A mixed bacterial population in a continuous culture with and without kaolinite

Chromobacterium lividum and a Pseudomonas sp. were grown in pure and mixed continuous culture with and without the clay-mineral, kaolinite. Irrespective of the growth conditions, C. lividum adhered to the wall of the culture vessel whereas the Pseudomonas sp. showed no such tendency, at least visually. During mixed culture studies, the organism which was initially established in the culture dominated. The ratio between C. lividum and the Pseudomonas sp. was about 20:1 when C. lividum was first established and 1:2 when the Pseudomonas sp. was first grown. The indirect fluorescent antibody technique provided a rapid method for differentiating the mixed cultures when the bacterial concentration was sufficient for microscopic analysis. During both pure and mixed continuous culture studies, the addition of kaolinite reduced the C. lividum but not the Pseudomonas sp. population.