PECULIARITIES IN THE STRUCTURE OF CHROMOSOMAL DNAS FROM THIOBACILLUS-FERROOXIDANS STRAINS ADAPTED TO GROWTH ON MEDIA WITH PYRITE OR ELEMENTAL SULFUR

Structural properties of XbaI-digested chromosomal DNAs from four Thio bacillus ferrooxidans strains adapted to growth on media with pyrite o r elemental sulfur were studied by pulsed-held gel electrophoresis. Th e strains of different origin differed in the responses of their genom es to a change in the energy source. No changes in the chromosomal DNA s were observed for strains VKM B-458, 458As2, and 458M. The adaptatio n of strain TFBk to growth in media with pyrite or elemental sulfur re sulted in the appearance of new bands in the XbaI-restriction patterns of chromosomal DNA, the disappearance of certain bands, and changes i n the number of generated fragments of the same length as compared to restriction patterns of the culture grown in medium with FeSO4. After several passages of strain 458As2 on medium with elemental sulfur as t he only energy source, amplification of the 28-kb fragment of DNA coul d no longer be revealed, and the resistance of this strain to As3+ dec reased. The influence of the strain origin, i.e., the place and substr ate from which the strain was isolated, and the energy source in the g rowth medium on the peculiarities of the chromosomal DNA structure wer e discussed.