Acute Toxicity Of Three Drugs To Perinereis Aibuhitensis And Their Bacteriostatic Effect In Vivo

According to incomplete statistics,shrimp farming and its related supporting industries such as breeding,feed and disease,processing and so on,can reach 400 billion yuan annually.It can be said that shrimp farming is an important pillar industry in China's aquaculture industry.In recent years,affected by macro-economy and disease occurrence,the production of shrimp culture in China has decreased,but basically maintained stability.Germplasm is the prerequisite for the sustainable development of shrimp breeding industry.In the process of shrimp seedling cultivation,artificial gonad ripening and egg cell cultivation are the basic links of high quality shrimp seedling cultivation.Nutrition and diet selection are the key to shrimp parent shrimp ripening cultivation.At present,in the prawn breeding and seedling cultivation countries,polychaetes are commonly used as living diets in prawn parent shrimp cultivation and ripening.However,it is reported that there are high concentration pathogens in the body of Perinereis bidentata,which may be transferred to prawns by feeding.Therefore,based on the current situation and problems of production practice,we urgently need to study the methods of reducing pathogenic microorganisms in Perinereis bidentata so as to provide new ideas for Disease Control Strategies in shrimp culture.In this study,thiosulfate citrate bile salt sucrose agar medium(TCBS agar medium)was used to preliminarily screen dominant strains and the total number of colonies cultured in Perinereis bidentata by plate coating method,and 16 S rDNA sequence analysis of the selected strains was carried out to study the microorganisms in Perinereis.The acute toxicity of gentamicin,polyhexamethylene biguanide and florfenicol to Perinereis bicolor was studied in this paper,and the safe concentration of the three drugs to Perinereis bicolor was revealed.On this basis,we carried out the study of using three drugs to purify the microorganisms in the silkworm.The experimental results can provide basic data for the purification of microorganisms in the silkworm.The experimental results showed that eight strains were detected in the body of Perinereis bidentata which had not been purified.Vibrio alginolyticus,Vibrio cyclitrophicus,Aeromonas hydrophila,Aeromonas sobria,Vibrio parahemolyticus,Pseudomonas putida,Pseudomonas aeruginosa and Mendoza Pseudomonas respectively.(Pseudomonas mendocina).Conclusion:(1)Gentamycin can not only kill Vibrio in the body of Silkworm effectively,but also produce post-antibiotic effect(PAE)in the course of treatment,which can inhibit the growth of bacteria continuously,but has low antimicrobial activity against Pseudomonas aeruginosa.(2)Polyhexamethylene biguanide can reduce the proportion of microorganisms in the body of Perinereis bidentata in a short time,and has the characteristics of broad-spectrum antimicrobial activity.However,due to the low tolerance of biological individuals to the disinfectant,low dosage of biguanide can not completely inhibit some drug-resistant strains.(3)Flufenicol has good antimicrobial activity against Pseudomonas aeruginosa with natural resistance,but it can not be completely dissolved in water,so it can not fully play its therapeutic effect in water,and its effective drug concentration is also high.(4)In the orthogonal test,120 ug/L gentamicin+10 ug/L polyhexamethylene biguanide+80 mg/L florfenicol was determined for 72 hours,120 ug/L gentamicin+15 ug/L polyhexamethylene biguanide+160 mg/L florfenicol for 24 hours,and the bacteriostasis efficiency was over 99.9%.These two combination conditions were the best dosage regimen.CA9 group can kill most pathogens quickly in a short time,while CA8 group can effectively inhibit the growth of bacteria for a long time.