aerobic
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Aerobic anoxygenic phototrophic (AAP) bacteria harvest light energy using bacteriochlorophyll-containing reaction centers to supplement their mostly heterotrophic metabolism. While their abundance and growth have been intensively studied in coastal environments, much less is known about their activity in oligotrophic open ocean regions. Therefore, we combined in situ sampling in the North Pacific Subtropical Gyre, north of O'ahu island, Hawaii, with two manipulation experiments. Infra-red epifluorescence microscopy documented that AAP bacteria represented approximately 2% of total bacteria in the euphotic zone with the maximum abundance in the upper 50 m. They conducted active photosynthetic electron transport with maximum rates up to 50 electrons per reaction center per second. The in situ decline of bacteriochlorophyll concentration over the daylight period, an estimate of loss rates due to predation, indicated that the AAP bacteria in the upper 50 m of the water column turned over at rates of 0.75-0.90 d-1. This corresponded well with the specific growth rate determined in dilution experiments where AAP bacteria grew at a rate 1.05 ± 0.09 d-1. An amendment of inorganic nitrogen to obtain N:P = 32 resulted in a more than 10 times increase in AAP abundance over 6 days. The presented data document that AAP bacteria are an active part of the bacterioplankton community in the oligotrophic North Pacific Subtropical Gyre and that their growth was mostly controlled by nitrogen availability and grazing pressure.IMPORTANCEMarine bacteria represent a complex assembly of species with different physiology, metabolism, and substrate preferences. We focus on a specific functional group of marine bacteria called aerobic anoxygenic phototrophs. These photoheterotrophic organisms require organic carbon substrates for growth, but they can also supplement their metabolic needs with light energy captured by bacteriochlorophyll. These bacteria have been intensively studied in coastal regions, but rather less is known about their distribution, growth, and mortality in the oligotrophic open ocean. Therefore, we conducted a suite of measurements in the North Pacific Subtropical Gyre to determine the distribution of these organisms in the water column and their growth and mortality rates. A nutrient amendment experiment showed that aerobic anoxygenic phototrophs were limited by inorganic nitrogen. Despite this, they grew more rapidly than average heterotrophic bacteria, but their growth was balanced by intense grazing pressure.
- Klíčová slova
- North Pacific Subtropical Gyre, Station ALOHA, aerobic anoxygenic phototrophs, bacteriochlorophyll a, marine bacteria,
- MeSH
- aerobní bakterie MeSH
- bakteriochlorofyly * metabolismus MeSH
- dusík metabolismus MeSH
- fototrofní procesy * MeSH
- mořská voda mikrobiologie MeSH
- voda metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriochlorofyly * MeSH
- dusík MeSH
- voda MeSH
BACKGROUND: Aerobic anoxygenic phototrophic (AAP) bacteria are heterotrophic bacteria that supply their metabolism with light energy harvested by bacteriochlorophyll-a-containing reaction centers. Despite their substantial contribution to bacterial biomass, microbial food webs, and carbon cycle, their phenology in freshwater lakes remains unknown. Hence, we investigated seasonal variations of AAP abundance and community composition biweekly across 3 years in a temperate, meso-oligotrophic freshwater lake. RESULTS: AAP bacteria displayed a clear seasonal trend with a spring maximum following the bloom of phytoplankton and a secondary maximum in autumn. As the AAP bacteria represent a highly diverse assemblage of species, we followed their seasonal succession using the amplicon sequencing of the pufM marker gene. To enhance the accuracy of the taxonomic assignment, we developed new pufM primers that generate longer amplicons and compiled the currently largest database of pufM genes, comprising 3633 reference sequences spanning all phyla known to contain AAP species. With this novel resource, we demonstrated that the majority of the species appeared during specific phases of the seasonal cycle, with less than 2% of AAP species detected during the whole year. AAP community presented an indigenous freshwater nature characterized by high resilience and heterogenic adaptations to varying conditions of the freshwater environment. CONCLUSIONS: Our findings highlight the substantial contribution of AAP bacteria to the carbon flow and ecological dynamics of lakes and unveil a recurrent and dynamic seasonal succession of the AAP community. By integrating this information with the indicator of primary production (Chlorophyll-a) and existing ecological models, we show that AAP bacteria play a pivotal role in the recycling of dissolved organic matter released during spring phytoplankton bloom. We suggest a potential role of AAP bacteria within the context of the PEG model and their consideration in further ecological models.
