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Environmental Microbiology and Microbial Ecology

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Vertical Stratification Of Sediment Microbial Communities Along Geochemical Gradients Of A Subterranean Estuary Located At The Gloucester Beach Of Virginia, United States, Yiguo Hong, Jiapeng Wu, Stephanie Wilson, Bk Song Jan 2019

Vertical Stratification Of Sediment Microbial Communities Along Geochemical Gradients Of A Subterranean Estuary Located At The Gloucester Beach Of Virginia, United States, Yiguo Hong, Jiapeng Wu, Stephanie Wilson, Bk Song

VIMS Articles

Subterranean estuaries (STEs) have been recognized as important ecosystems for the exchange of materials between the land and sea, but the microbial players of biogeochemical processes have not been well examined. In this study, we investigated the bacterial and archaeal communities within 10 cm depth intervals of a permeable sediment core (100 cm in length) collected from a STE located at Gloucester Point (GP-STE), VA, United States. High throughput sequencing of 16S rRNA genes and subsequent bioinformatics analyses were conducted to examine the composition, diversity, and potential functions of the sediment communities. The community composition varied significantly from the surface ...


Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof Jan 2018

Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof

VIMS Articles

DNA stable isotope probing (SIP) was used to track the uptake of organic and inorganic carbon sources for TACK archaea(Thaumarchaeota/Aigarchaeota/Crenarchaeota/Korarchaeota) on a cruise of opportunity in the North Atlantic. Due to water limitations, duplicate samples from the deep photic (60–115 m), the mesopelagic zones (local oxygen minimum; 215–835 m)and the bathypelagic zone (2085–2835 m) were amended with various combinations of12C- or13C-acetate/urea/bicarbonate to assess cellular carbon acquisition. The SIP results indicated the majority of TACK archaeal operational taxonomic units(OTUs) incorporated13C from acetate and/or urea into newly synthesized DNA within ...


Microbes As Engines Of Ecosystem Function: When Does Community Structure Enhance Predictions Of Ecosystem Processes?, Emily B. Graham, Joeseph E. Knelman, Et Al, Bk Song Jan 2016

Microbes As Engines Of Ecosystem Function: When Does Community Structure Enhance Predictions Of Ecosystem Processes?, Emily B. Graham, Joeseph E. Knelman, Et Al, Bk Song

VIMS Articles

Microorganisms are vital in mediating the earth’s biogeochemical cycles; yet, despite our rapidly increasing ability to explore complex environmental microbial communities, the relationship between microbial community structure and ecosystem processes remains poorly understood. Here, we address a fundamental and unanswered question in microbial ecology: ‘When do we need to understand microbial community structure to accurately predict function?’ We present a statistical analysis investigating the value of environmental data and microbial community structure independently and in combination for explaining rates of carbon and nitrogen cycling processes within 82 global datasets. Environmental variables were the strongest predictors of process rates but ...


Structure And Function Of Zooplankton-Associated Bacterial Communities In A Temperate Estuary Change More With Time Than With Zooplankton Species, Samatha L. Bickel, Kam W. Tang, Hans-Peter Grossart Mar 2014

Structure And Function Of Zooplankton-Associated Bacterial Communities In A Temperate Estuary Change More With Time Than With Zooplankton Species, Samatha L. Bickel, Kam W. Tang, Hans-Peter Grossart

VIMS Articles

Zooplankton support distinct bacterial communities in high concentrations relative to the surrounding water, but little is known about how the compositions and functionalities of these bacterial communities change through time in relation to environmental conditions. We conducted a year-long field study of bacterial communities associated with common zooplankton groups as well as free-living bacterial communities in the York River, a tributary of Chesapeake Bay. Bacterial community genetic fingerprints and their carbon substrate usage were examined by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA and by Biolog EcoPlates, respectively. Zooplankton-associated communities were genetically distinct from free-living bacterial communities but ...


