Structural analysis of molecular species of nocardomycolic acids from Nocardia erythropolis by the combined system of gas chromatography and mass spectrometry

Amycolatopsis oliviviridis sp. nov., a novel polylactic acid-bioplastic-degrading actinomycete isolated from paddy soil

A novel bioplastic-degrading actinomycete, strain SCM_MK2-4^T, was isolated from paddy soil in Thailand. The 16S rRNA gene sequence showed that strain SCM_MK2-4^T belonged to the genus Amycolatopsis, with the highest sequence similarity to Amycolatopsisazurea JCM 3275^T (99.4 %), and was phylogenetically clustered with this strain along with Amycolatopsislurida JCM 3141^T (99.3 %), A. japonica DSM 44213^T (99.2 %), A. decaplanina DSM 44594^T (99.0 %), A. roodepoortensis M29^T (98.9 %), A. keratiniphilasubsp. nogabecina DSM 44586^T (98.8 %), A. keratiniphilasubsp. keratiniphila DSM 44409^T (98.5 %), A. orientalis DSM 40040^T (98.4 %) and A. regifaucium GY080^T (98.3 %). A combination of DNA-DNA hybridization results ranging from 42.8±3.2 to 66.2±1.4 % with the type strains of A. azurea and A. lurida and some different phenotypic characteristics indicated that the strain could be distinguished from its closest phylogenetic neighbours. Whole-cell hydrolysates of the strain were shown to contain meso-diaminopimelic acid, arabinose, galactose, glucose, ribose, mannose, rhamnose and xylose. The predominant menaquinone was MK-9(H4). The major cellular fatty acid profile consisted of iso-C15 : 0, iso-C16 : 0, summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2OH) and C16 : 0. The polar lipid composition of the strain consisted of phosphatidyl-N-methylethylethanolamine, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylglycerol, aminophospholipids, an unidentified phospholipid and two unidentified glycolipids. The G+C content of the genomic DNA was 68.2 mol%. On the basis of phylogenetic analyses, DNA-DNA hybridization experimentation and the phenotypic characteristics, it was concluded that strain SCM_MK2-4^T represents a novel species of the genus Amycolatopsis, for which the name Amycolatopsis oliviviridis sp. nov. is proposed. The type strain is SCM_MK2-4^T (=TBRC 7186^T=JCM 32134^T).

Killing of Mycolic Acid-Containing Bacteria Aborted Induction of Antibiotic Production by Streptomyces in Combined-Culture

Co-culture of Streptomyces with mycolic acid-containing bacteria (MACB), which we termed “combined-culture,” alters the secondary metabolism pattern in Streptomyces and has been a useful method for the discovery of bioactive natural products. In the course of our investigation to identify the inducing factor(s) of MACB, we previously observed that production of pigments in Streptomyces lividans was not induced by factors such as culture extracts or mycolic acids. Although dynamic changes occurred in culture conditions because of MACB, the activation of pigment production by S. lividans was observed in a limited area where both colonies were in direct contact. This suggested that direct attachment of cells is a requirement and that components on the MACB cell membrane may play an important role in the response by S. lividans. Here we examined whether this response was influenced by dead MACB that possess intact mycolic acids assembled on the outer cell membrane. Formaldehyde fixation and γ-irradiation were used to prepare dead cells that retain their shape and mycolic acids of three MACB species: Tsukamurella pulmonis, Rhodococcus erythropolis, and Rhodococcus opacus. Culturing tests verified that S. lividans does not respond to the intact dead cells of three MACB. Observation of combined-culture by scanning electron microscopy (SEM) indicated that adhesion of live MACB to S. lividans mycelia were a significant interaction that resulted in formation of co-aggregation. In contrast, in the SEM analysis, dead cells were not observed to adhere. Therefore, direct attachment by live MACB cells is proposed as one of the possible factors that causes Streptomyces to alter its specialized metabolism in combined-culture.

