Microbial predation accelerates granulation and modulates microbial community composition.

Chan, SH; Ismail, MH; Tan, CH; Rice, SA; McDougald, D

Microbial predation accelerates granulation and modulates microbial community composition.

Chan, SH Ismail, MH Tan, CH Rice, SA McDougald, D

Permalink

Publisher:: Springer Science and Business Media LLC
Publication Type:: Journal Article
Citation:: BMC microbiology, 2021, 21, (1), pp. 91
Issue Date:: 2021-03-27

Open Access

Copyright Clearance Process

Recently Added
In Progress
Open Access

This item is open access.

Adobe PDF

Download full textAdobe PDF (3.96 MB)

View on publisher's site

View statistics

Full metadata record

Field	Value	Language
dc.contributor.author	Chan, SH
dc.contributor.author	Ismail, MH
dc.contributor.author	Tan, CH
dc.contributor.author	Rice, SA
dc.contributor.author	McDougald, D
dc.date.accessioned	2021-04-14T05:16:35Z
dc.date.available	2021-03-08
dc.date.available	2021-04-14T05:16:35Z
dc.date.issued	2021-03-27
dc.identifier.citation	BMC microbiology, 2021, 21, (1), pp. 91
dc.identifier.issn	1471-2180
dc.identifier.issn	1471-2180
dc.identifier.uri	http://hdl.handle.net/10453/148091
dc.description.abstract	<h4>Background</h4>Bacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge.<h4>Results</h4>Four independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and diversity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of 'Candidatus Accumulibacter' was positively correlated with the formation of compact aggregates and granules.<h4>Conclusion</h4>Predation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of 'Candidatus Accumulibacter' was necessary for the formation of granules in the absence of protozoa.
dc.format	Electronic
dc.language	eng
dc.publisher	Springer Science and Business Media LLC
dc.relation.ispartof	BMC microbiology
dc.relation.isbasedon	10.1186/s12866-021-02156-8
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	This is a post-peer-review, pre-copyedit version of an article published in BMC microbiology. The final authenticated version is available online at: https://dx.doi.org/10.1186/s12866-021-02156-8.	en_US
dc.subject	06 Biological Sciences, 07 Agricultural and Veterinary Sciences, 11 Medical and Health Sciences
dc.subject.classification	Microbiology
dc.title	Microbial predation accelerates granulation and modulates microbial community composition.
dc.type	Journal Article
utslib.citation.volume	21
utslib.location.activity	England
utslib.for	06 Biological Sciences
utslib.for	07 Agricultural and Veterinary Sciences
utslib.for	11 Medical and Health Sciences
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - ithree - Institute of Infection, Immunity and Innovation
utslib.copyright.status	open_access	*
dc.date.updated	2021-04-14T05:16:29Z
pubs.issue	1
pubs.publication-status	Published
pubs.volume	21
utslib.citation.issue	1

Abstract:

Background

Bacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge.

Results

Four independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and diversity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of 'Candidatus Accumulibacter' was positively correlated with the formation of compact aggregates and granules.

Conclusion

Predation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of 'Candidatus Accumulibacter' was necessary for the formation of granules in the absence of protozoa.

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10453/148091