Isolation And Identification Of Bacteria From Aquacultural Wastewater And Immobilization For Ammonia Degradation

Since 1980, the mariculture in China has developed so quickly that the production has now reached the top in the world. It is well known that intensive mariculture give off excessive amounts of nutrients into the environment, thus encourages eutrophicatition and red tide in the coastal region. For this reason, the bioremediation of maricultural wastewater has attracted serious attention all over the world. But to our knowledge, only very few reports about the treatment of maricultural wastewater by enforcing native bacteria were existed in the literature. In this work, the nutrient condition in the prawn farming pond during the process of culture was investigated firstly and tow strains of bacteria which could degradate ammonia were isolated and purified from the maricultural wastewater, then the ammonia degradating potentials of both strains were studied, at last, both strains of bacteria were identified by the sequence of their 16S rDNA.At first, the levels of nitrogen and phosphate in the water of Jiaozhou Bay and prawn farming pond were investigated in 2002 and 2004. The results showed that both nutrients in prawn farming pond in 2004 decreased markedly than that in 2002. The concentrations of PO4-P, NO3-N, NO2-N and NRrN decreased 65.7%, 64.9%, 60% and 44.8%, respectively. On the other hand, in Jiaozhou Bay, the concentration of NH4-N increased 47%, while the concentrations of NOs-N, NOi-N and PCVP decreased 22.6%, 30.1% and 65.2%, respectivelySecondly, two strains of bacteria were isolated from the aquacultural wastewater of turbots and prawns, and they were named Stadl and Sam2 respectively. Further study have confirmed that both of them could oxidize ammonia and their oxidizing abilityincreased on the existence of glucose in the medium.Immobilized of Stadl and Sam2 by activated carbon were used to treat aquacultural wastewater. Two apparent results were shown as follows: 1) Ammonia oxidizing rates of Stadl and Sam2 were 51.0%* 37.0%, respectively. 2) Addition of activated carbon had improved their oxidizing ability at least 29% and 22%, respectively. Therefore, it is recommended to use those bacteria immobilized with activated carbon in organic nutrient rich water.16S rDNA sequencing was employed to identify those isolated bacteria, Stadl and Sam2. According to "Gapped BLAST and PSI-BLAST: a new generation of protein database search programs" through The DNA Data Bank of Japan, their genus were supposed to be halomonas with more than 99% homology. A Phylogenetic tree were also drew. This is the first report that halomonas was used to treat wastewater effectively.