王 玥,白 淼,江海溶,張明露*,張 燦

氯/氯胺和紫外順序消毒對(duì)管網(wǎng)抗性基因的去除

王 玥1,白 淼1,江海溶1,張明露1*,張 燦2*

(1.北京工商大學(xué)生態(tài)環(huán)境學(xué)院,北京 100048；2.北京建筑大學(xué)環(huán)境與能源工程學(xué)院,北京 102616)

為探究供水系統(tǒng)中氯/氯胺與低壓紫外順序消毒對(duì)抗生素抗性基因(ARGs)分布特征的影響,采用生物膜反應(yīng)器模擬供水管網(wǎng),對(duì)管網(wǎng)出水和生物膜進(jìn)行60mJ/cm2低壓紫外線(254nm)消毒,并利用高通量定量PCR技術(shù)檢測(cè)模擬管網(wǎng)進(jìn)、出水及生物膜內(nèi)的典型ARGs和遺傳原件(MGEs).結(jié)果表明,管網(wǎng)反應(yīng)器運(yùn)行150d,氯和氯胺管網(wǎng)出水ARGs總相對(duì)豐度分別為0.13和0.137,生物膜ARGs分別為2.45和0.277,表明供水管網(wǎng)中低劑量的氯或氯胺可有效降低水相和生物膜相中ARGs的相對(duì)豐度達(dá)90%,且氯胺消毒對(duì)生物膜中的ARGs控制作用更顯著.氯和氯胺消毒后管網(wǎng)出水再經(jīng)低壓紫外線照射后,ARGs相對(duì)豐度分別為0.0682和0.0537,管網(wǎng)生物膜中ARGs的相對(duì)豐度分別為2.01和0.194. ARGs與MGEs間的相關(guān)性發(fā)生顯著變化,轉(zhuǎn)座子與和的相關(guān)性增強(qiáng),與和相關(guān)性減弱,而整合子與及的相關(guān)性增強(qiáng).研究表明,將紫外線消毒工藝設(shè)置在用水終端可以顯著降低氯和氯胺管網(wǎng)水中ARGs豐度,但對(duì)管網(wǎng)生物膜中的ARGs影響較小.

模擬管網(wǎng)；抗性基因；氯化消毒；低壓紫外；高通量定量PCR

20世紀(jì),抗生素的發(fā)現(xiàn)挽救了生命的同時(shí)也帶來(lái)了新型的污染物,抗生素抗性基因(ARGs)和抗性細(xì)菌(ARB),作為新型污染物會(huì)通過(guò)人類和牲畜的糞便投放到環(huán)境中,已成為公眾關(guān)注的焦點(diǎn)問(wèn)題[1-2].目前,ARGs在多種水環(huán)境中均有不同程度的檢出[3-4].研究表明,ARGs在飲用水中的污染程度現(xiàn)已日益加劇,飲用水供水系統(tǒng)很有可能已經(jīng)是ARGs的富集場(chǎng)所,迫切需要加強(qiáng)關(guān)于如何有效控制供水管網(wǎng)中ARGs的研究.

紫外線(UV)消毒對(duì)微生物具有廣譜消毒效果,消毒效率高,且不產(chǎn)生有毒有害副產(chǎn)物,但其沒(méi)有持續(xù)消毒效果,存在光復(fù)活、暗復(fù)活現(xiàn)象[5].研究表明,低劑量的紫外線消毒后,細(xì)菌可被重新激活,且其內(nèi)部基因依舊保留轉(zhuǎn)移能力,然而較高的紫外線消毒后,重新活化的細(xì)胞數(shù)量不僅減少且其轉(zhuǎn)移能力顯著降低[6-7].由于紫外線消毒直接作用于DNA,因此為去除ARGs提供極大可能.已有研究在實(shí)驗(yàn)室條件下采用低壓紫外對(duì)城市污水進(jìn)行消毒,發(fā)現(xiàn)當(dāng)紫外線劑量為5～10mJ/cm2時(shí),紅霉素和四環(huán)素類ARGs濃度大幅降低,甚至低于儀器檢出限[8].此外,飲用水水廠可以減少一定程度的ARGs,但殘留的ARGs仍可能通過(guò)水平基因轉(zhuǎn)移造成二次污染.當(dāng)前有關(guān)飲用水中抗性基因去除的研究并不多見(jiàn).

