Metabolism of select amino acids in bacteria from the pig small intestine

Abstract

This study investigated the metabolism of select amino acids (AA) in bacterial strains (Streptococcus sp., Escherichia coli and Klebsiella sp.) and mixed bacterial cultures derived from the jejunum and ileum of pigs. Cells were incubated at 37°C for 3 h in anaerobic media containing 0.5-5 mM select AA plus [U-14C]-labeled tracers to determine their decarboxylation and incorporation into bacterial protein. Results showed that all types of bacteria rapidly utilized glutamine, lysine, arginine and threonine. However, rates of the utilization of AA by pure cultures of E. coli and Klebsiella sp. were greater than those for mixed bacterial cultures or Streptococcus sp. The oxidation of lysine, threonine and arginine accounted for 10% of their utilization in these pure bacterial cultures, but values were either higher or lower in mixed bacterial cultures depending on AA, bacterial species and the gut segment (e.g., 15% for lysine in jejunal and ileal mixed bacteria; 5.5 and 0.3% for threonine in jejunal mixed bacteria and ileal mixed bacteria, respectively; and 20% for arginine in ileal mixed bacteria). Percentages of AA used for bacterial protein synthesis were 50-70% for leucine, 25% for threonine, proline and methionine, 15% for lysine and arginine and 10% for glutamine. These results indicate diverse metabolism of AA in small-intestinal bacteria in a species- and gut compartment-dependent manner. This diversity may contribute to AA homeostasis in the gut. The findings have important implications for both animal and human nutrition, as well as their health and well-beings.

Regulatory role for l-arginine in the utilization of amino acids by pig small-intestinal bacteria

“…The rapid and quantitatively significant utilization and metabolism of nutritionally essential AA (EAA) by pig small-intestinal bacteria helps to explain the relatively low portal balance of dietary AA in mammals. The findings also suggest that the bacterial metabolism of AA in the small intestine plays an important role in host nutrition and nitrogen balance (Stoll et al 1998;Dai et al 2010Dai et al , 2011aFuller and Reeds 1998;Bergen and Wu 2009). Moreover, because of the diverse functions of arginine in cells ), this AA may be crucial for the growth and survival of intestinal bacteria both at the species level and across the bacterial communities of different gut compartments (Dai et al 2010(Dai et al , 2011a.…”

“…All bacterial cultures were maintained in an anaerobic semi-defined medium described previously (Dai et al 2011a;Williams et al 2005) except with following modifications (per liter): 10 g casitone, 2.5 g yeast extract, 2 g soluble starch, 2 g glucose, 1 g maltose, 1 g cellobiose, 5 g sodium lactate, 0.2 g NH 4 Cl. The ''reducing agent solution'' contained 2.05 g Na 2 SÁ9H 2 O and 2.05 g cysteine-HCl per 100 mL of boiled distilled water.…”

“…Recent findings indicate that bacteria in the small intestine may be active in AA metabolism both in vivo and in vitro (Booijink 2009;Dai et al 2010Dai et al , 2011aFuller and Reeds 1998). The rapid and quantitatively significant utilization and metabolism of nutritionally essential AA (EAA) by pig small-intestinal bacteria helps to explain the relatively low portal balance of dietary AA in mammals.…”

Microbiome Disturbances and Autism Spectrum Disorders

“…Gut microbiota synthesize various essential vitamins and cofactors, such as folate and vitamin B 12 , which may affect DNA and histone protein methylation (Le Galliard et al, 2008;LeBlanc et al, 2013). Bacteria also metabolize complex lipids, proteins, and carbohydrates, including those that are indigestible by the host (Hooper et al, 2002;Saulnier et al, 2008;Dai et al, 2012). Bacterial fermentative processes result in the production of various short chain fatty acids (SCFAs), such as acetic, propionic, and butyric acid (BA) (Hooper et al, 2002).…”

Avaliação do metabolismo in vitro da budleína A e correlatos

“…A eliminação de CO 2 dos adutos pela atividade microbiana foi comum para ambas substâncias e é condizente com estudos realizados com linhagens de bactérias isoladas de intestino de porco, sendo inclusive a quantidade de CO 2 produzida utilizada para quantificar o metabolismo das diferentes culturas (Dai et al, 2012 4.5.2.2. 4β,5-diidro-2',3'-epoxi-15-desoxigoyazensolido Estas deduções são feitas principalmente pela presença ou não do íon de m/z 261,11 nos espectros de EM/EM, o qual indica e perda na forma neutra da cadeia lateral adicionada da cisteína.…”