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Mayer R. E., Reischer G., Ixenmaier S., Derx, J., Blaschke A. P., Ebdon J., Linke R., Egle, L., Ahmed W., Blanch A, Byamukaa D., Savill M., Mushi D., Cristóbal H., Edge T., Schade M., Aslan A., Brooks Y., Sommer R., Masago Y., Sato M., Taylor H., Rose J., Wuertz S., Shanks O., Piringer H., Mach R., Savio D., Zessner M.; Farnleitner A.H.


Global distribution of human-associated fecal genetic markers in reference samples from six continents

Environ. Sci. Technol., in press


Numerous bacterial genetic markers are available for the molecular detection of human sources of fecal pollution in environmental waters. However, widespread application is hindered by a lack of knowledge regarding geographical stability, limiting implementation to a small number of well-characterized regions. This study investigates the geographic distribution of five human-associated genetic markers (HF183/BFDrev, HF183/BacR287, BacHum-UCD, BacH, and Lachno2) in municipal wastewaters (raw and treated) from 29 urban and rural wastewater treatment plants (750−4400000 population equivalents) from 13 countries spanning six continents. In addition,genetic markers were tested against 280 human and nonhuman fecal samples from domesticated, agricultural and wild animal sources. Findings revealed that all genetic markers are present in consistently high concentrations in raw (median log10 7.2−8.0 marker equivalents (ME) 100 mL−1) and biologically treated wastewater samples (median log10 4.6−6.0 ME 100 mL−1) regardless of location and population. The false positive rates of the various markers in nonhuman fecal samples ranged from 5% to 47%. Results suggest that several genetic markers have considerable potential for measuring human-associated contamination in polluted environmental waters. This will be helpful in water quality monitoring, pollution modeling and health risk assessment (as demonstrated by QMRAcatch) to guide target- oriented water safety management across the globe.



Gonzo E.E., Wuertz S., and Rajal V.B.

Net growth rate of continuum heterogenous biofilms with inhibition kinetics
npj Biofilms and Microbiomes 4 (1), 5


Biofilm systems can be modeled using a variety of analytical and numerical approaches, usually by making simplifying assumptions regarding biofilm heterogeneity and activity as well as effective diffusivity. Inhibition kinetics, albeit common in experimental systems, are rarely considered and analytical approaches are either lacking or consider effective diffusivity of the substrate and the biofilm density to remain constant. To address this obvious knowledge gap, an analytical procedure to estimate the effectiveness factor (dimensionless substrate mass flux at the biofilm-fluid interface) was developed for a continuum heterogeneous biofilm with multiple limiting-substrate Monod kinetics to different types of inhibition kinetics. The simple perturbation technique, previously validated to quantify biofilm activity, was applied to systems where either the substrate or the inhibitor is the limiting component, and cases where the inhibitor is a reaction product or the substrate also acts as the inhibitor. Explicit analytical equations are presented for the effectiveness factor estimation and, therefore, the calculation of biomass growth rate or limiting substrate/inhibitor consumption rate, for a given biofilm thickness. The robustness of the new biofilm model was tested using kinetic parameters experimentally determined for the growth of Pseudomonas putida CCRC 14365 on phenol. Several additional cases have been analyzed, including examples where the effectiveness factor can reach values greater than unity, characteristic of systems with inhibition kinetics. Criteria to establish when the effectiveness factor can reach values greater than unity in each of the cases studied are also presented.



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Kundu A., Wuertz S., and Smith W.A.

Quantitative microbial risk assessment to estimate the risk of diarrheal diseases from fresh produce consumption in India

Food Microbiology, in press


This study estimates illness (diarrhea) risks from fecal pathogens that can be transmitted via fecal- contaminated fresh produce. To do this, a quantitative microbial risk assessment (QMRA) framework was developed in National Capital Region, India based on bacterial indicator and pathogen data from fresh produce wash samples collected at local markets. Produce wash samples were analyzed for fecal indicator bacteria (Escherichia coli, total Bacteroidales) and pathogens (Salmonella, Shiga-toxin producing E. coli (STEC), enterohemorrhagic E. coli (EHEC)). Based on the E. coli data and on literature values for Cryptosporidium and norovirus, the annual mean diarrhea risk posed by ingestion of fresh produce ranged from 18% in cucumbers to 59% in cilantro for E. coli O157:H7, and was <0.0001% for Cryptosporidium; for norovirus the risk was 11% for cucumbers and up to 46% for cilantro. The risks were drastically reduced, from 59% to 4% for E. coli O157:H7, and from 46% to 2% for norovirus for cilantro in post-harvest washing and disinfection scenario. The present QMRA study revealed the potential hazards of eating raw produce and how post-harvest practices can reduce the risk of illness. The results may lead to better food safety surveillance systems and use of hygienic practices pre- and post-harvest.


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Cokro A.A., Law Y., Williams R. B.H., Cao Y., Nielsen P.H., Wuertz S.

Non-denitrifying polyphosphate accumulating organisms obviate requirement for anaerobic condition

Water Res. 111:393-403.