為探究不同消毒方式的供水管網(wǎng)系統(tǒng)中低壓紫外線消毒后ARGs的分布及其去除效果,本文以模擬管網(wǎng)反應(yīng)器內(nèi)的抗性基因?yàn)檠芯繉?duì)象,向管網(wǎng)中分別添加低濃度的氯和氯胺,采集管網(wǎng)進(jìn)、出水及生物膜進(jìn)行低壓紫外線(254nm)照射,并通過(guò)高通量定量PCR技術(shù)探究氯/氯胺和紫外線順序消毒對(duì)部分典型ARGs及MGEs的控制情況及去除機(jī)制,以期為終端水處理凈化工藝對(duì)氯和氯胺消毒管網(wǎng)水ARGs的傳播和控制提供理論依據(jù)和技術(shù)支持,保障飲水安全.

1 材料與方法

1.1 模擬給水管網(wǎng)系統(tǒng)

通過(guò)連續(xù)運(yùn)行生物膜反應(yīng)器(CDC)以模擬實(shí)際的供水管網(wǎng)系統(tǒng)[9-10].運(yùn)行過(guò)程中,利用磁力攪拌器的轉(zhuǎn)子帶動(dòng)隔板轉(zhuǎn)動(dòng),模擬實(shí)際管網(wǎng)內(nèi)的水利條件.采用聚碳酸酯材質(zhì)(PE)的掛片模擬給水管網(wǎng)管道,磁力攪拌器轉(zhuǎn)速控制在200～300r/min,水力停留時(shí)間為12h.進(jìn)水口為消氯后的實(shí)驗(yàn)室自來(lái)水(來(lái)自城市管網(wǎng)),余氯為0.4～0.6mg/L,濁度為0.62～0.72NTU, TOC為2.28～2.42mg/L, pH值為7.4～7.8.投藥進(jìn)樣口分別采用40mg/L的次氯酸鈉和氯胺溶液連續(xù)進(jìn)樣,通過(guò)調(diào)整投藥進(jìn)樣泵的轉(zhuǎn)速以保證反應(yīng)器內(nèi)部總氯濃度始終為0.5mg/L,并每天檢測(cè)進(jìn)水口及出水口的總氯及余氯變化.穩(wěn)定運(yùn)行后,每隔30d采集水樣測(cè)定,共運(yùn)行150d.實(shí)驗(yàn)共運(yùn)行6臺(tái)反應(yīng)器,1、2、3號(hào)反應(yīng)器通過(guò)蠕動(dòng)泵連續(xù)添加次氯酸鈉溶液,4、5、6號(hào)反應(yīng)器連續(xù)添加氯胺溶液.

1.2 各相樣品的收集

水相樣品:通過(guò)蠕動(dòng)泵對(duì)水樣進(jìn)行富集,將微生物過(guò)濾至孔徑為0.22μm、直徑為90mm的濾膜上,在超凈臺(tái)中用刮刀刮取20L水樣過(guò)濾所得濾膜上的微生物菌群,共吸取12mL無(wú)菌PBS溶液對(duì)刮刀和濾膜表面的菌群進(jìn)行洗脫,得到水相樣品.

生物膜相樣品:取CDC反應(yīng)器的5個(gè)掛片置于50mL無(wú)菌離心管中,加入12mL PBS溶液,震蕩2min,再用超聲儀進(jìn)行脫附,重復(fù)3遍.

1.3 目的基因的確定和高通量定量PCR(HT- qPCR)

選取了環(huán)境中常見(jiàn)的53種抗生素抗性基因進(jìn)行高通量定量PCR檢測(cè),同時(shí)選取16S rRNA通用引物對(duì)抗性基因的濃度進(jìn)行相對(duì)定量.

