Incompatibility groups of epsilon-caprolactam biodegradation plasmids from bacteria of Pseudomonas genus

Incompatibility of epsilon-caprolactam biodegradation plasmids pBS262, pBS263, pBS264, pBS265, pBS266, pBS267, pBS268, pBS270, pBS276, pBS269 with the tester plasmids of P-1, P-2, P-7, P-9 incompatibility groups in the system of strains of P. putida line BSA, as well as the character of plasmid interaction with the number of P. aeruginosa and P. putida bacteriophages have been studied. The majority of the studied plasmids belongs to IncP-7, IncP-9 or simultaneously to IncP-7 and IncP-9 incompatibility groups. The ability to restrict the growth of some bacteriophages of P. aeruginosa and P. putida has been demonstrated for some plasmids.     

Effect of naphthalene biodegradation plasmids on physiological characteristics of rhizospheric bacteria of the genus Pseudomonas

Specific growth rate, duration of the lag phase, stability of plasmids, and activities of the key enzymes involved in naphthalene biodegradation were studied in rhizospheric pseudomonades carrying structurally similar plasmids pOV17 and pBS216. It was demonstrated that these plasmids determined various levels of catechol 2,3-dioxygenase activities. The structural rearrangements in the plasmid pBS216 could "switch off" the genes of catechol oxidation meta-pathway. It was shown that certain combinations of biodegradation plasmids and bacterial hosts, such as Pseudomonas chlororaphis PCL1391(pBS216), P. chlororaphis PCL1391(pOV17), and P. putida 53a(pOV17), were considerably more efficient than natural variants in their growth characteristics and stability of the biodegradation activity, having a potential for bioremediation of soils polluted with polycyclic aromatic hydrocarbons (PAHs).     

Construction of cyanobacterial-bacterial consortium on the basis of axenic cyanobacterial cultures and heterotrophic bacteria cultures for bioremediation of oil-contaminated soils and water ponds

The ways of the creation of cyanobacterial-bacterial communities with a high remediation potential for cleaning of oil-contaminated soils and water reservoirs are considered. A special methodology was elaborated for the obtaining of bacteriologically pure (axenic) cultures of cyanobacteria: Phormidium sp. K-1, Oscillatoria sp. A-2, and Oscillatoria sp. C-3. It was shown that 14 strains of bacteria associated with these cyanobacteria manifest a hydrocarbon-oxidizing activity. They belong to the genera Pseudomonas, Alcaligenes, Arthrobacter, and Bacillus. The usage of oil-degrading bacteria, which we isolated from water reservoirs or took from collections, allowed us to construct artificial cyanobacterial-bacterial communities with a high hydrocarbon-oxidizing activity. In field experiments on the landfill site Khimpromservis Aktobe, the high remediatory effect of cyanobacterial-bacterial associations between Phormidium sp. K-1 sp. and bacteria Pseudomonas stutzeri A1, Pseudomonas sp. N2, and P. alcaligenes A5 was demonstrated. The results obtained are the basis for the elaboration of microbiological technologies of environment protection using cyanobacteria.     

Activation of indigenous micorflora in oil-contaminated soils using photoluminescent films

A stimulating effect of sunlight transformed by a photoluminescent polymer film on the abundance dynamics and fermentation and respiration of indigenous microflora in oil-contaminated soils was investigated. Polymer film doped with photoluminophores based on inorganic Eu-complexes and common glasshouse film was used as a cover material for oil-contaminated soils at experimental and control sites. The application of photoluminescent film has been reported to stimulate a hundredfold growth of the microflora population, with the soil respiration intensity and catalase activity being increased by a factor of 2.5–3, respectively. The extents of biodegradation of petroleum hydrocarbons within 60 days were up to 70 and 30% of the overall background pollution level for the experimental and control site, respectively. Residual hydrocarbons extracted from samples of the contaminated soils were analyzed by infrared spectroscopy to show the appearance of additional absorption bands at 3350, 1600, and 1710 cm^?1, thus indicating the formation of metabolites during enzymatic oxidation of oil. Chromatographic data corroborated the occurrence of intense oxidation. The hydrocarbon biodegradation factor increases sixfold when the photoluminescent films are used.     

Biological fixation of nitrogen and growth of bacteria of the genus Azotobacter in liquid media in the presence of perfluorocarbons

The addition of perfluorocarbons (perfluorodecalin, carbogal, and perfluoromethyldecalin) to nitrogen-free liquid media during the submerged cultivation of bacteria of the genus Azotobacter was followed by (1) increases in biomass accumulation and nitrogenase activity and (2) fixation of molecular nitrogen. Addition of perfluorodecalin (5 vol %) to the culture medium of A. chroococcum ACB 121 contributed to increases in biomass accumulation, cell concentration (of more than by five times), nitrogenase activity (of 3.4 times), and total nitrogen content in the medium (of 4.5 times).     

Screening method for detection of hydrocarbon-oxidizing bacteria in oil-contaminated water and soil specimens

Toxic action of crude oil on the living world and ecosystems in general is a global problem of both aquatic and terrestrial environments. Bearing in mind the possibility of biodegradation of this toxicant, the procedures of determining counts and activity of cultivable microorganisms, and especially of bacteria responsible for degradation processes, are of great significance. The aim of this work was to study the possibility of modifying some solid media by adding triphenyltetrazolium chloride reagent as an indicator of the dehydrogenase activity, to develop a simple screening method for a simultaneous assessment of the count and activity of cultivable hydrocarbon-oxidizing bacteria in the oil-contaminated environments. The modified method appeared to be rapid and very suitable for the intended purposes.     

