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Full-Text Articles in Life Sciences
Natural Variation And Evolutionary Responses To Climate Change Stressors In Marine Invertebrates, Joanna Sarah Griffiths
Natural Variation And Evolutionary Responses To Climate Change Stressors In Marine Invertebrates, Joanna Sarah Griffiths
LSU Doctoral Dissertations
Our rapidly changing climate is putting many species at risk of extinction and there is an urgent need to understand how species will respond to these changes. In this dissertation, I evaluate how three species of marine invertebrates (corals, oysters, and copepods) respond to stressful conditions in their current environments and how plasticity and evolutionary adaptation could alter their response to future climate change stressors. I first employed a space for time study to elucidate population differences in the response of cold-water corals, Balanophyllia elegans, to future ocean acidification. I found evidence that upwelling history (natural low pH exposure) influences …
Antimicrobial Properties Of Different Chitosans Against Gram-Negative And Gram-Positive Foodborne Pathogens In Food Products, Nancy Katherine Rubio Zapata
Antimicrobial Properties Of Different Chitosans Against Gram-Negative And Gram-Positive Foodborne Pathogens In Food Products, Nancy Katherine Rubio Zapata
LSU Doctoral Dissertations
Chitosan is a polymer derived of the deacetylation of chitin that is one of the most abundant material in nature. Chitosan solutions applied as edible coatings, and dipping solutions have shown positive results in the extension of shelf life on seafood and meat products. The purpose of this study was to evaluate the antimicrobial activities of a newly invented high molecular weight water-soluble (HMWWS) chitosan against selected Gram-negative (Salmonella Typhimurium, Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae) and Gram-positive (Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus) foodborne pathogens (initial inoculation of 6.5 Log). Chitosans with …
Human Norovirus In Artificial And Environmental Marine Water: Development Of Antibody Based Rapid Methods, Morgan Maite
Human Norovirus In Artificial And Environmental Marine Water: Development Of Antibody Based Rapid Methods, Morgan Maite
LSU Doctoral Dissertations
Norovirus (NoV) is the principal cause of viral gastroenteritis in the United States. It has been linked to filter-feeding molluscan shellfish, that bioaccumulate the virus from contaminated surrounding waters. The consumption of raw or undercooked contaminated oysters may result in acute gastroenteritis. We investigated the occurrence of NoV GI and GII and microbial indicators of fecal contamination in oysters and harvesting water from areas along the Louisiana Gulf Coast. We developed a filtration and concentration method for the detection of NoV from oyster harvesting waters. Lastly, this body of work compares commonly used molecular techniques (RT-PCR) and a commercial enzyme …
Detection Of Clostridium Difficile In Louisiana Oysters, Harvesting Water And Sewage, Da Liu
Detection Of Clostridium Difficile In Louisiana Oysters, Harvesting Water And Sewage, Da Liu
LSU Master's Theses
ABSTRACT Clostridium difficile infection (CDI) was generally considered as a hospital-associated disease; however, recent studies indicated that foods might also play a role in its epidemical chain. From August-2013 to February-2014, oyster samples and harvesting water samples were collected monthly from 6 commercial oyster harvesting areas along Louisiana Gulf Coast and analyzed for total aerobic bacteria, fecal coliforms, coliphage and pathogenic C. difficile. In this study, C. difficile were isolated from 9 (47.37%) of 19 oyster samples and 3 (37.5%) of 8 harvesting water samples and all isolations were carrying the toxin B-encoding gene (tcdB). Toxin B positive C. difficle …
Development Of Safe And Ready To Eat Frozen Oyster Products Using Microwave Steam-Venting Technology, Luis Alberto Espinoza
Development Of Safe And Ready To Eat Frozen Oyster Products Using Microwave Steam-Venting Technology, Luis Alberto Espinoza
LSU Doctoral Dissertations
The Gulf Coast region, principally Louisiana, leads the nation in oyster production. The National Marine Fisheries Service reported that 19.7 million pounds of oyster meat, valued at $62.3 million dollars were harvested from the Gulf Coast region in 2010. One of the main concerns for this industry is the health risk associated with the consumption of oysters, particularly for at-risk populations. Oysters are filter feeders. They tend to concentrate microbes present in surrounding waters, some of which can cause severe illness in susceptible humans. Among pathogens that contaminate the gastrointestinal system of oysters, Vibrio spp (especially V. parahaemolyticus and V. …
Treatments To Reduce The Risk Of Vibrio Species In Vitro And In Shucked Oysters, Ronson Renard Scott
Treatments To Reduce The Risk Of Vibrio Species In Vitro And In Shucked Oysters, Ronson Renard Scott
LSU Master's Theses
