Weekly Science Talk｜Little Lactobacillus can also achieve great things

Lactic acid bacteria are a type of bacteria that are very "friendly" to humans. Not only do they not make people sick, but they can also improve our health. In daily life, we can often see products made from them.

Lactobacillus plantarum is a member of lactic acid bacteria and one of the common probiotics. It has been widely used in food, animal feed, industrial production, health care and other fields.

However, not all plant lactobacillus can be used by humans. Some strains are relatively fragile and may trigger stress responses when encountering strong acid or high salt environments, which directly affects their physiological activity and thus reduces their fermentation performance. This requires us to have not only excellent strains, but also corresponding fermentation technologies to cooperate with their production and maximize their production performance.

Faced with these problems, Professor Chen Wei's team from the School of Food Science and Engineering at Jiangnan University began to collect, screen, organize and conduct in-depth research on probiotics native to China. After years of hard work, they not only bred several strains of Lactobacillus plantarum with excellent performance, but also successfully developed the corresponding fermentation technology. In the end, the research project "Directed Breeding and Fermentation Key Technologies of Stress-Resistant Lactobacillus Plantarum" led by Professor Chen Wei won the second prize of the National Technological Invention Award in 2018.

From food to food

China's long history and rich food culture provide many opportunities for the study of Lactobacillus plantarum. Fermented foods with unique characteristics from all over the country have gathered into a treasure-like resource library. Professor Chen Wei's team has worked tirelessly to collect and screen a large number of traditional fermented foods, and isolated more than 2,100 strains of Lactobacillus plantarum that are tolerant to high-acid and high-salt environments from various fermented foods such as kimchi, aged vinegar, and fermented dough.

In order to further explore the tolerance mechanism of Lactobacillus plantarum to different environmental conditions, the team mapped the whole genome of multiple strains of bacteria, identified key genetic elements, and developed a variety of directional breeding techniques and probiotic function evaluation models based on this. In this process, they not only obtained functional strains with excellent tolerance to acid, salt, bile salt, low temperature, heavy metals, etc., but also obtained 7 strains of Lactobacillus plantarum with excellent physiological functions such as alleviating heavy metal toxicity, antagonizing pathogenic bacteria infection, and reducing the harm of biological toxins through directional screening, filling the gap in this field in my country.

Optimizing fermentation technology to improve production performance

While obtaining excellent strains, stimulating the production potential of Lactobacillus plantarum also requires advanced fermentation technology. In order to give full play to the excellent fermentation performance of Lactobacillus plantarum, Chen Wei's team created a multi-strain two-step combined fermentation method and a multi-strain synergistic fermentation method. The multi-strain two-step combined fermentation method is to use Lactobacillus plantarum in combination with multiple other strains. After aerobic and anaerobic fermentation, the feed raw materials are fermented. The feed processed by this method is not only richer in nutrients, but also greatly improves the palatability of the feed. The multi-strain synergistic fermentation method uses proteolytic strains and Lactobacillus plantarum to synergize fermentation to solve the problem of poor growth of Lactobacillus plantarum in fermented milk, greatly expanding its application in the manufacture of fermented dairy products. Based on this technology, Bright Dairy has established a new probiotic fermented milk production line with an annual output of 200,000 tons, and the sales of related products reached 1.14 billion yuan in 2017. The achievements of Professor Chen Wei's team have been authorized by a number of invention patents worldwide. The related products created by this method have not only enhanced the core competitiveness of my country's probiotics industry, but also provided consumers with more choices.

(Text: Niu Mingze, Ph.D., Sichuan University. Expert: Tang Bo, Research Librarian, Zhongguancun Guoke Modern Agricultural Industry Science and Technology Innovation Research Institute)

China Association for Science and Technology Department of Science Popularization

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