Screening and Identification of a Bacillus licheniformis Strain with High Electro-transfection Efficiency and Elevated Biomass
[Objective]Bacillus licheniformis is an important chassis cell for expressing heterologous proteins in the fermentation industry.Screening B.licheniformis strains with easy electro-transfection and high biomass provides strain resources for effectively improving the host modification efficiency and protein expression level.[Method]Screening of strains with high homology to B.licheniformis from soil was carried out through enrichment,gyrB amplification,and 16S rDNA sequence analysis.The electro-transfection efficiency and biomass of the screened strains were compared and analyzed with the commonly used chassis cell B.licheniformis 2709 in the industry.The screened strains with easy electro-transfection and high biomass were identified morphologically and physiologically and biochemically as well as were subjected to antibiotic susceptibility assay and growth in high temperature and alkaline environment.[Result]Ten strains with high homology to B.licheniformis were screened.Among them,the strain 1-33 presented the highest electro-transfection efficiency with a maximum value of 6700 transformants per μg DNA,which was 13.7 times higher than that of B.licheniformis 2709.Cultured in semi-solid soymeal-corn flour medium and SR liquid medium,the maximum biomass of strain 1-33 was found to be 5.2×1010 CFU/mL and 6.8 g/L,respectively,surpassing B.licheniformis 2709 by 1.71 and 1.3-fold.Further morphological and physiological experiments identified strain 1-33 as Bacillus licheniformis,which had sensitivity to various commonly used antibiotics and good alkaline and heat resistance.[Conclusion]A B.licheniformis strain 1-33 with high electro-transfection efficiency and elevated biomass is screened,thereby foundation for its further development as an efficient host for exogenous protein expression in industrial process is established.
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