- Klíčová slova
- pufM gene, Aerobic anoxygenic phototrophs, Aquatic microbial ecology, Freshwaters, Long-term sampling, Microbial seasonal succession, PEG model, Photoheterotrophs,
- MeSH
- aerobní bakterie genetika metabolismus MeSH
- Bacteria genetika MeSH
- biomasa MeSH
- fototrofní procesy * MeSH
- fytoplankton genetika MeSH
- jezera * mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
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
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- látky znečišťující životní prostředí MeSH
Aerobic anoxygenic phototrophic (AAP) bacteria are an important component of freshwater bacterioplankton. They can support their heterotrophic metabolism with energy from light, enhancing their growth efficiency. Based on results from cultures, it was hypothesized that photoheterotrophy provides an advantage under carbon limitation and facilitates access to recalcitrant or low-energy carbon sources. However, verification of these hypotheses for natural AAP communities has been lacking. Here, we conducted whole community manipulation experiments and compared the growth of AAP bacteria under carbon limited and with recalcitrant or low-energy carbon sources under dark and light (near-infrared light, λ > 800 nm) conditions to elucidate how they profit from photoheterotrophy. We found that AAP bacteria induce photoheterotrophic metabolism under carbon limitation, but they overcompete heterotrophic bacteria when carbon is available. This effect seems to be driven by physiological responses rather than changes at the community level. Interestingly, recalcitrant (lignin) or low-energy (acetate) carbon sources inhibited the growth of AAP bacteria, especially in light. This unexpected observation may have ecosystem-level consequences as lake browning continues. In general, our findings contribute to the understanding of the dynamics of AAP bacteria in pelagic environments.
- Klíčová slova
- acetate, aerobic anoxygenic phototrophic bacteria, carbon limitation, freshwater lakes, lignin, microbial ecology,
- MeSH
- aerobní bakterie metabolismus růst a vývoj MeSH
- Bacteria metabolismus růst a vývoj genetika MeSH
- ekosystém MeSH
- fototrofní procesy * MeSH
- heterotrofní procesy MeSH
- jezera mikrobiologie MeSH
- světlo MeSH
- uhlík * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- uhlík * MeSH
Several aerobic metabolic pathways for the degradation of benzene, toluene, ethylbenzene and xylene (BTEX), which are provided by two enzymic systems (dioxygenases and monooxygenases), have been identified. The monooxygenase attacks methyl or ethyl substituents of the aromatic ring, which are subsequently transformed by several oxidations to corresponding substituted pyrocatechols or phenylglyoxal, respectively. Alternatively, one oxygen atom may be first incorporated into aromatic ring while the second atom of the oxygen molecule is used for oxidation of either aromatic ring or a methyl group to corresponding pyrocatechols or protocatechuic acid, respectively. The dioxygenase attacks aromatic ring with the formation of 2-hydroxy-substituted compounds. Intermediates of the "upper" pathway are then mineralized by either ortho- or meta-ring cleavage ("lower" pathway). BTEX are relatively water-soluble and therefore they are often mineralized by indigenous microflora. Therefore, natural attenuation may be considered as a suitable way for the clean-up of BTEX contaminants from gasoline-contaminated soil and groundwater.
- MeSH
- aerobní bakterie enzymologie metabolismus MeSH
- benzen metabolismus MeSH
- benzenové deriváty metabolismus MeSH
- biodegradace MeSH
- toluen metabolismus MeSH
- uhlovodíky chemie metabolismus MeSH
- xyleny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- benzen MeSH
- benzenové deriváty MeSH
- ethylbenzene MeSH Prohlížeč
- toluen MeSH
- uhlovodíky MeSH
- xyleny MeSH
Aerobic anoxygenic photoheterotrophic (AAP) bacteria represent a functional group of prokaryotic organisms that harvests light energy using bacteriochlorophyll-containing photosynthetic reaction centers. They represent an active and rapidly growing component of freshwater bacterioplankton, with the highest numbers observed usually in summer. Species diversity of freshwater AAP bacteria has been studied before in lakes, but its seasonal dynamics remain unknown. In this report, we analysed temporal changes in the composition of the phototrophic community in an oligo-mesotrophic freshwater lake using amplicon sequencing of the pufM marker gene. The AAP community was dominated by phototrophic Gammaproteobacteria and Alphaproteobacteria, with smaller contribution of phototrophic Chloroflexota and Gemmatimonadota. Phototrophic Eremiobacteriota or members of Myxococcota were not detected. Interestingly, some AAP taxa, such as Limnohabitans, Rhodoferax, Rhodobacterales or Rhizobiales, were permanently present over the sampling period, while others, such as Sphingomonadales, Rhodospirillales or Caulobacterales appeared only transiently. The environmental factors that best explain the seasonal changes in AAP community were temperature, concentrations of oxygen and dissolved organic matter.
