Isolation And Identification Of Beneficial Microbial Degradation Of Ammonia Nitrogen In Aquaculture Ponds

This experiment isolated bacteria from the water and soil sample，which werefrom the two shrimp aquaculture farming areas in Rizhao and Dongying during Juneto October. The two shrimp aquaculture farming areas have four different modespond.The aim was to screen the effect of good strains of ammonia degradation andstatistics the number of strain.Through16SrDNA sequences analysis and determinethe screening of strains;combined with the strains of ammonia and nitrite degradationrate and the strain type, we selected two different types of strains that can be added tothe Litopenaeus vannamei farming,investigated the safety of the two bacterias forLitopenaeus vannamei.The main results were as follows:1. Isolation and screening of ammonia-degradingmicroorganisms from the aquaculture pondsBy direct separation and enrichment culture, separated many nitrosation bacteriasand nitrifying bacterias from shrimp culture ponds in Rizhao and Dongying,whichhave4kinds of different cultivation patterns. With the direct separation and purifies to66strains altogether,20strains had high degeneration ability of ammonia and they arenitrosobacteria.With the enrichment culture,233nitrobacterium and201nitrosobacteriawere isolated.Finally,66strains had high degeneration ability and the effect stable tothe nitrite,the highest of nitrite moval rate was100%.13strains had high degenerationability and effect stable strain to the ammonia,the highest of ammonia moval was83.63%.Statistics on the number of the strains,the study showed that the number ofstrains were more in June,July and August.By comparing two different ways isolatedstrains,enriched culture method had certain advantages over the direct separation.2.Identification of ammonia-degrading microorganisms fromthe aquaculture ponds On the last chapter of the screened all strains with high degradation wereidentified according to the analysis of16S rDNA sequences.The strains showed>97%sequence similarities to the standard strain,which are Marinobacter spp.(18) andPseudoalteromonas spp.(21).They have the hightest possession of abundance ratio.And the remaining strains belong to Vibrio spp.（7）, which are more than97%similarity。Then the remaining strains are Halomonas spp.（4）,Marinomonas spp.（3）,Desemzia incerta （1）,Exiguobacterium aurantiacum （1）,Alteromonas spp.（1）,Thalassospira spp.（1）,Sphingomonas spp.（1）.They showed>99%sequencesimilarities to the strains. Depending on the type of strains, the degradation rate andseparate source have chosen two bacteria (strain7RO29and strain8DH26).By themeans of morphological, physiological and biochemical tests, and16S rDNAsequence analysis, two bacterial strains isolated from shrimp culture pond wereidentified.The results showed that two bacteria are Halomonas sp. and Vibrioalginolyticus3.The safety inspection of isolated microorganisms inLitopenaeus vannameiTo test the security of the strain7RO29and the strain8DH26，Litopenaeusvannamei was selected as the experimental material, two different strains of bacteriawere added into Litopenaeus vannamei farming waters,and the concentration of strainwere104cfu/ml、106cfu/ml、108cfu/ml.The study showed that when concentration oftwo strains were below108cfu/ml and106cfu/ml,they showed no apparent differenton the control group. Therefore, the two strains could be applied in production.