Reaction of airborne Rhizobium meliloti to some environmental factors.

Survival of Rhizobium meliloti 102F5 in aerosols at 20 C was maximal at high relative humidity (RH) and minimal at low RH. Relatively high concentrations of NO(2), SO(2), or formaldehyde were needed to significantly reduce viability of R. meliloti in aerosols at 50% RH. Except for the reduction in activity of formaldehyde by SO(2), there was no additive or antagonistic effect of mixing pollutants. High environmental RH enhanced bactericidal activity of NO(2) and SO(2). High RH minimized and low RH accentuated the biological effect of ultraviolet light of 300 to 400 nm wavelength.