PMID- 34896809
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20231221
IS  - 1879-2448 (Electronic)
IS  - 0043-1354 (Linking)
VI  - 209
DP  - 2022 Feb 1
TI  - Effects of eukaryotic predation on nitrifying MABR biofilms.
PG  - 117911
LID - S0043-1354(21)01105-2 [pii]
LID - 10.1016/j.watres.2021.117911 [doi]
AB  - This research explored the effects of eukaryotic predation on nitrifying 
      membrane-aerated biofilm reactor (MABR) biofilms. Past research on heterotrophic 
      MABR biofilms showed that predation could create internal voids that promoted 
      sloughing. However, the no past research addressed the effects of predation on 
      nitrifying MABRs, even though nitrification is the most common MABR application. 
      Nitrifying biofilms are typically denser, and ammonia oxidizing bacteria (AOB) 
      form large, dense clusters within the biofilm. This could affect their 
      susceptibility to predation. Nitrifying biofilms were grown in flat-sheet MABRs. 
      Images of the biofilm were captured using optical coherence tomography (OCT). For 
      detachment tests, an increased shear flow (Re congruent with140) was used, and a shear 
      rheometer was used to measure the biofilm mechanical properties. The nitrifying 
      community was analyzed with fluorescence in situ hybridization (FISH) and 
      quantitative PCR (qPCR). Predation increased internal void ratios from 54 +/- 5% to 
      69 +/- 6%. Biofilms were weakened by predation, with a storage modulus (G') and 
      loss modulus (G'') of 242 +/- 135 and 1,649 +/- 853 Pa with predation and 
      3,644 +/- 1,857 and 23,334 +/- 11,481 Pa for the control with suppressed predation. 
      Predation increased the relative biofilm detachment from 4 +/- 5 to 18 +/- 12%, 
      decreased the amount of biomass, i.e., the average biofilm thickness, from 
      502 +/- 150 to 266 +/- 54 microm, and decreased the nitrification flux from 1.00 to 
      0.61 g NH(4)(+)-N/m(2)day. Also, predation decreased the abundance of nitrite 
      oxidizing bacteria (NOB) relative to AOB, consistent with the observed 
      nitritation. These results show that predation can significantly impact the 
      structural stability, bacterial community and removal rates of nitrifying MABR 
      biofilms. Lumping the effects of predation into the detachment or decay 
      coefficients of biofilm models may not accurately reflect the behavior of 
      nitrifying MABR biofilms.
CI  - Copyright (c) 2021 Elsevier Ltd. All rights reserved.
FAU - Kim, B
AU  - Kim B
AD  - University of Notre Dame, Department of Civil and Environmental Engineering and 
      Earth Sciences 156 Fitzpatrick Hall, Notre Dame, IN 46556, United States.
FAU - Nerenberg, R
AU  - Nerenberg R
AD  - University of Notre Dame, Department of Civil and Environmental Engineering and 
      Earth Sciences 156 Fitzpatrick Hall, Notre Dame, IN 46556, United States. 
      Electronic address: nerenberg.1@nd.edu.
LA  - eng
PT  - Journal Article
DEP - 20211130
PL  - England
TA  - Water Res
JT  - Water research
JID - 0105072
SB  - IM
OTO - NOTNLM
OT  - Biofilms
OT  - MABRs
OT  - Mechanical properties
OT  - Nitrification
OT  - Protozoa
EDAT- 2021/12/14 06:00
MHDA- 2021/12/14 06:01
CRDT- 2021/12/13 12:58
PHST- 2021/08/10 00:00 [received]
PHST- 2021/11/05 00:00 [revised]
PHST- 2021/11/27 00:00 [accepted]
PHST- 2021/12/14 06:01 [medline]
PHST- 2021/12/14 06:00 [pubmed]
PHST- 2021/12/13 12:58 [entrez]
AID - S0043-1354(21)01105-2 [pii]
AID - 10.1016/j.watres.2021.117911 [doi]
PST - ppublish
SO  - Water Res. 2022 Feb 1;209:117911. doi: 10.1016/j.watres.2021.117911. Epub 2021 
      Nov 30.