analysis-interactions-between-endobiotics-human-gut-microbiota-using

Analysis of Interactions between Endobiotics and Human Gut Microbiota Using In Vitro Bath Fermentation Systems

Human intestinal microorganisms have recently become an important target of research in promoting human health and preventing diseases. Consequently, ...

Hunan University of Science and Engineering

()-equol is one of the major metabolites of daidzein that is produced by human and animal gut bacteria. Most of the physiological functions of soybean isoflavones, such as anti-oxidative activity, anti-cancer activity, and cardiovascular protection have been ascribed to ()-equol. However, only 30-50% people contain this kind of equol-producing bacteria, and therefore are able to convert daidzein to ()-equol. Administration of ()-equol may be more beneficial than soybean isoflavones. The aim of this study was to construct an engineered ()-equol resistant  to enhance ()-equol production . First, transposon mutagenesis libraries were constructed and screened to isolate the ()-equol resistant mutant  strain BL21 () in order to overcome the inhibitory effects of ()-equol on bacterial growth. Bacterial full genome scan sequencing and  overexpression results revealed that the  gene was responsible for this resistance. Second, the ()-equol-producing genes L-, L-, L-, and L- of  strain 20-92 were synthesized and cloned into compatible vectors, pETDuet-1 and pCDFDuet-1. These plasmids were subsequently transformed into BL21 (DE3) and its mutant BL21 (). Both engineered BL21 (DE3) and BL21 () could use daidzein as substrate to produce ()-equol under both anaerobic and aerobic conditions. As expected, engineered BL21 () had faster growth rates than BL21 (DE3) when supplemented with high concentrations of ()-equol. The yield and the daidzein utilization ratio were higher for engineered BL21 (). Interestingly, engineered BL21 () was able to convert daidzein to ()-equol efficiently under aerobic conditions, providing a convenient method for ()-equol production . In addition, a two-step method was developed to produce ()-equol using daidzin as substrate.

To Construct an Engineered ()-Equol Resistant  for  ()-Equol Production.

Antimicrobial resistance is on the rise while the number of antibiotics being brought to market continues to drop. Drug-resistant genes and drug-resistant bacteria infection have seriously threatened human health. Therefore, antimicrobial resistance presents an ongoing challenge that requires multifaceted approaches including: biomedical innovation; improved surveillance of antibiotic consumption and antimicrobial resistance generated rates; prevention of health-care-associated infections and transmission of multidrug-resistant bacteria and environmental dissemination; rapid microbiological diagnosis; and curtailed clinical and veterinary misuse. Fortunately, combating antimicrobial resistance has been highly valued and supported by the government, scientists and entrepreneurs of various countries. With the continuous introduction of new technologies, new products, and new management measures, the problem of antimicrobial resistance must be controlled and alleviated.

[Progress in strategies to combat antimicrobial resistance].

The surface exopolysaccharide of Bifidobacterium spp. was found to be involved in many processes, including bacterial colonization and host immune modulation. Here, we report the draft genome sequence of an exopolysaccharide-producing strain of Bifidobacterium longum, BB-79.

Draft Genome Sequence of Bifidobacterium longum BB-79, a Strain That Produces Acid Exopolysaccharide.

Exopolysaccharides (EPSs) are carbohydrate polymers that are synthesized and present on the surface of bifidobacteria. Due to their potential applications in diverse sectors, such as food, biotechnology, cosmetics, and medicine, EPSs synthesized by bifidobacteria have recently attracted more attention. EPS production not only has benefits in food and health but also has effects on probiotics in the microbial ecosystem. In this study, we investigated the interaction between bifidobacteria EPSs and human gut microbiota in vitro using thin-layer chromatography, 16S rDNA high-throughput sequencing, and gas chromatography. The results showed that human gut microbiota has the capacity to degrade EPSs, although the degradation rate was approximately 50% after fermenting for 48 h. On the other hand, EPSs regulate the human gut microbiota. Fermented samples in the VI_Bif group clustered together according to the bacterial community compared to the VI_Starch group, in which starch was added as a carbon source. The bifidobacteria EPS promoted the growth of phylum Deinococcus_Thermus, class Deinococci, order Deinococcales, and genus Coprococcus. EPSs also increased the production of propionic acid compared to the starch group. The detection results of Dionex ICS 5000 high-purity capillary ion chromatography system showed that EPSs had absorption peaks of fucose, rhamnose, galactose/acetyl glucosamine, glucose, and ribose, and the molecular proportion of these monosaccharides was approximately 2: 2: 440: 3: 53. The monosaccharide composition of this EPS appears to be more complex than previously reported for bifidobacteria EPS. Additional studies are needed to elucidate its structure and functions.

Effects of bifidobacteria-produced exopolysaccharides on human gut microbiota in vitro.

To further investigate the bacterial community and identify the bacterial biomarkers between venom secretion and non-venom secretion snakes, 50 intestinal samples (25 large intestine, 25 small intestine) were obtained from 29 snakes (13 gut samples from Deinagkistrodon, 26 from Naja and 11 from Ptyas mucosa). 16S rDNA high-throughput sequencing results showed that 29 bacterial phyla, 545 bacterial genera, and 1,725 OTUs (operational taxonomic units) were identified in these samples. OTU numbers and the Ace, Chao, Shannon, and Simpson indexes were very similar among the three breeds of snakes included in this study. The Bacteroidetes, Firmicutes, Fusobacteria and Proteobacteria were predominant bacterial phyla. The relative abundance at the phylum level among these samples was similar, and the difference between small and large intestinal samples was not obvious. However, at the genus level, venom secretion snakes Deinagkistrodon and Naja clustered together according to different breeds. 27, 24, and 16 genera were identified as core microbes for Deinagkistrodon, Naja, and Ptyas mucosa, respectively. Interestingly, the relative abundances of genera Hafnia_Obesumbacterium, Providencia, and Ureaplasma were found to be significantly higher in non-venom secretion snakes, and the genera Achromobacter, Cetobacterium, Clostridium innocuum group, Fusobacterium, Lachnoclostridium, Parabacteroides, and Romboutsia were only detected in venom secretion snakes. The function of these bacteria in venom secretion needs to be further studied, and these venom secretion related genera may be the promising target to improve venom production.

Article	Year
To Construct an Engineered ()-Equol Resistant for ()-Equol Production. Frontiers in microbiology\| PubMed ID: 29915570	2018
[Progress in strategies to combat antimicrobial resistance]. Sheng wu gong cheng xue bao = Chinese journal of biotechnology\| PubMed ID: 30152220	2018
Draft Genome Sequence of Bifidobacterium longum BB-79, a Strain That Produces Acid Exopolysaccharide. Microbiology resource announcements\| PubMed ID: 30533788	2018
Effects of bifidobacteria-produced exopolysaccharides on human gut microbiota in vitro. Applied microbiology and biotechnology\| PubMed ID: 30569218	2019
Comparative analysis of intestinal bacteria among venom secretion and non-secrection snakes. Scientific reports\| PubMed ID: 31004115	2019

Huahai Chen

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