Bacterial Community Structure Analysis In Typical Aquaculture Water By Pcr-dgge Technology And Its Correlation With Environmental Factors

With the restructuring of aquaculture and sustainable development, the requirement of ecological farming is around the corner. Shrimp aquaculture is one of the mainstay industries in China. As we know the key to the success of aquaculture is water environment. Physicochemical factors, microorganisms, and the relationship between aquatic organisms play a crucial role in the health of the ecological farming system.In this paper, the typical shrimp water in the Canton River Delta was studied by PCR-DGGE technology. Experiment platform has been established and optimized. The DGGE fingerprint analysis combined with statistical analysis methods were applied to study the temporal and spatial changes of bacteria group structure in aquaculture water. And its relationship with the corresponding physical and chemical indicators was discussed. This study lays the foundation of the methods and provides reference data for the future study on aquaculture water.The main results are as follows:a. Optimiziton of the PCR-DGGE system for aquaculture water was proved effectively improved the result of DGGE: CTAB method used to extract total DNA, the conditions of Touchdown PCR (td-PCR)was optimized, DGGE was defined to be 40%-55%, 75V, 57℃, 18 hours, and silver staining, clonning and sequencing were used.b. Quantity One 4.6.2 was applied with the DGGE profiles to move background noise, identificate lanes and bands, automatic analyze the relative quantity and similarity. Parallel samples proved DGGE can distinguish subtle differences in samples and show good reproducibility.c. The aquaculture water samples of different space and different date were detected by the optimized PCR-DGGE system. DGGE fingerprint analysis revealed that there was a complex microbial species in shrimp pools. The bacterial structure and quantity showed great change in different samples.d. UPGMA cluster analysis and multidimensional scaling (MDS) results indicated that time change showed a greater impact on the bacterial structure than the spatial change. In addition, microbial preparation may have an impact on the microbiologic population. e. Sequencing results showed that beta Proteobacteria, alpha Proteobacteria, Bacillus and Clostridia is likely to be the dominant species in aquaculture water. Nitrospirae, Bifidobacterium, Nitrobacter, Desulfovibrio, Bdellovibrio may be common species in aquaculture water. Most detected bacteria were uncultured strains, and their genetic relationships were far from each other.f. Results of Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA) showed that enviromental indicators selected in this study covering most environmental factors associated with bacterial structure (94% and 76%). The relevance of these indicators can be summarized in three or four principal component factors. And the temperature, pH, ammonia nitrogen, total phosphorus, chlorophyll a, dissolved oxygen, nitrite and transparency played a very important role in the changes of bacterial community structure.