scholarly journals Abundance and Distribution of Synechococcus spp. and Cyanophages in the Chesapeake Bay

2011 ◽  
Vol 77 (21) ◽  
pp. 7459-7468 ◽  
Author(s):  
Kui Wang ◽  
K. Eric Wommack ◽  
Feng Chen
Keyword(s):  
Chesapeake Bay ◽  
Environmental Gradients ◽  
Salinity Gradient ◽  
Most Probable Number ◽  
Estuarine Ecosystem ◽  
Probable Number ◽  
Content Type ◽  
Carbon Pump ◽  
Host Mortality ◽  
Host Virus Interactions

ABSTRACTDespite the increasing knowledge ofSynechococcusspp. and their co-occurring cyanophages in oceanic and coastal water, little is known about their abundance, distribution, and interactions in the Chesapeake Bay estuarine ecosystem. A 5-year interannual survey shows thatSynechococcusspp. and their phages are persistent and abundant members of Chesapeake Bay microbial communities.Synechococcusblooms (106cells ml−1) were often observed in summer throughout the Bay, contributing 20 to 40% of total phytoplankton chlorophylla. The distribution of phycoerythrin-containing (PE-rich)Synechococcuscells appeared to mostly correlate with the salinity gradient, with higher abundances at higher salinities. Cyanophages infectious toSynechococcuswere also abundant (up to 6 × 105viruses ml−1by the most probable number assay) during summer months in the Bay. The covariation in abundance ofSynechococcusspp. and cyanophages was evident, although the latitude of observed positive correlation varied in different years, mirroring the changing environmental conditions and therefore the host-virus interactions. The impacts of cyanophages on hostSynechococcuspopulations also varied spatially and temporally. Higher phage-relatedSynechococcusmortality was observed in drought years. Virus-mediated host mortality and subsequent liberation of dissolved organic matter (DOM) may substantially influence oceanic biogeochemical processing through the microbial loop as well as the microbial carbon pump. These observations emphasize the influence of environmental gradients on naturalSynechococcusspp. and their phage population dynamics in the estuarine ecosystem.

scholarly journals Seasonal and Geographical Differences in Total and Pathogenic Vibrio parahaemolyticus and Vibrio vulnificus Levels in Seawater and Oysters from the Delaware and Chesapeake Bays Determined Using Several Methods

2020 ◽  
Vol 86 (23) ◽  
Author(s):  
Salina Parveen ◽  
John Jacobs ◽  
Gulnihal Ozbay ◽  
Lathadevi K. Chintapenta ◽  
Esam Almuhaideb ◽  
...  
Keyword(s):  
Chesapeake Bay ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Seawater Temperature ◽  
False Negative ◽  
Delaware Bay ◽  
Most Probable Number ◽  
Probable Number ◽  
Content Type ◽  
Pathogenic Vibrio

ABSTRACT Oyster and seawater samples were collected from five sites in the Chesapeake Bay, MD, and three sites in the Delaware Bay, DE, from May to October 2016 and 2017. Abundances and detection frequencies for total and pathogenic Vibrio parahaemolyticus and Vibrio vulnificus were compared using the standard most-probable-number–PCR (MPN-PCR) assay and a direct-plating (DP) method on CHROMagar Vibrio for total (tlh+) and pathogenic (tdh+ and trh+) V. parahaemolyticus genes and total (vvhA) and pathogenic (vcgC) V. vulnificus genes. The colony overlay procedure for peptidases (COPP) assay was evaluated for total Vibrionaceae. DP had high false-negative rates (14 to 77%) for most PCR targets and was deemed unsatisfactory. Logistic regression models of the COPP assay showed high concordances with MPN-PCR for tdh+ and trh+ V. parahaemolyticus and vvhA+ V. vulnificus in oysters (85.7 to 90.9%) and seawater (81.1 to 92.7%) when seawater temperature and salinity were factored into the model, suggesting that the COPP assay could potentially serve as a more rapid method to detect vibrios in oysters and seawater. Differences in total Vibrionaceae and pathogenic Vibrio abundances between state sampling sites over different collection years were contrasted for oysters and seawater by MPN-PCR. Abundances of tdh+ and trh+ V. parahaemolyticus were ∼8-fold higher in Delaware oysters than in Maryland oysters, whereas abundances of vcgC+ V. vulnificus were nearly identical. For Delaware oysters, 93.5% were both tdh+ and trh+, compared to only 19.2% in Maryland. These results indicate that pathogenic V. parahaemolyticus was more prevalent in the Delaware Bay than in the Chesapeake Bay. IMPORTANCE While V. parahaemolyticus and V. vulnificus cause shellfish-associated morbidity and mortality among shellfish consumers, current regulatory assays for vibrios are complex, time-consuming, labor-intensive, and relatively expensive. In this study, the rapid, simple, and inexpensive COPP assay was identified as a possible alternative to MPN-PCR for shellfish monitoring. This paper shows differences in total Vibrionaceae and pathogenic vibrios found in seawater and oysters from the commercially important Delaware and Chesapeake Bays. Vibrio parahaemolyticus isolates from the Delaware Bay were more likely to contain commonly recognized pathogenicity genes than those from the Chesapeake Bay.

