Diel variations in frequency of dividing cells and abundance of aerobic anoxygenic phototrophic bacteria in a coral reef system of the South China Sea

Liu, Rulong; Zhang, Yao; Jiao, Nianzhi

doi:10.3354/ame01371

Cited by 20 publications

(15 citation statements)

References 28 publications

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“…The most obvious is the difference in methodology. Incubations in our study were only 1 hour as opposed to the 18-72 h needed to detect the activity of AAP bacteria through the change in BChl a concentrations (Koblížek et al, 2005;Koblížek et al, 2007), whereas no incubation is needed for the frequency of dividing cell method (Hagströ m et al, 1979;Liu et al, 2010). Another methodological difference is that our approach assumes that AAP activity is adequately traced by the incorporation of 3 H-leucine.…”

Section: Discussionmentioning

confidence: 98%

“…Studies using the BChl-turnover approach found that growth rates of AAP bacteria were as much as 3 per day (Koblížek et al, 2005;Koblížek et al, 2007;Hojerová et al, 2011), substantially higher than bacterial growth rates expected for these systems (Ducklow, 2000). Similarly, frequency of dividing cell data indicate that growth rates of AAP bacteria are about threefold higher than rates for other bacteria (Liu et al, 2010). In the Delaware estuary, in contrast, AAP bacteria were 40-60% more active than other bacteria in taking up leucine.…”

Section: Discussionmentioning

confidence: 99%

“…AAP bacteria grew about twofold faster than the totalbacterial community according to direct count data from manipulation experiments with Mediterranean seawater . Likewise, the frequency of dividing AAP bacterial cells was about threefold higher than the frequency for the entire bacterial community in the South China Sea (Liu et al, 2010), again suggesting much higher growth rates for AAP bacteria. These differences in growth rate are higher than would be predicted based on theoretical calculations (Kirchman and Hanson, 2013).…”

Section: Introductionmentioning

confidence: 91%

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Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

2014

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Aerobic anoxygenic phototrophic (AAP) bacteria are well known to be abundant in estuaries, coastal regions and in the open ocean, but little is known about their activity in any aquatic ecosystem. To explore the activity of AAP bacteria in the Delaware estuary and coastal waters, single-cell 3 H-leucine incorporation by these bacteria was examined with a new approach that combines infrared epifluorescence microscopy and microautoradiography. The approach was used on samples from the Delaware coast from August through December and on transects through the Delaware estuary in August and November 2011. The percent of active AAP bacteria was up to twofold higher than the percentage of active cells in the rest of the bacterial community in the estuary. Likewise, the silver grain area around active AAP bacteria in microautoradiography preparations was larger than the area around cells in the rest of the bacterial community, indicating higher rates of leucine consumption by AAP bacteria. The cell size of AAP bacteria was 50% bigger than the size of other bacteria, about the same difference on average as measured for activity. The abundance of AAP bacteria was negatively correlated and their activity positively correlated with light availability in the water column, although light did not affect 3 H-leucine incorporation in light-dark experiments. Our results suggest that AAP bacteria are bigger and more active than other bacteria, and likely contribute more to organic carbon fluxes than indicated by their abundance.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

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Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

2014

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“…AAPB are primarily heterotrophic, but they also possess the capability of harvesting light for energy and are present in all of the world's oceans (19,20). AAPB are closely associated with phytoplankton to comprise the dissolved organic carbon (DOC) in marine environments (20,48), and they grow much faster than other heterotrophic bacteria (26). Since they are 2 to 3 times larger in cell size than other heterotrophic bacteria (36), AAPB can be grazed upon more easily by predators (37), and thus they contribute a larger proportion of carbon to the upper trophic levels.…”

mentioning

confidence: 99%

Formation of Polyhydroxyalkanoate in Aerobic Anoxygenic Phototrophic Bacteria and Its Relationship to Carbon Source and Light Availability

