Growth Rate of Gut Bacteria Related to Specific Diseases

NOVEMBER 12, 2015
Rachel Lutz
Changes in gut bacterial growth rates may be linked to onset of diseases, such as type 2 diabetes or irritable bowel syndrome, for example, according to research published in the journal Science.

Researchers from the Weizmann Institute of Science used genome-sequencing techniques to sequence the entire bacterial DNA in a sample. The researchers noted this is the first study of its kind – they examined how fast the various microbiome bacteria grew. The researchers constructed a picture of the types of bacteria present in the gut based on their relative abundance, which they were able to do based on the short sequences they developed.

“The sample’s bacteria are doing what bacteria do best: making copies of their genomes so they can divide,” explained lead researcher Eran Segal in a press release. “So most of the bacterial cells contain more than one genome – a genome and a half, for example, or a genome and three quarters.”

According to Segal, most bacterial strains have automated start and finish codes, which allowed the investigators to identify the starting points of the short sequences most prevalent in each sample. The least prevalent portions of the genome were the parts of the DNA that get coped last. By analyzing the relative amounts of starting DNA compared to the ending DNA, the researchers learned they would be able to estimate the growth rate for each bacteria strain.

First, the team tested the formulation in single strain cultures for which the growth rate could be controlled and observed. Then, they tested their method in multiple animal model systems before using the method in the DNA sequences of the fully complex human microbiomes.

The researchers determined their method successfully worked in the human microbiome DNA sequences. The estimated bacterial growth rates were approximately identical to the observed growth rates, they found.

“Now we can finally say something about how the dynamics of our microbiome are associated with a propensity to disease,” continued Eran Elinav, a research associate in Segal’s lab. “Microbial growth rate reveals things about our health that cannot be seen with any other analysis method.”

The researchers added that the changes in bacterial growth rates were associated with type 2 diabetes while others were tied to inflammatory bowel disease. The links between those growths, however, were not tied to the static microbiome studies focused on population.

This sequencing method could be used as a diagnostic tool in the future to detect disease or pathogen infection early on, according to the authors. The method may also be able to identify the effects of probiotic or antibiotic treatment. Moreover, the team hopes their findings can assist further research examining the connections between the gut and overall health. 

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