Engineering the Mycomembrane of Live Mycobacteria with an Expanded Set of Trehalose Monomycolate Analogues

Mycobacteria and related organisms in the Corynebacterineae suborder are characterized by a distinctive outer membrane referred to as the mycomembrane. Biosynthesis of the mycomembrane occurs through an essential process called mycoloylation, which involves antigen 85 (Ag85)-catalyzed transfer of mycolic acids from the mycoloyl donor trehalose monomycolate (TMM) to acceptor carbohydrates and, in some organisms, proteins. We recently described an alkyne-modified TMM analogue (O-AlkTMM-C7) which, in conjunction with click chemistry, acted as a chemical reporter for mycoloylation in intact cells and allowed metabolic labeling of mycoloylated components of the mycomembrane. Here, we describe the synthesis and evaluation of a toolbox of TMM-based reporters bearing alkyne, azide, trans-cyclooctene, and fluorescent tags. These compounds gave further insight into the substrate tolerance of mycoloyltransferases (e.g., Ag85s) in a cellular context and they provide significantly expanded experimental versatility by allowing one- or two-step cell labeling, live cell labeling, and rapid cell labeling via tetrazine ligation. Such capabilities will facilitate research on mycomembrane composition, biosynthesis, and dynamics. Moreover, because TMM is exclusively metabolized by Corynebacterineae, the described probes may be valuable for the specific detection and cell-surface engineering of Mycobacterium tuberculosis and related pathogens. We also performed experiments to establish the dependence of probe incorporation on mycoloyltransferase activity, results from which suggested that cellular labeling is a function not only of metabolic incorporation (and likely removal) pathway(s), but also accessibility across the envelope. Thus, whole-cell labeling experiments with TMM reporters should be carefully designed and interpreted when envelope permeability may be compromised. On the other hand, this property of TMM reporters can potentially be exploited as a convenient way to probe changes in envelope integrity and permeability, facilitating drug development studies.

Antimicrobial Treatment Options for Granulomatous Mastitis Caused by Corynebacterium Species

Corynebacterium species are increasingly recognized as important pathogens in granulomatous mastitis. Currently, there are no published treatment protocols for Corynebacterium breast infections. This study describes antimicrobial treatment options in the context of other management strategies used for granulomatous mastitis. Corynebacterium spp. isolated from breast tissue and aspirate samples stored from 2002 to 2013 were identified and determined to the species level using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 16S RNA sequencing, and rpoB gene targets. The MICs for 12 antimicrobials were performed using Etest for each isolate. Correlations of these with antimicrobial characteristics, choice of antimicrobial, and disease outcome were evaluated. Corynebacterium spp. from breast tissue and aspirate samples were confirmed in 17 isolates from 16 patients. Based on EUCAST breakpoints, Corynebacterium kroppenstedtii isolates (n = 11) were susceptible to seven antibiotic classes but resistant to β-lactam antibiotics. Corynebacterium tuberculostearicum isolates (n = 4) were multidrug resistant. Two nonlipophilic species were isolated, Corynebacterium glucuronolyticum and Corynebacterium freneyi, both of which have various susceptibilities to antimicrobial agents. Short-course antimicrobial therapy was common (median, 6 courses per subject; range, 1 to 9 courses). Patients with C. kroppenstedtii presented with a hot painful breast mass and underwent multiple surgical procedures (median, 4 procedures; range, 2 to 6 procedures). The management of Corynebacterium breast infections requires a multidisciplinary approach and includes culture and appropriate sensitivity testing to guide antimicrobial therapy. Established infections have a poor outcome, possibly because adequate concentrations of some drugs will be difficult to achieve in lipophilic granulomata. Lipophilic antimicrobial therapy may offer a therapeutic advantage. The role of immunotherapy has not been defined.

