Preliminary Study On The Efficiency Of Aerobic Denitrification And Genomic Denitrification Gene In Vibrio Parahaemolyticus

Ammonia and nitrite are the main pollutants in aquaculture water,which is very harmful to aquatic environment and aquatic animals.Biological denitrification is an effective method to control nitrogen pollution in water.The Vibrio Parahaemolyticus HA2 by screening from the breeding environment and identification was the research object,by different nitrogen source culture(NH4+-N,NO3--N,NO2--N)explore the strain denitrification ability,growth condition and gas product change.The strain was sequenced by denovo whole genome.The genome sequence assembly,gene encoding prediction,NR,GO again,compare the COG,KEGG database,get complete nitrification and denitrification prediction of functional genes,further speculated that the strain is analyzed with the model of denitrification.The strain HA2 can grow in the three kinds of medium,from the three growth curve fitting results can be concluded that the bacteria in the NH4+-N,NO3--N,NO2--N in growth limit k values were 4.769,5.477,5.567.Three kinds of medium the strain growth rate from big to small in turn was: NH4+-N,NO3--N,NO2--N.The removal rate of NH4+-N was 99.97% at the 45 h,and the removal rate of NO3--N at60 h was 99.95%,and NO2--N removal rate was 36.87% at 60 h.In the process of test by measuring three kinds of sealing gas changes in fermentation tank,three kinds of medium N2 were increased,increasing rate from big to small in turn is: NO2--N and NO3--N,NH4+-N.The p H values in the three cultures were significantly increased and the denitrification was confirmed.The HA2 genome to forecast and COG database,checked NR database,predict ammonia single oxygenase(AMO),hydroxyl amine oxidase(HAO),nitrate reductase(NAP),nitrite reductase(NIR),nitric oxide reductase(NOR),nitric oxide reductase(N2OR),including nitrification,denitrification,a full set of functional genes,therefore,nitrification and denitrification speculated that the strain model of NH4+-N to NH2 OH,NO2--N and NO3--N,N2.The prediction results of nitrate reductase showed that the strain HA2 contained only a large number of NAP sequencefragments,and did not predict the NAR sequence fragment.Therefore,it was confirmed that the bacteria had good aerobic denitrification capability.The strain HA2 has long-term research value,and the preservation method of this strain is a technical problem that must be solved.This experiment adopts vacuum cryopreservation method screening efficient protectant,first of all,performance efficient single protectant,then the Box-Behnke response surface test method for design the best performance of compound with protective agent.The results showed that the protective effect of sucrose,maltose,skimmed milk and mannitol was better when the concentration was 10% and 15%.The protective effect of mannitol,sucrose and skimmed milk was significantly higher than that of single time.Through the Box-Behnken response surface experiment method,the fitting of mannitol,sucrose,skimmed milk multivariate quadratic regression equation,and to predict the optimal formula ratio: 12.33%,12.16% skimmed milk and sucrose12.16% mannitol.