Survival of Mycobacterium avium in Drinking Water Biofilms as Affected by Water Flow Velocity, Availability of Phosphorus, and Temperature

Abstract

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 of M. avium in drinking water biofilms. The growth of biofilms was followed by culture and DAPI (4,6-diamidino-2-phenylindole) staining, and concentrations of M. avium were determined by culture and fluorescence in situ hybridization methods. The spiked M. avium survived in biofilms for the 4-week study period without a dramatic decline in concentration. The addition of phosphorus (10 g/liter) increased the number of heterotrophic bacteria in biofilms but decreased the culturability of M. 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 of M. 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 of M. avium in biofilms. In conclusion, the results show that in terms of affecting the survival of slowly growing M. avium in biofilms, temperature is a more important factor than the availability of nutrients like phosphorus.

Pyrosequence Analysis of the hsp65 Genes of Nontuberculous Mycobacterium Communities in Unchlorinated Drinking Water in the Netherlands

“…However, since NTM species can grow under oligotrophic conditions (5,23), distribution of drinking water without a disinfection residual might increase the risk of NTM growth during distribution of the drinking water. On the other hand, studies have demonstrated that certain NTM species are especially resistant to monochloramine and that shifts from chlorine to monochloramine disinfection in drinking water treatment resulted in enhanced numbers of NTM in the drinking water distribution system (24)(25)(26).…”

Análise bacteriológica da água de consumo comercializada por caminhões-pipa

“…Nesse estudo, foi observada que na parte da tarde as temperaturas encontravam-se naturalmente mais elevadas (30±1ºC) quando comparadas às temperaturas das amostras da mesma água coletada pela manhã (20±1ºC). Esses resultados foram semelhantes ao estudo realizado por Torvinen, et al (2007) que observaram elevadas contagens microbianas com o aumento da temperatura nos sistemas de distribuição de água potável.…”

“…Dentre os materiais utilizados o SS 316 e o policloreto de polivinila (PVC) foram termodinamicamente favoráveis para 6 tipos bacterianos, SS 304 para 18 tipos, e Copper, Polipropileno (PP) e Polietileno (PE) para 25 tipos de bactérias. A adesão é dependente da afinidade entre as propriedades físico-químicas da superfície bacteriana e dos materiais (Simões et al, 2007;Torvinen et al, 2007).…”

Le réseau de distribution d’eau potable : un écosystème complexe lié à des enjeux de santé publique

“…Toutefois, il est difficile d'étudier les biofilms formés dans le réseau de distribution en raison des contraintes industrielles occasionnées par le remplacement de sections de canalisation. Pour ce faire, des dispositifs expérimentaux ont été développés afin d'étudier la structure et la dynamique des biofilms formés sous l'action d'eau potable (BOE-HANSEN et al, 2003;DELAHAyE et al, 2006;KJELLERUP et al, 2004;MATHIEU et al, 2009;PARIS et al, 2007;PEREIRA et al, 2002;TORvINEN et al, 2007). Le principe de ces systèmes pilotes repose sur la colonisation de supports de même nature que les matériaux utilisés dans la construction des ouvrages de stockage et de distribution de l'eau potable.…”