bacteria, beta-glucan, cholesterol lowering, reishi, short chain fatty acid, triterpene

Ganaderma lucidium and gut microbiome

This is a continuation of a previous post comparing the cholesterol lowering abilities of a statin and a Ganaderma lucidium extract.

Bile and cholesterol is released by the gall bladder. Excess is excreted in feces
Cholesterol and bile acids are released by the gall bladder into the duodenum of the small intestine. where they may be reabsorbed.

 

Effect of experimental diets on intestinal phyla and the Lactobacillus genus

This is figure 6 in the Meneses 2016 publication.   Liberty was taken to add phylogenic classification of five members of the human microbiome.

Colonic microbiome families in response to high cholesterol (Ch), ,Ch with simvastatin, Ch with Ganoderma lucidium polysaccharides simvastatin,
Major families of colonic bacteria in response to a high cholesterol dietic (Ch), Ch with the statin simvastatin and Ch with Ganaderma lucidium polysaccharides. The high dose 2 of Gl polysaccharides comes closest to returning the microbiome profile to normal.

Actinobacteria were not well represented in this particular mouse study.  Bifidobacterium breve is considered a probiotic bacterium.    Members of the Propionibacterium genus are considered by some to be beneficial.  Which short chain fatty acids are beneficial and which are detrimental is also a topic of ongoing research.   Finally, There are members of the Fimicules phylum that make very good colonic inhabitants (Lactobacillus acidophilus) and others that one would just as soon not have to host (Clostridium difficile).  Meneses and coworkers used PCR to quantitate the Lactobacillus genus.   They found very impressive increases of this good genus with high doses of both Gl extracts.

5: Effect of experimental diets on mouse microbiomes

Microbiome response to high cholesterol diet (Ch), Ch with a statin, Ch with Ganoderma lucidium polysaccharides.
Meneses (2016) profiled major genera of fecal bacteria in response to a high cholesterol diet, Ch diet with a statin, and the Ch diet wtih Ganaderma lucidium polysaccharides polysaccharides and a static

A very nice heat map of select genera is being omitted.  The Meneses 2016 publication is available to the public in  PubMed.

Which members of the mouse microbiome are able to digest Gl  β-glucans?

In searching the NCBI/protein database protein database I found no evidence of β-1,3-glucanase in the mouse.  A search of for ”  β-glucanase and mouse” revealed a study  “Genome sequencing and assembly of sDMDMm2 microbiota.  These multispecies are 12 bacterial species of a Stable Defined Moderately Diverse Mouse Microbiota in the mouse #2 (sDMDMm2) for colonizing germ-free mice with defined microbiota.”

The modified question was if any of these bacteria have a gene for  β-glucanase in?

Acutalibacter muris not found
Akkermansia muciniphila yes
Bacteroides caecimuris  yes
Bifidobacterium animalis subsp. animalis not found
Blautia coccoides not found
Enterococcus faecalis not found
Flavonifractor plautii not found
Lactobacillus reuteri   yes
Muribaculum intestinale yes
Turicimonas muris not found
[Clostridium] clostridioforme not found
[Clostridium] innocuum not found

The Lactobacillus reuteri protein sequence was used to Blast search the bacteria database.  Many other species of Lactobacilli were found including Lactobacillus acidophillus.

Short Chain Fatty Acids and Bug Wars

The authors cited references regarding the low solubility of β-glucans in the gut that could result in decreased absorption of cholesterol and triglycerides as well as the greater excretion of fecal bile acids and cholesterol.  Whether the increased load of bile acids and/or cholesterol entering the colon had any influence on the microbiome was not discussed.  Material in the caecum might be interesting to test in future studies.    The potential role of short chain fatty acids produced by the intestinal microbiome on cholesterol and fatty acid metabolism was not examined in this study.   Short chain fatty acids enter the portal vein with the liver being the first stop before entering the general circulation.

A role for the polyphenols?

It should be noted that the triterpenes in Gl extracts are themselves cholesterol derivatives. The authors citd references in the literature finding an association in the polyphenols of Gl and improved lipid profiles.

ganoderic_acid
Ganoderic acid has the same cholesterol backbone as many steroid hormones. May it control cholesterol levels by regulation of gene expression as steroid hormones do?

We cannot ignore the possibility that ganoderic acid or another triterpene had an influence on cholesterol metabolism.  Either way, this is a very nice study.

References

Chang CJ, Lin CS, Lu CC, Martel J, Ko YF, Ojcius DM, Tseng SF, Wu TR, Chen YY, Young JD, Lai HC.(2015) Ganoderma lucidum reduces obesity in mice by modulating the composition of the gut microbiota. Nat Commun. 6:7489.  PubMed

Meneses ME, Martínez-Carrera D, Torres N, Sánchez-Tapia M, Aguilar-López M, Morales P, Sobal M, Bernabé T, Escudero H, Granados-Portillo O, Tovar AR. (2016) Hypocholesterolemic Properties and Prebiotic Effects of Mexican Ganoderma lucidum in C57BL/6 Mice. PLoS One.11(7):e0159631  PubMed

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