FIG. 1.

Growth rate and PCR amplification analysis of the lacS gene in S. solfataricus Gθ and LacS⁻ mutant derivatives. (A) Cell density was monitored at 600 nm in mineral medium supplemented with 0.1% yeast extract, 0.1% Casamino Acids, and 0.1% glucose for cultures of the wild-type Gθ (▵) and mutant GθW (•). Growth trends for the mutants Gθwb1 and Gθwb2 and the parental Gθ matched perfectly. (B) Amplicons were obtained with two pairs of primers, IVS1-IVS2 and lacFw-lacRe, designed on the wild-type DNA sequence to amplify a 248-bp internal region (lane A) or the entire 1,470-bp coding sequence (lane E). Corresponding amplification products from mutant GθW (lanes B and F), as well as Gθwb1 (lanes C and G) and Gθwb2 (lanes D and H), genomic DNAs were analyzed by agarose gel electrophoresis with reference to a mixture of pBR328 DNA cleaved with BglI and pBR328 DNA cleaved with HinfI used as a molecular weight marker (lane M). OD₆₀₀, optical density at 600 nm.