Impacts Of Freshwater Flushing On Anammox Community Structure And Activities In The New River Estuary, Usa, Ja Lisa, B Song, Cr Tobias, Ka Duernberger Jan 2014

Impacts Of Freshwater Flushing On Anammox Community Structure And Activities In The New River Estuary, Usa, Ja Lisa, B Song, Cr Tobias, Ka Duernberger

VIMS Articles

Anaerobic ammonium oxidation (anammox) and denitrification are 2 microbial nitrogen removal processes that may play an important role in controlling the intensity and duration of estuarine and coastal eutrophication. Sediment communities in the New River Estuary, North Carolina were investigated to determine the dynamics of anammox activity and community structure in conjunction with environmental conditions. N-15 tracer incubation experiments with sediment slurries were used to measure anammox and denitrification rates and estimate anammox contribution to total N-2 production. Molecular analyses targeting the hydrazine oxidoreductase (hzo) gene were conducted to examine the structure of anammox communities and quantify the abundance of ...


Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, Yw Luo, Mam Friedrichs, Sc Doney, Mj Church, Hw Ducklow Jan 2010

Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, Yw Luo, Mam Friedrichs, Sc Doney, Mj Church, Hw Ducklow

VIMS Articles

Previous studies have focused on the role of labile dissolved organic matter (DOM) (defined as turnover time of similar to 1 d) in supporting heterotrophic bacterial production, but have mostly neglected semilabile DOM (defined as turnover time of similar to 100 to 1000 d) as a potential substrate for heterotrophic bacterial growth. To test the hypothesis that semilabile DOM supports substantial amounts of heterotrophic bacterial production in the open ocean, we constructed a 1-dimensional epipelagic ecosystem model and applied it to 3 open ocean sites: the Arabian Sea, Equatorial Pacific and Station ALOHA in the North Pacific Subtropical Gyre. The ...


Comparison Of Cell-Specific Activity Between Free-Living And Attached Bacteria Using Isolates And Natural Assemblages, Hp Gropssar, Kw Tang, T Kiorboe, H Ploug Jan 2007

Comparison Of Cell-Specific Activity Between Free-Living And Attached Bacteria Using Isolates And Natural Assemblages, Hp Gropssar, Kw Tang, T Kiorboe, H Ploug

VIMS Articles

Marine snow aggregates are microbial hotspots that support high bacterial abundance and activities. We conducted laboratory experiments to compare cell-specific bacterial protein production (BPP) and protease activity between free-living and attached bacteria. Natural bacterial assemblages attached to model aggregates (agar spheres) had threefold higher BPP and two orders of magnitude higher protease activity than their free-living counterpart. These observations could be explained by preferential colonization of the agar spheres by bacteria with inherently higher metabolic activity and/or individual bacteria increasing their metabolism upon attachment to surfaces. In subsequent experiments, we used four strains of marine snow bacteria isolates to ...


Microbial Abundance, Composition And Enzymatic Activity During Decomposition Of Copepod Carcasses, Kw Tang, Kml Hutalle, Et Al Nov 2006

Microbial Abundance, Composition And Enzymatic Activity During Decomposition Of Copepod Carcasses, Kw Tang, Kml Hutalle, Et Al

VIMS Articles

Literature suggests that zooplankton carcasses are prevalent at times in both freshwater and marine environments, and could be important substrate sources for water column microbes (Dubovskaya et al. 2003, Hydrobiologia 504:223-227; Tang et al. 2006b, Estuar Coast Shelf Sci 68:499-508). We conducted laboratory experiments to investigate the decomposition of copepod carcasses by ambient microbes from Lake Dagow, Germany. Bacteria rapidly colonized and decomposed the carcasses, mainly from the inside. The ambient bacterial abundance increased 2-fold or more at the peak of decomposition, but decreased afterward, presumably due to protozoan grazing. Initial increase in ambient bacteria was faster at ...


