Screening and Evaluation of Lactic Acid Bacteria for Dongbei Suancai Fermentation
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Abstract:
In order to obtain the lactic acid bacteria strains suitable for the fermentation of Dongbei Suancai, the growth performance and fermentation characteristics of 10 lactic acid bacteria strains isolated from fermented vegetables were evaluated in this study. It was found that Lactiplantibacillus plantarum YJ132 and Leuconostoc mesenterides subsp. mesenterides UA107 exhibited significant fermentation potential: After 16 h of fermentation, the optical densities at 600 nm (OD600) of their fermentation broth increased to 1.707 and 1.672, respectively, whilst their pHs decreased to 3.93 and 3.88, respectively. After 24 h of fermentation, the titratable acidity (TA) reached 65.62 g/L and 63.21 g/L, respectively, and the degradation rate of nitrite reached 96.41% and 95.78%, respectively. Even after 24 h of cultivation in a 5% NaCl solution, the OD600 remained above 1.51. Overall evaluation of YJ132 and UA107 revealed their suitability as fermentation strains for Dongbei Suancai. Using YJ132 and UA107 for Suancai fermentation, the final product had a TA content of 35.96 g/L. The contents of reducing sugar and soluble protein decreased to 6.51 mg/g and 111.27 μg/g, respectively. The nitrite content was significantly reduced in the early stage of fermentation compared with the control group (P<0.01). The inoculated LAB inhibited the proliferation of harmful bacteria, such as Escherichia coli (P<0.01), and increased the microbial diversity in the Suancai with Lactobacillus being the dominant bacterial group during the middle and late fermentation stages. Accordingly, it is inferred that YJ132 and UA107 improve the quality of Suancai by regulating the microbial community. In summary, YJ132 and UA107 are excellent LAB strains that are suitable for the fermentation of Dongbei Suancai.
