Efficient saccharification of bamboo biomass by secretome protein of the cellulolytic bacterium Serratia marcescens LY1 based on whole-genome and secretome analysis

The biorefining of lignocelluloses using microbial degradation methods based on highly efficient microbial strains has received widespread attention. In the present study, a cellulolytic bacterium Serratia marcescens LY1 was isolated and the complete genome sequence of S. marcescens LY1 was assembled into a ring chromosome of 5,171,649 bp and a circle plasmid of 143,701 bp. Functional annotation revealed that a total of 130 genes were annotated in CAZyme families. Secretome sequencing revealed glycoside hydrolase family 3 protein and l-arabinose isomerase, which were annotated. The enzyme activities showed that the endoglucanase, xylanase, laccase, and lignin peroxidase activities peaked on the third day, while exoglucanase, manganese peroxidase, and β-glucosidase peaked on the fourth day. Furthermore, the secretome of S. marcescens LY1 was extracted for bamboo biomass hydrolysis, resulting in the highest yield of released reducing sugars was detected from the third day of secretome culture, with a value of 42.27 ± 0.46 g/L, and the secretomes of the third and fourth days were combined, resulting in the highest reducing sugar quantity of 51.59 ± 1.04 g/L. These findings indicate that the strain S. marcescens LY1 exhibits efficient saccharification of bamboo biomass and has potential use in bamboo biomass bioconversion and energy utilization.