Screening and ARTP mutagenesis-based breeding of high-cellulase-producing strains

While lignocellulose is an abundant renewable resource, the discovery of microorganisms capable of degrading lignocellulose is important for its full utilization. In this study, 26 soil samples were collected from Jigongshan National Nature Reserve, Xinyang, China. The Congo red staining method was used to isolate strains capable of degrading lignocellulose from the soil samples. A strain W-6-1, isolated from the soil samples was able to effectively degrade lignocellulose, with the filter paper activity (FPA) in the fermentation broth reaching 3.34 ± 0.32 U/mL. Integrating morphological traits, 16S rRNA phylogeny and physiological-biochemical assays, the isolate was identified as Bacillus sp. W-6-1. Three rounds of atmospheric and room-temperature plasma (ARTP) mutagenesis were employed to further enhance the lignocellulose-degrading ability of this strain. The best mutant (strain M3-35), which was selected from the surviving colonies, achieved an FPA of 6.11 ± 0.27 U/mL, representing an 83% increase over the wild-type strain W-6-1. Moreover, after multiple successive transfers, the FPA of strain M3-35 remained stable. The mutant M3-35 generated in this work provides a promising laboratory-derived candidate for exploring lignocellulose bioconversion.