Abstract:

Eight strains of facultative anaerobic bacteria with higher capacity to produce protease were isolated and screened
from high-quality liquor pit mud. Out of the 8 strains, 3 strains producing higher endopeptidase, aminopeptidase and
carboxypeptidase activities including HDS4, HDS6 and HDS8 were selected and identified by morphological, physiological
and biochemical properties and 16S rDNA sequence analysis as Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus
thuringiensis. Mixed-culture fermentation with the 3 strains yielded an increase of 8.907%, 6.181% and 8.781% in
endopeptidase, aminopeptidase and carboxypeptidase activities compared with single-culture fermentation, respectively.

Key words: protease, pit mud, identification, screening, liquor