Viral lysis alters the optical properties and biological availability of dissolved organic matter derived from picocyanobacteria Prochlorococcus

Phytoplankton contribute almost half of the world's total primary production. The exudates and viral lysates of phytoplankton are two important forms of dissolved organic matter (DOM) in aquatic environments and fuel heterotrophic prokaryotic metabolism. However, the effect of viral infection on the composition and biological availability of phytoplankton-released DOM is poorly understood. Here, we investigated the optical characteristics and microbial utilization of the exudates and viral lysates of the ecologically important unicellular picophytoplankton Prochlorococcus. Our results showed that Prochlorococcus DOM produced by viral lysis (Pro-vDOM) with phages of three different morphotypes (myovirus P-HM2, siphovirus P-HS2 and podovirus P-SSP7) had higher humic-like fluorescence intensities, lower absorption coefficients and higher spectral slopes compared to DOM exuded by Prochlorococcus (Pro-exudate). The results indicate that viral infection altered the composition of Prochlorococcus-derived DOM and might contribute to the pool of oceanic humic-like DOM. Incubation with Pro-vDOM resulted in a greater dissolved organic carbon (DOC) degradation rate and decreases in the absorption spectral slope and heterotrophic bacterial growth rate compared to incubation with Pro-exudate, suggesting that Pro-vDOM was more bioavailable compared to Pro-exudate. In addition, the stimulated microbial community succession trajectories were significantly different between the Pro-exudate and Pro-vDOM treatments, indicating that viral lysates play an important role in shaping the heterotrophic bacterial community. Our study demonstrated that viral lysis altered the chemical composition and biological availability of DOM derived from Prochlorococcus, which is the numerically dominant phytoplankton in the oligotrophic ocean. Importance The unicellular picocyanobacterium Prochlorococcus is the numerically dominate phytoplankton in the oligotrophic ocean, contributing to the vast majority of marine primary production. Prochlorococcus releases a significant fraction of fixed organic matter into surrounding environment and supports a vital portion of heterotrophic bacterial activity. Viral lysis is an important biomass loss process of Prochlorococcus. Yet little is known about whether and how viral lysis affects Prochlorococcus-released dissolved organic matter (DOM). Our paper shows that viral infection alters the optical properties (such as the absorption coefficients, spectral slopes and fluorescence intensities) of released DOM and might contribute to a humic-like DOM pool and carbon sequestration in the ocean. Meanwhile, viral lysis also releases various intracellular labile DOM including amino acids, protein-like DOM and lower-molecular weight DOM, increases the bioavailability of DOM and shapes the successive trajectory of the heterotrophic bacterial community. Our study highlights the importance of viruses in impacting the DOM quality in the ocean.

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Optical properties of dissolved organic matter relate to different depth-specific patterns of archaeal and bacterial community structure in the North Atlantic Ocean

FEMS Microbiology Ecology ◽

10.1093/femsec/fiw224 ◽

2016 ◽

Vol 93 (1) ◽

pp. fiw224 ◽

Cited By ~ 12

Author(s):

Elisa Guerrero-Feijóo ◽

Mar Nieto-Cid ◽

Eva Sintes ◽

Vladimir Dobal-Amador ◽

Víctor Hernando-Morales ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Community Structure ◽

Bacterial Community ◽

Dissolved Organic Matter ◽

North Atlantic ◽

Bacterial Community Structure ◽

North Atlantic Ocean ◽

The North ◽

The North Atlantic

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Viral infection of algal blooms leaves a unique metabolic footprint on the dissolved organic matter in the ocean

Science Advances ◽

10.1126/sciadv.abf4680 ◽

2021 ◽

Vol 7 (25) ◽

pp. eabf4680

Author(s):

Constanze Kuhlisch ◽

Guy Schleyer ◽

Nir Shahaf ◽

Flora Vincent ◽

Daniella Schatz ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Primary Production ◽

Viral Infection ◽

Algal Blooms ◽

Trophic Levels ◽

Dynamic Changes ◽

Marine Food Web ◽

Key Players ◽

Marine Food

Algal blooms are hotspots of primary production in the ocean, forming the basis of the marine food web and fueling the dissolved organic matter (DOM) pool. Viruses are key players in controlling algal demise, thereby diverting biomass from higher trophic levels to the DOM pool, a process termed the “viral shunt.” To decode the metabolic footprint of the viral shunt in the environment, we induced a bloom of Emiliania huxleyi and followed its succession using untargeted exometabolomics. We show that bloom succession induces dynamic changes in the exometabolic landscape. We found a set of chlorine-iodine–containing metabolites that were induced by viral infection and released during bloom demise. These metabolites were further detected in virus-infected oceanic E. huxleyi blooms. Therefore, we propose that halogenation with both chlorine and iodine is a distinct hallmark of the virus-induced DOM of E. huxleyi, providing insights into the metabolic consequences of the viral shunt.