Simple and rapid characterization of mycolic acids from Dietzia strains by using MALDI spiral-TOFMS with ultra high mass-resolving power

Mycolic acids have been used as important chemotaxonomic markers. In this study, a newly developed matrix-assisted laser desorption/ionization time-of-flight mass spectrometer with a spiral ion trajectory (MALDI spiral-TOFMS) was applied to the characterization of mycolic acids of three type strains of validated species belonging to the genus Dietzia (D. papillomatosis 105045(T), D. kunjamensis NBRC 105042(T) and D. timorensis NBRC 104184(T)), by analysis of total fatty acid methyl ester fractions. In addition, owing to the high mass-resolving power of MALDI spiral-TOFMS, adjacent peaks (0.036 Da mass differences) were successfully separated, and weak peaks corresponding to oxygenated mycolic acids were detected. For all samples, the distributions of carbon-chain lengths were mainly in the range of C30-C42 and the average number of carbon-chain lengths was about 37, which agreed reasonably well with reported results for the genus Dietzia. The number of double bonds and/or cyclopropane rings was 0-2. Relative peak intensities of each mycolic acid methyl ester were used to compare the mycolic acids of the three strains. The mycolic acids of D. papillomatosis and D. kunjamensis were characterized by a high content of mycolic acids with 0-1 double bond or cyclopropane ring and an almost equal content of mycolic acids with odd- and even-numbered carbon-chain lengths. In contrast, mycolic acids of D. timorensis were characterized by a high content of mycolic acids with 1-2 double bonds and/or cyclopropane rings with an even-numbered carbon-chain length. By using MALDI spiral-TOFMS, mycolic acids from three type strains of the genus Dietzia were characterized easily and rapidly.

Microbacterium saccharophilum sp. nov., isolated from a sucrose-refining factory

A Gram-stain-positive, non-motile, non-spore-forming, rod-shaped bacterium, designated strain K-1T, was isolated from soil at a sucrose refinery in Japan. The strain grew at 9–37 °C (optimum, 30 °C) and at pH 6–11 (optimum, pH 7.0). Phylogenetic analysis based on the full-length 16S rRNA gene sequence of strain K-1T revealed that it was a member of the genus Microbacterium . High 16S rRNA gene sequence similarities were found between strains K-1T and both Microbacterium pumilum NBRC 101279T (99.7 %) and Microbacterium deminutum NRRL B-24453T (99.5 %). However, the DNA–DNA hybridization values between strain K-1T and M. pumilum NBRC 101279T and M. deminutum NRRL B-24453T were only 12 % and 10 %, respectively. The DNA G+C content of strain K-1T was 73 mol%. The major fatty acids of strain K-1T were anteiso-C15 : 0 and anteiso-C17 : 0, and the major menaquinones were MK-12 and MK-13. The diamino acid in the cell-wall peptidoglycan was lysine. On the basis of these results, strain K-1T is considered to represent a novel species of the genus Microbacterium , for which the name Microbacterium saccharophilum sp. nov. is proposed. The type strain is K-1T ( = NBRC 108778T = NCIMB 14782T).

Friedmanniella flava sp. nov., a soil actinomycete

A novel actinomycete, strain W6T, was isolated from a soil sample of Yunnan Province, China. The bacterium was aerobic, non-motile, non-spore-forming and Gram-stain-positive. Genetic, phenotypic and chemical properties of the isolate were studied. 16S rRNA gene sequence data suggested that the novel isolate belonged to the genus Friedmanniella and shared 98.6 % sequence similarity with Friedmanniella antarctica DSM 11053T and Friedmanniella okinawensis DSM 21744T, the most closely related species. The cell-wall peptidoglycan contained ll-diaminopimelic acid, and mycolic acids were absent. The main menaquinone was MK-9(H4) and the predominant fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The phospholipid profile contained phosphatidylglycerol, phosphatidylinositol, phosphatidylcholine and diphosphatidylglycerol. The DNA G+C content of strain W6T was 72 mol%. Strain W6T showed 30.0 % and 28.5 % DNA–DNA relatedness, respectively, to F. antarctica DSM 11053T and F. okinawensis DSM 21744T. The combined genotypic and phenotypic data showed that strain W6T should be assigned to the genus Friedmanniella as a representative of a novel species, for which the name Friedmanniella flava sp. nov. is proposed. The type strain is W6T ( = CGMCC 4.6856T = JCM 17701T).

