Hydrogenophaga, a new genus of hydrogen-oxidizind bacteria that includes Hydrogenophaga flava comb. nov. (formerly Pseudomonas flava), Hydrogenophaga palleronii (formerly Pseudomonas palleronii), Hydrogenophaga pseudoflava (formerly Pseudomonas pseudoflava and 'Pseudomonas carboxydoflava'), and Hydrogenophaga taeniospiralis (formerly Pseudomonas taeniospiralis)