Browsing by Subject "aquaculture"
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Item A Study of the Antagonistic Activity of Bacillus subtilis Strain T1 Against Shrimp Pathogen Vibrio parahaemolyticus Strain D4(2018-01-01) Avery, Sarah; Schreier, Harold J; Biological Sciences; Biological SciencesAcute hepatopancreatic necrosis disease (AHPND), also known as early mortality syndrome (EMS), is caused by strains of Vibrio parahaemolyticus containing the PirAB toxin and has been devastating to shrimp aquaculture globally. Current methods for prevention rely on the use of antibiotics that leads to the development of antibioticresistant bacteria. In vitro, Bacillus subtilis strain T1 was found to possess antagonistic activity against EMS-causing V. parahaemolyticus strain D4 and is a candidate for use as a probiotic in the aquaculture industry. Competitive growth experiments examined the effect of T1 on D4 growth. Using qPCR to assess T1 and D4 growth, these studies showed that T1 was capable of inhibiting D4 growth in a density-dependent manner, with complete inhibition occurring when the T1 starting density was 104 -fold higher than D4. Using a mariner-based transposon system, T1 mutants were generated to identify genes involved in D4-inhibitory activity. Of over 3,000 colonies screened using an overlaybased assay, 17 were identified as having either complete or partial loss of activity. Eleven mutants contained insertions within an ~30-kb DNA cluster that included lipopeptide and polyketide biosyntheses genes. One of these mutants, A3-41, which contained an insertion within a non-ribosomal peptide synthetase gene utilized for lipopeptide biosyntheses, was found to have lost the ability to inhibit D4 growth in coculture experiments. Two mutants were found to contain insertions within stationary phase regulators, spo0A (sporulation gene regulator) and oppA (first gene of the oligopeptide transporter system operon) suggesting that D4 inhibitory activity is associated with a stationary phase product. Consistent with the mutagenesis results, supernatant fractions prepared from stationary phase cultures of T1 were found to inhibit D4 growth in a dose-dependent manner while culture supernatants prepared from mutant A3-41 were not inhibitory. These results indicate that T1 produces and excretes a stationary phase metabolite(s) that has inhibitory activity against D4 and has implications for the use of T1 as a probiotic in shrimp aquaculture.Item Induced Spawning of F1 Wreckfish (Hapuku) ¯ Polyprion oxygeneios Using a Synthetic Agonist of Gonadotropin-Releasing Hormone(MDPI, 2019-07-08) Wylie, Matthew J.; Setiawan, Alvin N.; Irvine, Glen W.; Elizur, Abigail; Zohar, Yonathan; Symonds, Jane E.; Lokman, P. MarkWild-caught hapuku ( ¯ Polyprion oxygeneios) spawn readily in captivity, but although first filial (F1) hapuku complete vitellogenesis, females fail to undergo oocyte maturation and spawn or produce poor quality eggs. This study investigated whether administration of a synthetic agonist of gonadotropin-releasing hormone (GnRHa) could improve F1 hapuku spawning and complete the life-cycle in captivity. Spawning trials were conducted over 2 years in 2013 and 2014, when F1 were aged five and six years. In 2013, females previously conditioned under a variable or constant temperature regime were implanted with GnRHa (100 µg/kg−1) or blank implants constructed of powdered cellulose and cholesterol. Spawning was erratic and egg quality very poor in all tanks. No F2 offspring were produced by communal spawning. In contrast, viable F2 larvae were produced by strip-spawning and in vitro fertilization after a series of GnRHa injections. In 2014, two additional trials were conducted: females received ethylene-vinyl acetate copolymer (EVAc) matrix implants containing GnRHa (100 µg/kg−1) or blank implants and in the second trial, two GnRHa doses (100 µg/kg−1 and 50 µg/kg−1) were tested. Eggs were first detected in all tanks 12–17 days post-implantation when females received 100 µg/kg−1 GnRHa implants, but not in the lower dose or control tanks. In summary, this study achieved induction of female spawning with GnRHa implants (target dose 100 µg/kg−1) and the successful production of F2 hapuku in captivity by strip-spawning.Item Intensive oyster aquaculture can reduce disease impacts on sympatric wild oysters(Inter-Research, 2018-12-13) Ben-Horin, Tal; Burge, Colleen A.; Bushek, David; Groner, Maya L.; Proestou, Dina A.; Huey, Lauren I.; Bidegain, Gorka; Carnegie, Ryan B.Risks associated with disease spread from fish and shellfish farming have plagued the growth and public perception of aquaculture worldwide. However, by processing nutrients and organic material from the water column, the culture of many suspension-feeding bivalves has been proposed as a novel solution toward mitigating problems facing coastal water quality, including the removal of disease-causing parasites. Here we developed and simulated an epidemiological model describing sympatric oyster Crassostrea virginica populations in aqua culture and the wild impacted by the protozoan parasite Perkinsus marinus. Our model captured the indirect interaction between wild and cultured populations that occurs through sharing water-borne P. marinus transmission stages, and we hypothesized that oyster aquaculture can enhance wild oyster populations through reduced parasitism as long as cultured oysters are harvested prior to spreading disease. We found that the density of oysters in aquaculture, which is commonly thought to lead to the spread of disease through farms and out to nearby populations in the wild, has only indirect effects on P. marinus transmission through its interaction with the rate of aquaculture harvests. Sufficient aquaculture harvest, which varies with the susceptibility of farmed oysters to P. marinus infection and their lifespan once infected, reduces disease by diluting parasites in the environment. Our modeling results offer new insights toward the broader epidemiological implications of oyster aquaculture and effective disease management.Item The Rising Tide of Antimicrobial Resistance in Aquaculture: Sources, Sinks and Solutions(MDPI, 2017-06-01) Watts, Joy E. M.; Schreier, Harold J.; Lanska, Lauma; Hale, Michelle S.As the human population increases there is an increasing reliance on aquaculture to supply a safe, reliable, and economic supply of food. Although food production is essential for a healthy population, an increasing threat to global human health is antimicrobial resistance. Extensive antibiotic resistant strains are now being detected; the spread of these strains could greatly reduce medical treatment options available and increase deaths from previously curable infections. Antibiotic resistance is widespread due in part to clinical overuse and misuse; however, the natural processes of horizontal gene transfer and mutation events that allow genetic exchange within microbial populations have been ongoing since ancient times. By their nature, aquaculture systems contain high numbers of diverse bacteria, which exist in combination with the current and past use of antibiotics, probiotics, prebiotics, and other treatment regimens—singularly or in combination. These systems have been designated as “genetic hotspots” for gene transfer. As our reliance on aquaculture grows, it is essential that we identify the sources and sinks of antimicrobial resistance, and monitor and analyse the transfer of antimicrobial resistance between the microbial community, the environment, and the farmed product, in order to better understand the implications to human and environmental health.Item UMBC faculty, alumni entrepreneurs receive record-number of MIPS awards for tech collaborations(UMBC News) Demond, MarlaynaSix UMBC faculty members have just received grants from the Maryland Industrial Partnerships (MIPS) program to develop new technologies with potential to grow the state’s economy. This is UMBC’s largest number of winning proposals within a single proposal round since MIPS began in 1987.