scholarly journals Long-Term Study of Vibrio parahaemolyticus Prevalence and Distribution in New Zealand Shellfish

2015 ◽  
Vol 81 (7) ◽  
pp. 2320-2327 ◽  
Author(s):  
C. D. Cruz ◽  
D. Hedderley ◽  
G. C. Fletcher
Keyword(s):  
New Zealand ◽  
Vibrio Parahaemolyticus ◽  
Most Probable Number ◽  
Pcr Analysis ◽  
Potential Hazard ◽  
Probable Number ◽  
Content Type ◽  
The North ◽  
Long Term Study ◽  
Food Borne

ABSTRACTThe food-borne pathogenVibrio parahaemolyticushas been reported as being present in New Zealand (NZ) seawaters, but there have been no reported outbreaks of food-borne infection from commercially grown NZ seafood. Our study determined the current incidence ofV. parahaemolyticusin NZ oysters and Greenshell mussels and the prevalence ofV. parahaemolyticustdhandtrhstrains. Pacific (235) and dredge (21) oyster samples and mussel samples (55) were obtained from commercial shellfish-growing areas between December 2009 and June 2012. TotalV. parahaemolyticusnumbers and the presence of pathogenic genestdhandtrhwere determined using the FDA most-probable-number (MPN) method and confirmed using PCR analysis. In samples from the North Island of NZ,V. parahaemolyticuswas detected in 81% of Pacific oysters and 34% of mussel samples, while the numbers ofV. parahaemolyticustdhandtrhstrains were low, with just 3/215 Pacific oyster samples carrying thetdhgene.V. parahaemolyticusorganisms carryingtdhandtrhwere not detected in South Island samples, andV. parahaemolyticuswas detected in just 1/21 dredge oyster and 2/16 mussel samples. Numbers ofV. parahaemolyticusorganisms increased when seawater temperatures were high, the season when most commercial shellfish-growing areas are not harvested. The numbers ofV. parahaemolyticusorganisms in samples exceeded 1,000 MPN/g only when the seawater temperatures exceeded 19°C, so this environmental parameter could be used as a trigger warning of potential hazard. There is some evidence that the totalV. parahaemolyticusnumbers increased compared with those reported from a previous 1981 to 1984 study, but the analytical methods differed significantly.

scholarly journals Repeated Anaerobic Microbial Redox Cycling of Iron

2011 ◽  
Vol 77 (17) ◽  
pp. 6036-6042 ◽  
Author(s):  
Aaron J. Coby ◽  
Flynn Picardal ◽  
Evgenya Shelobolina ◽  
Huifang Xu ◽  
Eric E. Roden
Keyword(s):  
Microbial Communities ◽  
Microscopic Analysis ◽  
Redox Cycling ◽  
Most Probable Number ◽  
Rrna Gene ◽  
Electron Microscopic ◽  
16S Rrna Gene Analysis ◽  
Probable Number ◽  
Content Type ◽  
Floodplain Sediments

