Screening of Cold-Adapted Strains and Its Effects on Physicochemical Properties and Microbiota Structure of Mushroom Residue Composting

Abstract

Composting is an effective way to dispose of agricultural waste; however, its application is limited in the winter and in areas with low average annual temperatures. This study screened out a composite microbial agent (CMA) including Bacillus (B.) cereus QS7 and B. pumilus QM6 that could grow at 10–15 °C and investigated the effects of the CMA as an inoculant on the physicochemical parameters and microbial communities of compost made from mushroom residue mixed with sheep manure. The results showed that CMA inoculation prolonged the days of high temperature above 60 °C. When the ratio of mushroom residue to sheep manure was at 9:1, compost increased the accumulation of nitrogen, and reduced the electrical conductivity (EC). Under this ratio, the inoculation of CMA accelerated the degradation of organic matter (OM) (decreased by 12.22%) and total organic carbon (TOC) (decreased by 8.13%) and increased the germination rate and seed germination index (GI) to 100% and 106.86, respectively. Microbial community structure analysis showed that the relative abundance of Flavobacterium was 30.62% on day 15 and was higher after CMA inoculation in the high mushroom residue condition, which was higher than that of other groups, and the relative abundance of thermophilic fungi increased. This study demonstrated that CMA improves the quality and efficiency of mushroom residue and sheep manure composting, and it provides evidence to improve the efficiency of low-temperature composting.

Keywords

• mushroom residue
• sheep manure
• composite microbial agent
• physicochemical
• microbial community structure