High Degree of Similarity between Chromatium vinosum and Chromatium minutissimum as Revealed by Riboprinting

The riboprinting technique (restriction fragment length polymorphism [RFLP] analysis of PCR-amplified ribosomal DNA) was used to study five strains representing three species of the genus Chromatium. An RFLP analysis following digestion of the amplified small-subunit ribosomal DNA with 25 restriction enzymes revealed that the patterns obtained for all strains of Chromatium vinosum were identical. Chromatium gracile was different from C. vinosum with seven enzymes. On the other hand, Chromatium minutissimum produced the same patterns as C. vinosum with all enzymes, indicating that these organisms have a high degree of similarity. An RFLP analysis of the PCR-amplified spacer sequence between the 16S and 23S ribosomal DNAs gave similar results except that there was a larger number of differences between C. gracile and the other organisms examined.