Phân lập, tuyển chọn dòng vi khuẩn lactic trong nem chua thịt có tiềm năng ứng dụng làm vi khuẩn giống trong sản xuất nem chua

This study was conducted to isolate, select and identify lactic acid bacteria (LAB), which has properties that can be used a starter culture, from Vietnamese fermented pork sausage ‘nem chua’. The results showed that 19 bacterial strains were isolated on MRS agar medium. Most colonies were round, having opalescent white color to milky white color, raised or flat elevation, lobulated or intact margin. Among 19 lactic acid bacterial strains isolated from ‘Nem chua’, there were 36.8% homofermentative strains and 63.2% heterofermentative strains. In the study of the ability to produce lactic acid and reduce pH, strain NTL2 and NTV2 were able to reduce pH faster than the others (3.65 and 3.7 respectively). They also produced the highest amount of lactic acid (19.13 mg/mL and 18.23 mg/mL) in MRS broth. Based on the typical properties of LAB, 12 strains were selected for identification by 16s rDNA sequence analysis, showing that: 6 strains are Lacticaseibacillus rhamnosus; 2 strains are Lactobacillus casei; 2 strains are Lactiplantibacillus pentosus, 1 strain is Lactiplantibacillus argentoratensis line, 1 strain was identified as Lactobacillus saniviri strain.