[Applicability of MALDI Mass Spectrometry for Diagnostics of Phase Variants in Bacterial Populations]

Efficiency of MALDI mass spectrometry for differentiation between phenotypic phase variants (in colony morphology and virulence/avirulence) was investigated.for saprotrophic and opportunistically pathogenic bacteria of five genera (Acinetobacter, Arthrobacter, Rhodococcus, Corynebacterium, and Escherichia). Analysis of MALDI spectra (on the SA and HCCA matrices) included: (1) determination of similarity of the protein spectra as a percentage of the common protein peaks to the total amount of proteins, which reflects the phylogenetic relationships of the objects and has been recommended for identification of closely related species; (2) comparison of intensities of the common peaks; and (3) the presence of specific peaks as determinative characteristics of the variants. Under the standard analytical conditions the similarity between the MALDI profiles was shown to increase in the row: genus-species-strain-variant. Assessment of intensities of the common peaks was most applicable for differentiation between phase variants, especially in the case of high similarity of their profiles. Phase variants (A. oxydans strain K14) with similar colony morphotypes (S, R, M, and S(m)) grown on different media (LB agar, TSA, and TGYg) exhibited differences in their protein profiles reflecting the differences in their physiological characteristics. This finding is in agreement with our previous results on screening of the R. opacus with similar colony morphology and different substrate specificity in decomposition of chlorinated phenols. Analysis of MALDI spectra is probably the only efficient method for detection of such variants.

[Heterologous expression and characterization of L200F/D215K mutant of homoserine dehydrogenase from Corynebacterium pekinense AS1.299]

OBJECTIVE

To obtain a new homoserine dehydrogenase with better properties from Corynebacterium pekinense by the spatial structure transfromation.

METHODS

Double mutants L200F/D215A, L200F/D215E, L200F/D215G and L200F/D215K were constructed by site-directed mutagenesis and expressed in E. coli BL21. L200F/D215K was characterized for its highest catalytic efficiency and compared with that of L200F.

RESULTS

The Vmax of L200F/D215K was 36.92 U/mg, 1.24 times as that of L200F. The optimum reaction temperature of L200F/D215K was 37 degrees C, 2 degrees C higher than that of L200F. The optimum pH of L200F/D215K was 7.5, the same as that of L200F. The half-life time of L200F/D215K under optimum temperature was 4.16 h and was 1.12 times as that of L200F. Both L200F/D215K and L200F had good resistance to organic solvents and metal ions.

CONCLUSION

Through the spatial structure transformation, the enzymatic activity was increased, and the enzymology properties was optimized.

[Construction and characterization of R169H mutant of aspartokinase from Corynebacterium pekinense]

OBJECTIVE

Increasing the activity of aspartokinase (AK) from Corynebacterium pekinense.

METHODS

The gene of AK was constructed and mutated by site-specific mutagenesis. The mutational recombinant plasmid was heterologously expressed in Escherichia coli BL21. The mutational AK was purified by Ni(2+)-NTA column after ultrasonicating of the recombinant bacteria, and then identified by SDS-PAGE and Western blot. We compared the kinetic difference between R169H AK and WT AK by determining the enzymatic activities. Some other characteristics of R169H AK and WTAK were also studied.

RESULTS

The mutant R169H was successfully constructed. The molecular weight of AK was 48kDa. V(max) of R169H AK was 226.3 U/mg x s(-1), which was 2.3 times higher than that of WT AK. The optimum reaction temperature of R169H AK was 26 degrees C, the same as that of WT AK. The optimum reaction pH of R169H AK was 9.0, slightly higher than that of WT AK. The half-life period of R169H AK under optimum temperature and pH were 5.5h, much higher than that of WT AK. Lysine, threonine and methionine had an active effect on the activity of R169H AK when they were in low concentration.

CONCLUSION

The hydrogen bond between R169 and E92 was broken down in R169H AK, which could affect the degree of polymerization and further lowered the affinity of mutant AK with substrates and then decreased the inhibition inducing by the metabolites. Thus, the V(max) of mutant AK from R169H had increased by 2.3 times compared with that of WT AK.

[Role of associative microsymbionts in functioning of associative symbiosis]

AIM

Study the role of associative microsymbionts in biocenosis based on comparative evaluation of interbacterial and epithelial-bacterial interactions on the example of vaginal biotope.