目的基因的確定和高通量定量PCR(HT-qPCR) HT-qPCR檢測(cè)采用StepOnePlus?實(shí)時(shí)熒光定量PCR(Thermo),試劑盒為:TB Green? Premix Ex Taq? II (Tli RNaseH Plus)(Takara, Code No. RR820A).模板稀釋倍數(shù)為4倍.qPCR反應(yīng)條件:95℃預(yù)變性30s, 95℃變性5s,60℃退火延伸30s,共40個(gè)循環(huán).CT檢測(cè)限為40個(gè)循環(huán).

1.4 低壓紫外線照射實(shí)驗(yàn)

采用紫外平行光束儀進(jìn)行紫外照射,測(cè)試所用紫外燈功率為30W、254nm的低壓汞燈,待光源穩(wěn)定工作后用UV-B型紫外輻照計(jì)檢測(cè)培養(yǎng)皿表面中心的紫外線強(qiáng)度.

將樣品放置于遮光筒正下方,使用石英培養(yǎng)皿作為容器,用磁力攪拌器持續(xù)攪拌樣品以保證均勻照射.設(shè)定紫外強(qiáng)度為60mJ/cm2,在紫外實(shí)驗(yàn)前需將處理后的樣品通過(guò)紫外可見(jiàn)分光光度計(jì)測(cè)定吸光度,根據(jù)吸光度將樣品稀釋至3倍以排除樣品內(nèi)部顆粒物等造成的遮擋干擾,并依次分兩批取18mL水樣注入培養(yǎng)皿中,根據(jù)國(guó)際紫外線協(xié)會(huì)數(shù)據(jù)進(jìn)行紫外照射[11].

1.5 數(shù)據(jù)處理

使用Microsoft Excel 2010進(jìn)行數(shù)據(jù)分析,使用SPSS軟件(PASW Statistics 20.0)進(jìn)行統(tǒng)計(jì)分析.使用Canoco 5.0版軟件用于主成分分析(PCA)和冗余分析(RDA),以觀察樣品的分布特征及相關(guān)性.

2 結(jié)果與討論

2.1 模擬管網(wǎng)中ARGs的分布特征

2.1.1 模擬管網(wǎng)中抗性基因檢出數(shù)量 水相和生物膜相中共檢出39種ARGs(表1).結(jié)果顯示紫外線照射后,ARGs的數(shù)量及類型分布無(wú)明顯變化.

表1 模擬管網(wǎng)中抗性基因檢出數(shù)量

2.1.2 模擬管網(wǎng)水相中抗性基因豐度變化 由圖1可知,未經(jīng)紫外線照射的進(jìn)水中ARGs的相對(duì)豐度高于兩組管網(wǎng)出水,而經(jīng)紫外線照射后的進(jìn)水中部分ARGs的相對(duì)豐度升高,其中Beta Lactamase、FCA和MLSB類最為顯著,其相對(duì)豐度變化分別從0.671、0.0202、0.128升至1.62、0.0637、0.218. 其中,Beta Lactamase類在進(jìn)水中占比最大(占43%).未經(jīng)紫外線照射的管網(wǎng)出水中,ARGs類型分布區(qū)別較大,總豐度分別為0.13和0.137,但氯消毒后的管網(wǎng)出水以Beta Lactamase(9.67′10-2)為主,而氯胺消毒后的管網(wǎng)出水中ARGs分布比較均勻,以Aminoglycoside (2.88′10-2)、Beta Lactamase(9.80′10-3)、other/efflux (2.87′10-2)、Sulfonamide (1.96′10-2)和MGEs(3.43′10-2)類為主.

