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Effects of pH and Temperature on the Fatty Acid Composition of Bacillus acidocaldarius

CNR Laboratorio per la Chimica e Fisica di Molecole di Interesse Biologico, Arco Felice, Napoli, Italy, and Microbial Chemistry Laboratory, Department of Chemistry, The University, Manchester, England

ABSTRACT

The fatty acid composition of lipid extracts from cells of Bacillus acidocaldarius grown at temperatures of 50 to 70 C and pH values of 2 to 5 was determined by gas chromatography of the methyl esters. The most abundant fatty acids are 11-cyclohexylundecanoic and 13-cyclohexyltridecanoic, followed by anteiso- and iso-heptadecanoic; unsaturated acids are absent. Highly aerated cultures produce more of the iso and anteiso acids and less of the cyclohexyl acids. The effects of temperature and pH are interdependent; at lower pH, increasing temperature raises the proportion of the iso and anteiso acids, but at higher pH the effect of increasing temperature is reversed and the proportion of the cyclohexyl acids is increased.