ABSTRACTSome nitrate- and Fe(III)-reducing microorganisms are capable of oxidizing Fe(II) with nitrate as the electron acceptor. This enzymatic pathway may facilitate the development of anaerobic microbial communities that take advantage of the energy available during Fe-N redox oscillations. We examined this phenomenon in synthetic Fe(III) oxide (nanocrystalline goethite) suspensions inoculated with microflora from freshwater river floodplain sediments. Nitrate and acetate were added at alternate intervals in order to induce repeated cycles of microbial Fe(III) reduction and nitrate-dependent Fe(II) oxidation. Addition of nitrate to reduced, acetate-depleted suspensions resulted in rapid Fe(II) oxidation and accumulation of ammonium. High-resolution transmission electron microscopic analysis of material from Fe redox cycling reactors showed amorphous coatings on the goethite nanocrystals that were not observed in reactors operated under strictly nitrate- or Fe(III)-reducing conditions. Microbial communities associated with N and Fe redox metabolism were assessed using a combination of most-probable-number enumerations and 16S rRNA gene analysis. The nitrate-reducing and Fe(III)-reducing cultures were dominated by denitrifyingBetaproteobacteria(e.g.,Dechloromonas) and Fe(III)-reducingDeltaproteobacteria(Geobacter), respectively; these same taxa were dominant in the Fe cycling cultures. The combined chemical and microbiological data suggest that bothGeobacterand variousBetaproteobacteriaparticipated in nitrate-dependent Fe(II) oxidation in the cycling cultures. Microbially driven Fe-N redox cycling may have important consequences for both the fate of N and the abundance and reactivity of Fe(III) oxides in sediments.

scholarly journals Dynamics of Salmonella Shedding and Welfare of Hens in Free-Range Egg Production Systems

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Vaibhav C. Gole ◽  
Rebecca Woodhouse ◽  
Charles Caraguel ◽  
Talia Moyle ◽  
Jean-Loup Rault ◽  
...  
Keyword(s):  
Production System ◽  
Salmonella Enterica ◽  
Egg Production ◽  
Production Systems ◽  
Most Probable Number ◽  
Probable Number ◽  
Content Type ◽  
Free Range ◽  
Phage Types ◽  
Positive Correlations

ABSTRACT The current study investigated the effect of environmental stressors (i.e., weather changes) on Salmonella shedding in free-range production systems and the correlations with behavioral and physiological measures (i.e., fecal glucocorticoid metabolites). This involved longitudinal and point-in-time surveys of Salmonella shedding and environmental contamination on four commercial free-range layer farms. The shedding of Salmonella was variable across free-range farms and in different seasons. There was no significant effect of season on the Salmonella prevalence during this investigation. In this study, the combined Salmonella most probable number (MPN) counts in environmental (including feces, egg belt, dust, nest box, and ramp) samples were highest in samples collected during the summer season (4th sampling, performed in February). The predominant serovars isolated during this study were Salmonella enterica serovar Mbandaka and Salmonella enterica serovar Typhimurium phage types 135 and 135a. These two phage types were involved in several egg product-related Salmonella outbreaks in humans. Multilocus variable-number tandem-repeat analysis (MLVA) results indicated that MLVA types detected from human food poisoning cases exhibited MLVA patterns similar to the strains isolated during this study. All Salmonella isolates (n = 209) were tested for 15 different genes involved in adhesion, invasion, and survival of Salmonella spp. We also observed variations for sopA, ironA, and misL. There were no positive correlations between fecal corticosterone metabolite (FCM) and Salmonella prevalence and/or shedding in feces. Also, there were no positive correlations between Salmonella prevalence and Salmonella count (log MPN) and any of the other welfare parameters. IMPORTANCE In this study, the welfare of laying hens and Salmonella shedding were compared over a prolonged period of time in field conditions. This study investigated the long-term shedding of Salmonella serovars in a free-range egg production system. Given that there is increasing demand for free-range eggs, it is essential to understand the risks associated with such a production system.

