Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. Freeze-drying is such a method usually used for preservation of terrigenous bacteria. However, studies u...Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. Freeze-drying is such a method usually used for preservation of terrigenous bacteria. However, studies using freeze-drying method to preserving marine microorganisms remain very limited. In this study, we optimized the composition of protectants during the freeze-drying of Edwardsiella tarda, a fish pathogen that causes systemic infection in marine fishes. We found that the optimal composition of protectant mixture contained trehalose(8.0%), skim milk(12.0%), sodium citrate(2.0%), serum(12.0%) and PVP(2.0%). Orthogonal and interaction analyses demonstrated the interaction between serum and skim milk or sodium citrate. The highest survival rate of E. tarda was observed when the concentration of Na Cl was 10.0, 30.0 and between 5.0 and 10.0 g L^(-1) for preparing TSB medium, E. tarda suspension and protectant mixture, respectively. When E. tarda was frozen at-80℃ or-40℃ for 6 h, its survival rate was higher than that under other tested conditions. Under the optimized conditions, when the protectant mixture was used during freeze-drying process, the survival rate(79.63%–82.30%) of E. tarda was significantly higher than that obtained using single protectant. Scanning electron microscopy(SEM) image indicated that E. tarda was embedded in thick matrix with detectable aggregation. In sum, the protectant mixture may be used as a novel cryoprotective additive for E. tarda.展开更多
The main aim of this research was to identify fatty acids composition of Caspian Sea of white fish Rutilusfrisii kutum tissue and their changes during 12 months storage （-18 ℃ ）. The results showed, UFA （Unsaturat...The main aim of this research was to identify fatty acids composition of Caspian Sea of white fish Rutilusfrisii kutum tissue and their changes during 12 months storage （-18 ℃ ）. The results showed, UFA （Unsaturated Fatty Acid） and SFA （Saturated Fatty Acid） were 74/09 and 21/63%, respectively in fresh tissue. So that, DHA （C22：6） oleic acid （C 18：1c） had high amounts （15/07, 20/57） UFA and palmitic acid （C16：0） was the most （13/09%） SFA. The effects of freezing on fish tissue showed that UFA and SFA contents have reached to 58/79 and 22/17%, respectively at the end of cold storage. Also ω-3 and ω-6 series of fatty acids was 24/22 and 15/56% in fresh tissue, but their contents decreased to 8/68 and 5/11% at the end of period. Among, the fatty acids C22：6, C 18：1 c and C 16：0 had the most changes. The changes of fatty acids were significantly at 95% level expected for C18：0.展开更多
基金the National Natural Science Foundation of China (No. 31302206)Special Research Funds for Independent Innovation and Scientific & Technology Achievements Transformation of Shandong Province (No. 2014ZZCX06205)Agriculture Seed Improvement Project of Shandong Province
文摘Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. Freeze-drying is such a method usually used for preservation of terrigenous bacteria. However, studies using freeze-drying method to preserving marine microorganisms remain very limited. In this study, we optimized the composition of protectants during the freeze-drying of Edwardsiella tarda, a fish pathogen that causes systemic infection in marine fishes. We found that the optimal composition of protectant mixture contained trehalose(8.0%), skim milk(12.0%), sodium citrate(2.0%), serum(12.0%) and PVP(2.0%). Orthogonal and interaction analyses demonstrated the interaction between serum and skim milk or sodium citrate. The highest survival rate of E. tarda was observed when the concentration of Na Cl was 10.0, 30.0 and between 5.0 and 10.0 g L^(-1) for preparing TSB medium, E. tarda suspension and protectant mixture, respectively. When E. tarda was frozen at-80℃ or-40℃ for 6 h, its survival rate was higher than that under other tested conditions. Under the optimized conditions, when the protectant mixture was used during freeze-drying process, the survival rate(79.63%–82.30%) of E. tarda was significantly higher than that obtained using single protectant. Scanning electron microscopy(SEM) image indicated that E. tarda was embedded in thick matrix with detectable aggregation. In sum, the protectant mixture may be used as a novel cryoprotective additive for E. tarda.
文摘The main aim of this research was to identify fatty acids composition of Caspian Sea of white fish Rutilusfrisii kutum tissue and their changes during 12 months storage （-18 ℃ ）. The results showed, UFA （Unsaturated Fatty Acid） and SFA （Saturated Fatty Acid） were 74/09 and 21/63%, respectively in fresh tissue. So that, DHA （C22：6） oleic acid （C 18：1c） had high amounts （15/07, 20/57） UFA and palmitic acid （C16：0） was the most （13/09%） SFA. The effects of freezing on fish tissue showed that UFA and SFA contents have reached to 58/79 and 22/17%, respectively at the end of cold storage. Also ω-3 and ω-6 series of fatty acids was 24/22 and 15/56% in fresh tissue, but their contents decreased to 8/68 and 5/11% at the end of period. Among, the fatty acids C22：6, C 18：1 c and C 16：0 had the most changes. The changes of fatty acids were significantly at 95% level expected for C18：0.
