[The esterase activity of a pigmented bacterial group belonging to the Pseudomonas genus]. / Esteraznaia aktivnost' pigmentnoi gruppy bakterii roda Pseudomonas.

Bacteria belonging to the Pseudomonas genus and isolated from zonal soils in different geographical zones of the USSR as well as from the rhizosphere of cultivated and wild plants were tested for their esterase activity. The studied collection of cultures included 205 strains of different pigmented Pseudomonas species which, according to the conventional taxonomy, were assigned to the so-called "Pseudomonas fluorescens complex". As was shown in this study, many Pseudomonas species are potential producers of nonspecific esterases. P. maltophilia and P. geniculata synthesizing pyomelanin have the highest activity of esterase. The activity of esterase correlates with the formation of a melanin-like pigment in Pseudomonas cultures. It also correlates with the species to which a culture belongs, which makes it possible to use this property as an additional criterion for the identification of Pseudomonas species.

[Effect of various carbon sources on cholinesterase formation by Arthrobacter simplex var. cholinesterasus]. / Vliianie razlichnykh istochnikov ugleroda na obrazovanie kholinésterazy Arthrobacter simplex var. cholinesterasus

The effect of carbohydrates, aromatic alcohols, choline and acetylcholine on the biomass production and biosynthesis of choline esterase was studied with Arthrobacter simplex var. cholinesterasus. Fructose was found to be the best carbon source for the biomass accumulation and synthesis of choline esterase. Almost the same amount of the enzyme was produced on media with glucose and maltose as on the medium with fructose though the biomass yield was much lower. On the contrary, the biomass production was higher on media with acetylcholine and ethanol, but synthesis of the enzyme was inhibited. Choline was not assimilated by the culture. Differences in assimilation of glucose and fructose by the culture were found to depend on their concentration and the presence, or absence, of the inductor (acetylcholine) in the medium. Fructose was assimilated by the culture almost completely irrespective of its concentration and the presence of the inductor in the medium. Glucose was assimilated partly, best of all at a concentration of 0.5%. An increase of the concentration to 1% inhibited assimilation of glucose by the organism though had no effect on the biomass production and synthesis of the enzyme. The inductor stimulated assimilation of glucose by a factor of 1.5. Synthesis of choline esterase on the medium with acetylcholine at a concentration of 1% was increased more than twofold upon addition of glucose at a concentration of 0.1%. Biosynthesis of the enzyme rised with glucose concentration though accumulation of the biomass was inhibited. Inhibition of choline esterase synthesis on the medium with acetylcholine as a sole carbon source is due to a lack of energy and the absence of synthesis of carbon compounds which are acceptors of acetyl and methyl groups.

[Effect of nitrogen source on growth of Arthrobacter simplex and its biosynthesis of cholinesterase]. / Vliianie istochnika azota na rost Arthrobacter simplex i biosintez kholinésterazy

The effect of organic and inorganic forms of nitrogen on biomass accumulation and cholinesterase synthesis was studied with Arthrobacter simplex var. cholinesterasus. The culture assimilates nitrogen of ammonium compounds better than other forms of inorganic nitrogen; the best nitrogen source for biosynthesis of cholinesterase is ammonium phosphate. Nitrogen of nitrates is not assimilated. The amount of biomass is almost twice as high on the medium with peptone, casein or casein hydrolysate as on the medium with mineral nitrogen, while the activity of cholinesterase on these nitrogen sources decreases 1.5--2.0 times. Yeast extract as a nitrogen source increases biomass accumulation by a factor of 2.5 and does not supress synthesis of cholinesterase. The concentration of the enzyme synthesized per unit biomass on the medium with yeast extract is the same as on the medium containing ammonium phosphate. The effect of amino acids and amides, i.e. beta-alanine, proline, amides of aspartic and glutamic acids, and their mixtures, is similar to the action of yeast extract: they stimulate biomass accumulation and do not inhibit synthesis of the enzyme. Other amino acids supress synthesis of cholinesterase. The amount of accumulated biomass in the presence of glutamic acid is twice as high as in the case of any other amino acid, and three times as high as on the medium containing ammonium phosphate. Similar action of glutamic acid is manifested when it is used in mixtures with other amino acids. On the medium containing glutamic acid as a sole source of nitrogen, an increase in biomass production is accompanied with a decrease in biosynthesis of the enzyme by 50%. Repression of the biosynthesis is less if glutamic acid is added in mixtures with proline, beta-alanine and asparagine.