Unique bacterial associations were formed in the polluted soils from territory of the industrial factories Open Joint Stock Company "The Middle Volga Chemical Plant," Chapaevsk, Russia and Open Joint Stock Company "Lubricant Producing Plant," Perm, Russia. This study evaluates the influence of the biphenyl/polychlorinated biphenyls (PCB) on the formation of aerobic bacterial associations and their biodegradative potential. Enrichment cultivation of the soil samples from the territories of these industrial factories with PCB (commercial mixture Sovol) was lead for forming aerobic bacterial enrichment cultures showing a unique composition. The dominating in these bacterial cultures was the phylum Proteobacteria (Beta- and Gammaproteobacteria). Using biphenyl as a carbon source led to decrease of biodiversity in the final stable bacterial associations. Periodic cultivation experiments demonstrated that the association PN2-B has a high degradative potential among the six studied bacterial associations. PN2-B degraded 100% mono-chlorobiphenyls (94.5 mg/L), 86.2% di-chlorobiphenyls (22.3 mg/L), 50.9% Sovol, and 38.4% Delor 103 (13.8 mg/L). Qualitative analysis of metabolites showed that association performed transformation of chlorobenzoic acids (PCB degradation intermediates) into metabolites of citrate cycle. Twelve individual strain-destructors were isolated. The strains were found to degrade 17.7-100% PCB1, 36.2-100% PCB2, 18.8-100% PCB3 (94.5 mg/L), and 15.7-78.2% PCB8 (22.3 mg/L). The strains were shown to metabolize chlorobenzoic acids formed during degradation of chlorobiphenyls. A unique ability of strains Micrococcus sp. PNS1 and Stenotrophomonas sp. PNS6 to degrade ortho-, meta-, and para-monosubstituted chlorobenzoic acids was revealed. Our results suggest that PN2-B and individual bacterial strains will be perspective for cleaning of the environment from polychlorinated biphenyls.
Phytoplankton is a key component of aquatic microbial communities, and metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon (DOC). Yet, the impact of primary production on bacterial activity and community composition remains largely unknown, as, for example, in the case of aerobic anoxygenic phototrophic (AAP) bacteria that utilize both phytoplankton-derived DOC and light as energy sources. Here, we studied how reduction of primary production in a natural freshwater community affects the bacterial community composition and its activity, focusing primarily on AAP bacteria. The bacterial respiration rate was the lowest when photosynthesis was reduced by direct inhibition of photosystem II and the highest in ambient light condition with no photosynthesis inhibition, suggesting that it was limited by carbon availability. However, bacterial assimilation rates of leucine and glucose were unaffected, indicating that increased bacterial growth efficiency (e.g., due to photoheterotrophy) can help to maintain overall bacterial production when low primary production limits DOC availability. Bacterial community composition was tightly linked to light intensity, mainly due to the increased relative abundance of light-dependent AAP bacteria. This notion shows that changes in bacterial community composition are not necessarily reflected by changes in bacterial production or growth and vice versa. Moreover, we demonstrated for the first time that light can directly affect bacterial community composition, a topic which has been neglected in studies of phytoplankton-bacteria interactions.IMPORTANCE Metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon in aquatic environments, and yet how changes in the rate of primary production affect the bacterial activity and community composition remains understudied. Here, we experimentally limited the rate of primary production either by lowering light intensity or by adding a photosynthesis inhibitor. The induced decrease had a greater influence on bacterial respiration than on bacterial production and growth rate, especially at an optimal light intensity. This suggests that changes in primary production drive bacterial activity, but the effect on carbon flow may be mitigated by increased bacterial growth efficiencies, especially of light-dependent AAP bacteria. Bacterial activities were independent of changes in bacterial community composition, which were driven by light availability and AAP bacteria. This direct effect of light on composition of bacterial communities has not been documented previously.
Aerobic anoxygenic phototrophic (AAP) bacteria are microorganisms that can harvest light energy using bacteriochlorophyll a to supplement their predominantly organotrophic metabolism. Growth enhancement by light has repeatedly been demonstrated in laboratory experiments with AAP isolates. However, the ecological advantage of light utilization is unclear, as it has never been proven in the natural environment. Here, we conducted manipulation experiments in the NW Mediterranean and found that AAP bacteria display high growth rates which are controlled to a large extent by intense grazing pressure and phosphorous availability. Foremost, we found that, contrarily to the bulk bacterioplakton, AAP bacteria display higher growth rates when incubated under light-dark cycles than in complete darkness. These results represent the first direct evidence that natural populations of marine AAP bacteria can be stimulated by light.
Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit. Recent research has focused on optimising these natural processes to serve as effective bioremediation technologies, with particular emphasis on (a) the diversity and role of bacterial groups involved in dechlorination microbial processes, and (b) detection of bacterial enzymes and genes connected with dehalogenation activity. In this review, we summarise the different mechanisms of chloroethene bacterial degradation suitable for bioremediation and provide a list of dechlorinating bacteria. We also provide an up-to-date summary of primers available for detecting functional genes in anaerobic and aerobic bacteria degrading chloroethenes metabolically or co-metabolically.
Several aerobic bacteria possess unique catabolic pathways enabling them to degrade persistent organic pollutants (POPs), including polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polybrominated diphenylethers (PBDEs), and polychlorinated biphenyls (PCBs). The catabolic activity of aerobic bacteria employed for removal of POPs in the environment may be modulated by several biotic (i.e. fungi, plants, algae, earthworms, and other bacteria) and abiotic (i.e. zero-valent iron, advanced oxidation, and electricity) agents. This review describes the basic biochemistry of the aerobic bacterial catabolism of selected POPs and discusses how biotic and abiotic agents enhance or inhibit the process. Solutions allowing biotic and abiotic agents to exert physical and chemical assistance to aerobic bacterial catabolism of POPs are also discussed.
- MeSH
- aerobní bakterie izolace a purifikace metabolismus MeSH
- látky znečišťující životní prostředí metabolismus MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Microaerobic alternative of anaerobic digestion offers many advantages especially when sulfide concentration in the digester is high. For better understanding of the microaerobic technology more detailed characterization of biomass activity is needed. Two equal digesters were operated under the same condition except of microaeration in one of them. During long term operation of anaerobic and microaerobic digesters the sludge quality and the biomass activity was monitored. The activity of sulfide oxidizing bacteria of microaerobic biomass was significantly higher in comparison with anaerobic biomass. The activity of sulfate reducing bacteria was comparable. The activity of methanogenic bacteria activity depended on sulfide concentration more than on microaeration. The extent of foaming problems was lower in the microaerobic than in the anaerobic digester.
- MeSH
- aerobní bakterie metabolismus MeSH
- anaerobní bakterie metabolismus MeSH
- bioreaktory mikrobiologie MeSH
- methan analýza MeSH
- odpadní vody chemie mikrobiologie MeSH
- oxidace-redukce MeSH
- průmyslová mikrobiologie MeSH
- sírany chemie MeSH
- sulfidy chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
The degradation efficiencies of isomeric mononitrotoluenes (2- and 4-NTs) and dinitrotoluenes (2,4-DNT and 2,6-DNT) by either individual bacterial strains (Bacillus cereus NDT4, Pseudomonas putida NDT1, Pseudomonas fluorescens NDT2, and Achromobacter sp. NDT3) or their mixture were compared in submerged batch cultivations. The mixed culture degraded 2,4-DNT nearly 50 times faster than any of the individual strains. The mixed culture also demonstrated significantly shorter lag periods in 2,4-DNT degradation, a lack of nitrite or organic intermediates accumulation in the liquid medium and the ability to degrade a broader spectrum of nitrotoluenes over a wider concentration range. The presence of both readily degradable 2-NT (or 4-NT) and poorly degradable 2,6-DNT in the medium negatively affected 2,4-DNT biodegradation. However, the mixed bacterial culture still effectively degraded 2,4-DNT with only slightly lower rates under these unfavorable conditions, thus showing potential for the remediation of 2,4-DNT contaminated sites.
Aerobic bacterial strains from the salt water of Lake Red (Sovata, Romania) were cultivated. More than half of the 80 strains were G(-) and formed motile straight rods. Only a few strains produced acid from D-glucose and reduced nitrate to nitrite. Optimum NaCl concentration for growth varied between 5 and 15 % in the majority of the strains, so the isolates were regarded moderately halophilic. On the basis of the 16S rRNA gene sequence similarity almost half of the strains were identified as members of genus Halomonas. Other strains belonged to genera Marinobacter, Psychrobacter, Serratia, Morganella (?-Proteobacteria), Bacillus, Exiguobacterium, Planococcus (Firmicutes), and Arthrobacter, Micrococcus, Microbacterium, and Nesterenkonia (Actinobacteria).
- MeSH
- Actinobacteria genetika izolace a purifikace klasifikace metabolismus MeSH
- aerobní bakterie genetika izolace a purifikace klasifikace metabolismus MeSH
- biodiverzita MeSH
- chlorid sodný MeSH
- DNA bakterií genetika MeSH
- fenotyp MeSH
- fylogeneze MeSH
- Gammaproteobacteria genetika izolace a purifikace klasifikace metabolismus MeSH
- Halomonas genetika izolace a purifikace klasifikace metabolismus MeSH
- kultivační média MeSH
- plankton růst a vývoj MeSH
- počet mikrobiálních kolonií MeSH
- RNA ribozomální 16S genetika MeSH
- sekvenční analýza DNA MeSH
- sladká voda chemie mikrobiologie MeSH
- Geografické názvy
- Rumunsko MeSH
