豆腐乳中乳酸菌的分离鉴定与发酵特性研究

Identification and fermentation characteristics of lactic acid bacteria isolated from sufu

中文关键词:  豆腐乳  豆类酸奶  菌种鉴定  发酵乳酸菌  植物乳杆菌  干酪乳杆菌  发酵

英文关键词:sufu  soybean yoghurt  identification  Lactobacillus fermentum  Lactobacillus plantarum  Lactobacillus casei  fermentation

中文摘要:

      目的 分离鉴定农家自制传统发酵豆腐乳中的乳酸菌, 探讨其作为豆类乳酸菌发酵饮品菌株的可行性。方法 利用MRS(man rogosa sharp)培养基分离豆腐乳中的乳酸菌, 通过形态学观察、生理生化特性和16S rDNA基因序列分析进行鉴定, 并将所分离到的乳酸菌与适合于豆类植物发酵的植物乳杆菌FJAT-7926(Lactobacillus plantarum FJAT-7926)和干酪乳杆菌FJAT-7928 (Lactobacillus casei FJAT-7928)进行发酵特性的对比研究。结果 从豆腐乳中分离出1株乳酸菌, 命名为FJAT-46777, 该菌株菌体细胞为圆端直杆状或圆端弯曲杆状, 无芽孢, 革兰氏阳性, 过氧化氢酶阴性, 生理生化特征与发酵乳杆菌(Lactobacillus fermentum)一致, 对菌株的16S rDNA基因进行扩增测序、分子系统发育树分析, 也表明其为发酵乳杆菌。发酵乳杆菌FJAT-46777发酵的豆乳中乳酸菌增殖速度最快, 最终活菌数最高, 为9.42 lg(CFU/mL); pH值下降最快, 最终pH值最低, 为3.91; 滴定酸度上升速度最快, 最终滴定酸度最高, 为62 ΟT。结论 分离自豆类自然发酵食品中的发酵乳杆菌FJAT-46777, 对豆类植物为主的基质具有更优良的发酵特性, 发酵时间快, 乳酸菌含量高, 产酸能力强, 适用于发酵豆乳的开发。

英文摘要:

      Objective To isolate and identify lactic acid bacteria in traditional fermented sufu, in order to investigate the feasibility as strains of bean yoghurt beverage fermentation agents. Methods Lactic acid bacteria were isolated with man rogosa sharp medium and identified based on morphological observation, physiological biochemical characteristics and analysis by 16S rDNA gene sequence. The fermentation characteristics of the isolated lactic acid bacteria were studied, comparing with the characteristics of Lactobacillus plantarum FJAT-7926 and Lactobacillus casei FJAT-7928 which were suitable for fermentation of soybean milk. Result A strain of lactic acid bacteria was isolated from the sufu and designated as FJAT-46777. The cells of the strain were round-ended or round-end curved rods without spores, gram-positive, catalase-negative, the physiological and bio-chemical properties supported FJAT-46777 similar to L. fermentum. Phylogenetic tree of FJAT-46777 based on the analysis of their 16S rDNA sequences also indicated FJAT-46777 as L. fermentum. The proliferation rate of lactic acid bacteria in the fermented soybean milk of L. fermentum FJAT-46777 was the fastest, and the highest number of viable bacteria was 9.42 lg(CFU/mL). The pH value decreased fastest, and the final pH value was the lowest with a value of 3.91. The titration acidity increased the fastest, and the final titration acidity was the highest of 62 ΟT. Conclusion L. fermentum FJAT-46777 isolated from traditional fermented sufu showed better fermentation characteristics in legume-based substrates, with short fermentation time, high content of viable lactic acid bacteria and strong acid production capacity, which is suitable for the development of fermented soybean yogurt.