Examining Chemical Compound Biodegradation at Low Concentrations through Bacterial Cell Proliferation

• Published in: Environmental science & technology 2013-02, Vol.47 (4), p.1913-1921
• Main Authors: Czechowska, Kamila, Sentchilo, Vladimir, Beggah, Siham, Rey, Sylvain, Seyfried, Markus, van der Meer, Jan Roelof
• Format: Article
• Language: English
• Subjects: Applied sciences; Approximation; Biodegradation; Biodegradation, Environmental; Biomass; Cell Count; Cell culture; Cell Proliferation; Cells; Chemical compounds; Exact sciences and technology; Flow Cytometry; Global environmental pollution; Microbial Consortia - drug effects; Pollution; Pseudomonas - physiology; Sludge; Water Pollutants, Chemical - metabolism; Water Pollutants, Chemical - toxicity
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es303592c

We show proof of principle for assessing compound biodegradation at 1–2 mg C per L by measuring microbial community growth over time with direct cell counting by flow cytometry. The concept is based on the assumption that the microbial community will increase in cell number through incorporation of carbon from the added test compound into new cells in the absence of (as much as possible) other assimilable carbon. We show on pure cultures of the bacterium Pseudomonas azelaica that specific population growth can be measured with as low as 0.1 mg 2-hydroxybiphenyl per L, whereas in mixed community 1 mg 2-hydroxybiphenyl per L still supported growth. Growth was also detected with a set of fragrance compounds dosed at 1–2 mg C per L into diluted activated sludge and freshwater lake communities at starting densities of 104 cells per ml. Yield approximations from the observed community growth was to some extent in agreement with standard OECD biodegradation test results for all, except one of the examined compounds.