PHYLOGENY AND PHOTOSYNTHETIC FEATURES OF THIOBACILLUS-ACIDOPHILUS ANDRELATED ACIDOPHILIC BACTERIA - ITS TRANSFER TO THE GENUS ACIDIPHILIUMAS ACIDIPHILIUM-ACIDOPHILUM COMB. NOV

Phylogenetic analyses based on 16S rDNA sequences and genomic DNA-DNA relatedness showed that the sulphur-oxidizing facultative chemolithotr oph Thiobacillus acidophilus was closely related to members of the gen us Acidiphilium, which is a group of strictly aerobic, heterotrophic a cidophiles now categorized into aerobic photosynthetic bacteria. Lipop hilic pigment analyses revealed that zinc-chelated bacteriochlorophyll a and carotenoids occurred in appreciable amounts in T. acidophilus a nd all established species of the genus Acidiphilium, PCR experiments showed that T. acidophilus as well as Acidiphilium species contained p uf genes, encoding the photosynthetic reaction centre proteins and the core light-harvesting complex of the purple bacteria. There were high similarities between T, acidophilus and Acidiphilium species in the p rimary structure of their reaction centre proteins deduced from the nu cleotide sequence data, The phylogenetic tree of the reaction centre p roteins was in agreement with the 16S rDNA sequence-based phylogenetic tree in the relationship between T. acidophilus and Acidiphilium spec ies and between the Acidiphilium cluster and other purple photosynthet ic bacteria, Based on these results, together with previous phylogenet ic and phenotypic information, it is proposed to reclassify T, acidoph ilus (Guay and Silver) Harrison 1983 as Acidiphilium acidophilum comb, nov. The type strain is ATCC 27807(T) (= DSM 700(T)).