Probiotic lactic acid bacteria research could inspire novel functional foods

25 May 2020 --- Consuming foods rich in lactic acid bacteria (LAB) may enrich the intestines with these potentially probiotic microorganisms. This is according to a new study carried out by the Microbiome Applications for Sustainable Food Systems through Technologies and Enterprise (MASTER) project, which is one of the largest EU-funded grants for food microbiome studies in the Horizon 2020 program. The research also offers hints and methodologies to implement novel strategies for tracing the life of probiotics and other LAB from foods or supplements all the way to the human body. The team is now planning to work closely with industry.

“These results could be useful for the design of novel functional foods. Moreover, the approach followed could inspire future work of the industries in the probiotics business. Companies will probably want to check the occurrence of their strains in the gut by using genome-wide and strain-level approaches such as those used in this study,” Danilo Ercolini, Full Professor of Microbiology at University of Naples Federico II and Coordinator on the Task Force on Microbiome Studies, tells NutritionInsight.

The researchers used state-of-the-art computational analysis tools to reconstruct LAB genomes from around 300 foods and nearly 10,000 human fecal samples. The samples were gathered from different continents to allow the researchers to examine the distribution of LAB in humans based on geographical origin, as well as age and lifestyle. 

LAB were found in relatively low abundance in the human feces and their prevalence depended on age, lifestyle and geography. The LAB most frequently found in the human feces were Streptococcus thermophilus and Lactococcus lactis, which are commonly found in yogurt and cheese. The DNA sequences of about 3,000 LAB genomes were also compared. The analysis, published in Nature Communications, revealed a high level of similarity of LAB from food with those of LAB from the human gut – a surprising finding for the researchers. 

Ercolini explains that the team hadn’t known what to expect at the beginning of the undertaking. “The actual occurrence of lactic acid bacteria from food in the gut microbiome is something that has attracted attention and curiosity from the scientific community for a while. However, no study had yet explored that. The common idea is that fermented foods are good because they can provide useful bacteria for the gut. However, we wanted to investigate if those bacteria are actually present in the human gut.”

Thousands of live LAB can be found in the majority of fermented foods.Digging into fermentation
Thousands of live LAB can be found in the majority of fermented foods, such as yogurt, cheese, kefir, bakery products, fermented meats or fermented vegetables. Some of these LAB have probiotic properties and many fermented foods are believed to be naturally healthy as a result. The most common strains of LAB that are also probiotics are those belonging to Lactobacillus genus – which is seeing a name change this year. 

Fermentation has become an industry priority in a very short period of time, with fermentation starting to step outside the realm of just cultured foods and probiotics, according to a recent Kerry Health and Nutrition Institute webinar. However, the experts had flagged that the term “probiotic” risks overextension when discussing microbes in fermented foods.

Nonetheless, LAB are among the best-studied microorganisms across the globe, with fermentation processes having been studied for over a century. Notably, the practice of fermenting food as a strategy for the preservation of milk, meat and vegetables has been used for millennia. The role of LAB is to transform raw materials, to produce molecules that preserve the food and to contribute to the key characteristics, such as taste of the food. In other words, there would be no yogurt or cheese without the activity of these important microorganisms.

“As soon as more data becomes available, we will progress in checking the occurrence of LAB in food and the gut. Moreover, we plan to work more closely with industry by designing intervention studies involving the consumption of fermented foods or probiotics in particular categories of individuals to check the possibility of actually having LAB strains from foods passed to the gut microbiome. This could potentially hold health-related beneficial outcomes,” concludes Ercolini.

This study is the result of a collaboration from the University of Naples Federico II, the University of Trento, Teagasc, and APC Microbiome Ireland SFI Research Centre. In March, the latter organization announced the start of a four-year project with DuPont Nutrition & Bioscience to rebalance the gut bacteria of babies after antibiotics or Caesarean-section births. APC Microbiome Ireland also recently revealed that feeding kefir to mice modulates their behavior via the gut-brain axis. 

By Katherine Durrell