Screening and community succession and functional prediction of high-efficiency degradation microbial communities for rice straw at low-temperature.

Traditional straw return relies on microbial degradation, but cold winters delay it, risking crops. Therefore, a microbial community adapted to rice straw degradation in cold regions was constructed by restrictive consecutively sub-cultured under low-temperature limitations. The capabilities of the microbial community, such as adaptability, stability, and degradation power, were evaluated by analyzing straw degradation features, Characterization experiments and lignocellulose enzyme activities across multiple generations. 16S amplicon sequencing was used to monitor the changes in its structure over generations. Metagenomic sequencing uses CAZy and KEGG to classify gene functions. The results showed that the highest degradation efficiencies and enzyme activities were observed in the E and F generations, dominated by Proteobacteria, Bacteroidetes, and Fungi The stable microbial community was designated as LJ-7. Metagenomic analysis showed that functional genes of LJ-7 were mainly concentrated in glycoside hydrolase (GHs) and glycosyl transferase (GTs) related genes which contained many fiber and lignin-degrading enzyme genes. It is speculated that microbial enzymes degrade straw by breaking down its complex structure into monosaccharides or metabolizing quinone compounds for energy. This experiment successfully screened a microbial community capable of degrading rice straw at low temperatures, thus offering novel research insights and pathways for straw degradation in cold conditions.