High Salinity Relay as a Postharvest Processing Strategy To Reduce Vibrio vulnificus Levels in Chesapeake Bay Oysters (Crassostrea virginica)†

2011 ◽  
Vol 74 (11) ◽  
pp. 1902-1907 ◽  
Author(s):  
CORINNE AUDEMARD ◽  
HOWARD I. KATOR ◽  
MARTHA W. RHODES ◽  
THOMAS GALLIVAN ◽  
A. J. ERSKINE ◽  
...  
Keyword(s):  
Chesapeake Bay ◽  
High Salinity ◽  
Vibrio Vulnificus ◽  
Most Probable Number ◽  
Probable Number ◽  
Low Salinity ◽  
Moderate Salinity ◽  
Salinity Increase ◽  
The Impact ◽  
Postharvest Processing

In 2009 the U.S. Food and Drug Administration (FDA) announced its intention to implement postharvest processing (PHP) methods to eliminate Vibrio vulnificus from oysters intended for the raw, half-shell market that are harvested from the Gulf of Mexico during warmer months. FDA-approved PHP methods can be expensive and may be associated with unfavorable responses from some consumers. A relatively unexplored PHP method that uses relaying to high salinity waters could be an alternative strategy, considering that high salinities appear to negatively affect the survival of V. vulnificus. During relay, however, oysters may be exposed to rapid and large salinity increases that could cause increased mortality. In this study, the effectiveness of high salinity relay to reduce V. vulnificus to <30 most probable number (MPN) per g and the impact on oyster mortality were assessed in the lower Chesapeake Bay. Two relay experiments were performed during the summer and fall of 2010. Oysters collected from three grow-out sites, a low salinity site (14 to 15 practical salinity units [psu]) and two moderate salinity sites (22 to 25 psu), were relayed directly to a high salinity site (≥30 psu) on Virginia's Eastern Shore. Oysters were assayed for V. vulnificus and Vibrio parahaemolyticus (another Vibrio species of concern) densities at time 0 prior to relay and after 7 and 14 days of relay, using the FDA MPN enrichment method combined with detection by real-time PCR. After 14 days, both V. vulnificus and V. parahaemolyticus densities were ≤0.8 MPN/g, and decreases of 2 to 3 log in V. vulnificus densities were observed. Oyster mortalities were low (≤<4%) even for oysters from the low salinity harvest site, which experienced a salinity increase of approximately 15 psu. Results, although preliminary and requiring formal validation and economic analysis, suggest that high salinity relay could be an effective PHP method.

scholarly journals Distribution and Characterization of Salmonella enterica Isolates from Irrigation Ponds in the Southeastern United States

2015 ◽  
Vol 81 (13) ◽  
pp. 4376-4387 ◽  
Author(s):  
Zhiyao Luo ◽  
Ganyu Gu ◽  
Amber Ginn ◽  
Mihai C. Giurcanu ◽  
Paige Adams ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Geometric Mean ◽  
Multidrug Resistant ◽  
Most Probable Number ◽  
Sample Type ◽  
Probable Number ◽  
Content Type ◽  
Safety Standards ◽  
Produce Contamination ◽  
Southern Georgia

ABSTRACTIrrigation water has been implicated as a likely source of produce contamination bySalmonella enterica. Therefore, the distribution ofS. entericawas surveyed monthly in irrigation ponds (n= 10) located within a prime agricultural region in southern Georgia and northern Florida. All ponds and 28.2% of all samples (n= 635) were positive forSalmonella, with an overall geometric mean concentration (0.26 most probable number [MPN]/liter) that was relatively low compared to prior reports for rivers in this region.Salmonellapeaks were seasonal; the levels correlated with increased temperature and rainfall (P< 0.05). The numbers and occurrence were significantly higher in water (0.32 MPN/liter and 37% of samples) than in sediment (0.22 MPN/liter and 17% of samples) but did not vary with depth. Representative isolates (n= 185) from different ponds, sample types, and seasons were examined for resistance to 15 different antibiotics; most strains were resistant to streptomycin (98.9%), while 20% were multidrug resistant (MDR) for 2 to 6 antibiotics. DiversiLab repetitive extragenic palindromic-element sequence-based PCR (rep-PCR) revealed genetic diversity and showed 43 genotypes among 191 isolates, as defined by >95% similarity. The genotypes did not partition by pond, season, or sample type. Genetic similarity to known serotypes indicated Hadar, Montevideo, and Newport as the most prevalent. All ponds achieved the current safety standards for genericEscherichia coliin agricultural water, and regression modeling showed that theE. colilevel was a significant predictor for the probability ofSalmonellaoccurrence. However, persistent populations ofSalmonellawere widely distributed in irrigation ponds, and the associated risks for produce contamination and subsequent human exposure are unknown, supporting continued surveillance of this pathogen in agricultural settings.

