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Applied and Environmental Microbiology, January 2001, p. 225-230, Vol. 67, No. 1
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

Jimena A. Ruiz,1 Nancy I. López,1,2 Rubén O. Fernández,3 and Beatriz S. Méndez1,*

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.

* 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.

Applied and Environmental Microbiology, January 2001, p. 225-230, Vol. 67, No. 1
0099-2240/01/$04.00+0   DOI: 10.1128/AEM.67.1.225-230.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.


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Copyright © 2001 by the American Society for Microbiology. All rights reserved.