Objective Microorganisms play a key role in the fermentation process of cigar tobacco leaves. In order to better improve the quality of cigar tobacco leaves, it is necessary to screen the dominant strains of cigars and apply them to the fermentation of cigar tobacco leaves. Therefore, it is necessary to optimize and expand the biomass of the dominant strains.

Method 16S sequencing and physiological and biochemical analysis were carried out on a dominant strain ZLX10 screened from cigars to identify the strain. At the same time, the composition of culture medium (carbon source, nitrogen source and inorganic salt) and culture conditions (inoculation amount, liquid content and seed age) were optimized through single factor and orthogonal test to improve its biomass.

Result Based on 16S rDNA sequence comparison, the sequence homology between strain ZLX10 and Bacillus mojavensis (MT043920.1) reached 99.86%, and the strain had strong ability to degrade polysaccharide and protein macromolecule, which could be identified as Bacillus mojavenis. Through single factor and orthogonal test, the optimal medium formula of strain ZLX10 was obtained as follows: carbon source (sucrose) 50 g/L, nitrogen source (yeast extract) 20 g/L, inorganic salt (MgSO₄) 0.25 g/L, and the optimal culture conditions were 1% (V/V) of inoculum, 30 mL/250 mL of liquid content, and 24 h of seed age. The biomass of strain ZLX10 was 1.98 times that before optimization when cultured under the optimal conditions for 24 h.

Conclusion The biomass of strain ZLX10 can be significantly increased by optimizing the conditions, which provides a basis for artificial inoculation of fermented cigar tobacco leaves.