Diffusion through a double-sided plate: Development of a method to study alga-bacterium interactions

Bacteria and algae isolated from a wastewater oxidation pond were inoculated onto opposing surfaces of double-layer agar plates (Lutri plates) to determine the usefulness of such plates for studying microbial interactions. The altered growth characteristics of various algae depending on the species of bacteria on the adjacent medium surface indicated that there was diffusion of extracellular products through the agar, suggesting that this simple assay can be used for screening potential interactions of actively growing organisms

Microbial removal of chlorinated hydrocarbon pesticides from water

The removal of chlorinated hydrocarbon pesticides were examined by the use of two systems of microorganisms. One system was found to be composed of three Gram-negative bacteria. The second system was composed of four Gram negative bacteria, the three from the first system plus one additional organism. These organisms produced floc forming cultures which gave some evidence for the partial degradation of the pesticides by the identification of metabolic by-products and production of increased biomass. One of the organisms present in each system was shown to have small concentrations of bacteriochlorophyll and to function with CO2 as the only carbon source under anaerobic conditions. A complicated interrelationship of cross-feeding and synergistic growth was found to exist in the systems of mixed organisms. Light and electron microscopy studies showed initial pesticide removal was accomplished by adsorption to floc material formed by the systems, by absorption into the lipid material of the cells, and by a crystallization process carried out by certain cells. Flocculation was shown to be carried out by production of a polymer material of carbohydrate nature or by adsorption of individual cells to the highly charged pesticide material by means of surface charges. The environmental factors which regulated the flocculation process were examined and optimum conditions were determined. Both systems produced the best floc in shake cultures incubated at 30° C. The presence of light stimulated the amount and onset of floc formation in each system. Best flocculation was obtained when each system was grown in the presence of heptachlor and yeast extract. The optimum pH was 8.0 for System A and 7.0 for System D. System A showed best flocculation when 0.002% magnesium was present in the culture. Flocculation of System D cells was best with a magnesium concentration of 0.00002%.Biology and Biochemistry, Department o

The production of nutritious protein from petroleum

Six soil isolates were grown on a petroleum sulfonate medium and analyzed chromatographically to determine their amino acid composition. The organisms were also examined to determine their growth rate in the petroleum medium, their per cent conversion of hydrocarbon to dry cell mass, their protein content, and their possible use as a food or food supplement. It was found that the isolates varied extensively as to their amino acid composition. Several of the isolates proved to convert the hydrocarbons to cell mass with relative ease. The proteins of four of the isolates appear to be suitable as a good food source, and the protein of one of the remaining isolates appears to be a very good food supplement.Biology and Biochemistry, Department o

Diffusion through a Double-Sided Plate: Development of a Method to Study Alga-Bacterium Interactions

Bacteria and algae isolated from a wastewater oxidation pond were inoculated onto opposing surfaces of double-layer agar plates (Lutri plates) to determine the usefulness of such plates for studying microbial interactions. The altered growth characteristics of various algae depending on the species of bacteria on the adjacent medium surface indicated that there was diffusion of extracellular products through the agar, suggesting that this simple assay can be used for screening potential interactions of actively growing organisms