PMID- 32454336
OWN - NLM
STAT- MEDLINE
DCOM- 20200618
LR  - 20200618
IS  - 1879-1026 (Electronic)
IS  - 0048-9697 (Linking)
VI  - 734
DP  - 2020 Sep 10
TI  - Changes in syntrophic microbial communities, EPS matrix, and gene-expression 
      patterns in biofilm anode in response to silver nanoparticles exposure.
PG  - 139395
LID - S0048-9697(20)32912-0 [pii]
LID - 10.1016/j.scitotenv.2020.139395 [doi]
AB  - Understanding the toxic effect of silver nanoparticles (AgNPs) on various 
      biological wastewater treatment systems is of significant interest to 
      researchers. In recent years, microbial electrochemical technologies have opened 
      up new opportunities for bioenergy and chemicals production from organic 
      wastewater. However, the effects of AgNPs on microbial electrochemical systems 
      are yet to be understood fully. Notably, no studies have investigated the impact 
      of AgNPs on a microbial electrochemical system fed with a complex fermentable 
      substrate. Here, we investigated the impact of AgNPs (50 mg/L) exposure to a 
      biofilm anode in a microbial electrolysis cell (MEC) fed with glucose. The 
      volumetric current density was 29 +/- 2.0 A/m(3) before the AgNPs exposure, which 
      decreased to 20 +/- 2.2 A/m(3) after AgNPs exposure. The biofilms produced more 
      extracellular polymeric substances (EPS) to cope with the AgNPs exposure, while 
      carbohydrate to protein ratio in EPS considerably increased from 0.4 to 0.7. 
      Scanning electron microscope (SEM) imaging also confirmed the marked excretion of 
      EPS, forming a thick layer covering the anode biofilms after AgNPs injection. 
      Transmission electron microscope (TEM) imaging showed that AgNPs still penetrated 
      some microbial cells, which could explain the deterioration of MEC performance 
      after AgNPs exposure. The relative expression level of the quorum signalling gene 
      (LuxR) increased by 30%. Microbial community analyses suggested that various 
      fermentative bacterial species (e.g., Bacteroides, Synergistaceae_vadinCA02, 
      Dysgonomonas, etc.) were susceptible to AgNPs toxicity, which led to the 
      disruption of their syntrophic partnership with electroactive bacteria. The 
      abundance of some specific electroactive bacteria (e.g., Geobacter species) also 
      decreased. Moreover, decreased relative expressions of various extracellular 
      electron transfer associated genes (omcB, omcC, omcE, omcZ, omcS, and pilA) were 
      observed. However, the members of family Enterobacteriaceae, known to perform a 
      dual function of fermentation and anodic respiration, became dominant after 
      biofilm anode exposed to AgNPs. Thus, EPS extraction provided partial protection 
      against AgNPs exposure.
CI  - Copyright (c) 2020 Elsevier B.V. All rights reserved.
FAU - Zakaria, Basem S
AU  - Zakaria BS
AD  - Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, 
      Edmonton, AB T6G 1H9, Canada.
FAU - Dhar, Bipro Ranjan
AU  - Dhar BR
AD  - Civil and Environmental Engineering, University of Alberta, 9211-116 Street NW, 
      Edmonton, AB T6G 1H9, Canada. Electronic address: bipro@ualberta.ca.
LA  - eng
PT  - Journal Article
DEP - 20200512
PL  - Netherlands
TA  - Sci Total Environ
JT  - The Science of the total environment
JID - 0330500
RN  - 3M4G523W1G (Silver)
SB  - IM
MH  - Biofilms
MH  - Electrodes
MH  - Extracellular Polymeric Substance Matrix
MH  - *Metal Nanoparticles
MH  - *Microbiota
MH  - Silver
OTO - NOTNLM
OT  - Anode biofilm
OT  - Microbial electrolysis cell
OT  - Silver nanoparticles (AgNPs)
OT  - Syntrophic interaction
COIS- Declaration of competing interest The authors declare that there is no conflict 
      of interest regarding the publication of this research manuscript.
EDAT- 2020/05/27 06:00
MHDA- 2020/06/19 06:00
CRDT- 2020/05/27 06:00
PHST- 2020/03/11 00:00 [received]
PHST- 2020/05/10 00:00 [revised]
PHST- 2020/05/10 00:00 [accepted]
PHST- 2020/05/27 06:00 [pubmed]
PHST- 2020/06/19 06:00 [medline]
PHST- 2020/05/27 06:00 [entrez]
AID - S0048-9697(20)32912-0 [pii]
AID - 10.1016/j.scitotenv.2020.139395 [doi]
PST - ppublish
SO  - Sci Total Environ. 2020 Sep 10;734:139395. doi: 10.1016/j.scitotenv.2020.139395. 
      Epub 2020 May 12.