Tomitella biformata gen. nov., sp. nov., a new member of the suborder Corynebacterineae isolated from a permafrost ice wedge

Gram-reaction-positive, aerobic, non-spore-forming, irregular rod-shaped bacteria, designated AHU1821T and AHU1820, were isolated from an ice wedge in the Fox permafrost tunnel, Alaska. The strains were psychrophilic, growing at −5 to 27 °C. Phylogenetic analysis of the 16S rRNA and gyrB gene sequences indicated that the ice-wedge isolates formed a clade distinct from other mycolic-acid-containing bacteria within the suborder Corynebacterineae. The cell wall of strains AHU1821T and AHU1820 contained meso-diaminopimelic acid, arabinose and galactose, indicating chemotype IV. The muramic acids in the peptidoglycan were glycolated. The predominant menaquinone was MK-9(H2). The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and an unidentified glycolipid. The major fatty acids were hexadecenoic acid (C16 : 1), hexadecanoic acid (C16 : 0), octadecenoic acid (C18 : 1) and tetradecanoic acid (C14 : 0). Tuberculostearic acid was present in relatively small amounts (1 %). Strains AHU1821T and AHU1820 contained mycolic acids with 42–52 carbons. The DNA G+C content of the two strains was 69.3–71.6 mol% (T m). 16S rRNA, rpoB and recA gene sequences were identical between strains AHU1821T and AHU1820 and those of the gyrB gene showed 99.9 % similarity. Based on phylogenetic and phenotypic evidence, strains AHU1821T and AHU1820 represent a single novel species of a novel genus, for which the name Tomitella biformata gen. nov., sp. nov. is proposed. The type strain of Tomitella biformata is AHU1821T (=DSM 45403T =NBRC 106253T).

Friedmanniella luteola sp. nov., Friedmanniella lucida sp. nov., Friedmanniella okinawensis sp. nov. and Friedmaniella sagamiharensis sp. nov., isolated from spiders

Four Gram-positive, non-motile, aerobic actinobacteria were isolated from spiders and their webs. Their genetic, phenotypic and chemical properties were studied. The 16S rRNA gene sequence data suggested that the four novel isolates belonged to the genus Friedmanniella. Two strains (FA1T and FA2T) formed a cluster together with Friedmanniella capsulata and Friedmanniella lacustris and the other two strains (FB1T and FB2T) formed a cluster together with Friedmanniella antarctica and Friedmanniella spumicola. The cell-wall peptidoglycan contained ll-A2pm and mycolic acids were absent. Isoprenoid quinones were mainly composed of MK-9(H4), MK-9(H2) and MK-9 and the predominant fatty acids were 12-methyltetradecanoic acid (ai-C15 : 0) and 13-methyltetradecanoic acid (i-C15 : 0). The major polar lipids were phosphatidylinositol and phosphatidylglycerol. In addition, strain FA1T, FB1T, and FB2T contained diphosphatidylglycerol and phosphatidylcholine. The DNA G+C contents were: 72 mol%, 73 mol%, 74 mol% and 75 mol% for strains FA1T, FA2T, FB1T, and FB2T, respectively. DNA–DNA hybridization studies demonstrated that the novel strains showed low relatedness values to F. capsulata, F. lacustris, F. antarctica and F. spumicola. These data support the proposal that strains FA1T, FA2T, FB1T and FB2T represent novel species of the genus Friedmanniella. Therefore, the names Friedmanniella luteola (type strain FA1T=DSM 21741T=NBRC 104963T), Friedmanniella lucida (type strain FA2T=DSM 21742T=NBRC 104964T), Friedmanniella okinawensis (type strain FB1T=DSM 21744T=NBRC 104966T) and Friedmanniella sagamiharensis (type strain FB2T=DSM 21743T=NBRC 104965T) are proposed for these new strains.