MATERIALS AND METHODS

Corynebacterium spp., Staphylococcus aureus, Escherichia coli and Lactobacillus spp. and primary epitheliocytes isolated from the lower part of reproductive tract of women were used. Interactions by associant-macropartner vector were evaluated by changes of growth properties and antagonistic activity of the associant under the influence of exometabolites of vaginal epitheliocytes and expression of cytokines by epitheliocytes under the influence of associants. The nature of interaction by associant-dominant vector was evaluated by changes of adhesive properties and biofilm formation of associants and bactericidal activity of peroxide-producing lactobacilli.

RESULTS

Groups of associants that are opposite by their function in symbiosis were isolated. An example of associants that stabilize associative symbiosis by stimulating growth and antagonistic activity of dominant, moderate increase of cytokine production by epitheliocytes are corynebacteria, whose growth, biofilm formation, adhesion and antagonism during interaction with dominant and macropartner are also increased. The nature of interaction of associants of the other group (S. aureus and E. coli) with dominant and macropartner is the opposite. The determinative role of hydrogen peroxide in mechanisms of differentiation of associative microsymbionts and functioning of associative symbiosis ofvagina was shown.

CONCLUSION

The proposed approach allows to differentiate associative microsymbionts with various ecological roles, evaluate their contribution into maintenance of the stability of the symbiosis and open new possibilities of management of quality of microbiocenosis.

[Symbiotic interactions of corynebacteria and lactobacilli in realization of oxidative mechanisms of antagonism]

AIM

Study the interaction of vaginal corynebacteria and lactobacilli in realization of oxidative mechanism of antagonistic relations of bacteria.

MATERIALS AND METHODS

Effect of supernatants of corynebacteria inhibiting catalase on antagonism of peroxide producing lactobacilli to Staphylococcus aureus was studied.

RESULTS

High frequency (55.5 - 72.7%) of potentiating of antagonism of lactobacilli with medium and high level of hydrogen peroxide production under the effect of supernatants of corynebacteria inhibiting catalase was established. The frequency of potentiation of antagonism of lactobacilli and corynebacteriae depended on the intensity of hydrogen peroxide production and on the ability of corynebacteria to suppress catalase of staphylococci.

CONCLUSION

Potentiation of antagonism to S. aureus of peroxide producing lactobacilli and corynebacteria with catalase inhibitors gives evidence on realization of oxidative bacterial mechanism of colonization resistance in human organism.

[Macrophage apoptosis as a mechanism of pathogenic effect of diphtheria infectious agent]

AIM

Study of the apoptogenic effect of Corynebacterium diphtheriae toxigenic strains on mice peritoneal macrophages in vitro.

MATERIALS AND METHODS

Evaluation ofapoptosis induced by Corynebacterium diphtheriae, Corynebacterium pseudodiphtheriticum, Staphylococcus aureus, Streptococcus pyogenes strains was performed by characteristic morphological changes in macrophages in smears stained by azure eosin by Romanovsky-Giemsa.

RESULTS

Apoptogenic activity of diphtheria infectious agent was established to be determined by diphtheria exotoxin at early (after 1 hour) and surface structures and pathogenicity enzymes at later (3 hours) stages of effect.

CONCLUSION

The ability of diphtheria infectious agent to cause macrophage apoptosis is one of the mechanisms of realization of its pathogenic properties determined by the effect of diphtheria exotoxin, as well as its surface structures and pathogenicity enzymes. The increase of apoptogenic activity of toxigenic strains of C. diphtheriae in association with S. pyogenes may be a pathogenetic base of formation of prolonged forms of bacteria carriage against the background of chronic ENT pathology.

Identification of a cell-wall channel in the corynemycolic acid-free Gram-positive bacterium Corynebacterium amycolatum

As part of a comparative study of the cell wall of corynebacteria, a channel-forming protein was characterized in Corynebacterium amycolatum, a species devoid of corynemycolic acids. Corynebacterium amycolatum cells were disrupted and the cell envelope subjected to two different separation procedures, differential centrifugation to separate the different fractions of the cell envelope, and sucrose-step-gradient density centrifugation. The fractions obtained by the two methods were analyzed for lipid composition, NADH oxidase activity, and the formation of ion-permeable channels in lipid bilayers. High channel-forming activity was always detected in fractions expected to contain only cell-wall components. The highest NADH-oxidase activity was found in other fractions, indicating that the cell-wall fraction was distinct from the membrane fraction. The cell wall was found to contain an ion-permeable channel with a single-channel conductance of about 3.8 nS in 1 M KCl. The channel-forming protein, with an apparent molecular mass of 45 kDa, was purified to homogeneity using FPLC and preparative SDS-PAGE. Single-channel experiments suggested that the cell-wall channel is wide and water-filled and has a narrow selectivity for cations. Analysis of the fatty-acid composition of extractable lipids and delipidated cells suggested that the cell wall of C. amycolatum contains enough lipids to form an additional permeability barrier on the surface of the bacteria, thus accounting for the presence of the cell-wall channel.

