Research Of The Sulfonamide Resistance Genes Of Antibiotics In Aquaculture Environment

Antibiotics that double in the control of bacterial diseases and promote aquatic organism growth are becoming a major focus in the aquaculture industry.Recently,with the increase in antibiotics usage,the culture ecological environment is experiencing a setback caused by the antibiotic pollution.The polution effect has enhanced microbial communities with new types of environmental pollutant-antibiotic resistance genes,considered to be harmful to human.These pollutants can enter the human body through horizontal gene transfer,and ultimately endanger human health,arising wide attention at home and abroad.In the present research,we tried to take the sulfonamide antibiotics as the target chemicals and studied the pollution levels?that triggered the resistant strains through temporal variations of antibiotic residues and correlated them to the antibiotic resistance genes in aquaculture water and sediment in the Taihu River Basin.Considering the different cultured varieties i.e.crab,shrimp,perch,crucian carp,bream and vannamei,in the five study regions(including Wuxi,Huzhou,Changzhou,Suzhou,Yixing cities).Comparisons of the resistance genes at pollution levels with those similar to the natural waters were obtained to boost our knowledge of the antibiotic resistance genes in aquaculture water environment.Furthermore the research results revealed that:1?The distribution of sulfonamides in water and sediments from the different regions culturing different aquaculture varieties throughout the breeding cycle in 2015 had significant changes of sulfonamide concentrations with a low-high-low trend.2?The drug resistant microorganisms in the water and sediments samples from the different culture ponds were detected throughout the entire breeding process,,and the increment of sulfanilamide concentrations in the different pond water and sediment,microbial resistance rates showed a downward trend with higher concentrations,resulting in lower resistance rates for drug resistant bacteria.The drug resistance rate for the bacteria in sediment was higher than that in water under the same conditions.3?The 4 resistant strains were isolated and screened by resistant plate,through the cell physiological and biochemical characteristics and analysis of 16S rDNA sequence,the 4 screened resistant strains preliminarily determined as NHA1401 and NHA1402 were most probably Proteus mirabilis,while CBA1506,and SHA1501 were most probably Chryseobacterium sp and Staphylococcus sp respectively.4?The distribution of the sulfonamides resistance genes sul I and sul II of qualitative analysis by PCR in water and sediment in the Taihu Lake was based on the breeding regions and breeding varieties however,these were displayed in a similar breeding cycle at different periods(i.e.May-June,July-August,and September-October in 2015).The study results continued to reveal that in three different breeding periods,both resistance genes sul ? and ·sul ? were detected.The lowest detection rates of any 2 kinds of resistance genes were in the early stage(May-June),which were 80%and 65%.With the advance of the breeding process,sul ? showed a tendency to increase first and then decrease,and the detection rate of sul II resistance gene was increasing.At the same time,the resistance genes of sul I and sul II in the natural water and sediment in Taihu have also been detected.5.Water samples and sediment in ponds of different culture areas of Taihu were analyzed by fluorescence quantitative PCR method,the relative abundance of the sul I and sul II in the different periods of the same breeding cycle was shown,(1)the spatial relative abundance of the sulfonamide resistance genes against the similar cultivated species in the aquaculture ponds was not significantly different(P<0.05),with the maximum not exceeding the order of magnitude.(2)In any specified region,pond pollution of varieties such as vannamei,herring and perch pond was heavier than the shrimp and bream culture ponds.Another result revealed that the antibiotic pollution of shrimp,vannamei,perch,crucian carp,bream and herring aquaculture varieties were heavier in the pond water compared to the sediments while in the crab breeding ponds sediment pollution was heavier than water.In the aquaculture environment,both water and sediment,displayed the resistant genes and the differences were between 1-2 orders of magnitude.(3)With a few exceptions,90%of the maximum relative abundance of the sulfonamide resistance genes in any one breeding cycle and variety were observed during the mid breeding season(July-August).6?In the natural waters of Taihu,the geographic locality influenced the relative abundance of sulfonamide resistance genes in the water and sediment samples,with the latter having higher pollution resistance genes.Other comparisons revealed that the pollution degree of natural water samples was less than the culture areas,although the sediment pollution levels were comparable with those in the culture area.Studies in aquaculture environment have shown that the antibiotic resistant bacteria are not long-term fixed accumulators in pond and there is a relationship between the sulfonamide resistance genes in the breeding cycle,and the administration of antibiotics in aquaculture.Therefore,this study recommends strict control usage of antibiotics in farming environments,to prevent the production of resistance genes that provides a guarantee for human health.