A MODEL SYSTEM DERIVED FROM MARINE DIATOMS FOR INVESTIGATING THE ACTIVITY OF PARTICLE-ASSOCIATED BACTERIA

A model system for examining bacterial attachment to and degradation of marine particulate matter is described. The model particles consisted of a hydrophilic matrix derived from marine diatoms, contained primarily Si, Ca and Al oxides, and had high surface area relative to weight. A marine Pseudomonas sp. (NCMB 2021) attached readily to the particles. Biomass of free and particle-associated bacteria was quantified using direct counts, radiolabeling, and protein determination. Bacterial activity was assayed by measuring the hydrolysis of L-leucine-methylcumarinylamide, a fluorescently labeled substratum, that served as an analog to protein macromolecules. The cell-specific rate of substratum hydrolysis by attached bacteria was half that of free-living bacteria. © 1990.