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Comparison of the optical properties of dissolved organic matter in two river-influenced coastal regions of the Canadian Arctic

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2006.10.022 ◽

2007 ◽

Vol 72 (1-2) ◽

pp. 261-272 ◽

Cited By ~ 79

Author(s):

Leira Retamal ◽

Warwick F. Vincent ◽

Christine Martineau ◽

Christopher L. Osburn

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Dissolved Organic Matter ◽

Canadian Arctic ◽

Coastal Regions

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Optical Properties of Dissolved Organic Matter in Finnish and Estonian Lakes

Hydrology Research ◽

10.2166/nh.2003.0012 ◽

2003 ◽

Vol 34 (4) ◽

pp. 361-386 ◽

Cited By ~ 14

Author(s):

L. Sipelgas ◽

H. Arst ◽

K. Kallio ◽

A. Erm ◽

P. Oja ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Natural Waters ◽

Mean Value ◽

Published Data ◽

Optical Parameters ◽

Exponential Approximation ◽

Absorption Coefficients ◽

Specific Absorption ◽

The Mean

The main objective of the present study is to test various methods for describing the absorption spectra of coloured dissolved organic matter (CDOM) and to determine the numerical values of some optical parameters of CDOM in lakes with diverse water quality. First, the parameters of an exponential model in different spectral intervals were determined. In addition, the suitability of some other models for the approximation of CDOM spectra was estimated. Specific absorption coefficients of CDOM were calculated from the absorption coefficients and dissolved organic carbon (DOC) concentrations. The experimental initial data were differences between spectral attenuation coefficients of filtered and distilled water. Two datasets were used: 1) for 13 Estonian and 7 Finnish lakes (altogether 404 spectra between 350 and 700 nm) measured by the Estonian Marine Institute (EMI); 2) for 10 Finnish lakes (73 spectra) measured by the Finnish Environment Institute (FEI). The spectra of CDOM absorption coefficients (aCDOM) were calculated from experimental data taking into account the correction due to scattering properties of colloids in the filtered water. The total content of CDOM in natural waters of Estonian and Finnish lakes was expressed by means of aCDOM at the wavelength of 380 nm. It varied significantly, from 0.71 to 19.5 m−1, the mean value (of all the investigated lakes) being around 6.6 m−1. Slopes of the exponential approximation varied widely, from 0.006 to 0.03 nm−1. Averaged over all lakes values of slope for the interval 380-500 nm obtained from the EMI dataset are close to those obtained from the FEI dataset: from 0.014 nm−1 (without correction) to 0.016-0.017 nm-1 (with different types of correction). These results are in good correspondence with most published data. Attempts to describe the spectra in the region of 350-700 nm by means of hyperexponential functions (∽ exp(-αλη)) show that: (1) η < 1 (in the case of traditional exponential approximation η = 1); (2) a promising idea is to seek the best fit only for wavelengths λ > λ1, where λ1 will be chosen taking into account the real shape of aCDOM spectra. The mean value of the specific absorption coefficient (a*CDOM) at the wavelength 380 nm obtained in this study (0.44 L mg−1 m−1) is close to the values published in the literature, if we assume that a*CDOM (380) is calculated using the data of dissolved organic matter (DOM). The optically non-active fraction of DOM in our study was high and therefore a*CDOM (380) was considerably higher (1.01 L mg−1 m−1) than a*CDOM (380). The results of the present work could be used in the modeling of underwater light field as well as in the interpretation of radiation measurements and optical remote sensing results.

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Optical Properties of Dissolved Organic Matter in Urban Fountains

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/221/1/012112 ◽

2019 ◽

Vol 221 ◽

pp. 012112

Author(s):

Katarzyna Parszuto ◽

Renata Tandyrak ◽

Renata Augustyniak ◽

Jolanta Grochowska ◽

Michal Lopata ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Dissolved Organic Matter

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Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum

Frontiers in Marine Science ◽

10.3389/fmars.2020.588287 ◽

2020 ◽

Vol 7 ◽

Author(s):

Leanne C. Powers ◽

Rossana Del Vecchio ◽

Neil V. Blough ◽

Natasha McDonald ◽

Philippe Schmitt-Kopplin ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Dissolved Organic Matter ◽

Photochemical Transformation

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Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake

Biogeosciences ◽

10.5194/bg-14-1215-2017 ◽

2017 ◽

Vol 14 (5) ◽

pp. 1215-1233 ◽

Cited By ~ 6

Author(s):

