耐乙酸乳杆菌的筛选及其产乳酸特性

【背景】耐受乙酸的乳酸菌是传统谷物醋醋酸发酵过程中产生乳酸及其风味衍生物的重要功能微生物。【目的】从镇江香醋醋醅中分离鉴定具有耐乙酸特性的乳酸菌,并评价不同条件下该菌株的产乳酸能力。【方法】利用4%(体积比)乙酸含量的MRS培养基分离耐乙酸乳酸菌;对其进行16S rRNA基因鉴定、基因组测序、形态观察以及生理生化特性研究;考察不同乙酸浓度、葡萄糖浓度、发酵温度和时间对菌株产乳酸能力的影响。【结果】分离得到一株可耐受6%乙酸的乳杆菌Lactobacillus sp. JN500903;在厌氧静置、接种量5%、乙酸浓度5%、葡萄糖浓度40 g/L、发酵温度37°C、发酵时间10 d条件下,该菌株乳酸产量为16.1 g/L。【结论】乳杆菌JN500903能够耐受6%乙酸浓度,具有在酸性环境下合成乳酸的能力,有一定的应用潜力。

Screening and lactate-producing ability evaluation of acetic acid-tolerant lactic acid bacteria

Background] Acetic acid-tolerant lactic acid bacteria are important for lactic acid and its derivatives production during acetic acid fermentation in traditional cereal vinegar brewing process. Objective] To screen acetic acid-tolerant lactic acid bacteria from vinegar Pei of Zhenjiang aromatic vinegar, and evaluate its fermentation performance. Methods] Selective MRS medium containing 4% (volume ratio) acetic acid was used to isolate acetic acid-tolerant lactic acid bacteria. The isolated strain was identified by 16S rRNA gene sequencing, whole genome sequencing and morphological, physiological and biochemical analyses. Lactic acid-producing ability of the isolated stain was evaluated under different culture conditions. Results] A lactic acid bacterial strain JN500903 that resisted 6% acetic acid was screened and identified as Lactobacillus sp. The optimum conditions for lactic acid production were: anaerobic static culture, inoculum of 5%, acetic acid concentration of 5%, glucose concentration of 40 g/L, fermentation temperature at 37 °C and fermentation period of 10 d, the lactic acid production was 16.1 g/L under these conditions. Conclusion] Strain JN500903 can produce lactic acid under the 6% acetic acid stress, suggesting its potential for industrial application.