Bacterial scavenging: Utilization of fatty acids localized at a solid-liquid interface

A model oligotrophic aquatic system involving localization of fatty acids on a solid surface was used to quantitate scavenging by three bacteria; Leptospira biflexa patoc 1 which adheres reversibly, pigmented Serratia marcescens EF190 which adheres irreversibly, and a non-pigmented hydrophilic mutant of EF190. The Leptospira and pigmented Serratia displayed two distinct scavenging strategies which are related to their different methods of adhesion. The Leptospira efficiently scavenged [1-¹⁴C] stearic acid from the surface in 24 h, whereas the pigmented hydrophobic Serratia initially showed a faster rate of removal but the overall rate was considerably slower than that of the Leptospira. The hydrophilic, non-pigmented Serratia required 50h incubation to remove significant amounts of the labelled fatty acid. The greater scavenging ability of the hydrophobic pigmented Serratia strain compared to the hydrophilic non-pigmented mutant could not be attributed to differences in viability of fatty acid metabolism. The hydrophobicity of the pigmented Serratia allows for firmer adhesion and greater interaction with the surface localized nutrients.