研究表明,Beta Lactamase類ARGs在管網(wǎng)水中占有較高比例,在環(huán)境中廣泛存在,且Beta Lactamase類對(duì)幾種抗菌藥賦予了耐藥性[12-13].而兩組管網(wǎng)出水中ARGs種類的不同可能與管網(wǎng)生物膜脫落有關(guān)[14],研究表明生物膜可以通過(guò)調(diào)節(jié)其內(nèi)部的微生物群落來(lái)適應(yīng)不同種類的消毒劑[15],而成熟的生物膜在落入水體后可增加自來(lái)水中抗性菌的濃度,導(dǎo)致出水中ARGs含量升高,但微生物群落同樣影響了ARGs種類[16-18],這使得氯和氯胺消毒的管網(wǎng)出水中基因種類具有較大的差異性.紫外線照射后,兩組管網(wǎng)出水中ARGs豐度均呈現(xiàn)顯著降低,該現(xiàn)象在氯胺消毒后的管網(wǎng)水中尤為明顯,但其中Beta Lactamase及FCA類在紫外線照射后相對(duì)豐度出現(xiàn)不同程度上升,分別從9.80′10-3、9.01′10-4升至4.17′10-2、1.95′10-3.

圖1 模擬管網(wǎng)水相中抗性基因的相對(duì)豐度

圖2 模擬管網(wǎng)生物膜中抗性基因的相對(duì)豐度

2.1.3 模擬管網(wǎng)生物膜中抗性基因豐度變化 在供水系統(tǒng)中投加氯/氯胺有助于去除水中部分ARGs,且與紫外順序消毒可促進(jìn)ARGs含量進(jìn)一步降低,但紫外線消毒在單獨(dú)應(yīng)用時(shí)效果微弱.氯胺與紫外順序消毒使用時(shí)對(duì)ARGs的控制作用優(yōu)于氯與紫外順序消毒.由圖2可知,氯和氯胺生物膜中的ARGs總豐度分別為2.45和0.277.生物膜內(nèi)的ARGs豐度高于水相,這是由于生物膜形成的微環(huán)境會(huì)使得其內(nèi)部活躍或休眠狀態(tài)的細(xì)胞可以在不利的化學(xué)條件下觸發(fā)應(yīng)激反應(yīng)[19],成熟的生物膜會(huì)導(dǎo)致表型異質(zhì)性,可在壓力最大的生物膜區(qū)域形成持久性細(xì)胞以及存活但不可培養(yǎng)的(VBNC)細(xì)胞[20],因此,生物膜中發(fā)現(xiàn)的細(xì)菌通常比浮游細(xì)菌具有更強(qiáng)的抗生素抗性[21].與氯消毒相比,氯胺消毒管網(wǎng)生物膜中的ARGs豐度顯著降低,這是由于氯胺可以更好地穿透生物膜,但這不一定立即導(dǎo)致細(xì)胞的失活,而氯消毒雖然穿透速度較慢,但其更有效地滅活了生物膜表面的微生物,從而更易導(dǎo)致細(xì)胞失活(釋放)[22-23].

未經(jīng)紫外線照射的樣品中,氯消毒管網(wǎng)生物膜內(nèi)的ARGs豐度遠(yuǎn)高于氯胺消毒,可見(jiàn)氯胺消毒不易于生物膜內(nèi)ARGs的傳播和擴(kuò)散.與水相結(jié)果相比,生物膜相內(nèi)的ARGs在紫外線照射后豐度均呈下降趨勢(shì).紫外線照射后,兩組生物膜的Beta Lactamase類雖有不同程度下降,但在各樣品中依舊占有較高比例.

2.1.4 模擬管網(wǎng)多相界面下抗性基因主成分分析 如圖3所示,圖中前兩個(gè)PC解釋了總計(jì)84.56%的偏差,其中PC1解釋了69.44%的偏差,PC2解釋了15.12%的偏差.由圖可知,紫外線消毒前,樣品點(diǎn)分布較散,表明樣品間ARGs的相對(duì)豐度具有顯著差異性.紫外線消毒后,樣品內(nèi)ARGs的相對(duì)豐度均發(fā)生明顯變化,其中水相的進(jìn)水和氯胺消毒出水變化最為顯著,氯消毒出水變化程度較小.生物膜相的變化幅度較小,可見(jiàn)紫外線消毒對(duì)水體的影響強(qiáng)于生物膜.

