Characterisation of the fluorescence from freshwater, planktonic bacteria

Elliott, Sarah; Lead, Jamie R.; Baker, Andy

doi:10.1016/j.watres.2006.03.017

Cited by 100 publications

(54 citation statements)

References 26 publications

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“…1). These peaks represent aromatic amino acids, either free or as protein constituents, which have been described as tyrosine-like (ex/em 240-260/300-320 nm) and tryptophan-like (ex/em 270-290/330-350 nm) by other researchers (Coble, 1996;Elliott et al, 2006;Liu et al, 2007). The results indicate that ozonation of HOA and HIA leads to the emergence of a significant amount of aromatic amino acid functionalities.…”

Section: Structural Changes Examined By Eemmentioning

confidence: 73%

Fluorescence spectroscopic characterization of DOM fractions isolated from a filtered river water after ozonation and catalytic ozonation

et al. 2008

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Fluorescence spectra were applied to investigate the structural changes of four dominant dissolved natural organic matter (DOM) fractions of a filtered river water before and after ozonation and catalytic ozonation. The ozonation and catalytic ozonation with synthetic goethite (FeOOH) and cerium dioxide (CeO 2 ) were carried out under normal conditions, i.e. pH 7, reaction time of 10 min, and ozone/DOC ratio of about 1. The fluorescence spectra were recorded at both excitation-emission matrix (EEM) and synchronous scanning modes. EEM results reveal that ozonation of these DOM fractions causes a significant decrease of the aromaticity of humic-like structures and an increase of electron withdrawing groups, e.g., carboxylic groups. The catalysts can further improve the destruction of the humic-like structures in catalytic ozonation. Synchronous spectra reveal that ozonation of hydrophobic acid and hydrophilic acid (HIA) yields a significant amount of by-products with low aromaticity and low molecular weight. Catalytic ozonation enhances substantially the formation of these by-products from HIA and improves the destruction of highly polycyclic aromatic structures for all examined DOM fractions.

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Section: Structural Changes Examined By Eemmentioning

confidence: 73%

Fluorescence spectroscopic characterization of DOM fractions isolated from a filtered river water after ozonation and catalytic ozonation

et al. 2008

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“…1 shows that Peak C also develops during the exponential phase of the growth curve, exhibiting a lag in relation to the OD. The intensity of Peak C continues to increase even during stationary phase, in which cell deaths are equal to newly formed cells (Elliott et al, 2006;Hogg, 2005). Nevertheless a positive correlation between OD and Peak C fluorescence intensity is identified, R 2 ¼ 0.8624 (p < 0.001), supporting the association of Peak C with bacterial numbers.…”

Section: Resultsmentioning

confidence: 99%

“…4). P. aeruginosa has the most complex EEM spectra of the species analysed within this study (Dartnell et al, 2013;Elliott et al, 2006;Smith et al, 2004), with Peaks T, C and A C all immediately identified upon inoculation and during the lag phase (a period of acclimatisation; Hogg, 2005). The occurrence of Peaks C and A C at inoculation suggests it is likely that this FDOM is intracellular and produced within the cells during the initial overnight incubation; likely to be structural or functional proteins produced via microbial metabolic pathways, or potentially intracellular metabolic byproducts.…”

Section: Pseudomonas Aeruginosamentioning

confidence: 97%

“…Three bacterial species were cultured for analysis; Escherichia coli (ATCC 10536) was used as its presence in freshwaters can indicate sewage contamination (Sigee, 2004); Bacillus subtilis (ATCC 6633) was used as it is a ubiquitous soil bacterium (Graumann, 2007) that may be transferred into freshwater systems; and Pseudomonas aeruginosa (NCIMB 8295) as it is ubiquitous in freshwater systems (Elliott et al, 2006;Sigee, 2004).…”

