木质素降解细菌的筛选及园林废弃物降解研究

为获得能够高效降解园林废弃物的细菌,采用苯胺蓝和愈创木酚平板法从高温期堆肥中初筛得到木质素降解酶活力较高的菌株,再利用筛选出的菌株进行液态产酶和固态发酵试验,对漆酶(Lac)、锰过氧化物酶(MnP)和木质素过氧化物酶(LiP)的活力变化及菌株对园林废弃物的降解率进行测定。结果表明,从高温期堆肥中初筛得到3株木质素降解酶活力较高的细菌L-9、L-12和L~(-1)7;液态产酶试验测得L-9、L-12和L~(-1)7的Lac活力分别为8.61、12.26和2.20 U·mL~(-1);Mn P活力分别为11.16、14.75和16.24 U·mL~(-1);LiP活力分别为40.48、42.41和37.52 U·mL~(-1);固态发酵试验测得接种L-9、L-12和L~(-1)7菌株28 d后,园林废弃物的木质素降解率分别为14.88%、20.10%和11.25%;纤维素降解率分别为25.64%、28.47%和30.03%。综合评价菌株L-12具有较强的木质素降解能力,通过形态观察和16Sr DNA序列分析,将L-12鉴定为嗜热嗜脂肪地芽孢杆菌(Geobacillusstearothermophilus),可用于探究细菌降解木质素原理和工业化生产木质素降解菌剂。

Screening of lignin-degrading bacteria and study on degradation of garden waste

In order to obtain the bacteria degrading garden waste efficiently, aniline blue and guaiacol plate methods were employed to select bacteria with high lignin-degrading enzyme activity from garden waste compost in high temperature stage. Then the selected strains were applied to the liquid fermentation experiment and solid-state fermentation experiment, and the changes of laccase (Lac), manganese peroxidase (MnP), lignin peroxidase (LiP) and degradation rate of garden waste were monitored. Results showed that 3 strains with higher lignin-degrading enzyme activity were isolated as L-9, L-12 and L-17. The Lac activities of L-9, L-12 and L-17 in liquid fermentation were 8.61, 12.26 and 2.20 U·mL^-1, respectively; the MnP activities of which were 11.16, 14.75 and 16.24 U·mL^-1, respectively; the LiP activity of which were 40.48, 42.41 and 37.52 U·mL^-1, respectively. After 28 days of solid-state fermentation, the degradation rates of lignin in garden waste with L-9, L-12 and L-17 were 14.88%, 20.10% and 11.25%, respectively; the degradation rates of cellulose were 25.64%, 28.47% and 30.03%, respectively. In conclusion, L-12 was the most excellent strain with high enzyme activity and lignin degradation rate and was identified as Geobacillus stearothermophilus by morphology and 16S rDNA sequence analysis, which has a great potential to investigate the theory of lignin-degrading and produce industrial inoculant.