Torvinen Eila, Lehtola Markku J, Martikainen Pertti J, Miettinen Ilkka T
Environmental Microbiology Laboratory, National Public Health Institute, P.O. Box 95, FI-70701 Kuopio, Finland.
Appl Environ Microbiol. 2007 Oct;73(19):6201-7. doi: 10.1128/AEM.00828-07. Epub 2007 Aug 3.
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 microg/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 degrees C versus 7 degrees 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.
鸟分枝杆菌是饮用水系统中存在的一种潜在病原体。它是一种生长缓慢的细菌，能产生含有分枝菌酸的厚细胞壁，并且已知其比许多其他微生物更能抵抗氯。多项研究表明，病原菌在生物膜中的存活情况优于在水中。通过使用Propella生物膜反应器，我们研究了一般影响生物膜生长的因素（流速、磷浓度和温度）如何影响鸟分枝杆菌在饮用水生物膜中的存活。通过培养和DAPI（4',6'-二脒基-2-苯基吲哚）染色跟踪生物膜的生长，并通过培养和荧光原位杂交方法测定鸟分枝杆菌的浓度。在为期4周的研究期间，接种的鸟分枝杆菌在生物膜中存活，其浓度没有显著下降。添加磷（10微克/升）增加了生物膜中异养细菌的数量，但降低了鸟分枝杆菌的可培养性。这一结果的原因可能是磷增加了与其他微生物的竞争。流速增加对鸟分枝杆菌的存活没有影响，尽管它增加了生物膜的生长。较高的温度（20摄氏度与7摄氏度相比）增加了生物膜中异养细菌的数量以及鸟分枝杆菌的存活。总之，结果表明，就影响生长缓慢的鸟分枝杆菌在生物膜中的存活而言，温度是比磷等营养物质的可利用性更重要的因素。
