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Publikācija: Automated Flow Cytometry Approaches for Assessment of Chlorination Efficacy on Aquatic Bacterial Communities

Publication Type Conference paper
Funding for basic activity Research project
Defending: ,
Publication language English (en)
Title in original language Automated Flow Cytometry Approaches for Assessment of Chlorination Efficacy on Aquatic Bacterial Communities
Field of research 2. Engineering and technology
Sub-field of research 2.1. Construction and transportation engineering
Authors Alīna Neščerecka
Tālis Juhna
Frederik Hammes
Keywords -
Abstract Accurate and sensitive methods for bacterial viability assessment are essential for disinfection studies. Firstly, many disinfection processes (e.g., chlorination) occur at high rates, with cell damage and subsequent inactivation happening in a matter of seconds-to-minutes. Secondly, assessment of viability in indigenous bacterial communities are challenging due to small cell sizes, high (and often unknown) diversity in composition and physiological states and resistance to environmental stress. The goal of the study was to investigate chlorine disinfection of freshwater bacterial communities using a combination of SYBR Green I and Propidium Iodide (SGPI) and flow cytometry. Specifically, we (i) developed a rapid multi-plate approach to assess the effect of different sodium hypochlorite (NaOCl) concentrations, and (ii) used a newly-developed real-time flow cytometry (RT-FCM) system for detailed temporal measurements of disinfection. The SGPI combination differentiates between viable and non-viable bacteria based on the ability of PI to penetrate cells with damaged membrane. The 96-well multi-plate automated approach enabled the assessment of 10 NaOCl concentrations in triplicate in under 40 minutes, thereby providing a detailed assessment of the effect of chlorine on an unknown sample. Finally, RT-FCM was used as a tool to evaluate changes in bacterial viability in real-time at second-to-minute resolution. River water samples were exposed to 5 NaOCl concentrations from 0.175 – 1.4 mg L-1 free chlorine and measured continuously for 15 minutes. The results showed that intact cell counts decreased for 96% after 15 minutes (with 1.4 mg-Cl2 L-1). However, 92% of bacteria were inactivated during the first 5 minutes. The combination of these new analytical approaches allows for a precise and detailed determination of disinfection kinetics, and would be useful for assessing other disinfection agents for any indigenous community or bacterial pure culture.
Reference Neščerecka, A., Juhna, T., Hammes, F. Automated Flow Cytometry Approaches for Assessment of Chlorination Efficacy on Aquatic Bacterial Communities. In: How Dead is Dead Conference IV: Abstract Book, Switzerland, Zürich, 21-22 May, 2015. Zürich: 2015, pp.30-30.
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