Screening of acetic acid bacteria with high yield of acid from vinegar pei of Zhenjiang aromatic vinegar

Zhenjiang aromatic vinegar is traditionally fermented vinegar in China and bears valuable nutritions.In this study,acetic acid bacteria( AAB) with high yield of acetic acid were investigated by screening from vinegar Pei of Zhenjiang aromatic vinegar.Fifteen strains of producing acid bacteria were isolated and eight strains of AAB were identified by 16 S r DNA sequencing analysis.Among these eight strains,strain D-3-4 had a higher ability to produce acetic acid,reaching 60 g/L.The results of resistance testing to alcohol,temperature and acetic acid showed that the strain D-3-4 had the highest yield of acid when alcohol concentration was no more than 9%; but strain C-3-2-1 had the highest yield of acid and a conversion efficiency of alcohol when alcohol concentration was more than 9%.The study of thermo-tolerance demonstrated that strains D-3-4 and R-4-2 still had higher ability to yield acid,reaching 30 g/L at 42 ℃.The experiment of resistance to acetic acid showed strains D-3-4 and C-3-2-2had the highest yield of acid at 30 g/L acetic acid concentration.Totally,the acid production of strain D-3-4 was superior to other strains.Therefore,the strain D-3-4 was finally selected as the dominant AAB of high production.