芽孢八叠球菌(Sporosarcina sp.) N2的分离与低温降解木质素的特征解析

Sporosarcinasp. N2: isolation and degradation of lignin at low temperatures

摘要:

【背景】东北地区每年都会产生大量的作物秸秆类农业废弃物，低温导致自然条件下秸秆降解缓慢。【目的】筛选耐低温高效降解木质素的细菌，探究其木质素降解相关途径。【方法】通过形态学及16S rRNA基因测序进行菌株鉴定，在低温条件下进行木质素降解条件优化，利用转录组学方法对菌株木质素降解特征进行分析。【结果】筛选了一株能在15 ℃条件下高效降解木质素的菌株芽孢八叠球菌(Sporosarcinasp.) N2，低温培养8 d木质素的降解率为20.8%，条件优化后提高至31.7%。通过转录组测序分析确定不同时期间的差异表达基因，发现与抗冻、木质素降解相关的功能基因在不同降解时期上下调变化明显，通过其基因表达推测了该菌株木质素降解途径为苯甲酸途径与原儿茶酸途径。【结论】本研究丰富了低温木质素降解微生物资源，为后续秸秆低温生物强化降解提供了数据支持。

关键词:木质素;生物降解;芽孢八叠球菌;低温;酶活性

Abstract:

[Background] A large amount of crop straw as agricultural waste is produced in northeast China every year. Low temperature leads to slow degradation of straw under natural conditions.[Objective] To screen the bacterial strain capable of degrading lignin efficiently at low temperatures and explore the pathways of lignin degradation. [Methods] The strain was identified by morphological observation and 16S rRNA gene sequencing. The lignin degradation conditions were optimized at low temperatures, and transcriptome sequencing was employed to predict the pathways of lignin degradation.[Results] A strain Sporosarcina sp. N2 capable of efficiently degrading lignin at 15 ℃ was screened out. The degradation rate of lignin was 20.8% after 8 days of low temperature culture and increased to 31.7% after degradation condition optimization. The differentially expressed genes in different time periods were identified by transcriptome sequencing. The functional genes related to cold resistance and lignin degradation presented down-regulated or up-regulated expression in different degradation periods. According to the gene expression pattern, we hypothesized that the strain degraded lignin via the benzoic acid pathway and protocatechuic acid pathway. [Conclusion] This study enriched the microbial resources for degrading lignin at low temperatures and provided data support for enhancing microbial degradation of straw at low temperatures.

Key words:lignin;biodegradation;Sporosarcinasp.;low temperature;enzymatic activity