Isolation and identification of thermophilic cellulolytic bacterium Streptomyces Thermocarboxydus and its degradation effect on moso bamboo waste

A large amount of waste materials is produced during the processing of moso bamboo (Phyllostachys edulis) . High-temperature aerobic composting is an important way to utilize moso bamboo waste, among which the efficient degradation of cellulose is the key to improving the quality and efficiency of the composting process, the isolation and screening of high-temperature cellulose-decomposing bacteria is of great significance for the high-temperature composting degradation of bamboo waste. In this study, many samples were collected in the environments where lignocellulose exists, such as rice fields, grasslands, bamboo forests, forest soils, and high-temperature composting of straw in Hunan region. High-temperature cellulose-decomposing bacteria were enriched and cultivated at 50 ℃ using the cellulose from the remaining fine chips of bamboo processing as the sole carbon source. High-temperature cellulose-decomposing bacteria were isolated and screened by the hydrolysis ring method. The weight loss rate of moso bamboo, the activity of carboxymethyl cellulase (CMCase), and the activity of filter paper cellulase (FPase) under the liquid shaking flask fermentation conditions of different high-temperature cellulose-decomposing bacteria were compared to screen the strains with excellent degradation effect of moso bamboo fine debris. And the strains were identified, the degradation ability of moso bamboo at different temperatures, and the degradation rate of lignocellulose components were determined. The results showed that the cellulose-decomposing bacteria obtained by the hydrolysis ring method were mainly fungi and actinomycetes. Among them, the strain JFDF-S1 had the highest weight loss rate (20.35%) of the remaining fine chips from bamboo processing when it was cultured in liquid fermentation at 50 ℃ for 5 days, and was significantly higher than that of other strains. Meanwhile, the activity of CMCase and FPase produced by this strain were also significantly higher than those of other strains. It was identified as Streptomyces thermocarboxydus by colony morphology and molecular biology. The colony growth and cellulose degradation ability of the strain JFDF-S1 under the conditions of 30-55 ℃ were relatively good, which is consistent with the medium and high temperature conditions in the composting process. It can effectively degrade bamboo waste by efficiently degrading the hemicellulose and cellulose components in it. This study provides a theoretical basis for the development of microbial agents for the efficient degradation of bamboo waste using the high-temperature cellulose-decomposing strain JFDF-S1. It is conducive to improving the composting efficiency and quality of bamboo waste, promoting the recycling of bamboo waste and the healthy and sustainable development of the bamboo industry.