Xiao

Jiao

2011

Appl Environ Microbiol

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Aerobic anoxygenic phototrophic bacteria (AAPB) are unique players in carbon cycling in the ocean. Cellular carbon storage is an important mechanism regulating the nutrition status of AAPB but is not yet well understood. In this paper, six AAPB species (Dinoroseobacter sp. JL1447, Roseobacter denitrificans OCh 114, Roseobacter litoralis OCh 149, Dinoroseobacter shibae DFL 12 T , Labrenzia alexandrii DFL 11 T , and Erythrobacter longus DSMZ 6997) were examined, and all of them demonstrated the ability to form the carbon polymer polyhydroxyalkanoate (PHA) in the cell. The PHA in Dinoroseobacter sp. JL1447 was identified as poly-betahydroxybutyrate (PHB) according to evidence from Fourier transform infrared spectroscopy, differential scanning calorimetry, and 1 H nuclear magnetic resonance spectroscopy examinations. Carbon sources turned out to be critical for PHA production in AAPB. Among the eight media tested with Dinoroseobacter sp. JL1447, sodium acetate, giving a PHA production rate of 72%, was the most productive carbon source, followed by glucose, with a 68% PHA production rate. Such PHA production rates are among the highest recorded for all bacteria. The C/N ratio of substrates was verified by the experiments as another key factor in PHA production. In the case of R. denitrificans OCh 114, PHA was not detected when the organism was cultured at C/N ratios of <2 but became apparent at C/N ratios of >3. Light is also important for the formation of PHA in AAPB. In the case of Dinoroseobacter sp. JL1447, up to a one-quarter increase in PHB production was observed when the culture underwent growth in a light-dark cycle compared to growth completely in the dark.

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“…Other studies using different approaches to calculate growth rates of AAP have reported even higher differences in their growth rate relative to total bacteria. Liu et al (2010) reported a 4-fold higher average AAP growth rate, estimated on the basis of the fre- Table 2. Summary of growth rates of total bacteria (Total) and aerobic anoxygenic photo trophic bacteria (AAP) from marine and freshwater systems and the corresponding mean relative abundance of AAP.…”

Section: Discussionmentioning

confidence: 99%

Major contribution of both zooplankton and protists to the top-down regulation of freshwater aerobic anoxygenic phototrophic bacteria

Chaves¹,

Cottrell²,

Kirchman³

et al. 2015

Aquat. Microb. Ecol.

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Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes that use light as a secondary energy source to complement the consumption of organic matter. Despite this metabolic flexibility and their widespread distribution, their low relative abundances suggest that they may be subjected to strong regulatory processes. However, there is still little information on the regulation of AAP abundance, particularly in freshwaters. Here, we used a lake mesocosm experiment to address the top-down regulation of freshwater AAP by protists and zooplankton under 2 contrasting nutrient regimes. Our results support the hypothesis that freshwater AAP are subject to intense top-down regulation, and are selectively removed by grazers. The average gross growth rate of AAP was ca. 1.5 times higher, and grazing loss rates 1.6 times higher than those of the bulk bacterial community. Our results further indicate that whereas protists are the main predators of AAP, zooplankton may account for over a third of AAP losses, and both exhibit a greater selectivity for AAP relative to total bacteria. The mechanistic underpinning of this selectivity is still unclear, but it may be related to the average larger cell size of AAP, and to their higher potential growth rates relative to the bulk bacterial community. Our results further suggest that AAP may play a disproportionate role in the nutrition of lake zooplankton, and in the trophic transfer of organic carbon in lake food webs.KEY WORDS: Aerobic anoxygenic phototrophic bacteria · Grazing loss rate · Selective predation · Photoheterotrophy · Freshwater Resale or republication not permitted without written consent of the publisher FREE REE ACCESS CCESSContribution to AME Special 5 'SAME 13: progress and perspectives in aquatic microbial ecology ' Aquat Microb Ecol 76: 71-83, 2015 Lamy et al. , Mašín et al. 2012, Fauteux et al. 2015. Two possible hypotheses may explain their low in situ abundances: either light-derived energy has little effect on the growth and competitiveness of AAP, or, if there is an effect, there are other factors, unrelated to phototrophy, that may limit the ecological success of AAP bacteria more than that of other bacterial groups. Experimental evidence from marine environments suggests that AAP bacteria may have higher growth rates than the average bacteria (Koblízek et al. 2007, and therefore their generally low abundance should be due to high losses, either via grazing or viral infection. Indeed, the only study so far to have explored the different controls of the abundance of this group showed that protist grazing was the main regulator of the abundance of marine AAP bacteria . Beyond this marine study, however, there is still little information on the regulation of AAP abundance and activity, especially for inland waters, despite the fact that these photoheterotrophic mic robes have also been shown to be widespread in freshwater planktonic food webs (Mašín et al. 2008, Medová et al. 2011, Mašín et al. 2012, Cuperová et al. 2013,...

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Diel variations in frequency of dividing cells and abundance of aerobic anoxygenic phototrophic bacteria in a coral reef system of the South China Sea

Cited by 20 publications

References 28 publications

Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

Formation of Polyhydroxyalkanoate in Aerobic Anoxygenic Phototrophic Bacteria and Its Relationship to Carbon Source and Light Availability

Major contribution of both zooplankton and protists to the top-down regulation of freshwater aerobic anoxygenic phototrophic bacteria

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