Healthier dairy? Bacterial films and nanofiber membranes could boost probiotic potential

11 Mar 2019 --- Bacterial biofilms are typically the target of heavy-duty cleaning regimens, but these films aren't always bad news. In fact, growing them on thin sheets of nanofibers could be a great way to produce a fermented milk product that can deliver hardy probiotics to the digestive tract, according to research recently published in ACS’ Journal of Agricultural and Food Chemistry.

The announcement comes at a time when fermented dairy products are in the spotlight. Last week, NutritionInsight reported that consuming fermented dairy products (FDP) fortified with probiotic microbes can cause rapid positive changes in the gut microbiome, according to research endorsed by PepsiCo R&D Inc. and Knomics LLC, a Russian microbiome research company. The findings suggested that a single month of FDP consumption can significantly shift microbial composition and function, which may benefit overall health. 

Biofilms consist of bacterial cells that are tightly packed together in an extracellular matrix (ECM). Most prior biofilm research has focused on films formed by pathogenic bacteria, and more particularly on how to prevent their formation or how to detach or destroy the films. 

Meng-Xin Hu and colleagues instead wanted to find the best growing conditions for the bacteria Lactobacillus plantarum, found in fermented food products such as yogurt. The researchers were interested in ensuring that this organism could survive storage on the supermarket shelf, as well as transit through the stomach, which remains a challenge for most probiotics.

“The findings were surprising,” Hu tells NutritionInsight. “Nanofiber membranes could mimic the structure of natural ECM and support bacteria to adhesion and form biofilms which possess high resistance to unfriendly environment. The formed biofilms were interlocked with nanofibers, which formed a cohesive structure,” she notes. “Thus, the formed biofilms show fantastic stability and excellent gastrointestinal resistance.”

“When these kinds of biofilms are used as starter cultures, they show positive fermentative ability, reusability and higher survival of probiotics during shelf life,” Hu claims.

An accumulating body of epidemiologic and clinical evidence suggests that the fermented milk may act beneficially on obesity, metabolic risk factors and cardiovascular risk, Hu says. “Therefore, more and more fermented milk products are produced. During the manufacturing process of fermented milk product, starter cultures play an important role in the quality control of the fermented milk product. Besides, the cost of starter cultures is one of the main composition of total costs,” she explains. 

Meng-Xin Hu“Theoretically, all the fermented milk products can be produced with biofilm starter cultures. Biofilm starter cultures have the ability to replace the traditional starter cultures to produce fermented milk, or other fermented products in a suitable way.”

The researchers grew the bacteria on cellulose acetate membranes that mimic the structure of natural ECM. The huge surface area of these nanofiber membranes provided a scaffold for the bacteria. The microbes successfully formed colonies and then biofilms, which were used to ferment milk, on the membranes. 

The bacteria in biofilms were more resistant to simulated digestion than free-floating L. plantarum. During fermentation, the biofilms continually released live bacterial cells into the milk. Once the fermented milk was stored, the released cells retained in the milk were much longer-lived than cells in fermented milk produced by free-floating L. plantarum. The researchers say their findings lay the foundation for the use of biofilm-integrated nanofiber membranes as starter cultures in biotechnology and fermentation industries.

With the rapid development of science and technology, more and more people realize that dairy are important for their health, says Hu. “In order to support this, popular science for people is needed through media, news and books,” she continues. “Secondly, better products need to be developed in the industry.”

Hu also notes that there will be further research conducted in this space. 

Earlier this month, Chr. Hansen launched nu-trish LGG DA, an adjunct culture that gives a fast and robust fermentation when combined with a starter culture. The latest addition to the company’s culture range comes in a format for fermented plant bases at a time when NPD within plant-based foods is accelerating. According to the company, it was created to keep pace with growing probiotic demand as plant-based producers look for new ways to innovate in this space.

And last month, NutritionInsight reported that scientists were one step closer to uncovering how the gut microbiome affects our health, after isolating more than 100 previously unknown species of bacteria from healthy people’s intestines. The researchers created what they say is the most “comprehensive public database of human health-associated intestinal bacteria to date.” It could provide a wealth of information on treating different disorders, as well as a diverse range of potential probiotics.

By Elizabeth Green