Distribution of Pseudomonas aeruginosa in a riverine ecosystem.

The distribution of Pseudomonas aeruginosa in navigation pool 8 of the upper Mississippi River was investigated by acetamide broth enrichment of water, sediment, and swab (solid-water interface) samples. Among the 152 P. aeruginosa isolates, serological type 1 was most prevalent (34.2%), and a small number (13.2%) showed carbenicillin resistance. Pigmentation was variable, with only 44.7% elaborating typical blue-green pigment. P. aeruginosa was most commonly isolated from sediment, with solid-water interfaces (aufwuchs samples) also exhibiting high frequencies of isolation. Current velocity, oxygen and nutrient availability, surface tension, desiccation, and negative phototropism were important factors in the riverine distribution of this epibacterium.