María Encina Aulló-Maestro ◽

Peter Hunter ◽

Evangelos Spyrakos ◽

Pierre Mercatoris ◽

Attila Kovács ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Dissolved Organic Matter ◽

Seasonal Variability ◽

Chromophoric Dissolved Organic Matter ◽

Lake Balaton ◽

Spectral Slope ◽

Marked Variability ◽

Rich Material ◽

Development And Validation

Abstract. The development and validation of remote-sensing-based approaches for the retrieval of chromophoric dissolved organic matter (CDOM) concentrations requires a comprehensive understanding of the sources and magnitude of variability in the optical properties of dissolved material within lakes. In this study, spatial and seasonal variability in concentration and composition of CDOM and the origin of its variation was studied in Lake Balaton (Hungary), a large temperate shallow lake in central Europe. In addition, we investigated the effect of photobleaching on the optical properties of CDOM through in-lake incubation experiments. There was marked variability throughout the year in CDOM absorption in Lake Balaton (aCDOM(440) = 0. 06–9.01 m−1). The highest values were consistently observed at the mouth of the main inflow (Zala River), which drains humic-rich material from the adjoining Kis-Balaton wetland, but CDOM absorption decreased rapidly towards the east where it was consistently lower and less variable than in the westernmost lake basins. The spectral slope parameter for the interval of 350–500 nm (SCDOM(350–500)) was more variable with increasing distance from the inflow (observed range 0.0161–0.0181 nm−1 for the mouth of the main inflow and 0.0158–0.0300 nm−1 for waters closer to the outflow). However, spatial variation in SCDOM was more constant exhibiting a negative correlation with aCDOM(440). Dissolved organic carbon (DOC) was strongly positively correlated with aCDOM(440) and followed a similar seasonal trend but it demonstrated more variability than either aCDOM or SCDOM with distance through the system. Photobleaching resulting from a 7-day exposure to natural solar UV radiation resulted in a marked decrease in allochthonous CDOM absorption (7.04 to 3.36 m−1, 42 % decrease). Photodegradation also resulted in an increase in the spectral slope coefficient of dissolved material.

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Linking Shifts in Bacterial Community Composition and Function with Changes in the Dissolved Organic Matter Pool in Ice-Covered Baiyangdian Lake, Northern China

Microorganisms ◽

10.3390/microorganisms8060883 ◽

2020 ◽

Vol 8 (6) ◽

pp. 883

Author(s):

Shilei Zhou ◽

Yue Sun ◽

Minghui Yu ◽

Zhenpeng Shi ◽

Hang Zhang ◽

...

Keyword(s):

Organic Matter ◽

Bacterial Community ◽

Dissolved Organic Matter ◽

Bacterial Community Composition ◽

Environmental Parameters ◽

Northern China ◽

Mantel Test ◽

Biological Index ◽

Linear Discriminant ◽

Baiyangdian Lake

The relationship between CDOM (Chromophoric dissolved organic matter) and the bacterial community was investigated in ice-covered Baiyangdian Lake. The results showed that environmental parameters significantly differed in Baiyangdian Lake, whereas a-diversity was not significantly different. Moreover, the microbial and functional communities exhibited significant differences, and T (Temperature), pH, ORP (Oxidation-reduction potential), DO (Dissolved oxygen), NO3−-N, NH4+-N, and Mn (Manganese) were the main environmental factors of these differences, based on redundancy analysis and the Mantel test. Biomarkers of the microbial and functional communities were investigated through linear discriminant analysis effect size and STAMP analysis. The number of biomarkers in the natural area was highest among the typical zones, and most top functions were related to carbohydrate metabolism. Two protein-like components (C1 and C2) and one humic-like component (C3) were identified by parallel factor analysis, and C1 was positively related to C2 (R = 0.99, p < 0.001), indicating the same sources. Moreover, CDOM significantly differed among the typical zones (p < 0.001). The high biological index, fluorescence index, β:α, and low humification index indicated a strong autochthonous component and aquatic bacterial origin, which was consistent with the results of UV-vis absorption spectroscopy. Network analysis revealed non-random co-occurrence patterns. The bacterial and functional communities interacted closely with CDOM. The dominant genera were CL500-29_marine_group, Flavobacterium, Limnohabitans, and Candidatus_Aquirestis. Random forest analysis showed that C1, C2, and C3 are important predictors of α- and β-diversity in the water bacterial community and its functional composition. This study provides insight into the interaction between bacterial communities and DOM (Dissolved organic matter) in ice-covered Baiyangdian Lake.

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