014), while vegetarians showed the highest number of copies (P=0.048). The thermal denaturation of the butyryl-CoA:acetate CoA-transferase gene variant melting curve related to Roseburia/Eubacterium rectale spp. was significantly more variable in the vegetarians than in the elderly. The Clostridium cluster XIVa was more abundant in vegetarians (P=0.049) and in omnivores (P<0.01) than in the elderly group. Gastrointestinal microbiota of the elderly is characterized by decreased butyrate production capacity, reflecting increased risk of degenerative diseases.

These results suggest that the butyryl-CoA:acetate CoA-transferase gene is a valuable marker for gastrointestinal microbiota function. Recent evidence suggests that 1000–1150 different species are capable of living in the gut ecosystem. An individual harbours at least 160 species (Qin et al., 2010), with high interindividual variations in species diversity and evenness. It has Daporinad been reported that the microbiota

composition is influenced by diet (Larsen et al., 2010) and age (Mariat et al., 2009), as well as genetic factors (Khachatryan et al., 2008). The gastrointestinal microbiota produces short-chain fatty acids (SCFAs). Butyrate is of particular interest due to its anticarcinogenic and anti-inflammatory potential (Maslowski et al., 2009), its effects on the intestinal barrier (Peng et al., 2007), satiety (Cani et al., 2009) and Selleckchem BGB324 epigenetic regulation (Rada-Iglesias et al., 2007). Two of the most important groups of butyrate producers are Faecalibacterium prausnitzii from the Clostridium cluster IV, and the Eubacterium rectale/Roseburia spp. from the Clostridium cluster XIVa (Walker et al., 2010). Methane monooxygenase Both clusters (now also known as Ruminococcaceae and Lachnospiraceae) consist of producers and nonproducers of butyrate (Pryde et al., 2002).

Isolated dietary compounds have been shown to promote growth of butyrate producers (Hernot et al., 2009). For example, the consumption of inulin significantly stimulated growth of F. prausnitzii (Louis & Flint, 2009). In colonic in vitro model systems, resistant starch stimulated the growth of E. rectale (Leitch et al., 2007). Butyrate is easily taken up by the gut mucosa and faecal butyric acid levels give little information about the butyrate-producing capacity of the gut microbiota. Therefore, a function-based approach was suggested for the enumeration of butyrate-producing bacteria (Louis & Flint, 2007) targeting the butyryl-CoA:acetate CoA-transferase gene. Furthermore, the butyryl-CoA:acetate CoA-transferase route, using acetate as a cosubstrate, is suggested to be the most important route for butyrate production in the gut ecosystem (Duncan et al., 2004). Alternative routes are via butyrate kinase and phosphotransbutyrylase, which are found in a minority of bacteria (Louis et al., 2004) in the human gastrointestinal tract.