Influence of bacterial type and density on population growth of bacterial-feeding nematodes

The contribution of bacterial-feeding nematodes to litter decomposition and nutrient mineralization depends, in part, on the abundance of particular nematode species. Population dynamics will be constrained by edaphic factors, food availability and food quality. We report the population growth rates for six nematode species as affected by different bacterial isolates and by changes in food supply. Populations of Caenorhabditis elegans grew faster than any other nematode-bacterium combination when Bacillus polymyxa was supplied as food (λ=12.26 d−1). Caenorhabditis elegans also exhibited the greatest variation in population growth rate across the set of bacteria investigated. Acrobeloides bodenheimeri, A. buetschlii, Bursilla labiata, C. elegans, Cephalobus persegnis, and Rhabditis cucumeris did not develop or reproduce when fed Streptomyces halstedii scabies. Within the range of food concentrations considered, the six nematode species approached their respective maximal population growth rate between 104 and 105 colony-forming-units (CFUs) per nematode. Populations stopped growing when food concentrations declined to 103–104 CFUs per nematode. Between 103 and 106 CFUs per nematode, variation in population growth rate due to changes in food supply was greatest for C. elegans and was least for A. buetschlii.