Comprehensive study of Corynebacterium freneyi strains and extended and emended description of Corynebacterium freneyi Renaud, Aubel, Riegel, Meugnier, and Bollet 2001

In 2001, Corynebacterium freneyi was described as a new fermentative, alpha-glucosidase-positive Corynebacterium species related to C. xerosis based on data from three strains. During a review of our extensive culture collection we encountered 18 additional C. freneyi strains and further characterized them in detail. Thirteen of the 18 strains were isolated from female genital tract specimens without any obvious disease association. Phenotypically, C. freneyi can be easily differentiated from C. xerosis by its distinct wrinkled colonies whereas nearly all other routinely applied phenotypic tests do not allow a unanimous separation of C. freneyi from C. xerosis. Restriction length polymorphism analysis using CfoI of the 16S-23S rRNA gene intragenic spacer definitively allows differentiation between the two species. Surprisingly, comparative 16S rRNA gene analysis does not discriminate between C. freneyi and C. xerosis because the designated type strain of C. freneyi is not the most representative strain for this species. The present report also includes detailed data on the antimicrobial susceptibility pattern of C. freneyi presented here for the first time. Based on the large number of additional C. freneyi strains from our culture collection, we provide an extended and emended species description of C. freneyi.

A comprehensive proteome map of the lipid-requiring nosocomial pathogen Corynebacterium jeikeium K411

Corynebacterium jeikeium is a lipid-requiring pathogen that is considered as part of the normal microflora of the human skin and associated with severe nosocomial infections. Systematic reference maps of the cytoplasmic, cell surface-associated, and extracellular proteome fractions of the clinical isolate C. jeikeium K411 were examined by 2-DE coupled with MALDI-TOF MS. A sum total of 555 protein spots were identified by PMF, corresponding to 358 different proteins that were classified into functional categories and integrated into metabolic pathways. The majority of the proteins were linked to housekeeping functions in energy production and translation and to physiological processes in amino acid, carbohydrate, nucleotide, and lipid metabolism. A complete enzymatic machinery necessary to utilize exogenous fatty acids by beta-oxidation was detected in the cytoplasmic proteome fraction. In addition, several predicted virulence factors of C. jeikeium K411 were identified in the cell surface-associated and extracellular subproteome, including the cell surface proteins SurA and SurB, the surface-anchored pilus subunits SapA and SapB, the surface-anchored collagen adhesin CbpA, the cholesterol esterase Che, and the acid phosphatase AcpA.

Gordonia araii sp. nov. and Gordonia effusa sp. nov., isolated from patients in Japan

Two bacterial strains, IFM 10211T and IFM 10200T, were isolated from the sputum of two Japanese patients, and were subjected to a polyphasic taxonomic study. The two strains were found to have morphological, physiological and chemotaxonomic properties that were consistent with their assignment to the genus Gordonia, except for a few chemotaxonomic characteristics. Almost complete 16S rRNA gene sequences of the two strains were determined; the data showed that they are related distantly to Gordonia amarae, Gordonia hirsuta, Gordonia hydrophobica and Gordonia sihwensis, showing 16S rRNA gene sequence similarities to the type strains of these species of 96.2–97.9 %. DNA–DNA relatedness data coupled with the combination of genotypic and phenotypic data indicated that the two strains are representatives of two novel, separate species. The names proposed to accommodate these two strains are Gordonia araii sp. nov. (type strain IFM 10211T=DSM 44811T=NBRC 100433T=JCM 12131T) and Gordonia effusa sp. nov. (type strain IFM 10200T=DSM 44810T=NBRC 100432T=JCM 12130T).

