Characterization of non-discriminating tetramethylammonium hydroxide-induced thermochemolysis-capillary gas chromatography-mass spectrometry as a method for profiling fatty acids in bacterial biomasses.
Thermochemolysis using tetramethylammonium hydroxide (TMAH) as a method for profiling fatty acids (FAs) as methyl esters (FAMEs) was studied with respect to discrimination of bacterial fatty acid patterns in Gram-negative Pseudomonas putida in comparison with patterns obtained by classical preparation schemes (pressurized solvent extraction, alkaline saponification). A new, non-discriminating pyrolysis approach was used in these experiments. In this method, pyrolysis is carried out inside a deactivated stainless steel capillary constituting a part of the column train. This approach made it possible to distinguish analyte discrimination brought about by (i) the pyrolyzer set-up in conventional pyrolysis and (ii) chemical thermochemolysis reaction itself. Our results showed no significant discrimination for saturated, monounsaturated and cyclopropane FAs when using thermochemolysis temperatures up to 550 degrees C with the non-discriminating, capacitive-discharged based approach. Likewise, the cis/trans ratio of monounsaturated FAs was preserved. This is in sharp contrast to conventional pyrolysis systems (both Curie-point or flash pyrolyzers) using much longer thermochemolysis times. When using these systems, artificial monounsaturated FAMEs were formed during heat treatment resulting in biased species identification/classification. Hydroxy-FAs, chiefly bound covalently in lipopolysaccharides, could be almost quantitatively liberated by TMAH using non-discriminating pyrolysis (beyond 90%), whereas the recoveries were lower with conventional approaches. The new method makes it possible to profile fatty acids in very small amounts of both solid and liquid samples without significant sample preparation. This was exemplified by the results of TMAH-thermochemolysis of a fermentation broth taken from an in situ bioremediation reactor to monitor enhanced natural attenuation processes, and tomato roots which were subjected to cellulolytic bacteria attacks (Streptomyces), resulting in adsorption of these carboxymethyl-cellulose decomposing bacteria onto the root.
Poerschmann
Juergen
J
Center for Environmental Research, Permoserstrasse 15, 04318 Leipzig, Germany. juergen.poerschmann@ufz.de
Parsi
Ziba
Z
Górecki
Tadeusz
T
Augustin
Juergen
J
D018533:Biomass; D005227:Fatty Acids / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013696:Temperature
D005227:Fatty Acids; D000644:Quaternary Ammonium Compounds; C027917:tetramethylammonium