Caproate formation in mixed-culture fermentative hydrogen production

Ding, Hong-Bo; Tan, Giin-Yu Amy; Wang, Jing‐Yuan

doi:10.1016/j.biortech.2010.07.056

Cited by 120 publications

(91 citation statements)

References 17 publications

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“…3), indicating the importance of prokaryotes in the production of caproic acid. Caproic acid is a side product in the acidogenic fermentation of a complex biomass or sugars (37,38). It is generally produced by anaerobic bacteria such as Clostridium kluyveri (39) and Eubacterium pyruvativorans (40) or by cocultures of C. kluyveri with ruminal cellulolytic bacteria using cellulose as a substrate (41).…”

Section: Discussionmentioning

confidence: 99%

“…Although methanogens do not directly produce caproic acid, they can enhance caproic acid production through syntrophic cooperation between caproic-acid-producing bacteria and methanogens (5). Caproic acid formation and many other fermentation reactions are hydrogenogenic (38) under anaerobic conditions. The interspecies hydrogen transfer between caproic acid-producing or fermenting bacteria and methanogens controls hydrogen partial pressure under a certain threshold, which makes caproic acid formation and fermentation reactions thermodynamically more favorable.…”

Section: Discussionmentioning

confidence: 99%

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Prokaryotic Communities in Pit Mud from Different-Aged Cellars Used for the Production of Chinese Strong-Flavored Liquor

Tao

Rui

et al. 2014

Appl Environ Microbiol

164

228

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cChinese strong-flavored liquor (CSFL) accounts for more than 70% of all Chinese liquor production. Microbes in pit mud play key roles in the fermentation cellar for the CSFL production. However, microbial diversity, community structure, and cellar-agerelated changes in pit mud are poorly understood. Here, we investigated the prokaryotic community structure and diversity in pit-mud samples with different cellar ages (1, 10, 25, and 50 years) using the pyrosequencing technique. Results indicated that prokaryotic diversity increased with cellar age until the age reached 25 years and that prokaryotic community structure changed significantly between three cellar ages (1, 10, and 25 years). Significant correlations between prokaryotic communities and environmental variables (pH, NH 4 ؉ , lactic acid, butyric acid, and caproic acid) were observed. Overall, our study results suggested that the long-term brewing operation shapes unique prokaryotic community structure and diversity as well as pit-mud chemistry. We have proposed a three-phase model to characterize the changes of pit-mud prokaryotic communities. C hinese strong-flavored liquor (CSFL), also called "Luzhou flavor liquor," accounts for more than 70% of Chinese liquor production (1). It is produced by the unique and traditional Chinese solid-state fermentation technique, which has a history of several thousand years. In brief, a cellar is constructed by digging a rectangular soil pit in which the entire inner wall is covered with precultured pit mud. The precultured pit mud is usually prepared by mixing aged pit mud (as an inoculum), fresh common soil, and water and incubating the mixture for about a year in an anaerobic cellar before use. The raw materials for the fermentation, including wheat, sorghum, and corn, are mixed, crushed, and distilled by steaming. The steamed raw material is supplied with 2% to 3% (wt/wt) Daqu-starter, which mainly includes mold and yeast, and placed into the cellar. The cellar is sealed with common mud, and fermentation is allowed to proceed for 60 days. Fermented material is then taken out of the cellar and distilled to make Chinese liquor. The process described above is periodically repeated after new fermentation materials are supplied.Microbes in the pit mud produce various flavor components such as butyric acid, caproic acid, and ethyl caproate. In particular, ethyl caproate is recognized as a key component affecting the CSFL flavor and quality. In general, CSFL quality improves with increasing cellar age. High-quality liquor is produced only in old cellars, which are maintained at least for 20 years by continuous use (2, 3). In particular, some long-aged cellars have been used for several hundred years without interruption, and well-known CSFLs such as Wuliangye, Jiannanchun, and Luzhoulaojiao are brewed in such long-aged cellars (1, 4). High CSFL quality is attributed to the maturing process of pit mud, which results in a well-balanced microbial community structure and diversity in the pit mud to produce distinctive flavo...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Prokaryotic Communities in Pit Mud from Different-Aged Cellars Used for the Production of Chinese Strong-Flavored Liquor

Tao

Rui

et al. 2014

Appl Environ Microbiol

164

228

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“…Another interesting finding was the diet effect on gastric, ileal, and colonic caproate, which differed among gut sites, indicating that different caproate-producing bacteria dominated at the three gut sites. Caproate-producing bacteria can be found within different Clostridium clusters, such as clusters I, IV, XI, and XIV (41)(42)(43)(44)(45).…”

Section: Discussionmentioning

confidence: 99%

Changing Dietary Calcium-Phosphorus Level and Cereal Source Selectively Alters Abundance of Bacteria and Metabolites in the Upper Gastrointestinal Tracts of Weaned Pigs

Metzler‐Zebeli

Mann

Schmitz‐Esser

et al. 2013

Appl Environ Microbiol

101

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Several dietary ingredients may affect the bacterial community structure and metabolism in the porcine gut and may therefore influence animals' health and performance. This study investigated the effects of cereal source and calcium-phosphorus (CaP) level in the diet on bacterial microbiota and metabolites, nutrient intake, and gut environment in weaned pigs. Pigs (n ‫؍‬ 8/treatment) were fed wheat-barley-or corn-based diets with an adequate or high CaP level for 14 days. Effects on microbiota in the stomach, ileum, and midcolon were assessed using quantitative PCR. Data showed that Enterobacteriaceae, Campylobacter spp., and Helicobacter spp., which all contain highly immune reactive lipopolysaccharide (LPS), were abundant at all gut sites. Diet effects on bacteria and metabolites were moderate and occurred mainly in the upper gut, whereas no effects on bacteria, fermentation products, and LPS could be observed in the colon. Differences in carbohydrate intake with corn versus wheat-barley diets selectively stimulated Bifidobacterium in the stomach and ileum. There was a growth advantage for a few bacterial groups in the stomach and ileum of pigs fed the high versus adequate CaP level (i.e., gastric Enterobacteriaceae and ileal Enterococcus, Bacteroides-Prevotella-Porphyromonas, and Campylobacter). Interestingly, gastrointestinal pH was not affected by dietary CaP level. The present findings demonstrate the stability of the bacterial community and gut environment toward dietary changes even in young pigs. The results on stimulation of gastric and ileal Bifidobacterium by corn diets may be employed in nutritional strategies to support gut health after weaning.

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“…Ethanol is known to be a carbon source and reducing equivalent that promotes the chain elongation of carboxylic acids (Agler et al, 2012;Ding et al, 2010). In this study, ethanol was added at 2-2.5 g L À1 on day 5, 10, and 15 when its concentration dropped markedly during the mixed culture fermentation (Fig 2a).…”

Section: Effect Of Ethanol Additionmentioning

confidence: 99%

Carboxylic acid production from brewer’s spent grain via mixed culture fermentation

Liang

Chen

2015

Bioresource Technology

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Caproate formation in mixed-culture fermentative hydrogen production

Cited by 120 publications

References 17 publications

Prokaryotic Communities in Pit Mud from Different-Aged Cellars Used for the Production of Chinese Strong-Flavored Liquor

Prokaryotic Communities in Pit Mud from Different-Aged Cellars Used for the Production of Chinese Strong-Flavored Liquor

Changing Dietary Calcium-Phosphorus Level and Cereal Source Selectively Alters Abundance of Bacteria and Metabolites in the Upper Gastrointestinal Tracts of Weaned Pigs

Carboxylic acid production from brewer’s spent grain via mixed culture fermentation

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