Amycolatopsis echigonensis sp. nov. and Amycolatopsis niigatensis sp. nov., novel actinomycetes isolated from a filtration substrate

The taxonomic position of two actinomycete strains, LC2(T) and LC11(T), isolated from a filtration substrate made from Japanese volcanic soil, was determined using a polyphasic approach. The strains grew at temperatures from 5 to 45 degrees C, on media of pH between 6 and 11 and in the presence of 7 % NaCl. The major menaquinone was MK-9(H(4)). The major fatty acid was iso-C(16 : 0). A phylogenetic tree based on 16S rRNA gene sequences showed that the two strains formed a distinct evolutionary lineage within the genus Amycolatopsis. On the basis of their morphological, physiological and genotypic characteristics, the isolates are proposed to represent two novel species of the genus Amycolatopsis, for which the names Amycolatopsis echigonensis sp. nov. (type strain LC2(T) =IAM 15387(T) =CCTCC AB206019(T)), and Amycolatopsis niigatensis sp. nov. (type strain LC11(T) =IAM 15388(T) =CCTCC AB206020(T)) are proposed.

Immunological properties of trehalose dimycolate (cord factor) and other mycolic acid-containing glycolipids--a review

Mycolic acids are characteristic fatty acids of Mycobacteria and are responsible for the wax-like consistence of these microorganisms. Decades of research revealed that mycolic acid-containing glycolipids, in particular trehalose-6,6'-dimycolate (TDM, cord factor) as their best-studied representative, exert a number of immunomodifying effects. They are able to stimulate innate, early adaptive and both humoral and cellular adaptive immunity. Most functions can be associated with their ability to induce a wide range of chemokines (MCP-1, MIP-1alpha, IL-8) and cytokines (e.g., IL-12, IFN-gamma, TNF-alpha, IL-4, IL-6, IL-10). This review tries to link well-known properties of mycolic acid-containing glycolipids, e.g., stimulation of cellular and humoral immunity, granuloma formation and anti-tumor activity, with recent findings in molecular immunology and to give an outlook on potential practical applications.

High-performance liquid chromatography analysis of mycolic acids as an aid in laboratory identification of Rhodococcus and Nocardia species

High-performance liquid chromatography analysis of the p-bromophenacyl esters of mycolic acids from whole organisms gave chromatographic patterns that were useful in differentiation of Rhodococcus and Nocardia species. Rhodococcus equi, R. erythropolis, and R. rhodochrous contained more-polar mycolic acids and were easily separated from the less-polar mycolic acid-containing species of R. sputi, R. bronchialis, R. corallinus, R. rubropertinctus, and R. terrae. The less-polar mycolic acid-containing Rhodococcus species showed chromatographic patterns that partially overlapped (in elution times) the patterns of Nocardia asteroides, N. otitidiscaviarum, and N. brasiliensis, but the larger number of peaks in the last species made separation between the genera possible. Distinct chromatographic patterns were found for most species, except for R. equi strains that showed two different patterns. Strains of R. rubropertinctus and R. terrae appeared identical. N. asteroides and N. otitidiscaviarum showed similar mycolic acid patterns.

Determination of molecular species composition of C80 or longer-chain alpha-mycolic acids in Mycobacterium spp. by gas chromatography-mass spectrometry and mass chromatography