scholarly journals Correlation between Quantitative PCR and Culture-Based Methods for Measuring Enterococcus spp. over Various Temporal Scales at Three California Marine Beaches

2011 ◽  
Vol 78 (4) ◽  
pp. 1237-1242 ◽  
Author(s):  
Reagan R. Converse ◽  
John F. Griffith ◽  
Rachel T. Noble ◽  
Richard A. Haugland ◽  
Kenneth C. Schiff ◽  
...  
Keyword(s):  
Quantitative Pcr ◽  
Membrane Filtration ◽  
Empirical Relationship ◽  
Time Of Day ◽  
Most Probable Number ◽  
Spatial And Temporal Variability ◽  
Culture Methods ◽  
Fecal Indicator ◽  
Probable Number ◽  
Content Type

ABSTRACTSeveral studies have examined how fecal indicator bacteria (FIB) measurements compare between quantitative PCR (qPCR) and the culture methods it is intended to replace. Here, we extend those studies by examining the stability of that relationship within a beach, as affected by time of day and seasonal variations in source.Enterococcusspp. were quantified at three southern California beaches in the morning and afternoon using two qPCR assays, membrane filtration, and defined-substrate testing. While qPCR and culture-based measurements were consistently and significantly correlated, strength of the correlation varied both among and within beaches. Correlations were higher in the morning (0.45 < ρ < 0.74 [P< 0.002]) than in the afternoon (0.18 < ρ < 0.45 [P< 0.021]) and higher when the fecal contamination was concentrated (0.38 < ρ < 0.83 [P< 0.001]) than when it was diffuse (0.19 < ρ < 0.34 [P< 0.003]). The ratios of culture-based and qPCR results (CFU or most probable number [MPN] per calibrator cell equivalents [CCE]) also varied spatially and temporally. Ratios ranged between 0.04 and 0.85 CFU or MPN per CCE and were lowest at the beach affected by diffuse pollution. Patterns in the ratios over the course of the day were dissimilar across beaches, increasing with time at one beach and decreasing at another. The spatial and temporal variability we observed indicate that the empirical relationship between culture-based and qPCR results is not universal, even within a beach.

Shelf life study of handmade and industrially processed Minas frescal cheese

2019 ◽  
Vol 49 (6) ◽  
pp. 1207-1218
Author(s):  
Thamiris Evangelista Silva ◽  
Priscila Alonso dos Santos ◽  
Thamara Evangelista Silva ◽  
Kamilla Soares Silva ◽  
André Luiz Borges Machado ◽  
...  
Keyword(s):  
Microbiological Quality ◽  
Oxygen Demand ◽  
Storage Period ◽  
State Inspection ◽  
Most Probable Number ◽  
Probable Number ◽  
Content Type ◽  
Life Study ◽  
Thermotolerant Coliforms ◽  
Milk Pasteurisation