Influence of growth phase on the phospholipidic fatty acid composition of two marine bacterial strains in pure and mixed cultures

This in vitro study was conducted in order to determine the effects of hydrocarbons and growth phase on the phospholipid ester-linked fatty acid composition of two marine sedimentary hydrocarbon-degrading bacteria. These two strains, namely Corynebacterium sp. and Sphingomonas sp. 2MPII, were cultivated on either a simple soluble substrate (ammonium acetate) or a hydrocarbon (respectively n-eicosane and phenanthrene). The incubations were stopped at different times corresponding to point of lag (2 days), exponential (7 days) and stationary phases (21 and 56 days). The effects of growth phase and hydrophobic substrates were successfully demonstrated by a simple index, given as the sum of saturated fatty acids divided by the sum of unsaturated fatty acids ( summation operatorSFA/ summation operatorMUFA), ranging from 1.4 to 3, 0.3 to 0.6, and 0.5 to 1.0 for Corynebacterium sp., Sphingomonas sp. 2MPII, and mixed cultures, respectively. This result was validated by a principal component analysis. In pure cultures, the phospholipid fatty acid (PLFA) composition was strongly influenced by both the carbon source and the growth phase. Nevertheless, the two strains showed different "behaviors". For 2MPII, the main PLFA composition changes were observed at 2 days while they were progressive as a function of time for Corynebacterium sp. These differences could explain the evolution of PLFAs of mixed cultures.

Species identification of corynebacteria by cellular fatty acid analysis

We evaluated the usefulness of cellular fatty acid analysis for the identification of corynebacteria. Therefore, 219 well-characterized strains belonging to 21 Corynebacterium species were analyzed with the Sherlock System of MIDI (Newark, DE). Most Corynebacterium species have a qualitative different fatty acid profile. Corynebacterium coyleae (subgroup 1), Corynebacterium riegelii, Corynebacterium simulans, and Corynebacterium imitans differ only quantitatively. Corynebacterium afermentans afermentans and C. coyleae (subgroup 2) have both a similar qualitative and quantitative profile. The commercially available database (CLIN 40, MIDI) identified only one third of the 219 strains correctly at the species level. We created a new database with these 219 strains. This new database was tested with 34 clinical isolates and could identify 29 strains correctly. Strains that remained unidentified were 2 Corynebacterium aurimucosum (not included in our database), 1 C. afermentans afermentans, and 2 Corynebacterium pseudodiphtheriticum. Cellular fatty acid analysis with a self-created database can be used for the identification and differentiation of corynebacteria.

The cytosolic, cell surface and extracellular proteomes of the biotechnologically important soil bacteriumCorynebacterium efficiens YS-314 in comparison to those ofCorynebacterium glutamicum ATCC 13032

Reference maps of the cytosolic, cell surface and extracellular proteome fractions of the amino acid-producing soil bacterium Corynebacterium efficiens YS-314 were established. The analysis window covers a pI range from 3 to 7 along with a molecular mass range from 10 to 130 kDa. After second-dimensional separation on SDS-PAGE and Coomassie staining, computational analysis detected 635 protein spots in the cytosolic proteome fraction, whereas 76 and 102 spots were detected in the cell surface and extracellular proteomes, respectively. By means of MALDI-TOF-MS and tryptic peptide mass fingerprinting, 164 cytosolic proteins, 49 proteins of the cell surface and 89 extracellular protein spots were identified, representing in total 177 different proteins. Additionally, reference maps of the three cellular proteome fractions of the close phylogenetic relative Corynebacterium glutamicum ATCC 13032 were generated and used for comparative proteomics. Classification according to the Clusters of Orthologous Groups of proteins scheme and abundance analysis of the identified proteins revealed species-specific differences. The high abundance of molecular chaperones and amino acid biosynthesis enzymes in C. efficiens points to environmental adaptations of this recently discovered amino acid-producing bacterium.