The molecular species composition of alpha-mycolic acids ranging from C68 to C86 in 13 rapidly growing and 12 slowly growing mycobacterial species was determined by gas chromatography, gas chromatography-mass spectrometry, and mass chromatography. In gas chromatographic analysis, the molecular species of alpha-mycolic acids were well separated as trimethylsilyl ether derivatives of the methyl esters, according to their total carbon numbers. The total carbon and double-bond numbers of mycolic acids at each peak on gas chromatograms were determined from the [M]+, [M - 15]+, and [M - 90]+ ions on the mass spectrum, and straight and branched chain structures were identified by the mass fragment ions [A]+, due to C2--C3 cleavage [R-CH-O-Si(CH3)3]+, and [B]+, due to C3--C4 cleavage [(CH3)3-Si-O-CH-CH(R')-COOCH3]+. The concentration of odd- and even-carbon-numbered mycolic acids, which often overlap each other on gas chromatograms, and the composition of three homologous mycolic acids with different alpha units (C22:0, C24:0, and C26:0) were clearly determined by mass chromatography monitoring [M - 15]+ ions and [B - 29]+ ions, respectively. The molecular species composition of alpha-mycolic acids and their average carbon numbers (av. cn.) as a simple expression of the composition were calculated from the mass chromatograms. Each mycobacterial species examined was demonstrated to possess a characteristic profile of alpha-mycolic acid composition, and based on this the species were classified approximately into eight groups: C68 to C76 (av. cn. 72), dienoic, possessing a C20 alkyl branch at the 2 position (C22 alpha-unit) for Mycobacterium diernhoferi and Mycobacterium sp. strain 3707, a chromogenic rapid grower; C72 to C78 (av. cn. 75), dienoic with both C22 and C24 alpha units, containing a small or a large amount of odd-carbon-numbered molecules, for M. vaccae, M. rhodesiae, and M. phlei (chromogenic rapid growers); C72 to C80 (av. cn. 75 to 77), dienoic with C24 alpha-unit, containing a moderate or a large amount of odd-carbon-numbered molecules, for M. smegmatis, M. chitae, M. chelonae (M. chelonei), and M. fortuitum (nonchromogenic rapid growers); C78 to C82 (av. cn. 80), even-carbon-numbered dienoic with C24 alpha unit for M. agri and M. thermoresistible (rapid growers); C75 to C81 (av. cn. 77 to 79), odd-carbon-numbered dienoic with C24 alpha unit for M. nonchromogenicum complex (M. nonchromogenicum, M. terrae, and "M. novum") (slow growers); (vi) C76 to C84 (av. cn. 79 to 81), even-carbon-numbered dienoic with C24 alpha unit for MAIS complex including M. scrofulaceum, M. avium, and M. intracellulare (slow growers); (vii) C72 to C80 (av. cn. 77 to 79), even-carbon-numbered dienoic with C24 alpha unit for M. szulgai, M. gordonae, and M. kansasii (chromogenic slow growers); and (viii) C76 to C86 (av. cn. 79 to 81), even-carbon-numbered dienoic with C26 alpha unit M. bovis Ravenol and BCG and M. tuberculosis H37Rv. This study demonstrated that gas chromatography-mass spectrometric analysis of the molecular species composition of alpha-mycolic acid can give rapid, important, and very precise information for the identification of pathogenic and nonpathogenic mycobacterial species.

Isonicotinic acid hydrazide induced changes and inhibition in mycolic acid synthesis in Nocardia and related taxa

The mycolic acid compositions of Nocardia rubra and related bacteria grown in media containing different concentrations of antituberculous isonicotinic acid hydrazide (INH) were determined in detail by gas chromatography-mass spectrometry. On the basis of molecular species composition, average carbon numbers of mycolic acids were calculated. In Nocardia rubra, N. lutea and Rhodococcus rhodochrous IFO-13161, the ratio of mycolic to non-mycolic fatty acids and the average carbon numbers of mycolic acids were decreased at the INH concentrations of higher than 1 microgram/ml, paralleling with the significant inhibition of growth. In above three species the synthesis of longer chain mycolic acids (longer than C44 or C46 ) was inhibited more significantly than shorter homologues such as C38 or C40 . In contrast, neither growth inhibition nor change in corynomycolic acid composition was observed in Corynebacteria xerosis and Rhodococcus rhodochrous IFO-13165 at the concentration region of INH up to 100 micrograms/ml. The direct mass fragmentographic analysis of the trimethylsilylated (TMS) derivatives of mycolic acid methyl esters, monitoring [M-15] ions of individual molecular species, revealed that the chain shortening of total mycolic acid molecule by INH occurred more greatly in more highly unsaturated subclasses than in less unsaturated subclasses. Furthermore, mass fragmentographic analysis, monitoring fragment ions (A) and (B), due to straight chain and branched chain alkyl units, respectively, demonstrated the inhibition of mycolic acids was not attributed to the shortening of alpha-alkyl chain, but to the inhibition of chain elongation of C28 to C32 straight chain meromycolic acids. It was also indicated the amounts of trehalose mono- and di- mycolate (cord factor) decreased significantly with the addition of INH (1 to 20 micrograms/ml) in the above strains. From the results obtained above, INH appeared to inhibit the synthesis of mycolic acids longer than C44 or C46 specifically by inhibiting chain elongation or desaturation of precursor long chain fatty acids longer than C28 or C30.

