The hypothesis of this thesis was that there are proteins of ' F. psychrophilum' that are upregulated during growth at 8°C compared with 18°C. Two-dimensional polyacrylamide gel electrophoresis was used to examine low-temperature induced spot-pattern differences of two strains of 'F. psychrophilum' (FpG3 and 25). The spots of greatest interest were those that were only present at 8°C or those that were more prominent at 8°C vs. 18°C. One and six spots met these criteria for ' F. psychrophilum' strains FpG3 and 25, respectively. Internal amino acid sequence was obtained for two spots from FpG25 that were present only at 8°C and 4 spots from FpG25 that were upregulated at 8°C compared with 18°C. Based on available sequences in Genbank these proteins were most similar to a Flavo-specific protein antigen FspA precursor, a 50S ribosomal protein L7/L12 of 'F. psychrophilum' and four hypothetical proteins of 'F. psychrophilum'; FP2384, FP2412, FP2104 and FP2052.