The effects of acetate, propionate, and butyrate on the anaerobic thermophilic conversion of propionate by methanogenic sludge and by enriched propionate-oxidizing bacteria in syntrophy with Methanobacterium thermoautotrophicum delta H were studied. The methanogenic sludge was cultivated in an upflow anaerobic sludge bed (UASB) reactor fed with propionate (35 mM) as the sole substrate for a per...

Acetate, propionate, and butyrate are the main short-chain fatty acids (SCFAs) that arise from the fermentation of fibers by the colonic microbiota. While many studies focus on the regulatory role of SCFAs, their quantitative role as a catabolic or anabolic substrate for the host has received relatively little attention. To investigate this aspect, we infused conscious mice with physiological q...

Four ewes, each fitted with a rumen cannula and with catheters in the mesenteric artery and portal and mesenteric veins, received continuous intrarumen infusions of water or of short-chain fatty acids (SCFA). SCFA infusions were isoenergetic (83 kJ/h) and provided rumen molar proportions (acetate:propionate:butyrate) of 70:20:10, 50:40:10 or 50:20:30. The rumen SCFA production rate with the bas...

The usefulness of butyrate, acetate, propionate and l-lactate for the control of Campylobacter jejuni infections in broilers was assessed. For this purpose, the effect of these acids on the growth of C. jejuni in broth and intestinal mucous was determined, as well as their influence on the invasiveness of C. jejuni in intestinal epithelial cells. From these in vitro obtained results, one acid w...

This chapter reviews recent studies on blends of conventional cellulose esters (CEs), such as cellulose acetate (CA), cellulose propionate (CP), and cellulose butyrate (CB), with non-crystalline vinyl (co)polymers mainly comprising the N-vinyl pyrrolidone (VP) unit. The mixing behavior of the CE/VP-containing copolymer blends is seriously affected by the chain length (i.e., carbon number) and d...

An in vitro faecal incubation system was used to study the metabolism of complex carbohydrates by intestinal bacteria. Homogenates of human faeces were incubated anaerobically with added lactulose, pectin, the hemicellulose arabinogalactan, and cellulose, both before and after subjects had been pre-fed each carbohydrate. Fermentation of added substrate was assessed by the production of short-ch...

The primary alcohol/aldehyde dehydrogenase (coded by the aad gene) is responsible for butanol formation in Clostridium acetobutylicum. We complemented the non-sporulating, non-solvent-producing C. acetobutylicum M5 strain (which has lost the pSOL1 megaplasmid containing aad and the acetone-formation genes) with aad expressed from the phosphotransbutyrylase promoter and restored butanol producti...

Short-chain fatty acids (SCFAs) are microbial metabolites, mainly generated by the action of gut microbiota on dietary fibers. Acetate, propionate, and butyrate three main SCFAs produced typically in a 60:20:20 molar ratio colon. butyrate, when given individually as supplements, have shown protective role obesity hyperglycemia; however, sex-specific effects mixture SCFAs, ratio, regulation lipi...

Isocitratase, which cleaves isocitrate to glyoxylate and succinate and is a key enzyme in the glyoxylate cycle, is formed by Rhodopseudomonas palustris and R. capsulatus when grown on acetate or butyrate either anaerobically in light or aerobically in the dark. Only traces of the enzyme are present in organisms grown on succinate or malate. In contrast, isocitratase is detectable in traces only...