Production of tricarballylic acid by rumen microorganisms and its potential toxicity in ruminant tissue metabolism.

1. Rumen microorganisms convert trans-aconitate to tricarballylate. The following experiments describe factors affecting the yield of tricarballylate, its absorption from the rumen into blood and its effect on mammalian citric acid cycle activity in vitro. 2. When mixed rumen microorganisms were incubated in vitro with Timothy hay (Phleum pratense L.) and 6.7 mM-trans-aconitate, 64% of the trans-aconitate was converted to tricarballylate. Chloroform and nitrate treatments inhibited methane production and increased the yield of tricarballylate to 82 and 75% respectively. 3. Sheep given gelatin capsules filled with 20 g trans-aconitate absorbed tricarballylate and the plasma concentration ranged from 0.3 to 0.5 mM 9 h after administration. Feeding an additional 40 g potassium chloride had little effect on plasma tricarballylate concentrations. Between 9 and 36 h there was a nearly linear decline in plasma tricarballylate. 4. Tricarballylate was a competitive inhibitor of the enzyme, aconitate hydratase (aconitase; EC 4.2.1.3), and the inhibitor constant, KI, was 0.52 mM. This KI value was similar to the Michaelis-Menten constant (Km) of the enzyme for citrate. 5. When liver slices from sheep were incubated with increasing concentrations of tricarballylate, [14C]acetate oxidation decreased. However, even at relatively high concentrations (8 mM), oxidation was still greater than 80% of the maximum. Oxidation of [14C]acetate by isolated rat liver cells was inhibited to a greater extent by tricarballylate. Concentrations as low as 0.5 mM caused a 30% inhibition of citric acid cycle activity.

Citric acid production with mixed strains of Aspergillus niger

Seis linhagens de Aspergillus niger, provenientes de indústrias e 15 combinaçöes dessas linhagens, foram analisadas quantitativamente, em relaçäo à acidez total e à produçäo de ácido cítrico. O delineamento experimental permitiu determinar os efeitos da capacidade de combinaçäo e desse modo pode ser avaliada a contribuiçäo de cada linhagem nessas combinaçöes. Apenas em poucos casos, a fermentaçäo com mistura de linhagens mostrou uma tendência para uma produçäo de ácido cítrico intermediária em relaçäo à produçäo de linhagens isoladas. Dez combinaçöes de linhagens tiveram uma produçäo de ácido cítrico mais baixa do que a da linhagem combinada, de menor produçäo. Quatro combinaçöes apresentaram produçäo de ácido cítrico intermediária, e em apenas um caso, a produçäo de ácido cítrico excedeu a das linhagens combinadas

[Ability of various lactic bacteria to transform aspartate and glutamate]. / O sposobnosti nekotorykh molochnokislykh bakterii prevrashchat' aspartat i glutamat

Transformation of labelled glutamic and aspartic acids (5-14C, 4-14C) was studied in growth media of various strains of Streptococcus acetonicus. These strains which participate in production of cheese with excellent organoleptic properties are active in synthesis of di- and tricarboxylic acids, and also keto acids. Such a relationship was not found in the case of 5-14C-glutamic acid.

[Factors participating in regulation of protein biosynthesis].

Studies in the processes of protein biosynthesis regulation revealed a close dependence of the biosynthetic processes (synthesis of many precursors of proteins, nucleic acids, lipids, carbohydrates as well as of tricarboxylic cycle acids) on the processes of carboxylation in the organism. A possibility is shown of the biosynthetic processes stimulation by activating the carboxylation processes. On this bases a highly effective method to increase productivity of farm animals and poultry and that for considerable acceleration of the regeneration processes of the damaged tissues and blood with blood less were developed. It is also established that at extremal states of the organism (long complete fasting, late stages of cancer, thyreoid toxicosis, experimental atherosclerosis, etc.) in tissues there occurs biosynthesis of proteins with differing primary structure, physiochemical properties and enzymatic activity as compared to proteins of the normal animals. The same changes in the primary structure and properties of proteins in the process of their biosynthesis are observed with the surplus feeding the animals on certain amino acids aginst a background of protein free ration. Possible mechanisms of changes in the primary structure of proteins in the process of their biosynthesis at extremal states of the organism are under discussion. In experiments in vitro on the tissue preparations, on the cell-free protein-synthetizing systems as well as in experiments with animals in vivo the presence of synergic and antagonistic interrelation was established between certain amino acids in the process of their utilization for protein biosynthesis. These interrelations are established to take place at the stage of transfer ribonucleic acids aminoacylation. Some details of this phenomenon are found out. Amino acids are shown to play not only a substrate role but also the regulatory one in the process of protein biosynthesis.