In vitro synthesis of mycolic acids by the fluffy layer fraction of Bacterionema matruchotii

Biosynthetic activity for mycolic acid occurred in the fluffy layer fraction but not in the 5000g supernatant of Bacterionema matruchotii. With [1-14C]palmitic acid as precursor for the in vitro system, the predominant product was identified as C32:0 mycolic acid by radio-gas-liquid chromatographic (radio-GLC) and gas chromatographic/mass spectroscopic analyses; if [1-14C]stearic acid was used, two major radioactive peaks appeared on GLC: one corresponding to the peak of (C34:0 + C34:1) mycolic acids and the other to (C36:0 + C36:1) mycolic acids. By pyrolysis/radio-GLC analysis, C32:0 mycolic acid synthesized by [1-14C]palmitic acid was pyrolyzed at 300 degrees C to form palmitaldehyde (the mero moiety) and methyl palmitate (the branch moiety). The pH optimum for the incorporation of [1-14C]palmitate into bacterionema mycolic acids was 6.4 and the reaction required a divalent cation. The in vitro system utilized myristic, palmitic, stearic and oleic acids (probably via their activated forms) well as precursors, among which myristic and palmitic acids were more effective than the rest. Avidin showed no effect on the biosynthesis of mycolic acid from 14C-palmitate whereas cerulenin, a specific inhibitor of beta-ketoacyl synthetase in de novo fatty acid synthesis, inhibited the reaction at a relatively higher concentration. Thin-layer chromatographic analysis of lipids extracted from the reacting mixture without alkaline hydrolysis showed that both exogenous [1-14C]fatty acid and synthesized mycolic acids were bound to an unknown compound by an alkali-labile linkage and this association seemed to occur prior to the condensation of two molecules of fatty acid.

Separation and analysis of novel polyunsaturated mycolic acids from a psychrophilic, acid-fast bacterium, Gordona aurantiaca

More than 30 molecular species of highly unsaturated mycolic acids, ranging from C60 to C78 and possessing between two and seven double bonds, have been obtained from a new genus of acid-fast bacteria, Gordona aurantiaca. They were fully separated and identified as their trimethylsilyl ether derivatives by a combination of silica gel thin-layer chromatography (TLC), argentation thin-layer chromatography and gas chromatography/mass spectrometry (GC/MS). On silica gel thin-layer chromatography two adjacent spots, corresponding to mycolic acids possessing different structures of straight-chain and alpha-alkyl branch, were detected. The lower spot was separated by argentation TLC into four subclasses: monoenoic (including a small amount of saturated), dienoic, trienoic and tetraenoic mycolic acids ranging from C62 to C74 and possessing a C16:0, C18:0 or C20:0 alkyl branch at the C-2 position. The upper spot was separated by argentation TLC into five subclasses: dienoic (including a small amount of monoenoic), trienoic, tetraenoic, pentaenoic and hexaenoic (heptaenoic) acids ranging from C64 to C78 and possessing a C18:1 or C20:1 alkyl branch at the C-2 position. These types of mycolic acid structure differ from those reported previously in Mycobacteria and Nocardia, in the numbers of both carbon atoms and double-bonds and the intermediate length of the alpha-alkyl branch. The characteristic polyenoic structure of the straight-chain alkyl unit was also confirmed by GC/MS analysis of the meromycolaldehydes obtained after pyrolysis of the methyl mycolates. The major aldehydes obtained from the lower-spot mycolic acids were C44, C46, C48, C50 and C52, while those from the upper-spot mycolic acids were C48, C50, C52, C54 and C56, centering at C54. These aldehydes were also shown to possess between two and four double bonds in the lower-spot and between two and seven double bonds in the higher-spot mycolic acids, respectively. The physiological role of such highly polyunsaturated mycolic acids in psychrophilic acid-fast bacteria is discussed.

