Total Lipid Comparison of Parental and Derived Acid Resistant Sulfolobus solfataricus at Optimal and Extreme pH
Sulfolobus solfataricus is a thermoacidophile belonging to the phylum Crenarchaeota with optimal growth conditions of pH 3.0 and 80°C. Via serial passaging, we have developed S. solfataricus strains, named super acid resistant crenarchaeota (SARC), with an inheritable phenotype of growth at pH 1.0, below the wild-type limit. The cell membrane found in archaean acidophiles is composed of a tetraether monolayer, as opposed to the ether-lipid bilayer found in other domains of life. This monolayer membrane structure, coupled with an abundance of oligosaccharide headgroups, lends heavily to the proton impermeability required for growth at low pH. As membrance lipid composition plays such an important role in acid resistance, we aimed to determine whether the phenotype found in SARC also included an inheritable shift in lipid class production. Total lipid fractions were extracted from SARC and parental strains, separated via TLC and detected with strains. We found that SARC grown at pH 1.0 produced different TLC spot patterns than the parental strain grown at pH 3.0, but SARC grown at pH 3.0 did not. The data implies that differences in total lipid composition in SARC grown at low pH occurs due to environmental effects rather than a permanent genetic shift in expression.