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

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