Association between high polyhydroxybutyrate production and high stress resistance in Pseudomonas sp. 14-3 isolated from antarctic environments

AYUB ND; LÓPEZ NI; MÉNDEZ BS

Fundación de Investigaciones Biológicas, Cuidad de Mar del Plata, Argentina.

Congreso; Primer Congreso Argentino de Microbiología General (SAMIGE).; 2004

SAMIGE

Genes responsible for the synthesis of polyhydroxybutyrate (PHB) in Pseudomonas extremoaustralis, a new sp. isolated from a temporary pond in Antarctica, were cloned and analyzed. This species shows high stress resistance in association with high (up to 70 % of its cell dry weight) PHB production. It accumulates PHB using octanoate but not glucose as a carbon source. A PHB polymerase gene (phbC) was found downstream from genes coding for a beta-ketothiolase (phbA) and acetoacetyl-coenzyme A reductase (phbB). The phbC gene from this strain was introduced into Ralstonia eutropha PHB-4 (phbC-negative mutant), restoring the PHB phenotype. Genes encoding putative insertion sequences, introns, membrane transporters and plasmidic proteins, were found downstream of the phb gene cluster, resembling genomic islands. The association between mobile genetic elements and phb genes suggests that horizontal transfer could be an adaptive response of species inhabiting extreme environments.