Microaerobic growth in a polyhydroxyalkanoate-producing Pseudomonas

TRIBELLI, P.M.; MÉNDEZ, B.S.; LÓPEZ, N.I.

Mar del Plata, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Microaerobic growth in a polyhydroxyalkanoate-producing Pseudomonas Tribelli, Paula M.; Méndez, Beatriz S. and López, Nancy I. Dpto. de Química Biológica. Facultad de Ciencias Exactas y Naturales, UBA. paulatrib@qb.fcen.uba.ar   Pseudomonas sp. 14-3 is an Antarctic strain isolated in our laboratory that accumulates high amounts of polyhydroxyalkanoates (PHA). This reserve polymer is a sink for carbon and reducing equivalents having an important role in stress resistance and redox balance.  In Pseudomonas the transition from aerobic to anaerobic growth is regulated by Anr. This regulator controls several genes such as nitrate reductase and the ArcDABC operon related with the utilization of arginine. Genes involved in PHA biosynthesis of Pseudomonas sp. 14-3 have been characterized, showing a putative Anr-box, site of binding of Anr. It suggests its relationship with PHA biosynthesis. In this work, we identified anr and analyzed the growth of Pseudomonas sp. 14-3 under microaerobic conditions. This strain was able to growth in nitrate supplemented medium tightly closed bottles, producing until to 1.1 g/l of nitrite after 48 h of culture. Arginine fermentation supported survival and slow growth showing lower arginine deiminase activity compared with P. aeruginosa. Amplification by PCR, cloning and sequencing of anr showed that it was highly similar (88% of identity) to P. fluorescens PfO-1. The amplified fragment complemented an E.coli mutant of fnr, gene homologous to anr. Analysis of the regulation of PHA synthesis under microaerobic conditions will contribute to optimize its production in Pseudomonas.