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Doyle L.E., Yung P.Y., Mitra S.D., Wuertz S., Williams R.B.H., Lauro F.M., and Marsili E.

Electrochemical and genomic analysis of novel electroactive isolates obtained via potentiostatic enrichment from tropical sediment

Power Sources 356: 539-548.

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Nshimyimana J.P., Cruz M. C., Thompson R. J., and Wuertz S.
Bacteroidales markers for microbial source tracking in Southeast Asia

Water Res. 118:239-248.


[read article]  DOI: 10.1016/j.watres.2017.04.027


Orlofsky E., Bernstein N., Sacks M., Vonshak A., Benami M., Kundu A., Maki M., Smith W., Wuertz S., Shapiro K., and Gillor O.
Comparable levels of microbial contamination in soil and on tomato crops after drip irrigation with treated wastewater or potable water

Agr. Ecosyst. Environ. 215: 140-150.

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Odagiri M., Schriewer A., Daniels M.E., Wuertz S., Smith W.A., Clasen T., Schmidt W.P, Yujie J., Torondel B., Misra P.R., Panigrahi P. and Jenkins M.W.

Human fecal and pathogen exposure pathways in rural Indian villages and the effect of increased latrine coverage

Water Res. 100:232-244.

[read article] DOI: 10.1016/j.watres.2016.05.015

Law Y.Y., Kirkegaard R. H., Cokro A.A., Liu X., Arumugam K., Chao X., Stokholm-Bjerregaard M., Drautz-Moses D.I., Nielsen P.H., Wuertz S., and Williams R.B.H.
Integrative microbial community analysis reveals full-scale enhanced biological phospho­rus removal under tropical conditions

Sci. Rep. 6, 25719


Management of phosphorus discharge from human waste is essential for the control of eutrophication in surface waters. Enhanced biological phosphorus removal (EBPR) is a sustainable, efficient way of removing phosphorus from waste water without employing chemical precipitation, but is assumed unachievable in tropical temperatures due to conditions that favour glycogen accumulating organisms (GAOs) over polyphosphate accumulating organisms (PAOs). Here, we show these assumptions are unfounded by studying comparative community dynamics in a full-scale plant following systematic perturbation of operational conditions, which modified community abundance, function and physicochemical state. A statistically significant increase in the relative abundance of the PAO Accumulibacter was associated with improved EBPR activity. GAO relative abundance also increased, challenging the assumption of competition. An Accumulibacter bin-genome was identified from a whole community metagenomic survey, and comparative analysis against extant Accumulibacter genomes suggests a close relationship to Type II. Analysis of the associated metatranscriptome data revealed that genes encoding proteins involved in the tricarboxylic acid cycle and glycolysis pathways were highly expressed, consistent with metabolic modelling results. Our findings show that tropical EBPR is indeed possible, highlight the translational potential of studying competition dynamics in full-scale waste water communities and carry implications for plant design in tropical regions.

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Hinks J., Han EJY, Wang V.B., Seviour T.W., Marsili E,, Loo J.S.C., and Wuertz S.
Naphthoquinone glycosides for bioelectroanalytical enumeration of the faecal indicator Escherichia coli.

Microb. Biotechnol. 9: 746-757.

[read article] DOI: 10.1111/1751-7915.12373

Adell D., McBride G., Wuertz S., Conrad P.A., and Smith W.A.
Comparison of human and southern sea otter (Enhydra lutris nereis) health risks for infection with protozoa in nearshore waters.

Water Res. 104: 220-230.

[read article] DOI: 10.1016/j.watres.2016.08.004


Rice S.A., Wuertz S., Kjelleberg S.

Next‐generation studies of microbial biofilm communities

Microb. Biotechnol. 9: 677-680.

[read article] DOI: 10.1111/1751-7915.12390



Stefan Wuertz View All

Stefan was born and raised in Germany. He caught the travel bug early and went to study Microbiology at the National University of Ireland, Galway, before embarking on an interdisciplinary PhD in Environmental Sciences with Joe Cooney at the University of Massachusetts in the U.S. He did his post-doc in molecular biology on heavy metal resistance in bacteria in the laboratory of Max Mergeay at VITO in Belgium, in collaboration with Daniel van der Lelie and Jean-Marc Collard. During that time, Stefan was a recipient of an EU postdoctoral scholarship. Next he moved back to Germany and began working on public health and engineering-related research questions at Technical University Munich. In 2001, he obtained his Dr. habil. In Environmental Biotechnology and accepted a faculty position in Environmental Engineering at the University of California, Davis. In 2011, Stefan co-founded the Singapore Centre of Environmental Life Sciences Engineering at Nanyang Technological University and the National University of Singapore with Staffan Kjelleberg, Stephan Schuster, Mike Givskov and colleagues. Since 2016 he is a full-time Professor in the School of Civil and Environmental Engineering. When not in lab, he enjoys long-distance running, exploring Southeast Asian countries and culture, dappling in folk guitar music, and spending time with family.

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