Fouling

Event Date: 
Wednesday, November 26, 2014 - 19:00 - 19:45
Institution: 
UNSW
Title: 

“The microbial friends and foes of seaweeds”

Abstract: 

 

Seaweeds (macroalgae) form a diverse and ubiquitous group of photosynthetic organisms that play an essential role in many aquatic ecosystems, yet till recently very little was understood with respect to their associated microbiota. We now know that macroalgae are home to a diverse community of microorganisms, that display both temporal and spatial variation yet remain distinct from the surrounding seawater. Symbiotic interactions between marine microorganisms and macroalgae can have both positive (e.g. providing nutrients and morphogenic cues or protection from biofouling) and negative (e.g. disease) outcomes for the host. This talk will give an overview of the microorganisms typically associated with macroalgae with a focus on the bacterial symbionts. Details of how bacteria successfully colonize macroalgal hosts will be discussed with specific examples of the functional role of microbial epiphytes in macroalgal health (including disease) highlighted from a “holobiont” perspective.

 

Event Date: 
Wednesday, June 25, 2014 - 18:00 - 18:15
Institution: 
UNSW
Title: 

Nitric oxide treatment for the control of reverse osmosis membrane biofouling

Abstract: 

Biofouling remains a key challenge for membrane based water treatment systems.  This study investigated the dispersal potential of the nitric oxide (NO) donor compound, PROLI NONOate, on single species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis (RO) membranes, as well as on mixed species biofilms.  The potential of PROLI NONOate to control RO membrane biofouling was also examined.  Confocal microscopy revealed that different bacteria responded differently to PROLI NONOate exposure.  However, the addition of NO induced dispersal in all but two of the bacteria tested and successfully reduced mixed species biofilms.  The addition of 40 µM PROLI NONOate at 24 h intervals to a laboratory-scale RO system led to a 92% reduction in the rate of biofouling (pressure rise over a given period) by a bacterial community cultured from an industrial RO membrane.  Confocal microscopy and EPS extraction revealed that PROLI NONOate treatment led to a 48% reduction in polysaccharides, a 66% reduction in proteins and a 29% reduction in microbial cells compared to the untreated control.  A reduction in biofilm surface coverage (59% vs. 98%, treated vs. control) and average thickness (20 µm vs. 26 µm, treated vs. control) was also observed.  The addition of PROLI NONOate led to a 22% increase in the time required for the RO module to reach its maximum TMP, further indicating that NO treatment delayed fouling.  Pyrosequencing analysis revealed that the NO treatment did not significantly alter the microbial community composition of the membrane biofilm.  These results present strong evidence for the application of PROLI NONOate for prevention of RO biofouling in an industrial setting.

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