Endogenous Ethanol and Triglyceride Production by Gut Pichia kudriavzevii, Candida albicans and Candida glabrata Yeasts in Non-Alcoholic Steatohepatitis

Abstract

Nonalcoholic steatohepatitis (NASH) increases with fructose consumption and metabolic syndrome and has been recently linked with endogenous ethanol production, notably by high alcohol-producing Klebsiella pneumoniae (HiAlc Kpn). Candida yeasts are the main causes of auto-brewery syndromes but have been neglected in NASH. Here, the fecal ethanol and microbial content of 10 cases and 10 controls were compared. Ethanol was measured by gas chromatography-mass spectrometry. Species identification was performed by MALDI-TOF MS, and triglyceride production was assessed by a colorimetric enzymatic assay. The fecal ethanol concentration was four times higher in patients with NASH (median [interquartile range]: 0.13 [0.05–1.43] vs. 0.034 [0.008–0.57], p = 0.037). Yeasts were isolated from almost all cases but not from controls (9/10 vs. 0/10, p = 0.0001). Pichia kudriavzevii was the most frequent (four patients), while Candida glabrata, Candida albicans, and Galactomyces geotrichum were identified in two cases each. The concentration of ethanol produced by yeasts was 10 times higher than that produced by bacteria (median, 3.36 [0.49–5.60] vs. 0.32 [0.009–0.43], p = 0.0029). Using a 10% D-fructose restricted medium, we showed that NASH-associated yeasts transformed fructose in ethanol. Unexpectedly, yeasts isolated from NASH patients produced a substantial amount of triglycerides. Pichia kudriavzevii strains produced the maximal ethanol and triglyceride levels in vitro. Our preliminary human descriptive and in vitro experimental results suggest that yeasts have been neglected. In addition to K. pneumoniae, gut Pichia and Candida yeasts could be linked with NASH pathophysiology in a species- and strain-specific manner through fructose-dependent endogenous alcohol and triglyceride production.

Detection and Quantification of Some Ethanol-Producing Bacterial Strains in the Gut of Mouse Model of Non-Alcoholic Fatty Liver Disease: Role of Metformin

“…An explanation for our bizarre results came from a very recent work of Mbaye et al [ 39 ]. In their study, they found that the faecal ethanol contents were four times higher in NASH patients in comparison to control.…”

“…On Day 1, Day 3, Day 7, and Day 10, 500 μL of the bottle content was sampled followed by 10-fold serial dilutions and inoculation on MacConkey agar. The same method was used but with the addition of 5% and 10% ethanol to the bottle in order to identify alcohol-resistant non-fastidious Gram-negative bacteria [ 39 ]. Counting in this approach was expressed as log10 of cfu/mL.…”

Gut microbiota in MAFLD: therapeutic and diagnostic implications

“…Therefore, the alcohol produced by gut bacteria represents a potential factor in the development and progression of MAFLD and highlights the role of endogenous alcohol in the liver pathology associated with this metabolic disorder. 29 , 111 , 112 …”

The Ethanol-Producing Enterocloster bolteae and Limosilactobacillus fermentum are enriched in Nonalcoholic steatohepatitis

“…Zhu et al found high concentrations of ethanol in the blood of NASH patients, con rmed in patients' stools by Yuan et al [8,9]. Case-control studies have shown the involvement of speci c microorganisms in endogenous ethanol production, notably yeasts of the Candida and Pichia genus [12] and bacteria including Klebsiella pneumoniae, Limosilactobacillus fermentum and Lactococcus lactis [9,13].…”