Open AccessSurvival of Mycobacterium avium in Drinking Water Biofilms as Affected by Water Flow Velocity, Availability of Phosphorus, and Temperature
Author(s) -
Eila Torvinen,
Markku J. Lehtola,
Pertti J. Martikainen,
Ilkka T. Miettinen
Publication year - 2007
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.00828-07
Subject(s) - biofilm , phosphorus , bacteria , microbiology and biotechnology , biology , mycobacterium , heterotroph , chlorine , chemistry , genetics , organic chemistry
Mycobacterium avium is a potential pathogen occurring in drinking water systems. It is a slowly growing bacterium producing a thick cell wall containing mycolic acids, and it is known to resist chlorine better than many other microbes. Several studies have shown that pathogenic bacteria survive better in biofilms than in water. By using Propella biofilm reactors, we studied how factors generally influencing the growth of biofilms (flow rate, phosphorus concentration, and temperature) influence the survival ofM. avium in drinking water biofilms. The growth of biofilms was followed by culture and DAPI (4′,6′-diamidino-2-phenylindole) staining, and concentrations ofM. avium were determined by culture and fluorescence in situ hybridization methods. The spikedM. avium survived in biofilms for the 4-week study period without a dramatic decline in concentration. The addition of phosphorus (10 μg/liter) increased the number of heterotrophic bacteria in biofilms but decreased the culturability ofM. avium . The reason for this result is probably that phosphorus increased competition with other microbes. An increase in flow velocity had no effect on the survival ofM. avium , although it increased the growth of biofilms. A higher temperature (20°C versus 7°C) increased both the number of heterotrophic bacteria and the survival ofM. avium in biofilms. In conclusion, the results show that in terms of affecting the survival of slowly growingM. avium in biofilms, temperature is a more important factor than the availability of nutrients like phosphorus.