Microbiological Processes in a High-Temperature Oil Field

Thermophilic sulfate-reducing bacteria (SRB) oxidizing lactate, butyrate, and C₁₂–C₁₆ n-alkanes of oil at a temperature of 90°C were isolated from samples of water and oil originating from oil reservoirs of the White Tiger high-temperature oil field (Vietnam). At the same time, no thermophiles were detected in the injected seawater, which contained mesophilic microorganisms and was the site of low-temperature processes of sulfate reduction and methanogenesis. Thermophilic SRB were also found in samples of liquid taken from various engineering reservoirs used for oil storage, treatment, and transportation. These samples also contained mesophilic SRB, methanogens, aerobic oil-oxidizing bacteria, and heterotrophs. Rates of bacterial production of hydrogen sulfide varied from 0.11 to 2069.63 at 30°C and from 1.18 to 173.86 at 70°C g S/(l day); and those of methane production, varied from 58.4 to 100 629.8 nl CH₄/(l day) (at 30°C). The sulfur isotopic compositions of sulfates contained in reservoir waters and of hydrogen sulfide of the accompanying gas indicate that bacterial sulfate reduction might be effective in the depth of the oil field.     

Microbial potential for cleaning the oiled iron scale

The possibility of using microorganisms to clean oiled iron scale of metallurgical production was investigated with the goal of recuperation. A stable microbial association growing on mineral oil as the sole carbon source was isolated from a sample from oiled iron scale taken directly from a metallurgical plant. For microbial cultures isolated from this association, the taxonomic position, as well as their morphological and cultural characteristics, were determined. The microorganisms belonged to the genera Luteimonas, Alcanivorax, Flavobacterium, and Pseudomonas. Microbial associations oxidizing mineral oil were found to contain some microorganisms incapable of its utilization, which stimulated the hydrocarbon-oxidizing microflora. Application of the isolates, as well as of the strains from microbial collections, resulted in a 58% decrease in residual oil content in treated samples of the oiled iron scale.     

Characterization of Escherichia coli strains O157:H7, isolated on the territories of the Central Federal District

The characterization of E.coli strains O157:H7, isolated from humans and animals on some territories of the Central Federal District, is presented. Among the isolates from human outbreaks, related and, probably, related cultures prevailed, while among the isolates obtained from different animals mainly unrelated cultures have been detected. A conclusion has been made concerning the existence of several independent zoonotic reservoirs of E. coli O157:H7 infection on this territory. The advantages and drawbacks of the use of pulse electrophoresis in the characterization of E. coli O157:H7 are discussed. Grounds are given for the necessity of the patients examination with hemorrhagic enetrocolitis for the presence of E. coli O157:H7, as well as for the expediency of having a special item for the registration of this E. coli infection in relevant statistical forms.     

Changes in physicochemical properties of proteins, caused by modification with alkylhydroxybenzenes

Kinetic characteristics of model enzymes and physicochemical properties of globular proteins modified by chemical analogues of low-molecular-weight microbial autoregulators (alkylhydroxybenzenes, AHBs) have been studied. C₇ and C₁₂ AHB homologues were used, differing in the length of the alkyl radical and the capacity for weak physicochemical interactions. Both homologues affected the degree of protein swelling, viscosity, and the degree of hydrophobicity. The effects depended on the structure of AHBs, their concentration, and pH of the solution, which likely reflects changes in the charge of the protein globule and its solvate cover. Variations of hydrophobicity indices of AHB-modified enzymes (trypsin and lysozyme) were coupled to changes in the catalytic activity. The values of K _M, measured for the enzymes within both AHB complexes, did not change, whereas V _max increased (in the case of C₇ complexes) or decreased (C₁₂ complexes). Possible molecular mechanisms of changes in the physicochemical and catalytic parameters of enzymatically active proteins, induced by modification with structurally distinct AHBs, are described, with emphasis on targeted regulation of functional activity.     