Purpose The purpose of this study is to characterize and compare the results of the inspection mark of handmade and industrially processed Minas frescal cheese. It is one of the most commonly made and consumed cheeses in Brazil, and its production processes range from handmade cheeses produced in small household production sites to cheeses manufactured in large dairy factories subject to federal inspection. Design/methodology/approach The samples were stored for 10 days at 4°C in a biochemical oxygen demand chamber. Cheeses were analyzed using physicochemical analyzes, yield and syneresis indices and microbiological analyses. Findings The cheese A met the criterion of regulatory classification for very high humidity (65.32 g/100 g), while cheese B did not meet the criterion (54.38 g/100 g). Cheeses A (19.01 g/100 g) and B (24 g/100 g) showed average fat contents that did not comply with current legislation. The most probable number per g of thermotolerant coliforms was outside the acceptable range (>24 × 102 MPN/g), and Salmonella spp. were present in the tested samples. The highest yield was observed for handmade cheese (an average of 5.35 L of milk to produce 1 kg of cheese), which had the highest syneresis during the storage period (p = 0.004), reaching 14.26% on the 10th day of storage. Originality/value Municipal and state inspection certificates do not ensure the microbiological quality of Minas frescal cheese, indicating flaws in the good manufacturing practices and/or in the milk pasteurisation stage.

Modification of D-W model for corrosion rate of shale gas pipeline under the synergistic corrosion of SRB and CO2

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xingyu Peng ◽  
Xinyue Liu
Keyword(s):  
Corrosion Rate ◽  
Shale Gas ◽  
Correlation Method ◽  
Most Probable Number ◽  
Linear Regression Method ◽  
Corrosion Morphology ◽  
Probable Number ◽  
Content Type ◽  
Gray Correlation ◽  
Weight Loss Method

Purpose The purpose of this paper is to develop an equation for the synergistic corrosion of SRB and CO2 based on the D-W model. Design/methodology/approach The bacterial types in the a and ß pipelines were studied by the most probable number method, and the corrosion morphology of L360 in pipeline water samples was studied by surface analysis. The corrosion rate of L360 was studied using the weight loss method. The gray correlation method was used to calculate the degree of correlation between the influencing factors of corrosion under the synergistic effect of CO2 and SRB. The curve obtained from PIPESIM software and experiments data was then fitted using multiple non-linear regression method by MATLAB software. Findings The equation was used to predict the corrosion of the ß pipeline for verification, and it was found that seven out of ten excavation sites were within a 20% error range. Originality/value Using the gray correlation method, an equation that considers synergistic corrosion of SRB and CO2 has been developed based on the D-W model. The equation could be used to predict the corrosion rate of shale gas gathering pipelines through SRB and CO2 synergistic corrosion.

scholarly journals Individual Predisposition to Staphylococcus aureus Colonization in Pigs on the Basis of Quantification, Carriage Dynamics, and Serological Profiles

2014 ◽  
Vol 81 (4) ◽  
pp. 1251-1256 ◽  
Author(s):  
Carmen Espinosa-Gongora ◽  
Jan Dahl ◽  
Anders Elvstrøm ◽  
Willem J. van Wamel ◽  
Luca Guardabassi
Keyword(s):  
Staphylococcus Aureus ◽  
Humoral Response ◽  
Nasal Carriage ◽  
Most Probable Number ◽  
Cross Sectional ◽  
Probable Number ◽  
Content Type ◽  
Luminex Assay ◽  
Nasal Swabs ◽  
Cross Sectional Design

ABSTRACTPrevious research onStaphylococcus aureusin pigs focused on livestock-associated methicillin-resistantS. aureus(MRSA) and had a qualitative cross-sectional design. This study aimed to elucidate the frequency, load, and stability ofS. aureusnasal carriage in pigs over time and investigated possible associations between carriage and immune response. Nasal swabs were collected three times weekly from 480 tagged adult pigs in 20 Danish production farms.S. aureusand MRSA were quantified on selective media by the most-probable-number method. The levels of IgG against 10S. aureusantigens in serum were quantified in selected pigs by a Luminex assay. All the farms were positive forS. aureusand 15 for MRSA, leading to overall prevalences of persistent and intermittent carriers and noncarriers of 24, 52, and 23%, respectively. Carriage frequency and nasal loads were significantly higher on MRSA-positive farms. Logistic-regression modeling revealed the presence of individual pigs characterized by high nasal loads (≥10,000 CFU per swab) and stable carriage regardless of farm- and pen-associated factors. On the other hand, the humoral response was strongly influenced by these environmental factors. The existence of a minority of shedders contributing to maintenance ofS. aureuswithin farms opens up new perspectives on the control of MRSA in pig farming.

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