Molecular Assays For Detecting Aphanomyces Invadans In Ulcerative Mycotic Fish Lesions, Mw Vandersea, Rw Litaker, B Yonnish,, Et Al, H Kator, Et Al Feb 2006

Molecular Assays For Detecting Aphanomyces Invadans In Ulcerative Mycotic Fish Lesions, Mw Vandersea, Rw Litaker, B Yonnish,, Et Al, H Kator, Et Al

VIMS Articles

The pathogenic oomycete Aphanomyces invadans is the primary etiological agent in ulcerative mycosis, an ulcerative skin disease caused by a fungus-like agent of wild and cultured fish. We developed sensitive PCR and fluorescent peptide nucleic acid in situ hybridization (FISH) assays to detect A. invadans. Laboratory-challenged killifish (Fundulus heteroclitus) were first tested to optimize and validate the assays. Skin ulcers of Atlantic menhaden (Brevoortia tyrannus) from populations found in the Pamlico and Neuse River estuaries in North Carolina were then surveyed. Results from both assays indicated that all of the lesioned menhaden (n = 50) collected in September 2004 were positive ...


Interactions Between Marine Snow And Heterotrophic Bacteria: Aggregate Formation And Microbial Dynamics, Hp Grossart, T Kiorboe, Kw Tang, Et Al Feb 2006

Interactions Between Marine Snow And Heterotrophic Bacteria: Aggregate Formation And Microbial Dynamics, Hp Grossart, T Kiorboe, Kw Tang, Et Al

VIMS Articles

Macroscopic aggregates (marine snow) contribute to new production and nutrient dynamics in the upper ocean and vertical fluxes of organic matter to the deep ocean. To test whether microorganisms play a significant role in phytoplankton aggregate formation we studied particle abundance and size as well as abundance, colonization behaviour, and community composition of bacteria during the growth of 2 marine diatoms (Thalassiosira weissflogii and Navicula sp.) under axenic and non-axenic conditions. Community composition of free-living and attached bacteria during phytoplankton growth and aggregation was studied by amplification of 16S rRNA gene fragments and denaturing gradient gel electrophoresis (DGGE). Our results ...


Mycobacterium Pseudoshottsii Sp Nov., A Slowly Growing Chromogenic Species Isolated From Chesapeake Bay Striped Bass (Morone Saxatilis), Mw Rhodes, H Kator, Et Al, I Kaattari, Kimberly S. Reece, Wolfgang K. Vogelbein, Ca Ottinger May 2005

Mycobacterium Pseudoshottsii Sp Nov., A Slowly Growing Chromogenic Species Isolated From Chesapeake Bay Striped Bass (Morone Saxatilis), Mw Rhodes, H Kator, Et Al, I Kaattari, Kimberly S. Reece, Wolfgang K. Vogelbein, Ca Ottinger

VIMS Articles

A group of slowly growing photochromogenic mycobacteria was isolated from Chesapeake Bay striped bass (Morone saxatilis) during an epizootic of mycobacteriosis. Growth characteristics, acid-fastness and 16S rRNA gene sequencing results were consistent with those of the genus Mycobacterium, Biochemical reactions, growth characteristics and mycolic acid profiles (HPLC) resembled those of Mycobacterium shottsii, a non-pigmented mycobacterium also isolated during the same epizootic. Sequencing of the 16S rRNA genes, the gene encoding the exported repeated protein (erp) and the gene encoding the 65 kDa heat-shock protein (hsp65) and restriction enzyme analysis of the hsp65 gene demonstrated that this group of isolates is ...


Copepods As Microbial Hotspots In The Ocean: Effects Of Host Feeding Activities On Attached Bacteria, Kw Tang Jan 2005

Copepods As Microbial Hotspots In The Ocean: Effects Of Host Feeding Activities On Attached Bacteria, Kw Tang

VIMS Articles

Through ingestion a copepod introduces rich organic substrates into its guts and fecal pellets, where dense bacteria may exploit them and show fast growth. Thus, a copepod and its fecal pellets may be regarded as microbial hotspots in the ocean. This study investigated the effects of copepods' feeding activities on the associated bacteria, using the Most Probable Number (MPN) method. Starved Acartia tonsa (calanoid copepod) carried a background bacteria population of 103 to 10(4) copepod(-1). When fed axenic cultures of algae Rhodomonas salina or Dunaliella tertiolecta, the bacterial abundance increased curvilinearly with the copepods' ingestion rates. When fed ...


