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1、Effect of external resistance on the sensitivity of microbial fuel cellbiosensor for detection of different types of pollutantsYue Yia,b,Beizhen Xiea,b,Ting Zhaoa,b,Zhaoming Lia,b,Devard Stomc,Hong Liua,baInstitute of Environmental Biology and Life Support Technology,School of Biological Science and
2、 Medical Engineering,Beihang University,Beijing 100191,ChinabInternational Joint Research Center of Aerospace Biotechnology&Medical Engineering,Beihang University,Beijing 100191,ChinacInstitute of Biology,Irkutsk State University,Irkutsk 664025,Russiaa b s t r a c ta r t i c l ei n f oArticle histor
3、y:Received 18 May 2018Received in revised form 5 September 2018Accepted 6 September 2018Available online 17 September 2018The relatively poor sensitivity is the main bottleneck restricting the application of microbial fuel cell biosensor(MFC-biosensor)for toxicity monitoring.Previous studies have sh
4、own that external resistance(Rext)had an ob-viouseffectonsensorsensitivity.However,thesestudiesreporteddifferentresultsandthereasonofthisdiscrep-ancy was not clear.The objective of this research was to observe the effect of Rexton sensor sensitivity whendetecting different types of pollutants and re
5、veal its microbiological mechanism.Results demonstrated thatthe optimal Rextof MFC-biosensor varied with the type of pollutants.The optimal values for detectingavermectins,tetracyclines and heavy metals were 100,330 and 680,respectively.This discrepancy wasmainly due to the visible differences in an
6、odic microbial communities at different Rextsettings.Both Azospirillumand Acinetobacter were susceptible to Cd and Pb,occuping 19.20%of the anodic microbial population in 680 MFC-biosensor.Pseudomonas accounted for 10.73%in 330 MFC-biosensor and possessed the sensitivity totetracyclines.As for 100 M
7、FC-biosensor,the avermectin-intolerant Ocillibacter made up 2.55%of the anodicmicrobial community.This study indicated that the Rextof MFC-biosensor should be optimized according tothe potential pollutants.2018 Elsevier B.V.All rights reserved.Keywords:Microbial fuel cellBiosensorHeavy metalAntibiot
8、icExternal resistanceMicrobial community1.IntroductionWater supply safety is critical for urban construction and social sta-bility.With the continuous development of global industrialization,the type and quantity of toxic pollutants in aquatic environment are in-creasing annually.Reliable methods of
9、 water quality monitoring are in-dispensable for the guarantee of water supply safety.Physicochemicalmethods,which are broadly applied in conventional monitoring ofwater quality,are highly sensitive and accurate.However,thesemethods are inadequate to detect unconventional pollutants and failto provi
10、de a timely warning of water pollution.Moreover,thesemethodscannotgiveanindicationofbiologicaltoxicity.Genericbiosen-sors can compensate for the deficiencies of physicochemical methods.Fish,algae,invertebrates and bacteria are suggested as common indica-tor organisms 1.Amongvarious types of biosenso
11、rs,microbialfuel cellbiosensors(MFC-biosensors)have attracted growing interest in thearea of water quality alert in the last decade.Compared with other bio-sensors,MFC-biosensor can be self-sustainable without the require-ments of additional signal transducer devices and special chemicals,which make
12、s it a promising application in water quality monitoring2,3.MFC is a device which utilizes electricigens as catalysts and simulta-neously converts chemical energy from organic matter into electricity4.Presence of toxic agents can inhibit the activity of electricigens,and further leads to a decay in
13、output signal.Hence water quality canbe monitoredin real-timebymeasuringthechange of MFC outputvolt-age.The first biomonitoring system using MFC was reported by Kimet al.5.They installed the system at the inlet of a wastewater treat-ment plant and found that toxic substances including Pb2+and Cd2+co
14、uld inhibit MFC current,demonstrating the feasibility of monitoringbiotoxicitybyMFC.Sincethen,aseriesofconstructionalandoperationalparameters including external resistance(Rext)6,configuration 7,electrode material 8,contact time 9,shear rate 10 and flow mode11 were optimized to enhance sensor sensit
15、ivity.Among these parameters,Rextis considered to be an important fac-tor which directly impacts the power generation of MFC-biosensorand further affects sensor sensitivity 12,13.An early study reportedthat increasing Rextsettings(100,470,1000)had an adverse ef-fect on the sensitivity of MFC-biosens
16、or for detecting sodium dodecylsulfate 6.When monitoring a heavy metal shock induced by Cu2+,Jiang et al.11 observed that the sensitivity increased firstly,and thenreduced with the decrease of Rextfrom 3000 to 50.Another studyBioelectrochemistry 125(2019)7178 Corresponding author.E-mail address:(B.X
17、ie).https:/doi.org/10.1016/j.bioelechem.2018.09.0031567-5394/2018 Elsevier B.V.All rights reserved.Contents lists available at ScienceDirectBioelectrochemistryjournal homepage: by Yi et al.14 revealed that MFC-biosensor designed fortesting Cd2+obtained the highest sensitivity when Rextwas equal to50
18、0,andhigherorlowerRextsettingswouldbothdeterioratethesen-sitivity.Interestingly,these studies reported inconsistent effects of Rexton sensor sensitivity when monitoring different types of pollutants.This phenomenon suggested that the optimal Rextmight vary with thetype of pollutants but a comparison
19、 about the optimal Rextfor organicand inorganic pollutants has not been revealed yet.Besides,theinfluencing mechanism of Rextwas not clear.It was found in all the pre-viousstudiesthatRexthadsimilareffectsonMFCpowergeneration.Thiscould not explain the different effects of Rexton sensor sensitivity wh
20、endetecting various pollutants.Therefore,the mechanism needed to befurther studied.From the microbiological perspective,Rexthad a significant effect onanodic community structure 15,16.The species and distribution ofelectricigens had obvious differences under different Rextvalues17,18.Considering the
21、 discrepancies in microbial resistance to differ-ent types of toxic pollutants,it could be deduced that the optimal Rextmight vary with the type of pollutants.That is to say,Rextcould impactthemicrobialcommunitystructureofMFC-biosensorandfurtheraffectsits sensitivity.In this research,our objective w
22、as to investigate the effect of Rextonsensor sensitivity when detecting different types of pollutants and re-veal its microbiological mechanism.For this purpose,MFC-biosensorsloaded with different Rextvalues were constructed.After steady-operation,toxic pollutant tests were performed to study the re
23、lation-ship between optimal Rextand pollutant type.Three types of pollutants,including heavy metals,tetracyclines and avermectins,were tested andeach type was represented by two pollutants.Then,two types of com-bined contaminations represented by the binary metal mixture andmetal-tetracycline compos
24、ite pollutant were examined to assess thechange of optimal Rextinduced by combined contamination.Finally,high-throughput sequencing technology was employed to investigatetheanodicmicrobialcommunitiesestablishedunderoptimalRextvaluesfor different pollutants and the changes of community structures tot
25、oxic shocks.2.Materials and methods2.1.Chemicals and reagentsAnalytical reagents 3CdSO48H2O and PbCl2were purchased fromBeijing Lanyi Chemical Products Co.,Ltd.,China.Chlortetracycline hy-drochloride(CTC)and oxytetracycline hydrochloride(OTC)were ac-quired from Dalian Ronghai Biological Technology C
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