Gene structure,transcripts and calciotropic effects of the PTH family of peptides in <Emphasis Type="Italic">Xenopus</Emphasis> and chicken

Background  

Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) belong to a family of endocrine factors that share a highly conserved N-terminal region (amino acids 1-34) and play key roles in calcium homeostasis, bone formation and skeletal development. Recently, PTH-like peptide (PTH-L) was identified in teleost fish raising questions about the evolution of these proteins. Although PTH and PTHrP have been intensively studied in mammals their function in other vertebrates is poorly documented. Amphibians and birds occupy unique phylogenetic positions, the former at the transition of aquatic to terrestrial life and the latter at the transition to homeothermy. Moreover, both organisms have characteristics indicative of a complex system in calcium regulation. This study investigated PTH family evolution in vertebrates with special emphasis on Xenopus and chicken.     

Cause of abnormal acidity of lysozyme ionogenic active center groups at cell wall lysis

pH-Dependence of the kinetic parameters of Micrococcus lysodeicticus cell lysis under the action of the protein hen egg lysozyme at the pH 6.9-10.0 at 25 and 37 degrees C has been investigated. The pKb effective values for the lysozyme catalytic activity controlling group have been calculated. The DeltaHion value indicates that this group is the carboxyl one though its pK (9.15 at 25 degrees C) is found far for the limit of the carboxyl groups pK values. The cause of this abnormal pK values is supposed to be the strong negative charge of the bacterial cell wall. As a result the enzyme that catalyzes the hydrolysis ofcopolymer N-acetylglucosamine--N-acetylmuramic acid acts in the high acidity microenvironment.     

Taxonomic diversity of aerobic organotrophic bacteria from clean vietnamese soils and their capacity for oxidation of petroleum hydrocarbons

The dominant species and abundance of the cultured aerobic organotrophic bacteria were determined in the clean soils of the Republic of Vietnam. The total number of organotrophs varied from 2.0 × 10⁵ to 5.8 × 10⁸ CFU/g soil. A considerable fraction of the bacterial population (1.1 × 10⁵–9.5 × 10⁶ CFU/g soil) was able to utilize petroleum hydrocarbons as the sole carbon and energy source. Most of the organisms obtained in pure cultures were gram-positive bacteria; over 70% were hydrocarbon-oxidizing organisms. Analysis of 16S rRNA gene sequences resulted in tentative determination of the taxonomic position of 22 strains, with 12 belonging to the Firmicutes, 4, to the Proteobacteria, and 6 to the Actinobacteria. The most common bacteria capable of hydrocarbon oxidation belonged to the genera Acinetobacter, Bacillus, Brevibacillus, Chromobacterium, Cupriavidus, Gordonia, Microbacterium, Mycobacterium, and Rhodococcus. Some of the isolated Bacillus and Staphylococcus strains, as well as one Pseudomonas and one Sinomonas strain, did not utilize hydrocarbons. Gram-positive degraders, especially members of the order Actinomycetales, which exhibited high hydrocarbon-oxidizing activity, gained competitive advantage in the presence of hydrocarbons. This microbial group probably plays an important role in hydrocarbon degradation in tropical soils. Thus, Vietnamese soils, which had no history of petroleum contamination, support numerically significant and taxonomically diverse populations of h ydrocarbon-oxidizing bacteria.     

Adsorption chromatography of proteins

A method for adsorption chromatography of proteins is proposed. A protein solution is passed through a cellulose column at a pH value corresponding to an isoelectric point of the protein. Depending on the charge of unwanted proteins, they either remain at the origin (if charges of protein and ion-exchanger are opposite) or are released from the column (if charges of protein and ion-exchanger coincide). Elution volume of the purified protein is higher than for the second group of unwanted proteins because movement of the uncharged protein of interest includes its adsorption on cellulose followed by subsequent desorption caused by the elution buffer. Problems of optimization of buffers and adsorbents are discussed. Applicability of the method of adsorption chromatography is illustrated using purification of horseradish peroxidase as an example.