Isolation and Identification of an Unexpected Strain of Denitrifying Bacteria in the Intensive Ponds Sediment

Fan Limin,Qiu Liping,Wu Wei,Song Chao,Meng Shunlong,Hu Gengdong,Qu Jianhong,Chen Jiazhang(Freshwater Fisheries Research Centre,Chinese Academy of Fishery Sciences/Fishery Eco-environment Monitoring Center of Lower Reaches of Yangtze River/Ministry of Agriculture/Key Open Laboratory of Ecological Environment and Resources of Inland Fisheries,Wuxi Jiangsu 214081)

intensive ponds;sediment;culture medium;Thiobacillus denitrificans;Alicycliphilus denitrificans

In this study,an intensive pond in which GIFT tilapia(Oreochromis niloticus) were cultured was used as the experimental site.And sediments sampling were done in the pond.After that,enrichment and elective cultures were prepared anaerobically on these samples in 30 centigrade with the medium(named medium a) whose composition proved to be eminently satisfactory for Thiobacillus denitrificans,however sterilized in different ways.Through spread plate method,large numbers of round,brown and slightly uplift colonies were obtained which were different from the colonies of Thiobacillus denitrificans reported.And with the appearance of the colonies and the shape of the strain observed,the physiological and biochemical indicators detected,the sequences of 16SrDNA of the strain analyzed,and the phylogenetic tree based on the strain set up,the strain was proved to belong to the genera of Alicycliphilus and was named as the strain ADCF001.After being inoculated into the liquid medium referred above for 15 days,the strain couldn't be found in growth.Through detailed analysis,the results of the study could be presented as follows,The reason for that the strain could be enriched and electively cultured with the " medium a " however can'nt be observed in growth after being inoculated into " medium a " again could be ascribed to such factors as that the sterilizing way of all compositions sterilized all together made the chemical reactions happen,some components in sediments and the components in " medium a " composited another medium suitable for the strain ADCF001,and the " new medium " were transferred to the plates during the process of plate spreading and plate streaking.The strain ADCF001 might be one of the decomposers of the aromatic compounds in ponds.