Identification of oxylipins with antifungal activity by LC-MS/MS from the supernatant of Pseudomonas 42A2.

In microorganisms hydroxy fatty acids are produced from the biotransformation of unsaturated fatty acids. Such compounds belong to a class of oxylipins which are reported to perform a variety of biological functions such as anti-inflammatory or cytotoxic activity. These compounds have been found in rice and timothy plants after being infected by specific fungus. When grown in submerged culture with linoleic acid, Pseudomonas 42A2 accumulated in the supernatant several hydroxy fatty acids. In this work LC-MS/MS has been used to elucidate the structure of the components form the organic extract: 9-hydroxy-10,12-octadecadienoic acid; 13-hydroxy-9,11-octadecadienoic acid; 7,10-dihydroxy-8E-octadecenoic acid; 9,10,13-trihydroxy-11-octadecenoic acid and 9,12,13-trihydroxy-10-octadecenoic acid. Antimicrobial activity against several pathogenic fungal strains is presented: MIC (microg/mL) Verticillium dhaliae, 32; Macrophonia phaesolina, 32; Arthroderma uncinatum, 32; Trycophyton mentagrophytes, 64

Design and characterization of conductive biopolymer nanocomposite electrodes for medical applications

Metal-based electrodes, despite being the most widely used for biomedical applications, are limited by a poor reliable skin-surface interface and patients suffer from comfort issues. The most common problems/inconveniences are caused by stiff electrodes, skin irritation, allergic reaction or corrosion. In order to overcome these problems, we produced and tested flexible electrodes involving biopolymer nanocomposite materials. Conductive polymers have been intensively studied and applied in the field of organic photovoltaics and flexible organic electronics. Recently, the use of conductive biopolymer nanocomposite has also emerged as an interesting and promising material for biomedical applications. In this study, we have designed and characterized electrodes made of a flexible and conductive nanocomposite material using a biocompatible and biodegradable polymeric matrix of poly (3- hydroxyalkanoate) (PHA, in particular poly (3-hydroxybutyrate), PHB) containing conductive nanowires. The biopolymer nanocomposites and their electrical conductivities were investigated by optical microscopy, scanning electron microscopy (SEM) and electrical four-point probing. The electrical conductivities obtained in the different PHA-polymer nanocomposites containing different concentrations of conductive additives is discussed in relation to the nanocomposite structure at the microscopic level. Finally, our developed biopolymer nanocomposite prototype electrodes have successfully been tested for transcutaneous electrical nerve stimulation (TENS) and electrocardiography ECG applications in comparison to conventional electrodes

Exploiting the natural poly(3-hydroxyalkanoates) production capacity of Antarctic Pseudomonas strains: from unique phenotypes to novel biopolymers

Extreme environments are a unique source of microorganisms encoding metabolic capacities that remain largely unexplored. In this work, we isolated two Antarctic bacterial strains able to produce poly(3-hydroxyalkanoates) (PHAs), which were classified after 16S rRNA analysis as Pseudomonas sp. MPC5 and MPC6. The MPC6 strain presented nearly the same specific growth rate whether subjected to a temperature of 4 °C 0.18 (1/h) or 30 °C 0.2 (1/h) on glycerol. Both Pseudomonas strains produced high levels of PHAs and exopolysaccharides from glycerol at 4 °C and 30 °C in batch cultures, an attribute that has not been previously described for bacteria of this genus. The MPC5 strain produced the distinctive medium-chain-length-PHA whereas Pseudomonas sp. MPC6 synthesized a novel polyoxoester composed of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydroxyoctanoate-co-3-hydroxydecanoate-co-3-hydroxydodecanoate). Batch bioreactor production of PHAs in MPC6 resulted in a titer of 2.6 (g/L) and 1.3 (g/L), accumulating 47.3% and 34.5% of the cell dry mass as PHA, at 30 and 4 °C, respectively. This study paves the way for using Antarctic Pseudomonas strains for biosynthesizing novel PHAs from low-cost substrates such as glycerol and the possibility to carry out the bioconversion process for biopolymer synthesis without the need for temperature control