| China is a aquatic country.In 2018,the total aquatic product exceeded50 million tons,while grass carp(Ctenopharynodon idellus)is the most important freshwater farmed fish in China.The annual output of the country is over 6 million tons,accounting for 12% of all aquatic products..The Crisp flesh grass carp formed after feeding broad beans is crisp and thoroughly cooked but not mushy,tastes mellow and delicious,and is rich in nutrients and win more popularity in people.At present,the mechanism of embrittlement of grass carp has not been confirmed.Some scholars believe that it is a certain factor in broad bean activates the related genes of grass carp,which leads to the change of gene expression products causing embrittlement.In this study,the intestinal contents were collected by feeding grass carp common feed and broad bean feed,and the intestinal microbes of common grass carp and embrittled grass carp were studied by 16 S r DNA high-throughput sequencing technology,and the intestinal tract of grass carp after feeding with broad bean was discussed.The change law of the group tries to find the relationship between the embrittlement mechanism of grass carp and the intestinal flora,and provides a basis for studying the embrittlement mechanism of grass carp.The test results obtained are:1)Through OTU cluster analysis,a total of 4370323 high-quality sequences were obtained,the average effective rate of the samples was 93.24%,and the average OTUs of the grass carp in the control group was 546.The OTUs of the grass carp in the experimental group were 903.2)Through Alpha diversity Analysis showed that there were only three groups in the experimental group and the control group,so there was no significant difference between the experimental group and the control group.At the same time,the indexes of chao1,ace,shannon and simpson in the experimental group were significant.Higher than the control group,it indicated that the intake of broad bean was very obvious in changing the diversity index of the intestinal flora ofgrass carp.3)Through the Beta diversity analysis,it was found that there were significant differences in intestinal microbes between the experimental group and the control group,and the similarity in the embrittled grass carp group was lower than that of the common grass carp,indicating that feeding the broad bean resulted in grass carp.Changes in the intestinal flora,at the same time,there are individual differences in this change.4)Species annotations showed that the main dominant bacteria in the intestinal microflora of the experimental group at the level of the gate were Proteobacteria,which accounted for 60%,Fusobacteria and thick-walled bacteria.Fimicutes),the dominant bacteria of the intestinal microbes of the common grass carp of the control group accounted for 70% of the Fusobacterium,Proteobacteria,Absidia and Bacteroidetes,and the Proteobacteria of the experimental group increased by 40%.The Fusobacterium gate is reduced by 50%.5)Species annotations showed that the main dominant genus of the microbial flora of the experimental group of the embrittled grass carp in the experimental group were Acinetobacter and Aeromonas,respectively,accounting for 15% and 10%,respectively.The main dominant genus of the microbial flora of the common grass carp in the control group were 20% and 11%,respectively,of Aeromonas and Bacteroides,and 15% by Acinetobacter in the experimental group.The genus was reduced by 10% and the Aeromonas was reduced by 5%.6)Through functional predictive analysis,it was found that in the metabolic pathway of energy metabolism,cofactor and vitamin metabolism pathways and environmental information processing signal transduction pathway,the experimental group was significantly down-regulated compared with the control group.It indicates that the changes in the intestinal flora of grass carp caused by feeding the broad bean feed resulted in changes in metabolism and signal transduction.The above results indicate that the ratio of Proteobacteria is increased in the Crisp flesh grass carp compared with the grass carp fed with common feed,the proportion of Fusobacteria is decreased,and the Acinetobacter is significantly increased,while Bacteroides and Aeromonas are Significantly reduced bacteria.Therefore,it can be inferred that the embrittlement process after feeding grass carp must be related to the increase of Acinetobacter. |