Characterization of acyl-phosphatidylinositol from the opportunistic pathogen Corynebacterium amycolatum

The aim of the present study was to characterize a new lipid detected in the opportunistic pathogen Corynebacterium amycolatum. It was identified as acyl-phosphatidylinositol (acyl-PI), and revealed as a mixture of homologues compounds by electrospray ionization mass spectrometry, with pseudomolecular ions, (M-H)-, observed at 1099 (the major one) 1113, and 1127. Acyl-PI exclusively contained octadecenoyl on the inositol moiety (as 3-O-acyl), an unsaturated fatty acyl (mostly octadecenoyl) at sn-1 position of the glycerol and a saturated fatty acyl (mainly hexadecanoyl) at the sn-2 position. Acyl-PI constitutes a new natural substance and seems to be unique among the phospholipids of C. amycolatum. Other more complex molecules, previously undetected, and assigned in this work to several acyl forms of phosphatidylinositol trimannosides, lacked octadecenoyl in their polar heads. The present study reveals the existence of acyl-PI in C. amycolatum as rather unexpected finding and, additionally, gives evidence for the ability of this species to synthesize a great variety of inositol-containing phospholipids.

Effects of pure n-alkanes and crude oil on bacterial phospholipid classes and molecular species determined by electrospray ionization mass spectrometry

Phospholipids are major components of bacterial membrane. Furthermore, the growth in vitro on xenobiotics such as n-alkanes, aromatic compounds or alkanols bring about to a bacterial membrane adaptive response. Concerning this work, we studied the membrane lipid composition of a hydrocarbon-degrading gram-positive bacterium (Corynebacterium sp.) on a soluble substrate and we detected four different phospholipid classes: phosphatidylglycerol, phosphatidylinositol, cardiolipin and acyl phosphatidylglycerol. In addition, a study of the lipid composition was performed after an in vitro culture on either pure n-alkane or crude oil. The growths on such hydrophobic substrates showed major qualitative and quantitative modifications. In the case of a growth on either heneicosane or crude oil, an increase of odd-numbered fatty acids was observed. Furthermore, the phospholipid polar head group composition was highly influenced by the crude oil addition. These modifications were, respectively, interpreted as the consequence of hydrocarbon assimilation and membrane fluidity adaptation. Finally, Corynebacterium sp. was taken back on the initial ammonium acetate substrate in order to determine its restoration abilities after a petroleum contamination.

[Antibiotic resistance of hemolytic bacteria, depending on iron content in bacterial cells]

The study of sensitivity to antibiotic substances of different chemical structure and the mechanism of the antimicrobial action of hemolytic bacteria Bacillus sp., Corynebacterium sp. and Escherichia coli under the condition of high iron content in bacterial cells was carried out. An increase in antimicrobial resistance of iron-loaded Gram-positive bacteria, in contrast to Gram-negative ones, was shown.

PorH, a new channel-forming protein present in the cell wall of Corynebacterium efficiens and Corynebacterium callunae

Corynebacterium callunaeandCorynebacterium efficiensare close relatives of the glutamate-producing mycolata speciesCorynebacterium glutamicum. The properties of the pore-forming proteins, extracted by organic solvents, were studied. The cell extracts contained channel-forming proteins that formed ion-permeable channels with a single-channel conductance of about 2 to 3 nS in 1 M KCl in a lipid bilayer assay. The corresponding proteins from both corynebacteria were purified to homogeneity and were named PorHC.calland PorHC.eff. Electrophysiological studies of the channels suggested that they are wide and water-filled. Channels formed by PorHC.callare cation-selective, whereas PorHC.effforms slightly anion-selective channels. Both proteins were partially sequenced. A multiple sequence alignment search within the known chromosome ofC. efficiensdemonstrated that it contains a gene that fits the partial amino acid sequence of PorHC.eff. PorHC.callshows high homology to PorHC.eff. PorHC.effis encoded in the bacterial chromosome by a gene that is localized within the vicinity of theporAgene ofC. efficiens. PorHC.effhas no signal sequence at the N terminus, which means that it is not exported by the Sec-secretion pathway. The structure of PorH in the cell wall of the corynebacteria is discussed.

