Fluorescence In Situ Hybridization and Spectral Imaging of Coral-Associated Bacterial Communities

Ainsworth, Tracy D.; Fine, Maoz; Blackall, Linda L.; Høegh-Guldberg, Ove

doi:10.1128/aem.72.4.3016-3020.2006

Cited by 85 publications

(87 citation statements)

References 45 publications

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“…Flocs were fixed in 4% paraformaldehyde (Fisher, UK) overnight and were stained using the following compounds in accordance with the methods outlined by Chen et al (44): calcofluor white for the visualization of ␤-1,4 and ␤-1,3 polysaccharides (Sigma, UK), Nile red (Fisher, UK) for lipids and hydrophobic sites, concanavalin A, tetramethylrhodamine conjugate (Fisher, UK), for ␣-mannopyranosyl and ␣-glucopyranosyl sugars, FITC (Fisher, UK) for protein, and Syto 63 (Fisher, UK) for total cells and extracellular DNA. Fluorescence in situ hybridization was carried out as per the methods described by Ainsworth et al (45), using previously described probes for identifying total bacteria (46), Firmicutes (47), Gammaproteobacteria (48), and Actinobacteria (49).…”

Section: Methodsmentioning

confidence: 99%

Floc Formation Reduces the pH Stress Experienced by Microorganisms Living in Alkaline Environments

Charles

Rout

Patel

et al. 2017

Appl Environ Microbiol

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The survival of microorganisms within a cementitious geological disposal facility for radioactive wastes heavily depends on their ability to survive the calciumdominated, hyperalkaline conditions resulting from the dissolution of the cementitious materials. The results from this study show that the formation of flocs, composed of a complex mixture of extracellular polymeric substances (EPS), provides protection against alkaline pH values up to 13.0. The flocs were dominated by Alishewanella and Dietzia spp., producing a mannose-rich carbohydrate fraction incorporating extracellular DNA, resulting in Ca 2ϩ sequestration. EPS provided a ϳ10-m thick layer around the cells within the center of the flocs, which were capable of growth at pH values of 11.0 and 11.5, maintaining internal pH values of 10.4 and 10.7, respectively. Microorganisms survived at a pH of 12.0, where an internal floc pH of 11.6 was observed, as was a reduced associated biomass. We observed limited floc survival (Ͻ2 weeks) at a pH of 13.0. This study demonstrates that flocs maintain lower internal pHs in response to the hyperalkaline conditions expected to occur within a cementitious geological disposal facility for radioactive wastes and indicates that floc communities within such a facility can survive at pHs up to 12.0. IMPORTANCE The role of extracellular polymeric substances (EPS) in the survival of microorganisms in hyperalkaline conditions is poorly understood. Here, we present the taxonomy, morphology, and chemical characteristics of an EPS-based microbial floc, formed by a consortium isolated from an anthropogenic hyperalkaline site. Short-term (Ͻ2 weeks) survival of the flocs at a pH of 13 was observed, with indefinite survival observed at a pH of 12.0. Measurements from micro-pH electrodes (10-m-diameter tip) demonstrated that flocs maintain lower internal pHs in response to hyperalkaline conditions (pH 11.0, 11.5, and 12.0), demonstrating that floc formation and EPS production are survival strategies under hyperalkaline conditions. The results indicate how microbial communities may survive and propagate within the hyperalkaline environment that is expected to prevail in a cementitious geological disposal facility for radioactive wastes; the results are also relevant to the wider extremophile community.

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Section: Methodsmentioning

confidence: 99%

Floc Formation Reduces the pH Stress Experienced by Microorganisms Living in Alkaline Environments

Charles

Rout

Patel

et al. 2017

Appl Environ Microbiol

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“…2 illustrates that the vast majority of bacteria cultured, using either mucus-treated selection media or control media, belonged to the γ-proteobacteria. Members of this group are abundant on corals and have been identified using a range of methods, including culturebased (Ritchie & Smith 2004), molecular (Rohwer et al 2002), and fluorescence in situ hybridization and spectral imaging (Ainsworth et al 2006). Therefore, I think that this subset of culturable associates represents a valid group for the study of symbiotic interactions.…”

Section: Selection For Coral Symbiontsmentioning

confidence: 99%

Regulation of microbial populations by coral surface mucus and mucus-associated bacteria

Ritchie

2006

Mar. Ecol. Prog. Ser.

786

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“…Leica SP5 or similar microscopes) have aided a number of laboratory studies investigating the complex 3-dimensional structure of cells in natural phototrophic biofilms (Roldán et al 2004, Larson & Passy 2005 and in coral-associated bacterial communities (Ainsworth et al 2006). Such systems are under rapid development and, most recently, even sub-cellular pigment distributions within small unicellular cyanobacteria have been resolved (Vermaas et al 2008).…”

Section: Hs Imaging Systemsmentioning

confidence: 99%

Functional and structural imaging of phototrophic microbial communities and symbioses

Kühl¹,

Polerecký²

2008

Aquat. Microb. Ecol.

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In recent years, new imaging methods for mapping microhabitats, solute concentrations, microbial activity and photopigment content have been developed and increasingly applied in different areas of aquatic microbial ecology and biogeochemistry. Such techniques exhibit a spatial resolution similar to that of microsensors, but allow for instantaneous mapping of the 2-dimensional distribution and dynamics of solute and pigment concentrations over areas ranging from µm 2 to several cm 2 . Methods have been developed for imaging O 2 and CO 2 concentrations as well as pH with optical sensor foils (i.e. planar optodes), and for combined imaging of photopigments and photosynthetic activity via variable chlorophyll fluorescence. More recently, hyperspectral imaging has been employed to identify pigment content in individual cells and to visualize the spatial organization of functional groups in photosynthetic microbial communities. We give an overview of these emerging methods with a range of illustrative examples to demonstrate how they can provide useful information in functional and structural studies of a variety of aquatic microbial communities, such as sediments, biofilms, coral tissues or photosynthetic mats.

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Fluorescence In Situ Hybridization and Spectral Imaging of Coral-Associated Bacterial Communities

Cited by 85 publications

References 45 publications

Floc Formation Reduces the pH Stress Experienced by Microorganisms Living in Alkaline Environments

Floc Formation Reduces the pH Stress Experienced by Microorganisms Living in Alkaline Environments

Regulation of microbial populations by coral surface mucus and mucus-associated bacteria

Functional and structural imaging of phototrophic microbial communities and symbioses

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