Tamar Kohn | EPFL Graph Search

Are you an EPFL student looking for a semester project?

Work with us on data science and visualisation projects, and deploy your project as an app on top of GraphSearch.

2014 - present Associate Professor, EPFL and adjunct researcher, Eawag 2007 - 2013 Assistant Professor, EPFL 2004 - 2006 Postdoctoral researcher, UC Berkeley 2000 - 2004 PhD, Environmental Engineering, Johns Hopkins University 1999 Diploma, Environmental Sciences, ETHZ

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related units

Courses taught by this person

Related research domains

Related publications

People doing similar research

Biography

Official source

About this result

Related units (7)

Related units

Courses taught by this person (2)

Courses taught by this person

Related research domains (83)

Related research domains

Related publications (233)

Related publications

People doing similar research (102)

People doing similar research

ENV-200: Environmental chemistry

This course provides students with an overview over the basics of environmental chemistry. This includes the chemistry of natural systems, as well as the fate of anthropogenic chemicals in natural systems. It enables students to apply general chemical concepts to natural systems.

ENV-507: Fate and behaviour of environmental contaminants

The student will learn the important processes that control the transport and transformation of organic chemicals in the environment, as well as the formulation and solution of quantitative models to describe these processes.

Virus

A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria

Sewage treatment

Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is

Disinfectant

A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant ba

Observed Kinetics of Enterovirus Inactivation by Free Chlorine Are Host Cell-Dependent

Federica Cariti, Shannon Christa David, Tamar Kohn, Shotaro Torii

Virucidal efficacies of disinfectants are typically assessed by infectivity assay utilizing a single type of host cell. Enteroviruses infect multiple host cells via various entry routes, and each entry route may be impaired differently by a given disinfectant. Yet, it is unknown how the choice of host cells affects the observed inactivation kinetics. Here, we evaluated the inactivation kinetics of echovirus 11 (E11) by free chlorine, ultraviolet (UV) irradiation, and heat, using three different host cells (BGMK, RD, and A549). Inactivation rates were independent of the host cell for treatment of E11 by UV or heat. Conversely, E11 inactivation by free chlorine occurred 2-fold faster when enumerated on BGMK cells compared with RD and A549 cells. Host cell-dependent inactivation kinetics by free chlorine were also observed for echovirus 7, 9, and 13, and coxsackievirus A9. E11 inactivation by free chlorine was partly caused by a loss in host cell attachment, which was most pronounced for BGMK cells. BGMK cells lack the attachment receptor CD55 and a key subunit of the uncoating receptor β2M, which may contribute to the differential inactivation kinetics for this cell type. Consequently, inactivation kinetics of enteroviruses should be assessed using host cells with different receptor profiles.

2023

Selective elimination of enterovirus genotypes by activated sludge and chlorination

Tamar Kohn, Shotaro Torii

Enteroviruses, which are commonly circulating viruses shed in the stool, are released into the sewage system and only partially removed or inactivated, resulting in the discharge of infectious enteroviruses into the environment. Activated sludge and chlorination remove or inactivate enterovirus genotypes to different extents, and thus have the potential to shape the population that will be discharged. The goal of this study was to evaluate how activated sludge and chlorination treatment shape an enterovirus population at the genotype level, using a population of eight genotypes commonly found in sewage: CVA9, CVB1, CVB2, CVB3, CVB4, CVB5, E25, E30. Our results show that the extent of inactivation varied among genotypes, but also across sludge samples. We find that the effluent of activated sludge systems will be depleted in CVA9, CVB1 and CVB2 while E25 together with CVB3, CVB4 and CVB5 will be prevalent. Furthermore, we found that microbial inactivation was the main mechanism of infectivity loss in the activated sludge, while adsorption to the sludge flocs was not significant. During effluent chlorination, we also observed that CVB5, CVB3 and to a lesser extent E25 were less susceptible to chlorination while E30 was readily inactivated, and activated sludge-derived EPS provided further protection against chlorination. This study contributes to a better understanding of the variability of sewage treatment efficacy against different enteroviruses.

2023

Uptake without inactivation of human adenovirus type 2 by Tetrahymena pyriformis ciliates

Tamar Kohn, Margot Ninon Lauren Olive

Human adenoviruses are ubiquitous contaminants of surface water. Indigenous protists may interact with adenoviruses and contribute to their removal from the water column, though the associated kinetics and mechanisms differ between protist species. In this work, we investigated the interaction of human adenovirus type 2 (HAdV2) with the ciliate Tetrahymena pyriformis. In co-incubation experiments in a freshwater matrix, T. pyriformis was found to efficiently remove HAdV2 from aqueous phase, with ≥ 4 log10 removal over 72 hours. Neither sorption onto the ciliate nor secreted compounds contributed to the observed loss of infectious HAdV2. Instead, internalization was shown to be the dominant removal mechanism, resulting in the presence of viral particles inside food vacuoles of T. pyriformis , as visualized by transmission electron microscopy. The fate of HAdV2 once ingested was scrutinized and no evidence of virus digestion was found over the course of 48 hours. This work shows that T. pyriformis can exert a dual role on microbial water quality: while they remove infectious adenovirus from the water column, they can also accumulate and potentially protect infectious viruses from exposure to environmental or engineered stressors.

2023