不同浓度硫酸新霉素对生物絮团氨氮转化速率及抗生素抗性基因的影响

Effects of different concentrations of neomycin sulfate on ammonia nitrogen conversion rate and antibiotic resistance genes in biological flocs

为探究不同浓度硫酸新霉素对于生物絮团处理氨氮及抗生素抗性基因的影响,本实验对生物絮团水质及絮团指标、水体中抗生素含量和生物絮团中6种抗生素抗性基因的含量进行了检测。结果显示:在氨氮转化的速率上,初次加药连续监测显示未添加组(A组)、0.5 mg/L硫酸新霉素组(B组)、1 mg/L硫酸新霉素组(C组)和3 mg/L硫酸新霉素组(D组)的氨氮去除速率分别为(3.88±0.02)mg TAN/(g TSS·h)、(2.22±0.03)mg TAN/(g TSS·h)、(2.17±0.04)mg TAN/(g TSS·h)和(1.72±0.02)mg TAN/(g TSS·h),氨氮去除速率A组>B组>C组>D组。而间隔一个休药期(500℃·d)的第二次加药连续监测显示4个组的氨氮去除速率分别为(2.99±0.08)mg TAN/(g TSS·h)、(2.98±0.03)mg TAN/(g TSS·h)、(2.97±0.08)mg TAN/(g TSS·h)和(5.10±0.03)mg TAN/(g TSS·h),氨氮去除速率D组>A组>B组>C组。对水体抗生素检测发现,两次检测都未能测出水体中硫酸新霉素的存在。对抗生素抗性基因检测发现硫酸新霉素对于aph(3′)-Ia、aph(3′)-Ⅱa、aac(6′)-Ⅰb、aac(3)-Ⅱ这四种基因具有较大的选择和富集的能力。但B组的各抗生素抗性基因的拷贝数均为最低。实验结束后对4个实验组的异养菌菌落数量进行检测,发现了B组的菌群群落数量相较其他3组有明显提升。比较结果表明硫酸新霉素在第一次加药时随着浓度提高,对氨氮转化速率的影响越大。但在第二次加药时,添加的硫酸新霉素浓度对氨氮转化速率无负面影响,而高浓度的硫酸新霉素可以促进生物絮团氨氮的转化,但会显著增加抗生素抗性基因的拷贝数。

In this experiment,the effects of different concentrations of neomycin sulfate on ammonia nitrogen and antibiotic resistance genes in biological flocs were investigated.Meanwhile,the water quality and floc indexes of biological flocs were tested.The content of antibiotic-resistance genes was tested.In terms of the rate of ammonia nitrogen conversion,continuous monitoring of initial dosing showed that no addition group(group A),0.5 mg/L neomycin sulfate group(group B),1 mg/L neomycin sulfate group(group C).The removal rates of ammonia nitrogen in the mg/L neomycin sulfate group(group D)were(3.88±0.02)mg TAN/(g TSS·h),(2.22±0.03)mg TAN/(g TSS·h),and(2.17±0.04)mg TAN/(g TSS·h),respectively.And(1.72±0.02)mg TAN/(g TSS·h),ammonia nitrogen removal rate group A>group B>group C>group D.The continuous monitoring of the second dosing with a drug withdrawal period showed that the ammonia nitrogen removal rates of the four groups were(2.99±0.08)mg TAN/(g TSS·h),(2.98±0.03)mg TAN/(g TSS·h),(2.97±0.08)mg,respectively.TAN/(g TSS·h)and(5.10±0.03)mg TAN/(g TSS·h),ammonia nitrogen removal rate group D>group A>group B>group C.Antibiotic testing of water bodies found that both tests failed to detect the presence of neomycin sulfate in water bodies.The detection of antibiotic resistance genes found that neomycin sulfate had a greater effect on the four genes aph(3′)-Ⅰa,aph(3′)-Ⅱa,aac(6′)-Ⅰb,aac(3)-Ⅱ.The ability to select and enrich.However,the copy number of each antibiotic resistance gene in group B added with a lower concentration of neomycin sulfate was the lowest.After the experiment,the number of heterotrophic bacterial colonies in the four experimental groups was detected.It was found that the number of bacterial colonies in group B was significantly increased compared with the other three groups.The comparison results showed that the effect of neomycin sulfate on the conversion rate of ammonia nitrogen was greater when the concentration of neomycin sulfate was increased for the first time.However,in the second dosing,the added concentration of neomycin sulfate had no negative effect on the conversion rate of ammonia nitrogen,and even a high concentration of neomycin sulfate could promote the conversion of ammonia nitrogen in biological flocs.However,it would significantly increase the rate of antibiotic resistance gene copy number.This study provides data support for the use of neomycin sulfate in bio flocs.