Purification of PHBV depolymerase from S.omiyaensis and phytotoxic properties of isolated monomers

MEDINA V; MIYAZAKI SS; YASHCHUK O

Congreso; 45th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2009

A bacterial strain capable of degrading poly(3-hydroxybutyrate-cohydroxyvalerate) (PHBV) was isolated from a soil sample. This organism, was identified as Streptomyces omiyaensis SSM5670, secreted PHBV depolymerase into the culture minimum medium when PHBV was added as the only carbon source. The poly (3-hydroxybutyrate-co-hydroxyvalerate) depolymerase from S.omiyaensis SSM5670 was purificated from culture supernatant. This enzyme was concentrated 90-fold by high pressure ultrafiltration (Stirred Ultrafiltration Cells Modes 8200 Device, Milllipore) through YM 10 membrane then was purified to electrophoretic homogeneity by ion exchange column chromatography on DEAE-Sephadex A-50 and gel filtration on Sephadex G-150. The molecular mass of the PHBV depolymerase was estimated to be 24.0 kDa by 12% SDS-PAGE. The maximum activity was observed near pH 7.0 and 32ºC, the activity was lost at temperatures above 45ºC. The enzyme, released into the medium butyric and valeric monomers, 1mM of these compounds inhibited the bacterial growth up to 30%. The same inhibition effects were observed on Lactuca sativa when stabilized compost with PHBV was inoculated with this actinomycete. Concentrations of 5 mM of butyric and valeric acid released from PHBV samples showed full inhibition of seed germination. The phytotoxicity of these monomers increased with time contact and monomer concentration