Dinitrogen Fixation And Release Of Ammonium And Dissolved Organic Nitrogen By Trichodesmium Ims101, Mr Mulholland, Da Bronk, Dg Capone Nov 2004

Dinitrogen Fixation And Release Of Ammonium And Dissolved Organic Nitrogen By Trichodesmium Ims101, Mr Mulholland, Da Bronk, Dg Capone

VIMS Articles

Two methods used to measure dinitrogen (N-2) fixation (acetylene reduction and N-15(2) uptake) often result in different N-2 fixation rates. Part of the discrepancy may arise from the observation that Trichodesmium can release a fraction of their recently fixed N-2 as dissolved organic nitrogen (DON) and/or ammonium (NH4+). To resolve outstanding issues regarding N-2 fixation and the production of dissolved combined nitrogen (N) by Trichodesmium, we conducted a comprehensive analysis of N-2 fixation and the production of DON and NH4+ in cultures of Trichodesmium IMS101. We performed N-15(2) uptake experiments in parallel with acetylene (C2H2) reduction assays ...


Real-Time Pcr For Detection And Quantification Of The Protistan Parasite Perkinsus Marinus In Environmental Waters, Corinne Audemard, Kimberly S. Reece, Em Burreson Nov 2004

Real-Time Pcr For Detection And Quantification Of The Protistan Parasite Perkinsus Marinus In Environmental Waters, Corinne Audemard, Kimberly S. Reece, Em Burreson

VIMS Articles

The protistan parasite Perkinsus marinus is a severe pathogen of the oyster Crassostrea virginica along the east coast of the United States. Very few data have been collected, however, on the abundance of the parasite in environmental waters, limiting our understanding of P. marinus transmission dynamics. Real-time PCR assays with SybrGreen I as a label for detection were developed in this study for quantification of P. marinus in environmental waters with P. marinus species-specific primers and of Perkinsus spp. with Perkinsus genus-specific primers. Detection of DNA concentrations as low as the equivalent of 3.3 x 10(-2) cell per ...


Light Dependence Of [H-3]Leucine Incorporation In The Oligotrophic North Pacific Ocean, Mj Church, Hw Ducklow, Da Karl Jul 2004

Light Dependence Of [H-3]Leucine Incorporation In The Oligotrophic North Pacific Ocean, Mj Church, Hw Ducklow, Da Karl

VIMS Articles

The influence of irradiance on bacterial incorporation of [H-3] leucine was evaluated at Station ALOHA in the oligotrophic North Pacific subtropical gyre. Six experiments were conducted on three cruises to Station ALOHA to examine how [H-3]leucine incorporation varied as a function of irradiance. Two experiments were also conducted to assess the photoautotrophic response to irradiance (based on photosynthetic uptake of [C-14] bicarbonate) in both the upper and lower photic zones. Rates of [H-3]leucine incorporation responded to irradiance in a photosynthesis-like manner, increasing sharply at low light and then saturating and sometimes declining with increasing light intensity. The influence ...


Particle-Associated Flagellates: Swimming Patterns, Colonization Rates, And Grazing On Attached Bacteria, T Kiorboe, Hp Grossart, H Ploug, K Tang, B Auer Apr 2004

Particle-Associated Flagellates: Swimming Patterns, Colonization Rates, And Grazing On Attached Bacteria, T Kiorboe, Hp Grossart, H Ploug, K Tang, B Auer

VIMS Articles

Some pelagic flagellates colonize particles, such as marine snow, where they graze on bacteria and thus impact the dynamics of the attached microbial communities. Particle colonization is governed by motility. Swimming patterns of 2 particle-associated flagellates, Bodo designis and Spumella sp., are very different, the former swimming slowly in an erratic, random pattern, and the latter faster and along smooth helixes of variable amplitude and frequency. At spatial scales exceeding ca. 50 mum, the motility of B. designis can be described as a random walk and modeled as diffusion. Spumella sp. shows directional persistence of the helical axes up to ...