2.2 紫外線照射對(duì)抗性基因的影響

2.2.1 紫外線照射對(duì)抗性基因的削減作用 未經(jīng)紫外線照射的樣品中,水相中氯消毒對(duì)ARGs的去除率范圍為0.64log(FCA)～1.69log(MGEs),氯胺消毒對(duì)ARGs的去除率范圍為0.47log(Tetracycline)～ 1.84log(Beta Lactamase),其中氯對(duì)Aminoglycoside、MLSB、other/efflux、Sulfonamide、Tetracycline和MGEs類的去除率明顯高于氯胺消毒.但氯胺對(duì)于Beta Lactamase和FCA類抗性基因的去除效果強(qiáng)于氯消毒,且這兩類ARGs在紫外線照射后去除率并沒(méi)有增加,表明氯胺對(duì)Beta Lactamase和FCA類ARGs本身具有較強(qiáng)的去除能力.氯和紫外順序消毒對(duì)ARGs的去除率范圍變?yōu)?.94log (Vancomycin)～ 2.24log(MGEs),氯胺和紫外順序消毒對(duì)ARGs的去除率范圍變?yōu)?.92log (Tetracycline)～2.09log (Aminoglycoside),兩組管網(wǎng)出水中基因的去除效果發(fā)生明顯改變.氯胺和紫外順序消毒對(duì)Aminoglycoside、MLSB、other/efflux和Vancomycin類ARGs的去除效果優(yōu)于氯和紫外順序消毒.

圖3 模擬管網(wǎng)多相界面下抗性基因相對(duì)豐度的主成分分析(PCA)

生物膜相中氯和紫外順序消毒對(duì)ARGs的去除率范圍為0.04log (Beta Lactamase)～1.39log (Sulfonamide),氯胺和紫外順序消毒對(duì)ARGs的去除率范圍為0.04log(MGEs)～0.36log (Aminoglycoside、other/efflux);氯和紫外順序消毒對(duì)FCA、MLSB、Sulfonamide、Tetracycline、Vancomycin和MGEs類的去除效果強(qiáng)于氯胺和紫外順序消毒,在Sulfonamide類的去除效果上尤為顯著.

研究發(fā)現(xiàn),氯胺與氯消毒相比無(wú)法有效地控制供水系統(tǒng)中ARGs的豐度[24].而Hu認(rèn)為紫外線消毒能夠有效降低嗜鹽菌的豐度[25],這可能正是氯胺和紫外順序消毒后ARGs出現(xiàn)大幅降低的原因.紫外線消毒通常被認(rèn)為是削減ARGs極為有效的一種方法,但一些細(xì)菌由于細(xì)胞壁結(jié)構(gòu)或細(xì)胞外聚合物(EPS)的保護(hù)而具有抗紫外線輻射的能力[26],因此紫外線照射對(duì)水體ARGs的削減效果優(yōu)于生物膜.

圖4 紫外線照射后水相和生物膜抗性基因亞型的倍數(shù)變化

表2是水相和生物膜相中的ARGs亞型在消毒劑、紫外線照射及二者順序消毒后削減的log值.水相結(jié)果顯示,對(duì)于氯胺和紫外順序消毒,水中內(nèi)部整合子和的去除率較高,而的去除率也均略高于氯和紫外順序消毒.所以經(jīng)過(guò)紫外線照射后,氯胺消毒管網(wǎng)出水中ARGs削減的程度高于氯消毒管網(wǎng)出水.圖5(a)的相關(guān)性證實(shí)這幾類抗性基因亞型與整合子有著不同程度的正相關(guān)性.有研究認(rèn)為,部分ARGs()的減少主要是由于的減少[27-29].MGEs和細(xì)菌群落是影響ARGs變化的兩個(gè)關(guān)鍵因素,而Ren的研究顯示,紫外線消毒過(guò)程中,二者的影響效果基本相同[30].