Aerobic anoxygenic phototrophic (AAP) bacteria are a common component of freshwater microbial communities. They harvest light energy using bacteriochlorophyll a-containing reaction centers to supplement their predominantly heterotrophic metabolism. We used epifluorescence microscopy, HPLC, and infrared fluorometry to examine the dynamics of AAP bacteria in the mesotrophic lake Vlkov during the seasonal cycle. The mortality of AAP bacteria was estimated from diel changes of bacteriochlorophyll a fluorescence. The AAP abundance correlated with water temperature and DOC concentration. Its maximum was registered during late summer, when AAP bacteria made up 20% of total bacteria. The novel element of this study is the seasonal measurements of AAP mortality rates. The rates ranged between 1.15 and 4.56 per day with the maxima registered in early summer coinciding with the peak of primary production, which documents that AAP bacteria are a highly active component of freshwater microbial loop.
- MeSH
- aerobní bakterie klasifikace genetika izolace a purifikace účinky záření MeSH
- biodiverzita * MeSH
- fototrofní procesy MeSH
- jezera mikrobiologie MeSH
- kyslík metabolismus MeSH
- roční období MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyslík MeSH
Recognition of the environmental role of photoheterotrophic bacteria has been one of the main themes of aquatic microbiology over the last 15 years. Aside from cyanobacteria and proteorhodopsin-containing bacteria, aerobic anoxygenic phototrophic (AAP) bacteria are the third most numerous group of phototrophic prokaryotes in the ocean. This functional group represents a diverse assembly of species which taxonomically belong to various subgroups of Alpha-, Beta- and Gammaproteobacteria. AAP bacteria are facultative photoheterotrophs which use bacteriochlorophyll-containing reaction centers to harvest light energy. The light-derived energy increases their bacterial growth efficiency, which provides a competitive advantage over heterotrophic species. Thanks to their enzymatic machinery AAP bacteria are active, rapidly growing organisms which contribute significantly to the recycling of organic matter. This chapter summarizes the current knowledge of the ecology of AAP bacteria in aquatic environments, implying their specific role in the microbial loop.
- Klíčová slova
- aquatic food webs, bacterial growth, bacteriochlorophyll, microbial loop, photoheterotrophs,
- MeSH
- aerobní bakterie fyziologie MeSH
- biodiverzita MeSH
- ekologie MeSH
- fototrofní procesy fyziologie MeSH
- mikrobiologie vody * MeSH
- oceány a moře MeSH
- potravní řetězec MeSH
- vodní organismy fyziologie MeSH
- životní prostředí * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Geografické názvy
- oceány a moře MeSH
Aerobic anoxygenic phototrophs (AAPs) are photoheterotrophic prokaryotes that are widespread in many limnic and marine environments. So far, little is known about their distribution in peat-bog lakes. Seventeen peat-bog lakes were sampled during three summer seasons 2009, 2011, and 2012, and the vertical distribution of AAPs was determined by infrared epifluorescence microscopy. The analysis demonstrated that in the surface layers of the studied lakes, AAP abundance ranged from 0.3 to 12.04 × 10(5) cells mL(-1), which represents <1 to 18.3 % of the total bacteria. The vertical distribution of AAPs confirmed their presence in the upper parts of the water column with minimum numbers in the anoxic bottom waters. We have shown that the AAP abundance was significantly positively correlated with the water pH, and the highest proportion of photoheterotrophs was found in peat-bog lakes with a pH between 6.7 and 7.6. Our results demonstrated an influence of water acidity on the abundance of AAPs, which may reflect a fundamental difference in the microbial composition between acidic and pH neutral peat-bog lakes.
- Klíčová slova
- Aerobic anoxygenic phototrophic bacteria, Environmental factors, Humic and dystrophic lakes, Peat-bog lakes, pH,
- MeSH
- aerobní bakterie fyziologie MeSH
- jezera mikrobiologie MeSH
- kyslík MeSH
- mikrobiologie vody MeSH
- mokřady * MeSH
- monitorování životního prostředí MeSH
- půda * MeSH
- roční období MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyslík MeSH
- půda * MeSH
The article compares the ability of detection and detection times (TTD) of aerobic bacteria in the BacT/Alert FA, BacT/Alert SA, Bactec Plus Aerobic/F and Bactec Standard Aerobic/F bottles. Compared bottles were inoculated at the same time with the identical suspension of bacterial strain. All bottles detected bacterial pathogens even in the case of very low number of inoculated bacteria. The differences of TTD were detected between the bottles of compared hemocultivation systems. Bactec Plus Aerobic/F system is faster in the detection of the members of family Enterobacteriaceae at 1-3 hours, BacT/Aert FA system is faster in the detection of coagulase-negative staphylococci. Most difference was detected at Pseudomanas stutzeri, where the detection in BacT/Alert FA bottles was at 15 hours faster in opposite of Bactec Plus Aerobic/F bottles. In the bottles without sorbent Staphylococcus aureus and Streptococcus sanqui were detected faster in the system Bactec Standard Aerobic/F. The bottles BacT/Alert SA detected faster skin corynebacteria. Detected differences have not a practical importance for the blood stream infection diagnostics.