Mycolic acid composition and thermally adaptative changes in Nocardia asteroides

The nocardomycolic acid compositions of extractable and the cell wall-bound lipids from five strains of Nocardia asteroides (A-23007, A-23094, B-23006, B-23095, and IFO 3384) were compared by using gas chromatography-mass spectrometry. The molecular species composition of mycolic acid differed significantly among the strains of N. asteroides. The A-23007 strain possessed the shortest species, centering at C(44(46)), and the A-23094 and IFO-3384 strains followed, each centering at C(52). The B-23006 and B-23095 strains possessed the longest species, centering at C(56) or C(54), thus indicating that N. asteroides strains accommodate a heterogeneous group in respect to carbon numbers of mycolic acids. The doublebond isomers of mycolic acids from the representative strain IFO 3384 were fully separated and analyzed by argentation thin-layer chromatography, followed by gas chromatography-mass spectrometry. The reference strain (IFO 3384) possessed up to four double bonds on the straight chain of mycolic acids ranging from C(46) to C(60). All of the species possessed a C(14) alkyl branch at C-2. The more highly unsaturated subclasses consisted of the longer-chain mycolic acids. Marked changes in mycolic acid composition were induced by altering the growth temperature of strain IFO 3384. The cells grown at the higher temperature (50 degrees C) contained more saturated mycolic acids, whereas those grown at the lower temperature (17 degrees C) had more polyunsaturated (up to tetraenoic) mycolic acids, although a significant difference in carbon chain length was not detected. These changes in the degree of unsaturation of mycolic acids occurred shortly after shifting the growth temperature from 17 to 50 degrees C at logarithmic stages of the bacterial growth, thus indicating that N. asteroides can adapt to changes in the environmental temperature by altering the structure of mycolic acids of the cell walls.

Analysis of mycolic acids from a group of corynebacteria by capillary gas chromatography and mass spectrometry

The cell wall of leprosy-derived corynebacteria (a group of 'diphtheroids' isolated from human leprosy lesions and patients' blood) was previously shown to contain, in addition to peptidoglycan and arabinogalactan, mycolic acids. These alpha-branched beta-hydroxy fatty acids were attributed to the corynomycolic group, according to their RF in monodimensional thin-layer chromatography. In the present work, mycolic acids from leprosy-derived and reference corynebacteria have been fractionated by monodimensional and bidimensional thin-layer chromatography and by gas chromatography. Pyrolyzed mycolic acids have been analyzed on conventional packed columns, whereas intact methyl esters of mycolic acids with free and silylated beta-hydroxyl group have been analyzed on capillary columns, and their structure has been established by mass spectrometry. In all leprosy-derived corynebacteria, some 20 components containing 24-36 carbon atoms and 0-4 double bonds were obtained. The three major groups had 32, 34 and 36 carbons, and the frequency of unsaturated versus saturated chains increased proportionally to the molecular weight. For comparison, the main components of a reference corynebacterium. Corynebacterium diphtheriae PW8, had 30 and 32 carbons, and their hydrocarbon chains were essentially saturated. This work confirms the relative chemical homogeneity of different leprosy-derived corynebacteria and describes some peculiar traits in the chemical structure of this group of organisms. In addition, it shows the complexity of the mycolic acid fraction of corynebacterial cell wall and suggests that the mycolic acid pattern is a sort of fingerprint of each bacterial strain grown under standard conditions. Finally, the fractionation of intact corynomycolic acid methyl esters with free or silylated beta-hydroxyl group by capillary gas chromatography proved to be the best analytical procedure at present available for resolving this complex mixture of corynomycolate isomers. Structural determination of silylated samples by mass spectrometry is preferred because they have more diagnostic fragments.