Effect Of Probiotic Addition On The Physiological Indicators Of Sea Cucumber(Apostichopus Japonicus) Under Fenpropathrin Stress

A typical species of marine culture popular with consumers in northern regions,sea cucumbers is highly sought after for its health benefits.Fenpropathrin is a new type of pyrethroid insecticide with potential uses in pest control.Although fenpropathrin is not used in the manufacture of aquatic products,the formation of pesticide contamination in the aquatic environment is mainly influenced by runoff,leaching and spray drift.Due to the hydrophobic nature of pyrethroid pesticides,there is a possibility that they will gradually deposit in aquatic sediments during application.Probiotics have great potential for application in aquaculture.On the one hand,the addition of probiotics can significantly reduce physiological stress in aquatic animals in the face of various stresses,and on the other hand,probiotics can reduce pesticide-induced stress in aquatic animals and thus reduce oxidative stress caused by pesticide residues in aquaculture.Therefore,it is of academic importance to investigate the use of probiotics as an effective means of mitigating the toxic effects of methothrin in sea cucumbers.The key elements of the study and the associated results are described below:Ⅰ:Test of chronic toxicity of fenpropathrin to prickly ginsengTo investigate the effects of fenpropathrin on the toxicity of antioxidant properties,intestinalgut digestive enzyme levels,intestinalgut morphology and flora,and the expression of antioxidant and digestive-related m RNAs in the respiratory tree of sea cucumbers.In this study,five diets containing were formulated with different concentrations of fenpropathrin were formulated and fed to spinyprickly ginseng by adding different concentrations of fenpropathrin A（0 g/kg）,B（0.01 g/kg）,C（0.04 g/kg）,D（0.07 g/kg）and E（0.1 g/kg）to the basal diet.The results showed that total antioxidant capacity（T-AOC）and malondialdehyde（MDA）levels were significantly higher in group B than in groups A and C（P<0.05）.The activity of superoxide dismutase（SOD）was significantly lower in group B and significantly higher in group E（P<0.05）.Hydrogen peroxide（H₂O₂）activity was significantly lower in group D and significantly higher in group A（P<0.05）.Fenpropathrin exposure reduced the diversity of the intestinal flora of sedge ginseng in group D.At the phylum level,the relative abundance of sea cucumbers was increased in groups B,C,D and E compared to group A.Intestinal width was significantly reduced in all test groups of sea cucumbers compared to group A and significantly reduced to a minimum in group D（P<0.05）.Intestinal muscle thickness was significantly reduced in group C compared with the control group（P<0.05）.In addition,it was observed that the relative expression of the genes PEP,TRY and Hsp90 was significantly higher in group D than in the control group（P<0.05）.However,the relative expression of the genes PEP,Hsp70 was significantly lower in group E than in the control group（P<0.05）.Ⅱ:Effect of feed supplementation with a probiotic complex on sea cucumbers under fenpropathrin stressInvestigated the effect of probiotic bacteria on sea cucumber relief under fenpropathrin stress and its effect.By adding two different concentrations of different components of probiotics to the basal diet,A was the control group,BP and CP were added with low concentration（5 g/kg）and high concentration（20 g/kg）of probiotic No.1,respectively;DP and EP were added with low concentration（5 g/kg）and high concentration（20 g/kg）of probiotic No.6,respectively.Diets containing four different concentrations of probiotics were formulated and fed to sea cucumbers.The results showed that under the stress of fenpropathrin,the catalase（CAT）activity of the body cavity fluid of the test group decreased significantly（P<0.05）;hydrogen peroxide（H₂O₂）activity increased significantly（P<0.05）,and the increase was significant（P<0.05）in the high concentration test group compared to the low concentration probiotic test group.Under the high concentration of probiotic feeding,the malondialdehyde（MDA）activity of sea cucumbers increased significantly compared to the control group（P<0.05）;superoxide dismutase（SOD）activity in body cavity fluid of sedge ginseng test group increased significantly compared to control group（P<0.05）.Catalase activity（CAT）in the body cavity fluid of sea cucumbers was significantly reduced after the addition of Probiotic 6 to the diet（P<0.05）.At the phylum level,the most important genera in the sea cucumbers gut were Proteobacteria,Verrucomicrobia,Planctomycetes and Actinobacteria.The frequency of Proteobacteria decreased in groups BP,DP and EP and increased in group CP.The frequency of Verrucomicrobia increased in groups BP,DP and EP and decreased in group CP.The frequency of Planctomycetes increased in groups BP and DP and decreased in groups CP and EP.The abundance of Actinobacteria decreased in all test groups.The abundance of Acidobacteria increased in groups CP,DP and EP,the abundance of Firmicutes increased in groups BP,CP and EP and the abundance of Bacteroidetes decreased in all groups.In summary,the residues of fenpropathrin in the sediment pose a threat to the health of sea cucumbers.The administration of probiotics alleviated the stress of the sea cucumbers.