2.2.2 紫外線照射對(duì)抗性基因亞型的富集作用 如圖4所示,模擬管網(wǎng)的水相及生物膜相樣品中共檢測(cè)出ARGs亞型41個(gè)(包括MGEs).紫外線照射后,氯胺消毒管網(wǎng)出水中有18個(gè)ARGs發(fā)生富集,但9個(gè)ARGs的倍數(shù)變化(FC值)大于2,其中bla、和的富集倍數(shù)最大分別為4.25、4.08和4.00;氯消毒管網(wǎng)出水中僅有4個(gè)ARGs發(fā)生富集,且FC值均小于2,其中的FC值最大為1.79;氯和氯胺消毒生物膜中分別有3、7個(gè)ARGs產(chǎn)生富集,富集程度最大的分別是、, FC值是1.89和2.16.有研究認(rèn)為,紫外線消毒可通過(guò)RND外排系統(tǒng)的耐藥機(jī)制增強(qiáng)部分ARGs的豐度,如鄒爽等報(bào)道紫外線消毒富集了多個(gè)屬于該外排系統(tǒng)的基因[31].

2.2.3 抗性基因亞型相對(duì)豐度顯著性分析 以未經(jīng)紫外線照射的樣品結(jié)果為對(duì)照組,計(jì)算紫外線照射后ARGs亞型的P值(p-value).模擬管網(wǎng)水相和生物膜相的結(jié)果分別如表3和表4所示.紫外線照射后,水相中有11種ARGs亞型在氯和氯胺消毒管網(wǎng)出水中出現(xiàn)顯著差異,但氯胺消毒管網(wǎng)出水中的差異更為顯著,且、、、、僅在氯胺消毒管網(wǎng)出水中具有顯著差異;生物膜相中的ARGs亞型在氯消毒后具有較強(qiáng)的差異性,而在氯胺消毒后的生物膜中差異性較小,且通過(guò)與水相結(jié)果的對(duì)比,可發(fā)現(xiàn)紫外線照射對(duì)生物膜內(nèi)的ARGs影響較弱.

表2 水相和生物膜相中抗性基因亞型的去除率

表3 紫外線照射后水相中抗性基因亞型的P值

注:*表示值<0.05,代表有顯著差異;**表示值<0.01,代表有極顯著差異.

表4 紫外線照射后生物膜相中抗性基因亞型的P值

注:*表示值<0.05,代表有顯著差異;**表示值<0.01,代表有極顯著差異.

2.2.4 抗性基因與移動(dòng)原件的相關(guān)性分析 如圖5(a)所示,該部分ARGs選取自2.2.3中具有顯著差異的基因;其中,整合子包括,、;轉(zhuǎn)座子包括,、、、、、.圖5(a)中,前兩個(gè)軸分別解釋了98.75%和1.19%.可以觀察到,、、與整合子具有顯著正相關(guān)性;、、、bla、、、、、及與轉(zhuǎn)座子具有顯著正相關(guān);、、、、分別與整合子及轉(zhuǎn)座子具有正相關(guān)性,這與紫外線照射前后抗性基因相對(duì)豐度變化相一致.在Yan[32]的研究中同樣發(fā)現(xiàn)與和具有顯著正相關(guān)性,這可能是由于在1類整合子的3'-保守區(qū)段(CS)區(qū)域中起部分結(jié)構(gòu)的作用[33].

由圖5(b)可以觀察到,前兩個(gè)軸分別解釋了98.57%和1.00%,與未經(jīng)紫外線照射的結(jié)果具有明顯差異,ARGs亞型均與整合子及轉(zhuǎn)座子具有正相關(guān)性.與整合子、與轉(zhuǎn)座子分別具有顯著的正相關(guān)性,與未經(jīng)紫外線照射的結(jié)果相似;但、與整合子的相關(guān)性減弱,與轉(zhuǎn)座子的相關(guān)性增強(qiáng);、bla及與轉(zhuǎn)座子的相關(guān)性均出現(xiàn)不同程度的減弱,其中相關(guān)性削減的最嚴(yán)重,且同時(shí)發(fā)現(xiàn)及與整合子的相關(guān)性增強(qiáng).由于紫外線對(duì)基因產(chǎn)生的破壞導(dǎo)致紫外線照射后ARGs與MGEs之間的關(guān)系發(fā)生變化[34].在Habimana等[35]的研究中,通過(guò)DNA凝膠電泳證實(shí)氯消毒劑和紫外順序消毒不僅可以對(duì)ARGs ()造成損傷,且其損傷程度均大于消毒劑和紫外線單獨(dú)作用.

