Production of medium-chain volatile fatty acids by mixed ruminal microorganisms is enhanced by ethanol in co-culture with Clostridium kluyveri. 2015

Paul J Weimer, and Michael Nerdahl, and Dane J Brandl
US Dairy Forage Research Center, Agricultural Research Service, United States Department of Agriculture, Madison, WI 53706, USA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA. Electronic address: Paul.Weimer@ars.usda.gov.

Mixed bacterial communities from the rumen ferment cellulosic biomass primarily to C2-C4 volatile fatty acids, and perform only limited chain extension to produce C5 (valeric) and C6 (caproic) acids. The aim of this study was to increase production of caproate and valerate in short-term in vitro incubations. Co-culture of mixed ruminal microbes with a rumen-derived strain of the bacterium Clostridium kluyveri converted cellulosic biomass (alfalfa stems or switchgrass herbage) plus ethanol to VFA mixtures that include valeric and caproic acids as the major fermentation products over a 48-72h run time. Concentrations of caproate reached 6.1gL(-1), similar to or greater than those reported in most conventional carboxylate fermentations that employ substantially longer run times.

UI MeSH Term Description Entries
D002208 Caproates Derivatives of caproic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a carboxy terminated six carbon aliphatic structure. Hexanoates,Caproic Acid Derivatives,Caproic Acids,Hexanoic Acid Derivatives,Hexanoic Acids,Acid Derivatives, Caproic,Acid Derivatives, Hexanoic,Acids, Caproic,Acids, Hexanoic,Derivatives, Caproic Acid,Derivatives, Hexanoic Acid
D005232 Fatty Acids, Volatile Short-chain fatty acids of up to six carbon atoms in length. They are the major end products of microbial fermentation in the ruminant digestive tract and have also been implicated in the causation of neurological diseases in humans. Fatty Acids, Short-Chain,Short-Chain Fatty Acid,Volatile Fatty Acid,Acid, Short-Chain Fatty,Acid, Volatile Fatty,Fatty Acid, Short-Chain,Fatty Acid, Volatile,Fatty Acids, Short Chain,Short Chain Fatty Acid,Short-Chain Fatty Acids,Volatile Fatty Acids
D005285 Fermentation Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID. Fermentations
D000431 Ethanol A clear, colorless liquid rapidly absorbed from the gastrointestinal tract and distributed throughout the body. It has bactericidal activity and is used often as a topical disinfectant. It is widely used as a solvent and preservative in pharmaceutical preparations as well as serving as the primary ingredient in ALCOHOLIC BEVERAGES. Alcohol, Ethyl,Absolute Alcohol,Grain Alcohol,Alcohol, Absolute,Alcohol, Grain,Ethyl Alcohol
D000455 Medicago sativa A plant species of the family FABACEAE widely cultivated for ANIMAL FEED. Alfalfa,Lucerne
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012417 Rumen The first stomach of ruminants. It lies on the left side of the body, occupying the whole of the left side of the abdomen and even stretching across the median plane of the body to the right side. It is capacious, divided into an upper and a lower sac, each of which has a blind sac at its posterior extremity. The rumen is lined by mucous membrane containing no digestive glands, but mucus-secreting glands are present in large numbers. Coarse, partially chewed food is stored and churned in the rumen until the animal finds circumstances convenient for rumination. When this occurs, little balls of food are regurgitated through the esophagus into the mouth, and are subjected to a second more thorough mastication, swallowed, and passed on into other parts of the compound stomach. (From Black's Veterinary Dictionary, 17th ed) Rumens
D012418 Ruminants A suborder of the order ARTIODACTYLA whose members have the distinguishing feature of a four-chambered stomach, including the capacious RUMEN. Horns or antlers are usually present, at least in males. Goats, Mountain,Ruminantia,Oreamnos americanus,Goat, Mountain,Mountain Goat,Mountain Goats,Ruminant
D014631 Valerates Derivatives of valeric acid, including its salts and esters. Pentanoate,Pentanoates,Valerate
D047010 Clostridium kluyveri A species of gram-positive bacteria in the family Clostridiaceae. It is distinctive for its ability to ferment ETHANOL to caproic acid.

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