Polyphasic characterization of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (P(HB-co-HV)) metabolizing and denitrifying Acidovorax sp strains

For the purpose of denitrification in small drinking water plants, a bacterial mixed population was isolated from a packed bed column bioreactor with poly-3-hydroxybutyrate-co-3-hydroxyvalerate (P(HB-co-HV)) as a substrate for the denitrification of ground water (10 degreesC). Isolates 2nIII from the mixed culture, with the ability to denitrify and metabolize P(HB-co-HV), were used as starter cultures for the elimination of nitrate in ground water. The strains were characterized by diverse techniques. Classical phenotypic studies lead to rRNA group III of the genus Pseudomonas. Results obtained by molecular techniques demonstrated that the 2nIII strains are members of the Comamonadaceae and shows similarities to the genus Acidovorax. However, an integration of the 2nIII isolates within one of the known Acidovorax species is not possible for the moment. The 2nIII starter cultures clustered close to Av. temperans according to their whole cell proteins and fatty acids, whereas in DNA/DNA hybridization no significant DNA binding (< 25%) was found. In contrast a significant but low degree of: DNA/DNA hybridization was found between the 2nIII st rains and Av. facilis and Ar,. delafieldii. Our polyphasic results lead to the conclusion that the 2nIII strains may constitute a separate Acicdovorax species.