Biotransformation of volatile fatty acids by oleaginous and non-oleaginous yeast species.

The possibility of utilizing volatile fatty acids (VFA)-containing waste substrates from biotechnological and industrial processes was investigated by cultivating both oleaginous (Candida sp., Rhodotorula glutinis, Trichosporon cutaneum, Yarrowia lipolytica) and non-oleaginous (Kluyveromyces polysporus, Saccharomyces cerevisiae, Torulaspora delbrueckii) yeast species on acetic acid, propionic acid and a combination of either acid with glucose as carbon and energy sources. Both oleaginous and non-oleaginous yeasts grew on VFA.

New yeast-based approaches in production of palmitoleic acid.

Palmitoleic acid is found in certain dairy products and has broad applications in medicine and cosmetics. We tried to find a suitable producer of this acid among traditional biotechnological yeast species (Kluyveromyces polysporus, Torulaspora delbrueckii, Saccharomyces cerevisiae) characterized by high biomass yield and Candida krusei, Yarrowia lipolytica and Trichosporon cutaneum accumulating large amounts of lipids. The main factor affecting the content of palmitoleic acid was found to be the C/N ratio in the culture medium, with ammonium sulfate as an optimum nitrogen source leading to highest biomass yield with concomitantly increased lipid accumulation, and an increased content of ω6-linoleic acid, the precursor of prostaglandins, leukotrienes, and thromboxanes.

Multicomponent biosurfactants--A "Green Toolbox" extension.

The unflagging interest in the surfactants of biological origin, representing ecological alternatives to their synthetic counterparts, has enhanced R&D effort both to produce their new types and to resolve the bottlenecks of their commercialization. In this context, the rhamnolipids, offering a relatively large scale of potential applications, variety of congeners, low toxicity as well as stability towards the extremes of environment, logically attract attention. In this connection, the current state of knowledge concerning these compound exploitation, biosynthesis control and non-genetic factors affecting both production yield and final rhamnolipid product is surveyed.

Structural and physiochemical characterization of rhamnolipids produced by Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa in single strain and mixed cultures.

Rhamnolipids are naturally occurring biosurfactants with a wide range of potential commercial applications. As naturally derived products they present an ecological alternative to synthetic surfactants. The majority of described rhamnolipid productions are single strain Pseudomonas spp.

Pseudomonas biofilms: possibilities of their control.

Genus Pseudomonas includes a large number of species that can be encountered in biotechnological processes as well as in the role of serious human or plant pathogens. Pseudomonads easily form biofilms on various types of surfaces. The biofilm phenotype is characterized by an increased resistance to environmental influences including resistance to antibiotics and other disinfectants, causing a number of problems in health care, food industry, and other areas.

Characterization of rhamnolipids produced by non-pathogenic Acinetobacter and Enterobacter bacteria.

Rhamnolipid production by two non-pathogenic bacterial strains Acinetobacter calcoaceticus and Enterobacter asburiae, and established rhamnolipid producer Pseudomonas aeruginosa was investigated. Rhamnolipids were separated from supernatant and further purified by thin-layer chromatography. Mass spectrometry with negative electrospray ionization revealed rhamnolipid homologues varying in chain length and unsaturation.

Structural analysis of mycolic acids from phenol-degrading strain of Rhodococcus erythropolis by liquid chromatography-tandem mass spectrometry.

We used reversed phase liquid chromatography-electrospray ionization tandem mass spectrometry for direct analysis of mycolic acids (MAs) from four different cultivations of Rhodococcus erythropolis. This technique enabled us to identify and quantify the specific molecular species of MAs directly from lipid extracts of the bacterium, including the determination of their basic characteristics such as retention time and mass spectra. We identified a total of 60 molecular species of MAs by means of LC/MS.

Effect of surfactants on the biofilm of Rhodococcus erythropolis, a potent degrader of aromatic pollutants.

Bioremediation processes based on biofilms are usually very effective. The presence of (bio)surfactants in such processes can increase bioavailability of hydrophobic pollutants in aqueous phase. However, surfactants can affect the biofilm as well as individual microbial cells in different ways.

The genus Dracunculus--a source of triacylglycerols containing odd-numbered ω-phenyl fatty acids.

Reversed phase liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) was used to identify and quantify triacylglycerols (TAGs) having odd-numbered ω-phenylalkanoic acids from seeds of the flower plant Dracunculus vulgaris, and TAGs from the bacterium Rhodococcus erythropolis prepared by precursor directed biosynthesis from phenylalanine and having the corresponding even-numbered ω-phenylalkanoic acids. Model compounds, which are not commercially available, were prepared by organic synthesis and this allowed us to extend the number of identified natural TAGs to nearly 140 molecular species. Both synthetic and natural compounds containing ω-phenylalkanoic acids were found to have antioxidant and free radical scavenging properties.

Pivalic acid acts as a starter unit in a fatty acid and antibiotic biosynthetic pathway in Alicyclobacillus, Rhodococcus and Streptomyces.

A biosynthetic pathway using pivalic acid as a starter unit was found in three bacterial species, Alicyclobacillus acidoterrestris, Rhodococcus erythropolis and Streptomyces avermitilis. When deuterium-labelled pivalic acid was added to A. acidoterrestris and R.

RP-HPLC/MS-APCI analysis of branched chain TAG prepared by precursor-directed biosynthesis with Rhodococcus erythropolis.

Reversed phase liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) was used to analyze both synthetic triacylglycerols (TAG) having 1-3 branched fatty acids (FA) in the molecule, and natural TAG prepared by precursor directed biosynthesis from valine, leucine and isoleucine and the corresponding branched short-chain acids in cultivations of Rhodococcus erythropolis. The technique made it possible to identify and quantify TAG differing in a single branched-chain FA. Altogether 11 TAG were synthesized, out of which 8 were synthesized stereospecifically.

RP-HPLC/MS-APCI analysis of odd-chain TAGs from Rhodococcus erythropolis including some regioisomers.

We used reversed phase liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) for direct analysis of triacylglycerols (TAGs) from four different cultivations of Rhodococcus erythropolis CCM 2595. This technique enabled us to identify and quantify the specific molecular species of TAGs directly from lipid extracts of the bacterium, including the determination of their basic characteristics such as retention time and mass spectra. A total of 17 TAGs having at least one odd-numbered-chain FA (fatty acid) were found.