太空生存太空生存太空生存 (4).pdf
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1、Contents lists available at ScienceDirectBioresource Technologyjournal homepage: analysis of microbial fuel cell based biosensors developed witha mixed culture and Shewanella loihica PV-4 and underlying biologicalmechanismYue Yia,b,Beizhen Xiea,b,Ting Zhaoa,b,Hong Liua,baInstitute of Environmental B
2、iology and Life Support Technology,School of Biological Science and Medical Engineering,Beihang University,Beijing 100191,ChinabInternational Joint Research Center of Aerospace Biotechnology&Medical Engineering,Beihang University,Beijing 100191,ChinaG R A P H I C A L A B S T R A C TA R T I C L E I N
3、 F OKeywords:Microbial fuel cellBiosensorBODBiotoxicityInoculumA B S T R A C TMicrobial fuel cell based biosensors(MFC-biosensors)utilize anode biofilms as biological recognition elementsto monitor biochemical oxygen demand(BOD)and biotoxicity.However,the relatively poor sensitivity con-strains the
4、application of MFC-biosensors.To address this limitation,this study provided a systematic com-parison of sensitivity between the MFC-biosensors constructed with two inocula.Higher biomass density andviability were both observed in the anode biofilm of the mixed culture MFC,which resulted in better s
5、ensitivityfor BOD assessment.Compared with using mixed culture as inoculum,the anode biofilm developed withShewanella loihica PV-4 presented lower content of extracellular polymeric substances and poorer ability tosecrete protein under toxic shocks.Moreover,the looser structure in the S.loihica PV-4
6、 biofilm further facilitatedits susceptibilities to toxic agents.Therefore,the MFC-biosensor with a pure culture of S.loihica PV-4 deliveredhigher sensitivity for biotoxicity monitoring.This study proposed a new perspective to enhance sensor perfor-mance.1.IntroductionWater quality monitoring is par
7、amount for the guarantee of ecolo-gical safety and public health.Available monitoring items mostly focuson physical and chemical indicators such as pH and chemical oxygendemand.Only a few biochemical indexes represented by biologicaloxygen demand(BOD)are included(SEPA,2002).Among these para-meters,p
8、hysicalandchemicalindicatorsenabletheaccuratehttps:/doi.org/10.1016/j.biortech.2018.06.037Received 10 April 2018;Received in revised form 10 June 2018;Accepted 12 June 2018Corresponding author at:School of Biological Science and Medical Engineering,Beihang University,37 Xueyuan RD,Haidian DIST,Beiji
9、ng 100191,China.E-mail address:(B.Xie).Bioresource Technology 265(2018)415421Available online 13 June 20180960-8524/2018 Elsevier Ltd.All rights reserved.Tdetermination of the concentration of specific substance in aquaticenvironment,but the detection process requires skilled and time-con-suming ope
10、ration.Moreover,these indicators fail to provide a com-prehensive assessment of biotoxicity and cumulative toxicity,whichmakes these methods unsuitable for in situ and online monitoring.BODindex,which relates to the biodegradability of water,is evaluated bythe consumption of dissolved oxygen after i
11、ncubation for a fixed period(usually 5d)(APHA,1998).However,tediously long detection periodof BOD measurement disagrees with the demand of prompt alert andleads to the deficiency of fast-response detection method.Therefore,research on novel technology and equipment for timely and efficientwater qual
12、ity monitoring is of crucial importance.Microbial fuel cells(MFCs)are devices which convert chemicalenergy from organic matters into electricity with the catalysis of elec-troactive microorganisms(Logan,2009).Previous studies have vali-dated the feasibility to use MFC based biosensor(MFC-biosensor)t
13、omonitor BOD concentration and biotoxicity in water environment(Kimet al.,2003;Kim et al.,2007;Modin and Wiln,2012).Kim et al.(2003)developed a dual-chamber MFC for BOD quantification and observed agood linear relationship between Coulombic yield and BOD con-centration.Thereafter extensive efforts h
14、ave been made to improvesensor performance from the aspects of configuration design and op-eration parameter.For instance,scaling down the anode volume from25 mL to 5mL and the optimization of fuel-feeding rate could reducethe response time of BOD test to 36min(Moon et al.,2004),whileanother study m
15、anaged to extend the linear range to 1280mg/L byapplying an external voltage to MFC-biosensor(Modin and Wiln,2012).Research on the assessment of biotoxicity via MFC-biosensorstarted later than BOD sensor.The first MFC based toxicity sensor wasreported by Kim et al.(2007).They installed it in a waste
16、water treat-ment plant and successfully alerted the shocks of several heavy metalsand polychlorinated biphenyl.Since then,significant progress has beenmade to enhance the sensitivity and stability of detection process(Shenet al.,2013;Lorenzo et al.,2014;Jiang et al.,2015;Xu et al.,2015).Anode biofil
17、m is considered as the main sensing element for bothBOD concentration and biotoxicity monitoring.Fluctuations in waterquality would affect the metabolic activities and electron transfer pro-cesses of electroactive microorganisms and further lead to visiblechanges of output current or voltage(Jiang e
18、t al.,2018).Hence,elec-troactive biofilm colonized on the anode surface is a key factor to sensorperformance.MFC-biosensors in most of researches were constructedwith mixed cultures(Liu et al.,2014;Lorenzo et al.,2014;Wu et al.,2014;Xu et al.,2015;Yu et al.,2017).Only a few publications con-cerned a
19、bout the application of pure strain as sensing element.In arecent study,Atci et al.(2016)developed a MFC-biosensor with a pureculture of Geobacter sulfurreducens and observed a good linear correla-tion between current signal and acetate concentration.As for biotoxi-city sensor,a pure culture of Shew
20、anella oneidensis MR-1 was employedfor the first time to detect formaldehyde(Wang et al.,2013).However,the influence of the two types of inocula on the performance of MFC-biosensors has not been revealed yet.When studying the temporal-spatial changes of biofilms in microbialelectrolysis cells,Sun et
21、 al.(2015)reported that various inocula(mixedculture and Geobacter anodireducens)would result in discrepancies inbiofilm structure,viability and biomass density and further affectedelectricity generation directly.Since electricity generation was an im-portant factor for BOD quantification via MFC-bi
22、osensor(Modin andWiln,2012),different inocula might impact the sensor performancefor BOD determination.On the other hand,the contents of extracellularpolymeric substances(EPS)in biofilms might vary with different in-ocula as well.Due to the protective effect of EPS against toxic agentinvasion(Miao e
23、t al.,2017),various inocula might also influence thesensitivity of MFC-biosensor for biotoxicity monitoring.Therefore,this study aimed to investigate the effect of inoculum onthe sensitivity of MFC-biosensor,which has not been revealed yet andmight propose a new perspective to enhance the sensor per
24、formance.Shewanella loihica PV-4,which was a widely applicable strain of elec-troactive microorganisms with the superior capacity of extracellularelectron transport(Kim et al.,1999;Newton et al.,2009),was selectedto represent the pure culture inoculum and to develop pure cultureMFC-biosensors.Meanwh
25、ile,the effluent taken from a stably operatingMFC based on mixed culture was utilized to construct traditional mixedculture MFC-biosensors.Herein,a systematic analysis of the effect ofinoculum on sensor sensitivity was provided by employing the twotypes of MFC-biosensors for both BOD and biotoxicity
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