Vol 53, No 5 (2017)

The literature data on prokaryotic adaptation to changes in environmental conditions that lead to a change in the metabolism and, at the same time, are also exhibited in the preservation of many biochemical reactions of the central metabolism due to the functioning of alternative enzymes are summarized. Unlike isozymes, the alternative enzymes have different active sites and are encoded by different genes but catalyze the same key biochemical reaction of the central metabolism. Biochemical inconstancy and the immutability of a biochemical reaction in prokaryotes should be taken into account in metabolic engineering aimed at optimization of gene expression.

A heterogeneous biocatalyst for the biotransformation of nitriles and amides of carboxylic acids in the form of cells of nitrile-hydrolyzing bacteria immobilized on the carrier, was created based on multiwalled carbon nanotubes (MWCNTs). It was shown that bacterial cells form aggregates in contact with powderformed purified or unpurified MWCNTs. The amount of both gram-positive and gram-negative bacteria binding with unpurified MWCNTs was significantly higher than with purified. The nitrile hydratase and amidase activity of bacterial aggregates of purified MWCNTs was preserved to a greater extent as compared to that of unpurified MWCNTs and cells adhered to the surface of the carbonized pyrosealing material with MWCNTs. Both gram-positive Rhodococcus ruber gt1 and gram-negative Alcaligenes faecalis 2 remained viable when cultured in the presence of purified or unpurified MWCNTs. The obtained heterogeneous biocatalyst can be easily separated from the medium by filtration and can be used repeatedly.

The influence of glutamate dehydrogenase activity on the production of L-proline in the producer strain Brevibacterium flavum AP111 was studied. Transformants of the Brevibacterium flavum strain AP111 were obtained with the use of a recombinant plasmid previously constructed by us, pVOG10. It includes the encoding sequence of the gdh gene, which is responsible for the synthesis of glutamate dehydrogenase. The production of L-proline in transformants was shown to have increased by more than 40%. The results can serve as the basis for the use of this approach to improve strains producing other amino acids of the glutamine family.

A bacterial strain has been isolated from soil contaminated by waste from petrochemical production. Based on its cultural-morphological, physiological-biochemical properties and an analysis of the nucleotide sequence of the 16S rRNA gene and phylogenetic analysis data, the strain was defined as Pseudomonas plecoglossicida 2.4-D. The unique ability of this bacterium to use perfluorooctanyl sulfonate (PFOS) as the only source of carbon and energy is shown. When cultivated in a liquid medium, the strain completely utilizes this substance in 6 days. It is proved that P. plecoglossicida 2.4-D transforms PFOS to perfluoroheptanoic (perfluoroenanthic) acid, while free fluorine ions are released into the medium. Upon introduction into the soil, the strain was capable of PFOS degradation by 75%. The strain P. plecoglossicida 2.4-D is recommended for environmental protection. It can be used in the development of biotechnologies for the transformation (utilization) of fluoroorganic compounds.

The effect of growth media manipulation on the in vitro biofilm forming ability of Azotobacter chroococcum MTCC 25045 and Trichoderma viride ITCC 2211, both as individual cultures and co-culture was evaluated for 16 days. Growth curves (Bioscreen C lab system) and type of microbial population (planktonic and biofilm) helped to validate the aggregation and biofilm data. Modulation of combinations of routine growth media—Jensen’s broth (J) and potato dextrose broth (P) by changing their ratios (100, 75: 25, 50: 50, and 25: 75) was undertaken. In individual bacterial or fungal inoculation, the growth media–J25: P75 and P100 caused significantly (p < 0.01) higher growth, aggregation, and biofilm formation. In co-culture, J25: P75 medium showed enhanced planktonic as well as biofilm population, aggregation, and biofilm formation followed by J50: P50 and J75: P25 media. This is a first report on interrelationships among growth, aggregation and biofilm formation in relation to medium optimization for fungal-bacterial biofilm development.

The effect of infection with fungus Septoria nodorum strains differing in aggressiveness on the activity of hydrolytic enzymes (amylases and proteinases) and their protein inhibitors in the leaves of Triticum aestivum L. pretreated with salicylic and jasmonic acids was studied. It was shown that aggressive Septoria nodorum strains accelerated development, caused intensive necrotic reaction on the wheat leaves, increased the production of amylases and proteinases, and decreased the activity of their protein inhibitors. Salicylic and jasmonic acids altered the activity of the “hydrolase-inhibitor” complex, which indicated the possibility of regulation of the activity (content) of this group of compounds via exogenous effects, including the treatment of plants with inducers of resistance of various natures.

The effect of hydrogen sulfide (H₂S) donor sodium hydrosulfide (NaHS) on the heat resistance of wheat (Triticum aestivum L.) coleoptile cells, the formation of reactive oxygen species (ROS), and the activity of the antioxidant enzymes in them was investigated. The treatment of coleoptiles with 100 µM NaHS caused transient enhancement of the generation of the superoxide anion radical (O₂^•) and an increased hydrogen peroxide content. The activities of antioxidant enzymes—superoxide dismutase, catalase, and guaiacol peroxidase— and coleoptile resistance to damaging heat was later found to have increased. The biochemical and physiological effects of the hydrogen sulfide donor described above were inhibited by the treatment of wheat coleoptiles with the hydrogen peroxide scavenger dimethylthiourea, the NADPH oxidase inhibitor imidazole, the extracellular calcium chelator EGTA, and the phosphatidylinositol-specific phospholipase C inhibitor neomycin. A conclusion was made on the role of ROS generation, which is dependent on the activity of NADPH oxidase and calcium homeostasis, in the transduction of the H₂S signal, which induces antioxidant enzymes and the development of plant cell heat resistance.

We studied the adjuvant properties of micelles from nonionogenic detergents, liposome, and selenium nanoparticles containing extracellular and intracellular vaccine antigens of a weakly virulent α-hemolytic Escherichia coli B-5 strain used for the immunization of experimental animals. Triton X-100 was used as a nonionogenic detergent for micelle preparation. The liposomes were obtained on the basis of lecithin from a chicken egg and E. coli B-5 membrane lipids. Native lipoproteins of E. coli B-5 cells and peptides for the proteolytic hydrolysis of toxin-containing culture liquid were used as antigens for micelles and liposomes. The obtained data suggested that micelles, liposomes, and selenium nanoparticles can be used for immunization with cellular and extracellular E. coli antigens.

The parameters of the process of isolation, concentration, and gas chromatographic analysis of volatile organic compounds by solid-phase microextraction were optimized. With different amounts of a mixture of essential oils, the conditions of reproducibility of their determination were established based on the absolute values of the squares of chromatographic peaks obtained by capillary gas chromatography. It was found that the efficiency of the extraction of volatile compounds from gas phase by sorption on mixed polymer (consisting of polydimethylsiloxane and divinylbenzene) was significantly influenced by the structure of their molecules, while the sorption time and their content in the liquid phase influenced the significance of determination.