Q-305. Phenotype Microarray Comparisons of Bacillus subtilis 168 and FBC5 Mutant Impaired in Calcium Carbonate Precipitation

M. Marvasi1, M. Zurita2, P. Visscher3, G. Mastromei1, B. Perito1, L. Casillas-Martinez2;
1Univ. of Florence, Florence, ITALY, 2Univ. of Puerto Rico, Humacao, PR, 3Univ. of Connecticut, Storrs, CT.

Phenotype microarrays (PM) allow gene function comparisons of wild type and mutants based on differences in carbon, nitrogen, phosphorus and sulfur utilization. Using PM we have compared the physiology of Bacillus subtilis-168 and etfA-mutant (FBC5) incapable of calcite formation. As etfA is linked to fatty acid metabolism we initially compared differences in the carbon utilization by both strains. Consequently we compared 192 different carbon sources during growth of both strains in a calcium-rich medium. All PM plates were incubated for twenty-four hours at 37ºC. The etfA mutation apparently affected the carbon utilization patterns of the mutant as wild type grew in nineteen additional carbon sources than the mutant. Similar results were reported with the nitrogen, phosphorus and sulfur plates were the mutant utilized only a few substrates while wild type was able to use most substrates. Interestingly, FBC5 exhibits preferential growth at higher pH (up to 9.5) than the wild type. Physiological differences were also observed in the cytoplasmic proteins expressed when extracts of wild-type and FBC5 were compared using two-dimensional gel analyses. Two proteins belonging to the tricarboxilic acid cycle were differentially expressed in the mutant and the wild type during growth with calcium acetate. Our next step is to continue the identification of other proteins differentially expressed and pursue a structural study of cells to determine why only the wild type serves as platform for carbonate precipitation.