49
pH
The bacteria of the genus
Legionella
are tolerant to acid and can
survive in environments with pH 2.0. They have already been isolated in
environments with range of pH variation between 2.7 and 8.3. (Anand
et
al
., 1983; Sheehan,Henson & Ferris, 2005),
Natural environments with high humidity, as for example, forests with
high rainfall levels, favor the development of
Legionella
– it was found in
water accumulated in plants in these environments. The bacterium can also
be found in sea water and artificial environments with salt water. (Riffard
et
al
., 2001; Brooks
et al
., 2004) (Ortiz-Roque & Hazen, 1987).
Influence of temperature
Legionellae have been already found in underground waters and in subsoil
withwaterat the temperaturebelow20°C. Innatural environments thebacterium
can be present in very low concentrations to be detected by the culture methods,
but thiswater canbe introduced inanartificial systemwithphysical andchemical
conditions that can propitiate the proliferation of the Legionella.
The bacteria of the genus
Legionella
can be isolated in water systems
with up to 66 °C, but, in temperatures above 70 °C they are instantly
destroyed (Dennis, Green & Jones, 1984; Dennis, 1988). Kusnetsov
et
al
.(1996) found that all the strains of
Legionella
had the growth reduced at
temperatures between 44 and 45 °C, and the limit temperature for growth
of the microorganism is between 48.4 and 50 °C. With strains of Legionellae
of this same study, they confirmed the presence of carbon dioxide (CO
2
)
produced in the medium at temperatures of up to 51.6 °C, which suggests
the stability of respiratory enzymes of the bacterium at this temperature.