3 結(jié)論

3.1 添加低劑量的氯或氯胺消毒劑可以有效降低模擬管網(wǎng)水相和生物膜相中ARGs的相對(duì)豐度,且氯胺消毒對(duì)生物膜中的ARGs具有更好的控制作用,可降低90%以上.

3.2 氯或氯胺和60mJ/cm2低壓紫外線順序消毒可提高ARGs的去除率,其中,氯胺和紫外順序消毒對(duì)水相中ARGs的去除效果優(yōu)于氯和紫外線順序消毒,但均對(duì)生物膜中ARGs的影響較小.此外,紫外線與氯胺的順序消毒作用也能導(dǎo)致部分ARGs富集,如bla、和等.

3.3 通過(guò)RDA相關(guān)性分析,紫外線照射后,ARGs與MGEs間的相關(guān)性發(fā)生顯著變化,其中,轉(zhuǎn)座子與和的相關(guān)性增強(qiáng),與和相關(guān)性減弱,而整合子與及的相關(guān)性增強(qiáng).

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Research on removal of antibiotic resistance genes in pipe networks by chlorine/chloramine and UV sequential disinfection.

WANG Yue1, BAI Miao1, JIANG Hai-rong1, ZHANG Ming-lu1*, ZHANG Can2*

(1. School of Ecology and Environment, Beijing Technology and Business University, Beijing 100048, China；2.School of Environmental and Energy Engineering, Beijing University of Architecture and Technology, Beijing 102616, China)., 2022,42(5)：2136～2143

In order to explore the influence of chlorine/chloramine and low-pressure ultraviolet sequential disinfection on the distribution characteristics of antibiotic resistance genes (ARGs) in the water supply system, a biofilm reactor was used to simulate the water supply network. The effluent and biofilm of the pipe network were taken for 60mJ/cm2low-pressure ultraviolet (254nm) disinfection, and high-throughput quantitative PCR was used to detect the number of typical ARGs and mobile genetic elements (MGEs) in the inlet, outlet, and biofilm of the simulated pipe network. After 150days, the total relative abundance of ARGs in the effluent of chlorine and chloramine pipe network were 0.130 and 0.137, and the abundance of biofilm were 2.45 and 0.277, respectively. This indicated that low dose of chlorine or chloramine in the water supply pipe network could effectively reduce the relative abundance of ARGs in the water phase and biofilm phase by 90%, and chloramine disinfection has a more significant control effect on ARGs in biofilms. After UV disinfection, the relative abundances of ARGs in chlorine and chloramine disinfected pipe network water were 0.0682 and 0.0537, respectively. The relative abundances of ARGs in biofilms after chlorine and chloramine disinfection were 2.01 and 0.194, respectively. The correlation between ARGs and MGEs changed significantly. The correlation between the transposon andwas enhanced, and the correlation withandwas weakened, while the correlation between the integron and,-01,and-01 was enhanced. The results showed that the ultraviolet disinfection can significantly reduce the abundance of ARGs in the chlorine and chloramine disinfected pipe network water, but it had less effect on the ARGs in the pipe network biofilms.

simulated water distribution system；antibiotic resistance genes；chlorination；low-pressure UV；high-throughput quantitative PCR

X703.5

A

1000-6923(2022)05-2136-08

王 玥(1996-),男,北京人,北京工商大學(xué)研究生,主要從事環(huán)境微生物方面的研究.

2021-10-20

國(guó)家自然科學(xué)基金資助項(xiàng)目(51408010,52070193);北京市自然科學(xué)基金資助項(xiàng)目(8192053)

* 責(zé)任作者, 張明露, 教授, zhangminglu@th.btbu.edu.cn; 張燦, 副研究員,zhangcancqu@163.com