METHYLOSULFONOMONAS METHYLOVORA GEN-NOV, SP-NOV, AND MARINOSULFONOMONAS-METHYLOTROPHA GEN-NOV, SP-NOV - NOVEL METHYLOTROPHS ABLE TO GROW ONMETHANESULFONIC-ACID

Two novel genera of restricted facultative methylotrophs are described both Methylosulfonomonas and Marinosulfonomonas are unique in being a ble to grow on methanesulfonic acid as their sole source of carbon and energy. Five identical strains of Methylosulfonomonas were isolated f rom diverse soil samples in England and were shown to differ in their morphology, physiology, DNA base composition, molecular genetics, and 16S rDNA sequences from the two marine strains of Marinosulfonomonas, which were isolated from British coastal waters. The marine strains we re almost indistinguishable from each other and are considered to be s trains of one species. Type species of each genus have been identified and named Methylosulfonomonas methylovora (strain M2) and Marinosulfo nomonas methylotropha (strain PSCH4). Phylogenetic analysis using 16S rDNA sequencing places both genera in the alpha-Proteobacteria. Methyl osulfonomonas is a discrete lineage within the alpha-2 sub group and i s not related closely to any other known bacterial genus. The Marinosu lfonomonas strains form a monophyletic cluster in the alpha-3 subgroup of the Proteobacteria with Roseobacter spp. and some other partially characterized marine bacteria, but they are distinct from these at the genus level. This work shows that the isolation of bacteria with a un ique biochemical character, the ability to grow on methanesulfonic aci d as energy and carbon substrate, has resulted in the identification o f two novel genera of methylotrophs that ale unrelated to any other ex tant methylotroph genera.