Importance of Gram-positive naphthalene-degrading bacteria in oil-contaminated tropical marine sediments

AIMS: The aim of this study was to isolate, characterize and evaluate the importance of naphthalene-degrading bacterial strains from oil-contaminated tropical marine sediments. METHODS AND RESULTS: Three Gram-positive naphthalene-degrading bacteria were isolated from oil-contaminated tropical intertidal marine sediments by direct isolation or enrichment using naphthalene as the sole source of carbon and energy. Bacillus naphthovorans strain MN-003 can also grow on benzene, toluene, xylene and diesel fuel while Micrococcus sp. str. MN-006 can also grow on benzene. Staphylococcus sp. str. MN-005 can only degrade naphthalene and was not able to use the other aromatic hydrocarbons tested. Strain MN-003 possessed the highest maximal specific growth rate with naphthalene as sole carbon source. An enrichment culture fed with naphthalene as sole carbon source exhibited a significant increase in the relative abundances of the three isolates after 21 days of incubation. The three isolates constituted greater than 69% of the culturable naphthalene-degrading microbial community. Strain MN-003 outcompeted and dominated the other two isolates in competition studies involving batch cultures inoculated with equal cell densities of the three isolates and incubated with between 1 and 10 mg l-1 of naphthalene. CONCLUSIONS: Three Gram-positive naphthalene-degrading bacteria were successfully isolated from oil-contaminated tropical marine sediments. Gram-positive bacteria might play an important role in naphthalene degradation in the highly variable environment of oil-contaminated tropical intertidal marine sediments. Among the three isolates, strain MN-003 has the highest maximal specific growth rate when grown on naphthalene, and outgrew the other two isolates in competition experiments. SIGNIFICANCE AND IMPACT OF THE STUDY: This research will aid in the development of bioremediation schemes for oil-contaminated marine environments. Strain MN-003 could potentially be exploited in such schemes.     

Aerobic biodegradation of nonylphenol by cold-adapted bacteria

Three strains capable of mineralizing nonylphenol as sole carbon source were isolated from a sample of contaminated soil and characterized as two Pseudomonas spp. and a Stenotrophomonas sp. The two Pseudomonas spp. expressed characteristics typical of psychrophiles growing optimally of 10 °C and capable of growing at 0 °C. The Stenotrophomonas sp. was more likely psychrotrophic because it had an optimal temperature between 14 and 22 °C although it was not capable of growing at 4 °C. At 14 °C, one of the Pseudomonas spp. exhibited the highest rate of degradation of nonylphenol (4.4 mg l^–1 d^–1), when compared with axenic or mixed cultures of the isolates. This study represents, to the best of our knowledge, the first reported case of cold-adapted microorganisms capable of mineralizing nonylphenol.     

Indigenous oil-degrading bacteria in crude oil-contaminated seawater of the Yellow sea,China

Indigenous oil-degrading bacteria play an important role in efficient remediation of polluted marine environments. In this study, we investigated the diversity and abundance of indigenous oil-degrading bacteria and functional genes in crude oil-contaminated seawater of the Dalian coast. The gene copy number bacterial 16S rRNA in total were determined to be about 10¹⁰ copies L^?1 in contaminated seawater and 10⁹ copies L^?1 in uncontaminated seawater. Bacteria of Alcanivorax, Marinobacter, Novosphingobium, Rhodococcus, and Pseudoalteromonas were found to be predominant oil-degrading bacteria in the polluted seawater in situ. In addition, bacteria belonging to Algoriphagus, Aestuariibacter, Celeribacter, Fabibacter, Zobellia, Tenacibaculum, Citreicella, Roseivirga, Winogradskyella, Thioclava, Polaribacter, and Pelagibaca were confirmed to be the first time as an oil-degrading bacterium. The indigenous functional enzymes, including AlkB or polycyclic aromatic hydrocarbons ring-hydroxylating dioxygenases α (PAH-RHDα) coding genes from Gram-positive (GP) and Gram-negative bacteria (GN), were revealed and quite diverse. About 10¹⁰ to 10¹¹ copies L^?1 for the expression of alkB genes were recovered and showed that the two-thirds of all the AlkB sequences were closely related to widely distributed Alcanivorax and Marinobacter isolates. About 10⁹ copies L^?1 seawater for the expression of RHDαGN genes in contaminated seawater and showed that almost all RHDαGN sequences were closely related to an uncultured bacterium; however, RHDαGP genes represented only about 10⁵ copies L^?1 seawater for the expression of genes in contaminated seawater, and the naphthalene dioxygenase sequences from Rhodococcus and Mycobacterium species were most abundant. Together, their data provide evidence that there exists an active aerobic microbial community indigenous to the coastal area of the Yellow sea that is capable of degrading petroleum hydrocarbons.     

Use of Bacteria of the Genus Azotobacter for Bioremediation of Oil-Contaminated Soils

The rate of self-purification of oil-contaminated soil increases after introduction of bacteria of the genus Azotobacter. The bacteria can assimilate oil hydrocarbons as the sole source of carbon and energy, both in the presence of fixed nitrogen and during nitrogen fixation. The species Azotobacter chroococcum activates growth of hydrocarbon-oxidizing bacteria present in Devoroil.