Mycobacterium-Inducible Nramp In Striped Bass (Morone Saxatilis), Erin J. Burge, David T. Gauthier, Christopher A. Ottinger, Peter A. Van Veld Mar 2004

Mycobacterium-Inducible Nramp In Striped Bass (Morone Saxatilis), Erin J. Burge, David T. Gauthier, Christopher A. Ottinger, Peter A. Van Veld

VIMS Articles

In mammals, the natural resistance-associated macrophage protein 1 gene, Nramp1, plays a major role in resistance to mycobacterial infections. Chesapeake Bay striped bass (Morone saxatilis) is currently experiencing an epizootic of mycobacteriosis that threatens the health of this ecologically and economically important species. In the present study, we characterized an Nramp gene in this species and obtained evidence that there is induction following Mycobacterium exposure. The striped bass Nramp gene (MsNramp) and a 554-amino-acid sequence contain all the signal features of the Nramp family, including a topology of 12 transmembrane domains (TM), the transport protein-specific binding-protein-dependent transport system inner membrane ...


Supplementation Of Perkinsus Marinus Cultures With Host Plasma Or Tissue Homogenate Enhances Their Infectivity, Cg Earnhart, Ma Vogelbein, Gd Brown, Ks Reece, Sl Kaattari Jan 2004

Supplementation Of Perkinsus Marinus Cultures With Host Plasma Or Tissue Homogenate Enhances Their Infectivity, Cg Earnhart, Ma Vogelbein, Gd Brown, Ks Reece, Sl Kaattari

VIMS Articles

The protozoan oyster parasite Perkinsus marinas can be cultured in vitro in a variety of media; however, this has been associated with a rapid attenuation of infectivity. Supplementation of defined media with products of P. marinus-susceptible (Crassostrea virginica) and -tolerant (Crassostrea gigas, Crassostrea ariakensis) oysters alters proliferation and protease expression profiles and induces differentiation into morphological forms typically seen in vivo. It was not known if attenuation could be reversed by host extract supplementation. To investigate correlations among these changes as well as their association with infectivity, the effects of medium supplementation with tissue homogenates from both susceptible and tolerant ...


Trophic Uptake And Transfer Of Dmsp In Simple Planktonic Food Chains, Kw Tang, R Simo Mar 2003

Trophic Uptake And Transfer Of Dmsp In Simple Planktonic Food Chains, Kw Tang, R Simo

VIMS Articles

Recent field studies suggest that a large portion of phytoplankton-DMSP could be lost to grazing by protozoans, but the fate of the grazed DMSP remains uncertain. In the laboratory we studied trophic uptake and transfer of phytoplankton-DMSP through simple planktonic food chains using 2 experimental approaches: (1) A direct approach measured the ingestion and retention of phytoplankton-DMSP by the heterotrophic dinoflagellate Gyrodinium dominans. Overall, DMSP content of G. dominans estimated by the direct approach was highly variable, likely because of the low G. dominans biomass relative to phytoplankton in the samples. (2) An indirect approach, in which the omnivorous copepod ...


Bacterioplankton Dynamics In The York River Estuary: Primary Influence Of Temperature And Freshwater Inputs, G. E. Schultz, E. D. White, H. W. Ducklow Jan 2003

Bacterioplankton Dynamics In The York River Estuary: Primary Influence Of Temperature And Freshwater Inputs, G. E. Schultz, E. D. White, H. W. Ducklow

VIMS Articles

Bacterial community dynamics were investigated over seasonal and basin scales within the York River estuary, Virginia. Variables describing bacterioplankton dynamics were measured at 6 stations spanning the entire salinity gradient (0 to ca. 20 psu over 60 km). Samples were collected monthly from June 1996 through May 1997 and every other month from June 1997 through May 1998. Bacterial abundance and production were high throughout the estuary. Bacterial abundance ranged from 4.4 x 10(8) to 1.3 x 10(10) cells l(-1). Incorporation of (3)H-thymidine ranged from 10 to 863 pmol(-1) h(-1) while (3 ...


Widespread Distribution In Polar Oceans Of A 16s Rrna Gene Sequence With Affinity To Nitrosospira-Like Ammonia-Oxidizing Bacteria, Jt Hollibaugh, Hw Ducklow, N Bano Mar 2002

Widespread Distribution In Polar Oceans Of A 16s Rrna Gene Sequence With Affinity To Nitrosospira-Like Ammonia-Oxidizing Bacteria, Jt Hollibaugh, Hw Ducklow, N Bano

VIMS Articles

We analyzed the phylogenetic compositions of ammonia-oxidizing bacteria of the beta subclass of Proteobacteria from 42 Southern Ocean samples. We found a Nitrosospira-like 16S rRNA gene sequence in all 20 samples that yielded PCR products (8 of 30 samples from the Ross Sea and 12 of 12 samples from the Palmer Peninsula). We also found this sequence in Arctic Ocean samples, indicating a transpolar, if not global, distribution; however, slight differences between Arctic and Antarctic sequences may be evidence of polar endemism.


Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk Jan 2002

Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk

VIMS Articles

Recent studies have shown that in a number of humic-rich surface waters in North America, NH4+ is released when dissolved organic matter (DOM) is exposed to sunlight. However, photochemical NH4+ production has not been observed in all surface waters, and factors that contribute to it are not well understood. We hypothesized that the presence or absence of NH4+ photoproduction may be affected by the light exposure history of DOM, The present study was undertaken to determine whether DOM from surficial groundwaters, with minimal light exposure history, would produce labile nitrogen (N) photoproducts more consistently, In this study, estuarine surface waters ...


Microbial Loop Carbon Cycling In Ocean Environments Studied Using A Simple Steady-State Model, T. R. Anderson, H. W. Ducklow Oct 2001

Microbial Loop Carbon Cycling In Ocean Environments Studied Using A Simple Steady-State Model, T. R. Anderson, H. W. Ducklow

VIMS Articles

A simple steady-state model is used to examine the microbial loop as a pathway for organic C in marine systems, constrained by observed estimates of bacterial to primary production ratio (BP:PP) and bacterial growth efficiency (BGE). Carbon sources (primary production including extracellular release of dissolved organic carbon, DOC), cycling via zooplankton grazing and viral lysis, and sinks (bacterial and zooplankton respiration) are represented. Model solutions indicate that, at least under near steady-state conditions, recent estimates of BP:PP of about 0.1 to 0.15 are consistent with reasonable scenarios of C cycling (low BGE and phytoplankton extracellular release ...


Changes In Bacterioplankton Metabolic Capabilities Along A Salinity Gradient In The York River Estuary, Virginia, Usa, G. E. Schultz, H. W. Ducklow Sep 2000

Changes In Bacterioplankton Metabolic Capabilities Along A Salinity Gradient In The York River Estuary, Virginia, Usa, G. E. Schultz, H. W. Ducklow

VIMS Articles

Changes in metabolic capabilities of bacterial communities along the estuarine salinity gradient may affect the extent of organic matter processing and bacterial growth and accumulation during transit through the system; As part of a larger study of estuarine microbial processes, we attempted to quantify differences in bacterial community structure using Biolog plates. Biolog GN plates (Biolog, Inc., Hayward, CA, USA) were used to determine differences in bacterioplankton community metabolic potential. Biolog GN microplates are 96-well microtiter plates in which each well contains an individual carbon source as well the redox dye tetrazolium violet. As bacteria grow and oxidize each substrate ...


Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Mj Church, Da Hutchins, Hw Ducklow Feb 2000

Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Mj Church, Da Hutchins, Hw Ducklow

VIMS Articles

The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42 degrees S and 55 degrees S along 141 degrees E. Bacterial abundance, mean cell volume, and [H-3]thymidine and [H-3]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial ...


Autumnal Biomass And Potential Productivity Of Salt Marsh Fungi From 29 Degrees To 43 Degrees North Latitude Along The United States Atlantic Coast, Sy Newell, Lk Blum, Re Crawford, T Dai, M Dionne Jan 2000

Autumnal Biomass And Potential Productivity Of Salt Marsh Fungi From 29 Degrees To 43 Degrees North Latitude Along The United States Atlantic Coast, Sy Newell, Lk Blum, Re Crawford, T Dai, M Dionne

VIMS Articles

It has been established that substantial amounts of fungal mass accumulate in standing decaying smooth cordgrass (Spartina alterniflora) marshes in the southeastern United States (e.g., in standing decaying leaf blades with a total fungal organic mass that accounts for about 20% of the decay system organic mass), but it has been hypothesized that in marshes farther north this is not true. We obtained samples of autumnal standing decaying smooth cordgrass from sites in Florida to Maine over a 3-year period. The variation in latitude could not explain any of the variation in the living fungal standing crop las determined ...