Section: Bacterial Speciesmentioning

confidence: 99%

“…There is no direct evidence that the production of humic-like FDOM in freshwaters is the result of bacterial processing. However, Elliott et al (2006) attributed the presence of this FOM in laboratory samples to stress as opposed to a function that may inherently occur within aquatic systems. What is clear from the literature is that a more detailed understanding of microbial/OM interactions in freshwater systems is needed.…”

Section: Introductionmentioning

confidence: 99%

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The in situ bacterial production of fluorescent organic matter; an investigation at a species level

et al. 2017

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a b s t r a c tAquatic dissolved organic matter (DOM) plays an essential role in biogeochemical cycling and transport of organic matter throughout the hydrological continuum. To characterise microbially-derived organic matter (OM) from common environmental microorganisms (Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa), excitation-emission matrix (EEM) fluorescence spectroscopy was employed. This work shows that bacterial organisms can produce fluorescent organic matter (FOM) in situ and, furthermore, that the production of FOM differs at a bacterial species level. This production can be attributed to structural biological compounds, specific functional proteins (e.g. pyoverdine production by P. aeruginosa), and/or metabolic by-products. Bacterial growth curve data demonstrates that the production of FOM is fundamentally related to microbial metabolism. For example, the majority of Peak T fluorescence (> 75%) is shown to be intracellular in origin, as a result of the building of proteins for growth and metabolism. This underpins the use of Peak T as a measure of microbial activity, as opposed to bacterial enumeration as has been previously suggested. This study shows that different bacterial species produce a range of FOM that has historically been attributed to high molecular weight allochthonous material or the degradation of terrestrial FOM. We provide definitive evidence that, in fact, it can be produced by microbes within a model system (autochthonous), providing new insights into the possible origin of allochthonous and autochthonous organic material present in aquatic systems.

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Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA)

Spencer

Pellerin

Bergamaschi

et al. 2007

Hydrological Processes

163

122

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Abstract:Dissolved organic matter (DOM) concentration and composition in riverine and stream systems are known to vary with hydrological and productivity cycles over the annual and interannual time scales. Rivers are commonly perceived as homogeneous with respect to DOM concentration and composition, particularly under steady flow conditions over short time periods. However, few studies have evaluated the impact of short term variability (<1 day) on DOM dynamics. This study examined whether diurnal processes measurably altered DOM concentration and composition in the hypereutrophic San Joaquin River (California) during a relatively quiescent period. We evaluated the efficacy of using optical in situ measurements to reveal changes in DOM which may not be evident from bulk dissolved organic carbon (DOC) measurement alone. The in situ optical measurements described in this study clearly showed for the first time diurnal variations in DOM measurements, which have previously been related to both composition and concentration, even though diurnal changes were not well reflected in bulk DOC concentrations. An apparent asynchronous trend of DOM absorbance and chlorophyll-a in comparison to chromophoric dissolved organic matter (CDOM) fluorescence and spectral slope S 290 -350 suggests that no one specific CDOM spectrophotometric measurement explains absolutely DOM diurnal variation in this system; the measurement of multiple optical parameters is therefore recommended. The observed diurnal changes in DOM composition, measured by in situ optical instrumentation likely reflect both photochemical and biologically-mediated processes. The results of this study highlight that short-term variability in DOM composition may complicate trends for studies aiming to distinguish different DOM sources in riverine systems and emphasizes the importance of sampling specific study sites to be compared at the same time of day. The utilization of in situ optical technology allows short-term variability in DOM dynamics to be monitored and serves to increase our understanding of its processing and fundamental role in the aquatic environment.

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Characterisation of the fluorescence from freshwater, planktonic bacteria

Cited by 100 publications

References 26 publications

Fluorescence spectroscopic characterization of DOM fractions isolated from a filtered river water after ozonation and catalytic ozonation

Fluorescence spectroscopic characterization of DOM fractions isolated from a filtered river water after ozonation and catalytic ozonation

The in situ bacterial production of fluorescent organic matter; an investigation at a species level

Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA)

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