| Aquaculture plays a “backbone role” in ensuring food,nutrition,and financial security in China.However,under intensive aquaculture,the occurrence of diseases has brought huge economic losses to the breeding of important aquatic economic animals such as turbot(Scophthalmus maximus),sea cucumber(Apostichopus japonicus)and common carp(Cyprinus cardio)in Liaoning Province.Antibiotic drugs are mainly used to prevent and control the occurrence of diseases of these economic aquatic animals,but the drug resistance and drug residues caused by them do not meet the current nonresistance requirements in the prevention and control of aquaculture diseases.On this basis,to strengthen the prevention and control of aquatic economic animal diseases,we tried to conduct two-part research from these three perspectives,including the identification of pathogenic bacteria in key diseases,computer-aided prediction of the toxicity of Chinese herbal medicines,and the application of Chinese herbal medicine for immune prevention and control.In the first part,the ocular bacterial signatures of exophthalmic disease in farmed turbot and the skin bacterial signatures of skin ulceration syndrome in farmed sea cucumber are characterized based on microbiome analysis.The reproductive toxicity prediction model of organic compounds was subsequently constructed based on ensemble learning strategy.This model is further used to predict the toxicity of Chinese herbal medicines,which can provide theoretical guidance and technical guidance for the later screening of safe and effective Chinese herbal medicines based on the above-mentioned marker pathogens for the prevention and control of aquatic economic animal diseases.In the second part,taking sea cucumbers and common carp as the key research objects,two Chinese herbal medicine mixtures suitable for sea cucumber and common carp breeding were promoted and applied in Liaoning Province,which will provide more practical technical support and practical basis for the production of these two economic animals.The specific research results of the thesis are as follows:The relationship between exophthalmic disease and the ocular microbiota in farmed turbot to identify the characteristics of ocular pathogens has been investigated for the first time by using high-throughput 16 S r RNA gene sequencing.The results show that there are significant differences in ocular microbiota between healthy turbot and diseased turbot.And diseased turbot has lower microbial diversity than healthy turbot.The signature bacteria are members of the genus Aeromonas,which have been found in healthy turbot,and the increase in their abundance may be correlated with a decrease in microbial diversity and functional abnormalities of the ocular microbiota in turbot with exophthalmic disease.The relationship between skin ulceration syndrome and the skin microbiota in farmed sea cucumber to identify the characteristics of skin pathogens has been investigated for the first time by using high-throughput 16 S r RNA gene sequencing.The results show that the skin microbial diversity of diseased sea cucumbers is significantly lower than that of healthy sea cucumbers,and this change may be related to the change of skin microbial composition.The comparison of the skin microbiota composition and functional pathways of the two groups of sea cucumbers shows that there are significant differences in the skin microbial composition of healthy sea cucumbers and diseased sea cucumbers.Six genera,including Sulfitobacter,Roseovarius,Ruegeria,Vibrio,Tropicibacter,and Lesingera,are the skin bacterial signature genera in diseased sea cucumber.The increase in the abundance of these characteristic pathogens may be related to the changes in the KEGG metabolic pathway of the microbial community.Twenty-seven ensemble models were developed using support vector machine,random forest,and extreme gradient boosting methods and 9 molecular fingerprints calculated for a dataset containing 1823 chemicals collected in the literature.The best prediction performance was achieved by the Ensemble-Top12 model,with an accuracy of86.33% and an area under the receiver operating characteristic curve(AUC)of 0.937 in5-fold cross-validation and accuracy and AUC values of 84.38% and 0.920,respectively,in external validation.Compared with models in existing literature,our ensemble model achieves higher predictive performance.Based on our best ensemble model EensemblTop12 and the three existing toxicity prediction models,we predicted the reproductive toxicity,carcinogenicity,liver toxicity,and mutagenicity of the 6 single Chinese herbal medicines that were screened in the previous work.The results showed four prediction models can be used for the preliminary assessment of the toxicity of Chinese herbal medicine.The single herbal toxicity prediction results show that the Chinese herbal compound formula I screened by the four characteristic pathogens of skin ulcer syndrome is basically safe and non-toxic in our preliminary work,which can be used for immune prevention and treatment of pond cultured sea cucumbers.Then,we applied and promoted Chinese herbal compound formula I on a large scale in 24 sea cucumber farms in 6 cities and counties including Dalian City,Huludao City,Jinzhou City,Panjin City,Yingkou City and Suizhong County in Liaoning Province.The results show that the Chinese herbal compound formula I has these functions,which include the promotion of growth promotion,the improvement of non-specific immunity,the enhancement of disease resistance,the improvement of the quality of aquaculture water and the amino acid content of the sea cucumber body wall,and the reduction of the amount of antibiotics.So far,the application scale of Chinese herbal compound formula I in the breeding of drug-free sea cucumber has reached 141,900 cubic meters.After the use of Chinese herbal compound formula I,the production of sea cucumbers increased by an average of 24.53%,and the overall economic benefit has reached 110 million yuan.The toxicity prediction results of the single Chinese herbal medicine show that the Chinese herbal compound formula II screened in our previous work is basically safe and non-toxic,which can be used for immune prevention and control of common carp cultured in ponds.The antibacterial effect of Chinese herbal compound formula II on four characteristic pathogens based on turbot exophthalmia and other important fish diseases shows that Chinese herbal compound formula II has a good inhibitory effect on these four bacterial pathogens.We initially fed 8.24 acres of the compound Chinese herbal medicine formula II in the common carp pond,and the results showed that the compound Chinese herbal medicine significantly improved the growth performance and feed utilization of common carp.Specifically,the survival rate of carp has increased by7.59%,the weight gain rate has increased by 22.94%,and the feed coefficient has decreased by 1.59%.In addition,the Chinese herbal compound formula II also significantly improved the activity of non-specific immune enzymes such as acid phosphatase,alkaline phosphatase,superoxide dismutase and lysozyme in common carp serum.When the application area of Chinese herbal compound formula II in carp was expanded to 49.42 acres,the breeding process and increased the production of common carp by an average of 15.3%,the economic benefit increased to 350,000 yuan.In summary,this study has completed the following work:(1)The relationship between turbot exophthalmia and ocular microbiota was revealed for the first time based on microbiome analysis;(2)The relationship between sea cucmbers skin ulceration syndrome and skin microbiota was revealed for the first time based on microbiome analysis;(3)A ensemble reproductive toxicity prediction model with higher predictive performance was developed,which was further used for the preliminary assessment of the toxicity of Chinese herbal medicines;(4)The developed Chinese herbal compound formula I suitable for juvenile sea cucumber farming and the compound Chinese herbal compound formula II suitable for freshwater fish farming have been promoted and applied on a large scale in Liaoning Province for the first time,and good economic benefits have been achieved in aquaculture application. |
PDF Full Text Request