Growth kinetics of Aeromonas hydrophila in freshwaters supplemented with various organic and inorganic nutrients

Freshwaters of varying natural nutrient enrichment were used as growth media for the culture of an autochthonous, heterotrophic, freshwater bacterium, Aeromonas hydrophila. The growth rate of the bacterium in eutrophic waters was increased to the greatest extent by adding carbon, as glucose; generation times decreased by up to 65%. Additions of carbon and phosphorus increased the maximal cell densities by over 25-fold. In oligotrophic waters, bacterial growth was most strongly promoted by the simultaneous additions of carbon (as glucose) and phosphorus (as KH₂PO₄). In these waters, stationary phase densities were increased as much as 100-fold, with a corresponding 70% increase in growth rate. These data provide at least a partial explanation for the previously observed correlation between A. hydrophila densities and the trophic states of freshwaters.The authors are with the Department of Microbiology, Morrill Hall, University of Rhode Island, Kingston, Rhode Island 02881, USA