Characterization of lignin-degrading Bacillus subtilis YY-10 and construction of genetically engineered strains

In order to promote effective utilization of tobacco waste and sustainable production of tobacco enzyme additives, Bacillus subtilis YY-10, a nicotine-resistant lignin-degrading bacterium derived from tobacco, was investigated by genome sequencing, exoprotein composition analysis and gene editing techniques to evaluate its feasibility as an enzyme-producing host. The results showed that: 1) The YY-10 genome had a circular chromosome encoding 4 252 genes, which contained various active carbohydrate enzymes. The exoproteins of YY-10 were rich in pectate lyase and amylase. 2) A pectate lyase expression system was developed and introduced into the YY-10 host, resulting in a genetically engineered strain, YY-10-pelA. The strain achieved expression and secretion of the target enzyme, and exhibited enzyme activity about three times higher than the wild type, and demonstrated the ability to utilize alkaline lignin for growth under nutrient stress. 3) Compared with well-established B. subtilis hosts, YY-10 as an enzyme-producing host using tobacco waste for enzyme preparation showed considerable enzyme expression capacity and outstanding advantages in improving the sensory quality of tobacco.