title: Microbial demetallization of crude oil: nickel protoporphyrin disodium as a model organo-metallic substrate.
abstract: A soil isolate designated as YA-1 strain was selected for its ability to degrade nickel protoporphyrin disodium (NiPPDS). The strain was capable of utilizing NiPPDS as the sole source of carbon. This strain, a gram-negative aerobic rod, was identified as Pseudomonas azelaica YA-1 based on the result of its 16S rRNA analysis. Product analyses by HPLC showed that this strain can decompose the porphyrin ring to which a metal ion is bound. However, the use of whole bacterial cells cannot result in extensive NiPPDS degradation; therefore, the YA-1 enzyme was extracted and purified. This NiPPDS-degrading enzyme named as protoporphyrinase was purified from P. azelaica YA-1 by ammonium sulfate fractionation and sequential chromatographies using DEAE Toyopearl 650 M, CM Toyopearl 650 M and Biogel P-60 columns, with a yield of 11.3% based on the enzyme activity and an overall purification of 498-fold. The molecular weight of this enzyme is estimated to be 39,000 Da by SDS-PAGE and 34,000 Da by gel filtration. The optimum pH and temperature for the enzyme were 7.0 and 30 degrees C, respectively. The activity was stable at pH 2.0-11.0 and at temperatures below 50 degrees C. The enzyme activity was inactivated by ferric chloride, potassium ferricyanide, ZnCl2 and CdCl2.
authors.affiliation: Laboratory of Applied Microbiology, Graduate School of Agriculture, Hokkaido University, 9 Kita, 9 Nishi, Sapporo, Hokkaido 060-8589, Japan.
authors.forename: G R
authors.initials: GR
authors.lastname: Dedeles
authors.forename: A
authors.initials: A
authors.lastname: Abe
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: K
authors.initials: K
authors.lastname: Asano
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: A
authors.initials: A
authors.lastname: Yokota
authors.forename: F
authors.initials: F
authors.lastname: Tomita