COMPARISON OF A NEW THIOMICROSPIRA STRAIN FROM THE MID-ATLANTIC RIDGEWITH KNOWN HYDROTHERMAL VENT ISOLATES

A new autotrophic Thiomicrospira strain, MA-3, was isolated from the s urface of a polymetal sulfide deposit collected at a Mid-Atlantic Ridg e hydrothermal vent site. The DNA homology among three vent isolates, Thiomicrospira crunogena, Thiomicrospira sp. strain L-12, and Thiomicr ospira sp. strain MA-3, was 99.3% or higher, grouping them as the same species, T. crunogena (type strain, ATCC 35932). The fact that T. cru nogena and Thiomicrospira sp. strain L-12 were isolated from Pacific v ent sites demonstrates a cosmopolitan distribution of this species.