Co-synthesis of medium-chain-length polyhydroxyalkanoates and CdS quantum dots nanoparticles in Pseudomonas putida KT2440

• Published in: Journal of biotechnology Vol. 264; pp. 29 - 37
• Main Authors: Oliva-Arancibia, Barbara, Órdenes-Aenishanslins, Nicolás, Bruna, Nicolas, Ibarra, Paula S., Zacconi, Flavia C., Pérez-Donoso, José M., Poblete-Castro, Ignacio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.12.2017
• Subjects: Cadmium Compounds - chemistry; Cadmium Compounds - metabolism; CdS quantum dots; Coproduction; MCL-Polyhydroxyalkanoates; Particle Size; Polyhydroxyalkanoates - analysis; Polyhydroxyalkanoates - chemistry; Polyhydroxyalkanoates - isolation & purification; Polyhydroxyalkanoates - metabolism; Pseudomonas putida; Pseudomonas putida - metabolism; Quantum Dots - chemistry; Quantum Dots - metabolism; Sulfides - chemistry; Sulfides - metabolism; Coproduction; MCL; CdS quantum dots; PHA; QDots; Pseudomonas putida; MCL-Polyhydroxyalkanoates
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2017.10.013

•In this work, we used KT2440 to efficiently coproduce CdS Qdots and mcl-PHAs in batch cultures.•The PHA and biomass yields in KT2440 were almost not affected under coproducing conditions compared to the ones showed in cells where PHA was the only target compound.•The fluorescence of cells biosynthesizing CdS QDots depends on the concentration of cadmium used and exposure time.•TEM micrographs show that the PHA and QDots are localized at different sites of the cell, showing no apparent interaction.•To the best of our knowledge this is the first report showing the biological cosynthesis of two important chemicals for nanotechnological applications. Microbial polymers and nanomaterials production is a promising alternative for sustainable bioeconomics. To this end, we used Pseudomonas putida KT2440 as a cell factory in batch cultures to coproduce two important nanotechnology materials– medium-chain-length (MCL)-polyhydroxyalkanoates (PHAs) and CdS fluorescent nanoparticles (i.e. quantum dots [QDots]). Due to high cadmium resistance, biomass and PHA yields were almost unaffected by coproduction conditions. Fluorescent nanocrystal biosynthesis was possible only in presence of cysteine. Furthermore, this process took place exclusively in the cell, displaying the classical emission spectra of CdS QDots under UV-light exposure. Cell fluorescence, zeta potential values, and particles size of QDots depended on cadmium concentration and exposure time. Using standard PHA-extraction procedures, the biosynthesized QDots remained associated with the biomass, and the resulting PHAs presented no traces of CdS QDots. Transmission electron microscopy located the synthesized PHAs in the cell cytoplasm, whereas CdS nanocrystals were most likely located within the periplasmic space, exhibiting no apparent interaction. This is the first report presenting the microbial coproduction of MCL-PHAs and CdS QDots in P. putida KT2440, thus constituting a foundation for further bioprocess developments and strain engineering towards the efficient synthesis of these highly relevant bioproducts for nanotechnology.