Sorbitol-Fermenting Bifidobacteria As Indicators Of Diffuse Human Faecal Pollution In Estuarine Waters, Mw Rhodes, H Kator Oct 1999

Sorbitol-Fermenting Bifidobacteria As Indicators Of Diffuse Human Faecal Pollution In Estuarine Waters, Mw Rhodes, H Kator

VIMS Articles

Sorbitol fermenting bifidobacteria were evaluated as indicators of non-point source human faecal pollution to three sub-estuaries with elevated faecal coliform densities. Human-specific bifidobacteria correlated with identifiable human sanitary deficiencies in feeder streams to estuarine creeks in two of three watersheds examined, one rural and one moderately developed. Sorbitol-fermenting bifidobacteria were recovered at densities ranging from 1 to 90 colony-forming-units 100 ml(-1) in 11 of 258 water samples but were undetected in sediment (n = 68) and scat from resident wildlife (deer, muskrat and raccoon, n = 20). Failure to detect sorbitol-fermenting bifidobacteria in water samples during the summer months was consistent ...


Perkinsus Marinus Extracellular Protease Modulates Survival Of Vibrio Vulnificus In Eastern Oyster (Crassostrea Virginica) Hemocytes, Bd Tall, Jf La Peyre, Et Al, M Faisal Sep 1999

Perkinsus Marinus Extracellular Protease Modulates Survival Of Vibrio Vulnificus In Eastern Oyster (Crassostrea Virginica) Hemocytes, Bd Tall, Jf La Peyre, Et Al, M Faisal

VIMS Articles

The in vitro effects of the Perkinsus marinus serine protease on the intracellular survival of Vibrio vulnificus in oyster hemocytes were examined by using a time-course gentamicin internalization assay. Results showed that protease-treated hemocytes were initially slower to internalize V. vulnificus than untreated hemocytes. After 1 h, the elimination of V. vulnificus by treated hemocytes was significantly suppressed compared with hemocytes infected with invasive and noninvasive controls. Our data suggest that the serine protease produced by P. marinas suppresses the vibriocidal activity of oyster hemocytes to effectively eliminate V. vulnificus, potentially leading to conditions favoring higher numbers of vibrios in ...


The Bacterial Component Of The Oceanic Euphotic Zone, H. W. Ducklow Jan 1999

The Bacterial Component Of The Oceanic Euphotic Zone, H. W. Ducklow

VIMS Articles

Bacteria in the open sea remote from land are sustained strictly on local sources of organic production which should make understanding their nutrition and growth regulation easier than in nearshore systems, estuaries and lakes. Until now, a paucity of data from geographically isolated oceanic sites prevented ready :interpretation. In the past decade investigation of bacterial properties in oceanic systems has increased rapidly, stimulated in part by large oceanographic programs like the Joint Global Ocean Flux Study. Here I review comprehensive investigations of bacterial biomass and production dynamics in the subarctic north Atlantic and north Pacific, oligotrophic gyres in both oceans ...


Estimation Of Bacterial Respiration And Growth Efficiency In The Ross Sea, Antarctica, C. A. Carlson, N. R. Bates, H. W. Ducklow, D. A. Hansell Jan 1999

Estimation Of Bacterial Respiration And Growth Efficiency In The Ross Sea, Antarctica, C. A. Carlson, N. R. Bates, H. W. Ducklow, D. A. Hansell

VIMS Articles

Seawater cultures were conducted in large volume (36 l) gas impermeable tri-laminate bags for the purpose of empirically deriving bacterial growth efficiency (BGE) and carbon conversion factors (CCF) in the south central Ross Sea. This experimental design allowed for concomitant measurements of metabolic reactants (loss of total and dissolved organic carbon [TOC and DOG]) and products (gain of total carbon dioxide [TCO2] and bacterial biomass) to be made from a single incubation vessel. Some previous studies have relied on proxy measurements (e.g. O-2, H-3-thymidine incorporation and cell abundance) to determine BGE and CCF rather than direct carbon measurements. Our ...