Study On The Construction Of A Small Fish-Flower(Mint)Closed-Loop Symbiosis System And Its Microbial Community Structure Diversity

The fish-flower(mint)closed-loop symbiosis model is a safe,healthy,ecological and environmentally friendly green model that combines the recirculating aquaculture system and plant hydroponics technology.Currently,there are few studies on the construction of fish-flower closed-loop symbiosis system,water bodies,hydroponic plant roots,and the intestinal microbial community structure and diversity of cultured fish,especially the research on the root microorganisms of spearmint According to reports,this research started with this as a starting point.In this study,crucian carp as the breeding object and spearmint as the hydroponic object,the growth indicators of crucian carp and spearmint were determined,a stable fish-flower closed-loop symbiosis system was constructed,and molecular biology such as high-throughput sequencing was adopted.Methods To study the community structure and diversity of microbes in the water,the root system of spearmint and the intestine of crucian carp under the conditions of conventional and highest culture density.The main results are as follows:(1)The fish-flower(mint)closed-loop symbiosis system design and operation effect analysis.By constructing a fish-flower closed-loop symbiosis system,the growth indicators of crucian carp and spearmint were measured and analyzed.The results showed that the significant increase in plant height and stem thickness had an accumulation effect on the biomass of the plant,and it also promoted the growth of crucian carp and spearmint.The growth of spearmint.The construction of the system not only improves the space utilization rate,but also has higher ornamental value.(2)Research on the microbial community structure and its diversity in the fish-flower(mint)closed-loop symbiosis mode in the conventional and highest aquaculture density.The spatial distribution of microorganisms in the fish-flower closed-loop symbiosis system.The structure of microbial communities in different water layers by 16S rRNA gene sequencing showed that the water microbial communities in different aquaculture densities have high abundance and diversity.The dominant genera are mainly Polynucleobacter,Cetobacterium,Luteolibacter and Flavobacterium,etc.These relatively abundant genera affect the bacterial communities in different water layers.Diversity produces greater differences.At the same time,the PCA analysis of the samples between different water layers at different densities found that the distance between the culture bucket(H1)and the water collection bucket(H10)and other samples is quite different,indicating that the low aquaculture density and the difference between the different water layers The microbial community structure is quite different;the study on the richness and diversity of the microbial community in 20 samples shows that the microbial diversity in the second layer(G8)of hydroponic plant filtration is the highest,and the collection bucket(G10)is rich in microbes According to the comparison of the total number of OUTs,the total OUT proportions of the water collection bucket(H10)and the second layer of physical filtration(H3)are 7.57%and 5.58%,respectively,indicating the bacterial communities in the water layer where the H 10 and H3 samples are located.The structure is significantly different from other water layers.The microbial community structure of the root system of hydroponic planting of spearmint in the fish-flower symbiosis closed-loop system and its effect on water quality.Regular monitoring of water quality and analysis of the microbial community structure of the hydroponic spearmint root system based on 16S rRNA gene sequencing and redundancy analysis(RDA)of the dominant colony of the hydroponic spearmint root system showed that the genus Hydrogenophaga(Hydrogenophaga),yellow Flavobacterium,Luteolibacter,Rhodobacter and Runella are positively correlated with ammonia nitrogen,nitrite and total alkali,and negatively correlated with pH and phosphate;Aquincola is only positively correlated with total alkali;small pear Pirellula and Nitrospira are positively correlated with pH and phosphate,and negatively correlated with ammonia nitrogen,nitrite and total alkali.In the fish-flower symbiosis closed-loop model,the abundance of spearmint root microorganisms is reduced,while the microbes in the aquaculture water environment have high abundance and diversity,indicating that hydroponic spearmint can reduce and improve the concentration of nitrogenous compounds in the water body The micro-ecological balance in the breeding environment.The structure of the intestinal microbial community of the crucian carp in the fish-flower closed-loop symbiosis system.The comparative analysis of the structure of the intestinal microbes of the crucian carp under different culture densities showed that the dominant phyla of the intestinal microbes of the crucian carp in the fish-flower closed-loop symbiosis system are Proteobacteria,Fusobacteria,Verrucomicrobia and Firmicutes.As a beneficial bacteria,the relative abundance of cetaceans decreased in high-density culture;while the relative abundance of pathogenic bacteria Gemmobacter increased in high-density culture,indicating that under high-density culture,the intestinal tract of crucian carp The structure of the flora has undergone a certain change.The Simpson index in the gut of crucian carp with the highest culture density is greater than that of crucian carp with conventional culture density,which also indicates that high-density culture will reduce the diversity of crucian carp intestinal microbes.Although the samples in this study did not appear to be ill,it was found in preliminary experiments that a large number of fish died when the breeding density exceeded 10 kg/barrel.Therefore,the changes in the intestinal microbial community and the decline in diversity of crucian carp under high-density culture mode Stress warning.