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Applied and Environmental Microbiology, January 2001, p. 225-230, Vol. 67, No. 1
Departamento de Química
Biológica1 and Departamento de
Ciencias Biológicas,2 Facultad de Ciencias
Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires,
and Departmento de Radiobiología, Comisión
Nacional de Energía Atómica, 1650 San Martin, Buenos
Aires,3 Argentina
Received 24 July 2000/Accepted 17 October 2000
Pseudomonas oleovorans GPo1 and its polyhydroxyalkanoic
acid (PHA) depolymerization-minus mutant, GPo500 phaZ,
residing in natural water microcosms, were utilized to asses the effect
of PHA availability on survival and resistance to stress agents. The
wild-type strain showed increased survival compared to the PHA
depolymerase-minus strain. The appearance of a round cellular shape,
characteristic of bacteria growing under starvation conditions, was
delayed in the wild type in comparison to the mutant strain. Percent
survival at the end of ethanol and heat challenges was always higher in
GPo1 than in GPo500. Based on these results and on early experiments
(H. Hippe, Arch. Mikrobiol. 56:248-277, 1967) that suggested an
association of PHA utilization with respiration and oxidative
phosphorylation, we investigated the association between PHA
degradation and nucleotide accumulation. ATP and guanosine tetraphosphate (ppGpp) production was analyzed under culture conditions leading to PHA depolymerization. A rise in the ATP and ppGpp levels appeared concomitant with PHA degradation, while this phenomenon was
not observed in the mutant strain unable to degrade the polymer. Complementation of the phaZ mutation restored the wild-type phenotype.
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.1.225-230.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Polyhydroxyalkanoate Degradation Is Associated with Nucleotide
Accumulation and Enhances Stress Resistance and Survival of
Pseudomonas oleovorans in Natural Water Microcosms
*
Corresponding author. Mailing address: Departmento de
Química Biológica, Facultad de Ciencias Exactas y
Naturales, Ciudad Universitaria, Pabellón 2, 1428 Buenos Aires,
Argentina. Phone: 54-11-4576-3334. Fax: 54-11-4576-3342. E-mail:
bea{at}qb.fcen.uba.ar.
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