"Vibrio parahaemolyticus" (Vp) and "Vibrio vulnificus" (Vv) are halophilic bacteria naturally occurring in estuarine environments that may concentrate in filter feeding shellfish. Consumption of raw or under-cooked seafood contaminated with Vp or Vv may lead to the development of acute gastroenteritis or fatal septicemia in at-risk individuals, respectively. This research encompassed two separate but related projects: evaluation of a low temperature pasteurization (LTP) technique for the reduction of Vp and Vv in commercial quantities of shucked oysters (SO) and the investigation of the efficacy of a citrus fruit extract, BIOSECUR® F440D in reducing/eliminating Vv in vitro. Commercially available SO ("Crassostrea …
Antimicrobial Susceptibility, Genotypic Characterization, And Molecular Detection Of Vibrio Parahaemolyticus And Vibrio Vulnificus From Louisiana Oysters, Feifei Han
LSU Doctoral Dissertations
Members of the genus Vibrio are Gram-negative, halophilic bacteria that inhabit warm coastal and estuarine waters worldwide. Among pathogenic vibrios, Vibrio parahaemolyticus is the leading cause of seafood-related illnesses and Vibrio vulnificus causes the highest number of seafood-related deaths in the United States. Moreover, according to the U.S. Centers for Disease Control and Prevention, the incidence of infections of the two vibrios due to the consumption of oysters has shown a sustained increase since 2001, indicating further measures are needed to prevent human Vibrio illness. In this dissertation research, a total of 622 Vibrio isolates, consisting of 252 V. parahaemolyticus …
Cold Adaption Behaviors Of Vibrio Vulnificus And Vibio Parahaemolyticus In Oysters, Chiung-Ta Wu
Cold Adaption Behaviors Of Vibrio Vulnificus And Vibio Parahaemolyticus In Oysters, Chiung-Ta Wu
LSU Master's Theses
Vibrio vulnificus is an estuarine bacterium that can cause primary septicemia as well as other serious wound infections. Vibrio parahaemolyticus is a gram-negative, halophilic bacterium that may cause gastroenteritis, diarrhea, headache, vomiting, nausea, abdominal cramps and is the leading cause of gastroenteritis in United States. Consumption of raw oysters is believed to closely relate with infection with Vibrio vulnificus and Vibrio parahaemolyticus. All strains of V. parahaemolyticus produce tlh genes and the major virulence factors of V.parahaemolyticus are the tdh and trh genes. This study was conducted to determine if Vibrio vulnificus and Vibrio parahaemolyticus clinical and environmental strains display …
Detection Of Vibrio Vulnificus By Direct Colony Immunoblot, Reshani Nisansala Senevirathne
Detection Of Vibrio Vulnificus By Direct Colony Immunoblot, Reshani Nisansala Senevirathne
LSU Master's Theses
Vibrio vulnificus (Vv) is a natural occurring bacterium of world wide estuarine environments, which concentrate on filter feeding shellfish. Under cooked seafood contaminated with this pathogen is a leading cause of 95% of seafood-related, foodborne deaths. The development of a rapid, reliable and user-friendly method for Vv enumeration would help to reduce mortality rate. A direct colony immunoblot (DCI) method was developed and used as a rapid enumeration with high sensitivity and the specificity. This method was optimized using Vv agar plates incubated for 16 h at 35 °C. Colonies were transferred from incubated plates to polyvinylidene fluoride (PVDF) membranes …
Control Of Vibrio Vulnificus And Vibrio Parahaemolyticus In Oysters, Ligia Virginia Antonia Da Silva
Control Of Vibrio Vulnificus And Vibrio Parahaemolyticus In Oysters, Ligia Virginia Antonia Da Silva
LSU Doctoral Dissertations
Vibrio vulnificus and Vibrio parahaemolyticus are gram-negative halophilic bacteria found in the natural aquatic environment. V. vulnifcus and V. parahaemolyticus have been implicated in foodborne illness and can cause gastroenteritis that has been associated with consumption of raw or undercooked seafood. V. vulnificus can cause primary septicemia after its ingestion, and secondary septicemia through skin lesions in individuals with preexisting conditions such as elevated serum iron levels. Bacteriophages, viruses that invade and lyse bacteria, specific to V. vulnificus and V. parahaemolyticus are naturally found in seawater and oysters. Every summer, the oyster industry is threatened by recall of oysters due …
Purification Of Lysozyme From Shell Liquor Of Eastern Oysters (Crassostrea Virginica) And Its Use In Antimicrobial Films To Preserve Smoked Fish, Shreya Datta
LSU Master's Theses
The objective of our study was to purify lysozyme from the fluid filling cavity (shell liquor) of the eastern oysters (Crassostrea virginica) and determine the antimicrobial activity of purified lysozyme against foodborne pathogens in smoked salmon samples. Oyster shell liquor was collected over four seasons namely summer 2003, fall 2003, winter 2004, and spring 2004. Spring season showed the highest lysozyme concentration. Lysozyme was purified from 300 liters of oyster shell liquor by a two-step ion exchange chromatography using SP- and CM- Sepharose Fast Flow columns, respectively. Two hundred five mg of pure lysozyme was obtained which represented a recovery …