Substances that alter the intestinal environment to safely alter the composition of the microbiome

A recent study published in the journal scientific report, researchers report that the food preservative nisin remains intact during passage through the gastrointestinal (GI) tract. where nisin is Firmicutes and Proteobacteria.

study: Modulation of gut microbiota by nisin. Image credit: nobeastsofierce / Shutterstock.com

What is Nisin?

Some bacterial species produce antimicrobial peptides known as bacteriocins that are used as preservatives in the food industry. For example, Nisin Lactococcus lactishas broad-spectrum bactericidal activity and is used worldwide as a food preservative.

Nisin is effective in controlling Gram-positive bacteria such as: Clostridioides difficile. Nisin, when combined with other compounds such as ethylenediaminetetraacetic acid and cinnamaldehyde, is effective in controlling enterotoxigenic Gram-negative bacteria such as: Escherichia coli.

Previous studies have used chicken and mouse models to live efficacy of While nisin is effective on the microbiome, nisin efficacy has been proven in the following areas: ex vivo Experiments on the human microbiome. To date, no studies have evaluated this. live Effects of nisin in large mammals.

About research

In this study, researchers used a porcine model to elucidate the effects of orally ingested nisin on the gut microbiota. metagenomics This approach combines 16S ribonucleic acid (RNA) sequencing and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Nisin encapsulated in an ethylcellulose formulation, which prevents protein degradation in the gastrointestinal tract, passed through the small intestine and compared its effects on the gut microbiota with non-encapsulated nisin.

Piglets were fed encapsulated and non-encapsulated nisin directly into the pig diet. A control group was also included in this study, and the pig’s diet contained an ethylcellulose material used to encapsulate nisin.

Activity assays and MALDI-TOF MS were used to confirm the antibacterial activity and intact nisin levels present in each piglet fecal sample. Short-chain fatty acid (SCFA) concentrations in fecal samples were also analyzed to determine the level of gut microbiota activity.

The six SCFAs evaluated in this study included acetate, butyrate, isobutyric acid, isovaleric acid, propionic acid, and valeric acid. These measurements were taken at baseline, 4 days after treatment, and 10 days after the last treatment.

We used shotgun metagenomic sequencing and 16S rRNA profiling to assess gut microbiota composition at various time points during and after treatment. The Shannon index was calculated to estimate the alpha diversity of the gut microbiota of the three groups of piglets at different time points at baseline and after treatment. Unifrac and Bray-Curtis distances were also calculated to determine beta diversity.

Differential ranking was used to estimate the relative abundance of species after nisin treatment. Shotgun metagenomics was also used to assess the functional profile of the gut microbial community across the three groups.

Intact nisin causes reversible changes in the gut microbiota

At concentrations well below safe intake levels, intact nisin migrates through the gastrointestinal tract and alters the gut microbiota in the lower intestine, thereby affecting the relative abundance of Gram-positive bacteria. rice field.

However, these changes were reversible, with gut microbiota composition returning to normal 3 days after stopping nisin treatment. Furthermore, the diversity of the gut microbiota did not change significantly.

With nisin treatment, Lactic acid bacteria and other Gram-positive bacteria increased, increasing the relative abundance of Gram-negative bacteria. Escherichia coli. Furthermore, in the group that fed piglets encapsulated nisin or ethylcellulose material, Catenibacterium because of the increase Catenibacterium Bacteria may utilize the cellulose encapsulant as an energy source.

Changes in the relative abundance of Gram-positive and Gram-negative bacteria were also reflected in butyrate, acetate and propionate levels. To this end, nisin treatment reduced acetate and butyrate synthesis pathways and increased propionate synthesis.

Conclusion

Nisin was not degraded by proteolytic enzymes in the upper gastrointestinal tract and migrated intact to the lower intestine, altering the composition of the gut microbiota.

Nisin treatment also increased the relative abundance of Gram-negative bacteria, including: Escherichia coli and reduced its abundance Lactic acid bacteria and other Gram-positive bacteria. Importantly, the changes induced in the gut microbiome by nisin were reversible, and after cessation of nisin treatment, the gut microbiome composition recovered to its previous state.