Specific growth rate plays major role in microbial communities: Study

Scientists from the Tallinn University of Technology in Estonia (TalTech) Microbiomics Research Group conducted a study that involved fecal microbial consortia cultivation. Unlike pure microbial cultures, consortia cultivations use multiple strains and are designed to mirror what occurs in nature. 

The research team used apple pectin and fiber to determine their role in fecal microbiota. They also examined how the composition and metabolism of fecal microbiota change in transit at specific growth rates.

Growth rate vs fiber

Senior researcher Kaarel Adamberg, head of the Microbiomics Research Group of TalTech Department of Chemistry and Biotechnology, said the study suggests that the growth rate carries a much greater effect on the composition and metabolism of fecal microbiota compared to fiber. 

“From the point of view of nutrition, this means that the amount and diversity of dietary fibers determine the rate of passage of food in the digestive tract and, thus, the growth rate and activity of the gut microbiota. The effect of the transit rate has not been studied in detail so far and the study of combined effects of various factors must be continued in the future. This is an even more complicated task,"​ Adamberg said. 

The researchers then investigated if the same results would occur if the culture was stabilized at various dilution rates. They found that the culture adapted to the changing conditions under both high and low dilution rate and that they could indeed reproduce those results. This indicates that the specific growth rate plays a major role in the development of microbial communities. 

“Our work confirmed that dilution rate is a crucial trigger in consortia development. Some species, such as propionate-producing B. ovatus and B. vulgatus and butyrate-producing Faecalibacterium, were prevalent within the whole range of dilution rates, while the mucin-degrading bacterium A. muciniphila and some ruminococci were enriched at low dilution rates only.” ​The authors added, “This is new information for consortia cultivation, although it has long been known for pure cultures.”​

Adamberg said in this study, similar changes in the fecal microbiota were seen in adults' gut microbiota as in a previous study that examined fiber in the gut of children. 

“In addition, the fecal microbiota was able to adapt to the slow changes in acceleration rate. This could mean that if we are able reduce the time it takes for food to travel through the gut, i.e. increase the transit rate by making changes in dietary patterns, the bacterial community will adapt to the new transit rate and its metabolism will become more favorable to health.”​

Future implications

If consortia can be grown that are suitable for transplantation, it could result in the next generation of probiotics that would replace the fecal transplant. In other words, an artificial microbiota would be transplanted into a dysbiotic gut microbiota.

The report said more studies to help develop therapies are in the pipeline. “For further analysis of the interactions in complex consortia, other gut-relevant environmental conditions and substrates available in the colon will be studied. It should be stressed that, in addition to high-throughput sequencing analysis, it is necessary to concentrate on the growth and metabolism of fecal consortia to work out novel methods for bacterial therapies.”​

Source: Frontiers in Bioengineering and Biotechnology  ​

2020 Vol. 8 DOI=10.3389/fbioe.2020.00024  ​

“Use of Changestat for Growth Rate Studies of Gut Microbiota”  ​

Authors: K. Adamberg et al.