[Biosynthesis of somatotropin in a recombinant strain of Escherichia coli]. / Biosintez somatotropina rekombinantnym shtammom Escherichia coli.

A recombinant Escherichia coli K-12 strain was grown in the regime of chemostat with glucose limitation at a different flow rate and in the regime of turbidostat. The stability of its population and the dynamics of somatotropin biosynthesis were studied. The plasmid-containing strain became less stable as the flow rate in the fermenter dropped down, which was due, apparently, to a greater limitation. The level of somatotropin biosynthesis was higher at a low dilution rate (D = 0.075, 0.17 and 0.34 h-1). Possible factors responsible for this phenomenon are discussed.

[Characteristics of central metabolism in coryneform bacteria]. / Osobennosti tsentral'nogo metabolizma u korinepodobnykh bakterii.

The enzyme apparatus of the tricarboxylic acid cycle (TAC), the pathways involving carbohydrate catabolites in the cycle, and the anaplerotic mechanisms were comparatively studied in cultures belonging to two groups of coryneform bacteria, viz. corynebacteria and rhodococci, in order to assess their potential ability for oversynthesis of primary metabolites. It has been shown that corynebacteria and rhodococci (including those producing nucleotides and amino acids) are similar in the TAC structure and the enzyme activity, but differ in the operation of the glyoxylate shunt.

[Metabolic mechanism of adenine nucleotide synthesis from exogenous adenine in corynebacteria]. / Izuchenie metabolicheskogo mekhanizma sinteza adenilovykh nukleotidov iz ékzogennogo adenina u korinebakterii.

The purpose of this work was to study the activity of the key enzymes of intermediate metabolism in cultures belonging to several genera of coryneform bacteria, either capable or incapable of producing adenylic nucleotides from exogenous adenine. The results are indicative of an increase in the activity of polyphosphate-dependent hexokinase by the stationary growth phase in corynebacteria; in contrast, the activity of the enzyme in coryneform bacteria (rhodococci) remained unchanged. The absence of transketolase activity in the producing strains seems to account for the overproduction of ribose-5-phosphate.

[Carbohydrate metabolic characteristics of coryneform bacteria]. / Osobennosti metabolizma uglevodov u korinepodobnykh bakterii.

The peculiarities of glucose metabolism were studied in typical representatives of coryneform bacteria, and its relation to inorganic polyphosphate metabolism was shown. The activity of the first two enzymes in the pentose pathway was found to be low. The key enzymes of glycolysis were detected, viz. fructose-1,6-diphosphate aldolase and 3-phosphoglyceraldehyde dehydrogenase. The second enzyme was more active in Nocardia sp. B-293 similar in its properties to Nocardia erythropolis as compared to the enzymes of the pentose shunt. The existence of polyphosphate glucokinase more active than ATP-dependent hexokinase is indicative of inorganic polyphosphates being involved in the metabolism of the above microorganisms.

[Characteristics of the tricarboxylic acid cycle in Nocardia erythropolis]. / Osobennosti tsikla trikarbonovykh kislot u Nocardia erthyropolis.

The activity of enzymes involved in the tricarboxylic acid cycle was studied in Nocardia erythropolis IBFM B-293. It was found to be low and hardly change, with some exceptions, in the course of growth in the presence of various carbon sources. Acetate induced enzymes of the glyoxylate cycle which was here an important mechanism of oxalacetate synthesis. The absence of alpha-ketoglutarate dehydrogenase in the case of all studied substrates and the absence of 4-aminobutyrate aminotransferase, the key enzyme of the compensating 4-aminobutyrate shunt, suggest that the tricarboxylic acid cycle is decoupled. Therefore, this cycle does not operate as a mechanism generating energy in N. erythropolis, but fulfills mainly biosynthetic functions.

[Distribution of pyrimidine blocks in the DNA of Brevibacterium linens, Arthrobacter globiformis, Nocardia corallina and Nocardia rubra]. / O raspredelenii pirimidinovykh blokov v DNK Brevibacterium linens, Arthrobacter globiformis, Nocardia Corallina i Nocardia rubra

The nucleotide composition and the frequency of pyrimidine blocks were studied in DNA of the following bacteria: Brevibacterium linens (Weignamm, 1910) Breed, 1953; Arthrobacter globiformis (Conn, 1928) Conn et Dimmick, 1947; Nocardia corallina (Bergey et al., 1923) Waksman et Henrici, 1948; Nocardia rubra (Krassilnikov, 1949) Waksman et Henrici, 1948. These organisms are classed by some microbiologists as mycobacteria (the Mycobacteriaceae family) while other authors regard them as representatives of three families belonging to two orders. About 60 percent of all pyrimidines in DNA of these bacteria are found in the sequences pur-pyr-pur and pur-pyr-pyr-pur, the number of dipyrimidines being higher than the amount of monopyrimidine nucleotides. The content of dipyrimidine nucleotides in DNA of Nocardia corallina and Nocardia rubra is higher (16.8 mole %) than the content of dipyrimidine blocks in DNA of Brevibacterium linens and Arthrobacter globiformis, in which the quantity of dipyrimidines is almost the same (13.9 and 14.4 mole %). A new characteristic, the selected mean value, is suggested to evaluate differences in the distribution of pyrimidines in DNA.