Study Of Bacterial Genetic Diversity In Aquiculture Water

In recent years, with the rapid development of molecular biology techniques, it hasbecome possible to study the microbial community structure from the molecular level.Currently, a kind of analysis of microbial community structure that was new, fast and effectivewas created, called T-RFLP (Terminal Restriction fragment length of Polymorphism), becausethe technologies that were PCR (Polymerase Chain Reaction) and RFLP(Restriction Fragmentlength Polymorphism) were established, DNA sequencing technologies was improvedconstantly and these technologies were integrated. Compared with classical methods, itoffered a number of advantages. It was built on the basis of PCR, and needed no isolation andculture of bacteria, which avoided the disadvantages of culture methods. Moreover, themethod could detect all the bacteria in the environment including viable bacteria (cultivableand non- cultivable) and without degradation of dead bacteria. We studied the classification ofbacteria in shrimp pond by T-RFLP (Terminal Restriction fragment length of Polymorphism).Meanwhile, we studied the microbial diversity before and after adding Nitrobacteria intoshrimp ponds, and analyzed bacterial flora and quality changes on the impact of fisherybreeding.In this study, we analyzed the microbial diversity in the enrichment system of nitrifyingbacteria. The results showed that the enrichment of nitrifying bacteria was in the lag phasebetween 0h and 12h, and was into exponential phase on the 12h, then was into the stationaryphase on the 60h, and the quantity of bacteria reached 6.03×10~9; finally, nitrifying bacteriawas into the decline phase on the 120h. When nitrifying bacteria was into the stationary phaseon the 120h, Shannon Diversity (H′) decreased 67% compared with the initial data, ShannonDiversity (E′) increased 10.3%, and the abundance ratio of nitrifying bacteria was 97%. Whennitrifying bacteria was into the stationary phase, the number was more than other times, andthe number of mixed bacteria was much lower. Thus, nitrifying bacteria that was into thestationary phase was most suitable for adding to ponds. We tracked and monitored watersamples over a period of 6 months. Compared with T_RFLP results of water samples in thedifferent period in the ponds, we found to appear the peak of T_RF in all different time, whichrepresented the stable bacteria in shrimp pond. 17bp possibly represented more complexspecies of microbial, which was trouble to determine the specific species. 9 bp representedBrevibacillus shida, 23 bp represented Microbacterium orla, and 18 bp possibly representedeither Azoarcus indigen or Bordetella holmesii. Compared with Shannon Diversity (H′) andShannon Diversity (E′) in the different period in the ponds, we found that Shannon Diversity (H′) decreased gradually. The reason was possible that the weather cooled gradually andbacteria cannot adapt to the surrounding environment of ponds and died. Meanwhile, 10species of bacteria were studied by T_RFLP analysis of HaeⅢand MseⅠ, and were carriedout a distinction among them successfully.