Isolation,Identification And Application Of Phenol-Producing-Bacterium In Stinky Tofu Brine

Changsha stinky tofu is a famous traditional snack in China,which is widely loved by consumers.When it comes to stinky tofu,the“stinky”is impressive.One of the main compositioin of stinky tofu odor is phenol.At present,volatile components,microbial diversity community analysis and microbial changes of the fermentation and semi-fermented stinky tofu were studied and analyzed.However,the phenol-producing microorganisms in Changsha stinky tofu brine have not been reported.In this paper,the bacteria in Changsha stinky tofu brine were separated and cultured by self-made solid medium,and the phenol content in the isolated single colony fermentation broth was determined by solid phase microextraction combined with GC-MS.The results showed that 30 single strains from stinky tofu brine were isolated,and the phenol was identified in only two strains?as“A3”and“A15”?with the contents of 11.78%and 11.01%,respectively.The strains were more identified by16S rDNA sequencing identification,results showed“A3”was found to be Bacillus circulans,“A15”were the aneurinibacillus aneurinilyticus.Optimizing the culture conditions of“A3”and“A15”were devised by the single-factor and Box-Behnken test combined with response surface analysis.The results showed that the optimal culture condition of strain A3 was 39.50°C,pH value was 7.00,and liquid volume was 60.00.mL/250 mL,the OD₆₀₀ value was 1.88 under this condition;the optimal culture condition of strain A15 was temperature of43.00°C,pH value of 8.00,liquid loading of 60.00 mL/250 mL,and the OD₆₀₀ value was 1.77 under this condition.In addition,the volatile components of A3 and A15single-fermentation fermentation and mixed fermentation for 9 days were analyzed preliminarily,results showed that the highest yield of phenol and 4-methylphenol was obtained by fermentation of A3 single bacteria for 9 days.