Lawrence Berkeley National Laboratory

ABSTRACT=A sulfate reducing bacterium was isolated from the Paleta Creek site in San Diego Bay with 60mM lactate as the sole carbon source and electron donor, and 50mM sulfate as the electron acceptor. The novel isolate, strain PCS is an anaerobic, non-sporulating, gram-negative organism that is highly motile. The optimum temperature for growth of strain PCS was determined to be 370C. Preliminary 16S rDNA analysis revealed that the closest relative to strain PCS is Desulfovibrio africanus (98 % similar). Light microscopy and SEM images of individual cells reveal sigmoid morphology. Cells of strain PCS appear like slender curved rods during the early log phase and spiral in exponential/stationery phase to approx 5-10mM in length and 0.2mM in width. In this regard, strain PCS is less than half the width of its closest known relative D.africanus. The images also reveal the presence of lemon shaped/spherical structures approx 1mM in diameter especially in early log and stationa!