ORIGIN OF PALMITIC ACID CARBON IN PALMITATES FORMED FROM HEXADECANE-1-C-14 AND TETRADECANE-1-C-14 BY MICROCOCCUS CERIFICANS

Three degradation pathways of 1-octyl-3-methylimidazolium cation by activated sludge from wastewater treatment process

The biodegradability and degradation pathways of 1-octyl-3-methylimidazolium cation [OMIM](+) by microbial community of wastewater treatment plant in Jeonju city, Korea were investigated. It was found that [OMIM](+) could be easily degraded by the microbial community. New degradation products and pathways of [OMIM](+) were identified, which are partially different from previous results (Green Chem. 2008, 10, 214-224). For the analysis of the degradation pathways and intermediates, the mass peaks observed in the range m/z of 50-300 were screened by using a tandem mass spectrometer (MS), and their fragmentation patterns were investigated by MS/MS. Surprisingly, we found three different degradation pathways of [OMIM](+), which were separated according to the initially oxidized position i.e. middle of the long alkyl chain, end of the long alkyl chain, and end of the short alkyl chain. The degradation pathways showed that the long and short alkyl chains of [OMIM](+) gradually degraded by repeating oxidation and carbon release. The results presented here shows that [OMIM](+) can be easily biodegraded through three different degradation pathways in wastewater treatment plants.

Microbial assimilation of hydrocarbons. I. The fine-structure of a hydrocarbon oxidizing Acinetobacter sp

1. The fine-structure analysis of the hydrocarbon oxidizing microorganism, Acinetobacter sp., demonstrated a cytoplasmic modification resulting from growth on paraffinic and olefinic hydrocarbons. 2. Intracytoplasmic hydrocarbon inclusions were documented by electron microscopy with chemical identifications obtained by gas chromatography and X-ray diffraction. 3. These results demonstrate the ability of a microorganism to accumulate hydrocarbon substrates intracellularly which, in turn, indicates the transport across the cell membrane.

Comparative analysis of the lipids of Acinetobacter species grown on hexadecane

A comparative analysis of the cellular and extracellular lipids of Acinetobacter species HO1-N indicated basic physiological differences in hexadecane-grown cells. The cellular lipids obtained from hexadecane-grown cells were characterized by 3- and 18-fold increases in the phospholipid fraction and the mono- and diglyceride fraction, respectively, over that obtained from nutrient broth-yeast extract-grown cells. The cellular-associated pools of hexadecane were shown to comprise approximately 8% of the dry cell weight of hexadecane-grown cells. The extracellular lipids obtained from the culture broths of hexadecane-grown cells were comprised of triglyceride, mono- and diglyceride, free fatty acid, and wax ester. These lipids were either absent or present in minor concentrations in the culture broths of nutrient broth-yeast extract-grown cells. The exponential growth of Acinetobacter sp. on hexadecane was characterized by the significant accumulation of free fatty acid, monoglyceride, and diglyceride in the culture medium. Wax ester was shown to represent a minor portion of the extracellular lipids during the exponential growth phase, appearing in significant proportion only after the culture had entered the stationary phase of growth.

Metabolism of Propane, n -Propylamine, and Propionate by Hydrocarbon-Utilizing Bacteria

Studies were conducted on the oxidation and assimilation of various three-carbon compounds by a gram-positive rod isolated from soil and designated strain R-22. This organism can utilize propane, propionate, or n -propylamine as sole source of carbon and energy. Respiration rates, enzyme assays, and 14 CO 2 incorporation experiments suggest that propane is metabolized via methyl ketone formation; propionate and n -propylamine are metabolized via the methylmalonyl-succinate pathway. Isocitrate lyase activity was found in cells grown on acetate and was not present in cells grown on propionate or n -propylamine. 14 CO 2 was incorporated into pyruvate when propionate and n -propylamine were oxidized in the presence of NaAsO 2 , but insignificant radioactivity was found in pyruvate produced during the oxidation of propane and acetone. The n -propylamine dissimilatory mechanism was inducible in strain R-22, and amine dehydrogenase activity was detected in cells grown on n -propylamine. Radiorespirometer and 14 CO 2 incorporation studies with several propane-utilizing organisms indicate that the methylmalonyl-succinate pathway is the predominant one for the metabolism of propionate.

Microbial assimilation of hydrocarbons: cellular distribution of fatty acids

The distribution of cellular fatty acids in defined lipid classes was analyzed in Micrococcus cerificans after growth on specified hydrocarbons. Neutral lipid, phospholipid, and cell residue fatty acids were qualitatively and quantitatively determined for M. cerificans grown on nutrient broth, tetradecane (C(14)), pentadecane (C(15)), hexadecane (C(16)), and heptadecane (C(17)), respectively. Percentage of total cellular fatty acid localized in defined lipid classes from cells grown on the above growth substrates was (i) neutral lipid-11.8, 1.81, 7.74, 23.1, and 2%; (ii) phospholipid-74.5, 65, 66.43, 62.1, and 86%; (iii) cell residue lipid-13.5, 33.29, 25.82, 14.78, and 11.9%. Phospholipid fatty acid chain length directly reflected the carbon number of the alkane substrate, with 40, 84, 98, and 77% of the fatty acids being 14, 15, 16, and 17 carbons when cells were grown on C(14), C(15), C(16), and C(17)n-alkanes, respectively. The bound lipids of the cell residue after chloroform-methanol extraction were characterized by 2-hydroxydodecanoic and 2-hydroxytetradecanoic acids plus a broad spectrum of fatty acids ranging from C(10) to C(17) chain length. An increase in total unsaturated fatty acid localized in the phospholipids was noted from cells grown on alkanes greater than 15 carbons long. An extracellular accumulation of free fatty acid (FFA) was demonstrated in hexadecane-grown cultures that was not apparent in non-hydrocarbon-grown cultures. Identification of extracellular FFA demonstrated direct derivation from hexadecane oxidation. Studies supporting inhibition of de novo fatty acid biosynthesis in relationship to extracellular FFA and hexadecane oxidation are described. The ability to alter the fatty acid composition of membrane polar lipids in a predictable manner by the alkane carbon source provides an excellent model system for the investigation of membrane structure-function relationships in M. cerificans.

Microbial assimilation of hydrocarbons. I. Fatty acids derived from normal alkanes

Fatty acids derived from Micrococcus cerificans growing at the expense of odd- and even-carbon normal alkanes were studied. Results demonstrated that cultures grown with a variety of nonhydrocarbon substrates serving as sole carbon and energy source yielded only even-carbon fatty acids. Even-chain alkanes, dodecane through octadecane serving as sole carbon source, resulted in even-carbon fatty acids with direct correlation between carbon number of the major fatty acid species and carbon number of the alkane substrate. Odd-carbon alkanes, undecane through heptadecane serving as sole carbon source, yielded both odd- and even-carbon fatty acids. A transitional shift from even-carbon fatty acids to odd-carbon fatty acids was observed as the carbon number of the alkane substrate increased. Unsaturated fatty acids were found to comprise a significant percentage of all profiles. Analysis of unsaturated fatty acids showed all odd- and even-carbon acids analyzed were Delta(9) monounsaturated fatty acids.