, respectively. The Lac, MnP and LiP produced by the domesticated strain showed high activity at 20-60 ℃ and pH 3.0-9.0, and were stable, with the stability following the order of Lac>LiP>MnP. [Conclusion] The temperature gradient method can improve the activity of Bacillus at high temperature and widen the temperature and pH ranges for enzymatic reaction of lignin-degrading enzymes. Furthermore, it has potential for developing a special microbial agent for degrading garden waste.