Uriel Gutiérrez-Gómez1,2, Martín P Soto-Aceves2, Luis Servín-González1,2, Gloria Soberón-Chávez3,4. 1. Programa de Producción de Biomoléculas de Interés Biomédico en Bacterias y Hongos, Mexico, Mexico. 2. Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, Mexico, D.F., Mexico. 3. Programa de Producción de Biomoléculas de Interés Biomédico en Bacterias y Hongos, Mexico, Mexico. gloria@biomedicas.unam.mx. 4. Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, Mexico, D.F., Mexico. gloria@biomedicas.unam.mx.
Abstract
OBJECTIVE: To construct Pseudomonas aeruginosa PA14 derivatives that overproduce rhamnolipids (RL) by blocking the synthesis of the carbon-storage polymer polyhydroxyalkanoates (PHA) and by overexpressing the rhlAB-R operon that encodes for enzymes of RL synthesis and the RhlR transcriptional regulator. RESULTS: In contrast to previous results showing that overexpression of rhlAB-R genes in two P. aeruginosa strains (PAO1 and ATCC 9027) is sufficient to overproduce RL, we show that a PA14 derivative overexpressing the rhlAB-R operon did not increase the synthesis of these biosurfactants. In addition, PA14 mutants deficient in PHA production did not overproduce RL either. However, if the rhlAB-R genes were expressed in a mutant that is completely impaired in PHA synthesis, a significant increase in RL production was observed (59%). These results show that RL production in PA14 is limited both by the availability of fatty acid precursors and by the levels of the RhlA and RhlB enzymes that are involved in the synthesis of mono-RL. CONCLUSIONS: The limitation of RL production by P. aeruginosa PA14 is multifactorial and diverse from the results obtained with other strains. Thus, the factors that limit RL production are particular to each P. aeruginosa strain, so strain-specific strategies should be developed to increase their production.
OBJECTIVE: To construct Pseudomonas aeruginosa PA14 derivatives that overproduce rhamnolipids (RL) by blocking the synthesis of the carbon-storage polymerpolyhydroxyalkanoates (PHA) and by overexpressing the rhlAB-R operon that encodes for enzymes of RL synthesis and the RhlR transcriptional regulator. RESULTS: In contrast to previous results showing that overexpression of rhlAB-R genes in two P. aeruginosa strains (PAO1 and ATCC 9027) is sufficient to overproduce RL, we show that a PA14 derivative overexpressing the rhlAB-R operon did not increase the synthesis of these biosurfactants. In addition, PA14 mutants deficient in PHA production did not overproduce RL either. However, if the rhlAB-R genes were expressed in a mutant that is completely impaired in PHA synthesis, a significant increase in RL production was observed (59%). These results show that RL production in PA14 is limited both by the availability of fatty acid precursors and by the levels of the RhlA and RhlB enzymes that are involved in the synthesis of mono-RL. CONCLUSIONS: The limitation of RL production by P. aeruginosa PA14 is multifactorial and diverse from the results obtained with other strains. Thus, the factors that limit RL production are particular to each P. aeruginosa strain, so strain-specific strategies should be developed to increase their production.
Authors: Beatriz Pérez-Armendáriz; Carlos Cal-Y-Mayor-Luna; Elie Girgis El-Kassis; Luis Daniel Ortega-Martínez Journal: AMB Express Date: 2019-05-06 Impact factor: 3.298