Influence of anr on polyhydroxyalkanoate synthesis in Pseudomonas extremaustralis

PAULA M. TRIBELLI; LAURA J. RAIGER- IUSTMAN; BEATRIZ MENDEZ; NANCY I. LOPEZ

San Miguel de Tucuman

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

Polyhydroxyalkanoates (PHAs) are reserve polymers accumulated during unbalanced growth conditions. PHAs enhance survival and stress tolerance in bacteria and have biotechnologycal interest. We analyzed an Antarctic bacterium, Pseudomonas extremaustralis, that is able to accumulate large amounts of polyhydroxybutyrate (PHB). Genes of PHB synthesis, located in an adaptability island, shows an Anr-box in the promoter region. Anr is a global anaerobic regulator in Pseudomonas. We have previously characterized the microaerobic metabolism of P. extremaustralis and cloned anr gene.  The regulation by Anr on PHB genes is still unknown. We constructed an anr mutant of P.extremaustralis by crossover PCR deletion technique. To study the role of Anr on the PHB synthesis we used controled bioreactor cultures under different aeration conditions. Wild type biomass was higher than mutant biomass in all conditions Mutant strain showed a pleiotropic phenotype. In microaerobiosis the content of PHB in the wild type was 51% (w/w) while in the anr mutant was only 21%. In aerobiosis the PHB content was low for both strains. Results showed a relationship between Anr and PHB accumulation. Further studies of PHB genes expression by Real Time PCR will corroborate the action of Anr. Microaerobic PHB production could help to reduce cost of the process resultant from aeration.