Influence of aquatic microorganisms on Legionella pneumophila survival

The ability of aquatic bacteria Pseudomonas fluorescens SSD (Ps-D) and Pseudomonas putida SSC (Ps-C) to support the persistence of Legionella pneumophila (Lp-1) in an artificial water microcosm was investigated for 42 day, at two different incubation temperatures. At 4 °C, individually suspended Lp-1 was no longer detectable just after 24 hours, while in co-cultures with Pseudomonas, Lp1 showed a better survival capability. At 30 °C, Lp-1 alone displayed high survival rates over the entire period of observation. When Lp-1 was inoculated with Ps-C and Ps-D, its count showed a marked decrease, followed by a gradual and costant decline.