Specialist Group on Microbial Ecology and Water Engineering - IWA

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Meyer, R.L., Saunders, A.M., and Blackall, L.L. (2006) Putative glycogen-accumulatingorganisms belonging to the Alphaproteobacteria identified through rRNA-basedstable isotope probing. Microbiology 152: 419-429.Mino, T., Van Loosdrecht, M.C.M., and Heijnen, J.J. (1998) Microbiology andbiochemistry of the enhanced biological phosphate removal process. WaterResearch 32: 3193-3207.Nittami, T., McIlroy, S., Seviour, E.M., Schroeder, S., and Seviour, R.J. (2009)Candidatus Monilibacter spp., common bulking filaments in activated sludge, aremembers of Cluster III Defluviicoccus. Systematic and Applied Microbiology 32:480-489.Seviour, R.J., and McIlroy, S. (2008) The microbiology of phosphorus removal inactivated sludge processes- the current state of play. The Journal of Microbiology46: 115-124.Wong, M.-T., and Liu, W.-T. (2007) Ecophysiology of Defluviicoccus-related tetradformingorganisms in an anaerobic-aerobic activated sludge process. EnvironmentalMicrobiology 9: 1485-1496.Wong, M.-T., Tan, F.M., Ng, W.J., and Liu, W.-T. (2004) Identification and occurrenceof tetrad-forming Alphaproteobacteria in anaerobic-aerobic activated sludgeprocesses. Microbiology 150: 3741-3748.BIOCONTROL OF FOAMING MYCOLATA IN ACTIVATED SLUDGEWASTEWATER TREATMENT PLANTS USING BACTERIOPHAGES.Zoe Dyson & Steve PetrovskiBiotechnology Research CentreLa Trobe University, Bendigo, 3550, AustraliaFoaming is a major problem in activated sludge wastewater treatment plants worldwide.It leads to increases in maintenance costs, safety issues and poor quality effluent.Foaming is typically caused by the proliferation of filamentous hydrophobic bacteriaincluding Candidatus ‘Microthrix parvicella’ and those that produce mycolic acids intheir cell walls (the Mycolata). These include members of the genera Corynebacterium,Gordonia, Tsukamurella, Dietzia, Mycobacterium, Nocardia, Rhodococcus, Millisia andSkermania. Although many control strategies have been proposed, (Soddell 1999), nomethod is available to deal with all activated sludge foams. This certainly reflects ourlack of understanding of the microbial ecology of foams, and true extent of thebiodiversity of foaming bacteria. Finding suitable methods to identify precisely suchpopulations has been a long standing problem, and although FISH probes are nowavailable for some of these, many still can not be identified this way.Earlier work carried out here by Julie Thomas (Thomas et al., 2002) demonstrated thefrequent presence in activated sludge of bacteriophages infective for many of the foamingMycolata. Recently, we have extended this work by isolating from Australian_________________________________________________________________________________________________IWA <strong>Specialist</strong> <strong>Group</strong> on: Microbial Ecology and Water Engineering 14Newsletter December 2009
wastewater treatment plants additional phages which from host range studies are lyticagainst members of all the Mycolata genera. Our preliminary findings have shown thatcocktails of these phages can eliminate all the known foaming Mycolata species, at leastin closed pure culture systems. This work is now directed at looking at their killing ratesfor individual populations in complex Mycolata communities.We have also begun to characterise these phages. Morphological studies withtransmission electron microscopy show that the majority, which are double strandedDNA viruses, are in the family Caudoviriales, possessing the typical Siphoviridaemorphology (an icosahedral head and long non-contractile tail (see fig 1)). These phageshave very broad host ranges that can often be extended after passage through host cellsdifferent to those used for their initial isolation. This probably results from hostrestriction modification systems (Wilson, 1991).50 nmAFig 1 TEM images of selected Mycolata phagesA = TPA2, B = MSM1.B50 nmWe are in the process now of obtaining the complete genome sequence of about 30 ofthese phages using pyrosequencing technology. We hope this information might provideus with clues as to how they may be exploited for foam control.We also intend to look at their population dynamics in activated sludge using fluorescenttagging methods to determine their host ranges in situ and to see how we might bestapply these to foaming activated sludge communities.Acknowledgements: We thank Dr. Daniel Tillet and Prof. Bob Seviour for helpfuladvice, and Melbourne Water and South East Water for financial support. DT and RS areholders of an ARC Linkage grant._________________________________________________________________________________________________IWA <strong>Specialist</strong> <strong>Group</strong> on: Microbial Ecology and Water Engineering 15Newsletter December 2009
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Page 21 and 22: ISBN: 9781843390268 • October 200
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