Effect of bioaugmentation on biochemical characterisation and microbial communities in Daqu using Bacillus, Saccharomycopsis and Absidia

Summary Daqu , a saccharifying and fermenting agent for the production of Chinese vinegar and liquor, is manufactured through a spontaneous solid‐state fermentation process ( SSF ). To investigate the influence of bioaugmentation with native microorganisms on Daqu SSF process, physicochemical properties, microbial biomass, volatile compounds and microbial communities were analysed in laboratory‐scale Daqu . The results showed that the amylase activity of Daqu enhanced 6.35% ± 0.74% by inoculating Bacillus amyloliquefaciens , Saccharomycopsis fibuligera and Absidia corymbifera . Obviously higher microbial richness was found in the Daqu with bioaugmentation, although the microbial community structure remained relatively stable. Moreover, a total of twenty‐two volatile compounds were detected in the mature Daqu . Slightly increase in the content of alcohols was found in the enhanced group by fungal inoculation, including ethanol (46.58 ± 1.36 mg kg −1 ), isobutanol (0.19 ± 0.04 mg kg −1 ) and isoamyl alcohol (1.55 ± 0.13 mg kg −1 ). This study demonstrated that bioaugmentation had a positive effect on the amylase activity, main volatile compounds and microbial community richness.