Characterisation and comparison of bacterial communities on reverse osmosis membranes of a full-scale desalination plant by bacterial 16S rRNA gene metabarcoding

Abstract

Microbiomes of full-scale seawater reverse osmosis membranes are complex and subject to variation within and between membrane units. The pre-existing bacterial communities of unused membranes before operation have been largely ignored in biofouling studies. This study is novel as unused membranes were used as a critical benchmark for comparison. Fouled seawater reverse osmosis membrane biofilm communities from an array of autopsied membrane samples, following a 7-year operational life-span in a full-scale desalination plant in Western Australia, were characterised by 16S rRNA gene metabarcoding using the bacterial primers 515F and 806R. Communities were then compared based on fouling severity and sampling location. Microbiomes of proteobacterial predominance were detected on control unused membranes. However, fouled membrane communities differed significantly from those on unused membranes, reflecting that operational conditions select specific bacteria on the membrane surface. On fouled membranes, Proteobacteria were also predominant but families differed from those on unused membranes, followed by Bacteriodetes and Firmicutes. Betaproteobacteria correlated with stable, mature and thick biofilms such as those in severely fouled membranes or samples from the feed end of the membrane unit, while Alpha and Gammaproteobacteria were predominantly found in biofilms on fouled but visually clean, and moderately fouled samples or those from reject ends of membrane units. Gammaproteobacteria predominated the thin, compact biofilms at the mid-feed end of membrane units. The study also supported the importance of Caulobacterales and glycosphingolipid-producing bacteria, namely Sphingomonadales, Rhizobiales and Sphingobacteriia, in primary attachment and biofilm recalcitrance. Nitrate-and-nitrite-reducing bacteria such as Rhizobiales, Burkholderiales and some Pseudomonadales were also prevalent across all fouled membranes and appeared to be critical for ecological balance and biofilm maturation.

Anode surface bioaugmentation enhances deterministic biofilm assembly in microbial fuel cells

“…On day 3, corresponding with the average startup time of EDC+WW reactors, the only OTU that became differentially abundant in EDC+WW relative to the control planktonic communities belonged to Sphingobacteriia . This finding is consistent with the functional role attributed to Flavobacteriia and Sphingobacteriia , both of which were found to represent key members in the formation and functioning of biofilms in diverse environments (Battin et al, 2016; Nagaraj et al, 2017; Pollet et al, 2018), probably due to their ability to degrade diverse complex organic material and their superior attachment ability. Furthermore, Sphingobacteriia were previously reported in bioelectrochemical devices both at the plankton fraction and anodic biofilm as homoacetogens or fermenters of complex organic substances that support electrogenic species within the biofilm through syntrophic interactions (Gao et al, 2014).…”

Marine Biofilms: A Successful Microbial Strategy With Economic Implications

“…Proteobacteria and especially γproteobacteria dominated biofilm communities colonizing artificial surfaces in Toulon and Lorient, France (Briand et al, 2017), and in Mauritian coastal waters (Rampadarath et al, 2017). DNA metabarcoding showed that the proportion of γ-proteobacteria increased and dominated artificial surfaces with cupreous anti-fouling coating treatments (von Ammon et al, 2018).16S rRNA gene metabarcoding showed that proteobacteria dominated bacterial communities in used reverse osmosis membranes in a desalination plant, with β-proteobacteria being found in severely fouled membranes (Nagaraj et al, 2017). However, the community composition and diversity obtained by high throughput DNA sequencing technologies of biofilms is dependent on the DNA extraction method selected (Corcoll et al, 2017).…”

Environmental biofilm communities associated with early‐stage common dentex (Dentex dentex) culture

“…They are prevalent on desalination plant membranes (Nagaraj et al . ) and have been associated with rotifer ( Brachionus plicatilis ) culture. Although only identified in small numbers, representatives of denitrifying genera including Comamonas, Brachymonas, Nitrospira , Desulfovibrio , Thiobacillus, Acidovorax, Dechloromonas, Meganema and Hyphomicrobium were also found in all feeding phases.…”