U.S. Food and Drug Administration, Division of Seafood Science and Technology, Gulf Coast Seafood Laboratory, 1 Iberville Drive, Dauphin Island, AL 36528, USA; Auburn University Shellfish Laboratory, School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, 150 Agassiz Street, Dauphin Island, AL 36528, USA.
U.S. Food and Drug Administration, Division of Seafood Science and Technology, Gulf Coast Seafood Laboratory, 1 Iberville Drive, Dauphin Island, AL 36528, USA.
Int J Food Microbiol. 2020 Dec 16;335:108858. doi: 10.1016/j.ijfoodmicro.2020.108858. Epub 2020 Sep 26.
Routine handling of oysters is a common industry practice for off-bottom oyster aquaculture, which aims to produce a high-quality oyster. These practices expose oysters to elevated temperatures and interrupt filter feeding, which can increase Vibrio vulnificus and V. parahaemolyticus levels within the oyster. The resubmersion of oysters after exposure to conditions where the time-temperature controls are exceeded is as an effective mitigation strategy to allow elevated levels of Vibrio spp. to "recover", or return to ambient levels, prior to harvest. Previous work examined the effect of desiccation on recovery times; the objective of this study was to evaluate the effect of additional handling treatments [tumbled and refrigerated (TR), tumbled and not refrigerated (TNR), not tumbled and refrigerated (NTR), and not tumbled and not refrigerated (NTNR)] on the time needed for V. vulnificus, total V. parahaemolyticus, and pathogenic V. parahaemolyticus (tdh+/trh+) to recover in oysters. A set of non-treated (control) oysters remained submerged throughout the study to determine the ambient Vibrio spp. (inclusive of genotypes) levels within oysters. Vibrio spp. levels were measured immediately before (pre) and after (post) the treatments, and 1, 2, 4, 7, 10, and 14 days after resubmersion using a three-tube MPN real-time PCR method. The non-refrigerated oysters (TNR, NTNR) had Vibrio spp. levels 1.54 to 2.10 log MPN/g higher than the pre-treatment levels, while the Vibrio spp. levels in refrigerated oysters were not significantly higher than pre-treatment levels. After resubmersion, Vibrio spp. levels increased by 0.84 to 1.78 log MPN/g in the refrigerated oysters (TR, NTR). Vibrio spp. levels in oysters returned to ambient after 1-7 days of resubmersion, depending on the handling treatment and the Vibrio spp. These results provide data on handling treatments not previously reported and further support the seven-day resubmersion requirement for farmers in Alabama using the adjustable longline system.
贝类的常规处理是底播贝类养殖的常见行业做法，旨在生产高质量的贝类。这些做法会使贝类暴露在高温下并中断滤食，从而增加贝类中的创伤弧菌和副溶血性弧菌水平。在贝类暴露于时间-温度控制超过的条件下重新浸泡是一种有效的缓解策略，可以使高水平的弧菌“恢复”或在收获前恢复到环境水平。先前的工作研究了干燥对恢复时间的影响；本研究的目的是评估额外的处理方式[翻滚和冷藏（TR）、翻滚但不冷藏（TNR）、不翻滚但冷藏（NTR）和不翻滚且不冷藏（NTNR）]对创伤弧菌、总副溶血性弧菌和致病性副溶血性弧菌（tdh+/trh+）在贝类中恢复所需时间的影响。一组未经处理（对照）的贝类在整个研究过程中保持浸没状态，以确定贝类中环境弧菌 spp.（包括基因型）水平。在处理前后（处理前和处理后）立即测量 Vibrio spp.水平，并在重新浸泡后 1、2、4、7、10 和 14 天使用三管 MPN 实时 PCR 方法进行测量。未冷藏的贝类（TNR、NTNR）的 Vibrio spp.水平比处理前高 1.54 到 2.10 对数 MPN/g，而冷藏的贝类的 Vibrio spp.水平与处理前相比没有显著升高。重新浸泡后，冷藏贝类（TR、NTR）的 Vibrio spp.水平增加了 0.84 到 1.78 对数 MPN/g。根据处理方式和 Vibrio spp.，重新浸泡后 1-7 天贝类中的 Vibrio spp.水平恢复到环境水平。这些结果提供了以前未报告的处理方式的数据，并进一步支持了阿拉巴马州使用可调式延绳钓系统的农民 7 天重新浸泡的要求。
