Complete genome sequence provides insights into the biodrying-related microbial function of Bacillus thermoamylovorans isolated from sewage sludge biodrying material.

To enable the development of microbial agents and identify suitable candidate used for biodrying, the existence and function of Bacillus thermoamylovorans during sewage sludge biodrying merits investigation. This study isolated a strain of B. thermoamylovorans during sludge biodrying, submitted it for complete genome sequencing and analyzed its potential microbial functions. After biodrying, the moisture content of the biodrying material decreased from 66.33% to 50.18%, and B. thermoamylovorans was the ecologically dominant Bacillus, with the primary annotations associated with amino acid transport and metabolism (9.53%) and carbohydrate transport and metabolism (8.14%). It contains 96 carbohydrate-active- enzyme-encoding gene counts, mainly distributed in glycoside hydrolases (33.3%) and glycosyl transferases (27.1%). The virulence factors are mainly associated with biosynthesis of capsule and polysaccharide capsule. This work indicates that among the biodrying microorganisms, B. thermoamylovorans has good potential for degrading recalcitrant and readily degradable components, thus being a potential microbial agent used to improve biodrying.

Decomposition of lignocellulose and readily degradable carbohydrates during sewage sludge biodrying, insights of the potential role of microorganisms from a metagenomic analysis.

Sewage sludge biodrying is a waste treatment method that uses bio-heat generated from organic degradation to remove moisture from sewage sludge. Lignocellulose and carbohydrate decomposition is important when assessing biodrying performance. This study investigated lignocellulose and carbohydrate decomposition, and the potential microbial functions during biodrying. We determined the lignocellulose and carbohydrate contents, assayed related enzyme activity, performed a complete metagenomic study on sewage sludge biodrying material during the thermophilic phase, annotated potential genetic function involved in the decomposition, and summarized the key metabolic pathways. The results indicated that lignocellulose, readily degradable carbohydrates, and starch, significantly decomposed after biodrying. During the thermophilic phase, the majority of lignocellulose and carbohydrate-related enzymes showed significantly higher activity, and glycoside hydrolases and glycosyl transferases showed higher gene counts and reads. Moreover, the top five microorganisms enriched with carbohydrate-active enzyme genes, i.e., Bacillus, Intrasporangium, Tetrasphaera, Rhodobacter, and Streptomyces, were also among the top ten ecologically dominant genera. These findings highlight the crucial phases for biodrying process, reveal the ecologically functional diversity of biodrying-originated microbial consortia, and suggest potential candidates for optimizing biodrying decomposition.