Alcaligenes faecalis subsp parafaecalis subsp nov., a bacterium accumulating poly-beta-hydroxybutyrate from acetone-butanol bioprocess residues

The authors have previously isolated a solvent tolerant bacterium, strain G (T), (T = type strain) capable to convert acetone-butanol bioprocess residu es into poly-beta -hpdroxybutyrate. Strain G(T) was initially identified as Alcaligenes spp by standard bacteriological tests. In this study the taxon omic position of the bacterium was investigated in detail. The 16S rDNA seq uence analysis, the G + C content of DNA (56 mol%) and the presence of ubiq uinone Q-S confirmed strain Gr as a representative of the genus Alcaligenes . In the polyamine pattern of the bacterium putrescine and cadaverine were detected, bur only trace amounts of 2-hydroxyputrescine. The extremely low content of 2-hydroxyputrescine is remarkable, since this unique diamine is a common marker for P-proteobacteria. Phylogenetic analyses of 16S rDNA dem onstrated that Alcaligenes sp. G(T) is most closely related to the species Alcaligenes faecalis (99.6% sequence similarity to A. faecalis HR4 and 98.7 % sequence similarity to A. faecalis [ATCC 8750(T) = DSM 30030(T)]. On the basis of DNA-DNA relatedness (56% similarity), the unique polyamine pattern , the physiological and biochemical differences strain G(T) could be distin guished from the species A. faecalis. Therefore, a new subspecies for the s pecies Alcaligenes faecalis is proposed; Alcaligenes faecalis subsp. parafa ecalis subsp. nov.