Regeneration of cofactors for use in biocatalysis

Cofactor-dependent enzymes catalyze many synthetically useful reactions. The high cost of cofactors, however, necessitates in situ cofactor regeneration for preparative applications. After two decades of research, several cofactors can now be effectively regenerated using enzyme or whole-cell based methods. Significant advances have been made in this area in the past three years and include the development of novel or improved methods for regenerating ATP, sugar nucleotides and 3-phosphoadenosine-5'-phosphosulphate. These approaches have found novel applications in biocatalysis.

Bacterial phospholipid molecular species analysis by ion-pair reversed-phase HPLC/ESI/MS

This work set out to optimize the detection and separation of several phospholipid molecular species on a reversed-phase column with the use of an electrospray ionization/mass spectrometry-compatible counter-ion. An application of this technique concerned a qualitative and quantitative analysis of bacterial membrane phospholipids extracted from Corynebacterium species strain 8. The phospholipid classes of strain 8 were identified as phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol, and a peculiar lipid compound, acyl phosphatidylglycerol. Most of the molecular species structures were elucidated, and regarding phosphatidylglycerol, the fatty acid positions were clearly determined with the calculation of the sn-2/sn-1 intensity ratio of the fatty acyl chain fragments.

The C-Terminal Domain of the Betaine Carrier BetP of Corynebacterium glutamicum Is Directly Involved in Sensing K+ as an Osmotic Stimulus

The glycine betaine carrier BetP of Corynebacterium glutamicum was recently shown to function both as an osmosensor and as an osmoregulator in proteoliposomes by sensing changes in the internal K(+) concentration as a measure of hyperosmotic stress. In vivo analysis of mutants carrying deletions at the C-terminal extension of BetP indicated that this domain participates in osmostress-dependent activity regulation. To address the question, whether a putative K(+) sensor is located within the C-terminal domain, several mutants with truncations in this domain were purified and reconstituted in proteoliposomes of Escherichia coli phospholipids, since this in vitro system allowed variation of the K(+) concentration at the lumenal side. Truncation of 12 amino acids led to a partly deregulated BetP in terms of osmoregulation; however, K(+) sensitivity was not impaired in this mutant. The deletion of 25 amino acid residues at the C-terminal end of BetP led to both deregulation of the carrier activity, i.e., high activity independent of external osmolality, and loss of K(+)-dependent transport stimulation, indicating that this region of the C-terminal domain is necessary for K(+) sensing and/or K(+)-dependent carrier activation. Immunological and proteolysis analyses showed that BetP and its recombinant forms were reconstituted in a right-side-out orientation, i.e., the C-terminal domain faces the lumen of the proteoliposomes and is thus able to detect the K(+) signal at the inside. This is the first experimental demonstration of a direct connection between an osmotic stimulus, i.e., the change in internal K(+), and a putative sensor domain.

Projection Structure and Oligomeric State of the Osmoregulated Sodium/Glycine Betaine Symporter BetP of Corynebacterium glutamicum

The high-affinity glycine betaine uptake system BetP, an osmosensing and osmoregulated sodium-coupled symporter from Corynebacterium glutamicum, was overexpressed in Escherichia coli with an N-terminal StrepII-tag, solubilized in beta-dodecylmaltoside and purified by streptactin affinity chromatography. Analytical ultracentrifugation indicated that BetP forms trimers in detergent solution. Detergent-solubilized BetP can be reconstituted into proteoliposomes without loss of function, suggesting that BetP is a trimer in the bacterial membrane. Reconstitution with E.coli polar lipids produced 2D crystals with unit cell parameters of 182A x 154A, gamma=90 degrees exhibiting p22(1)2(1) symmetry. Electron cryo-microscopy yielded a projection map at 7.5A. The unit cell contains four non-crystallographic trimers of BetP. Within each monomer, ten to 12 density peaks characteristic of transmembrane alpha-helices surround low-density regions that define potential transport pathways. Small but significant differences between the three monomers indicate that the trimer does not have exact 3-fold symmetry. The observed differences may be due to crystal packing, or they may reflect different functional states of the transporter, related to osmosensing and osmoregulation. The projection map of BetP shows no clear resemblance to other secondary transporters of known structure.

Identification of an anion-specific channel in the cell wall of the Gram-positive bacterium Corynebacterium glutamicum

A cation-selective channel (porin), designated PorA, facilitates the passage of hydrophilic solutes across the cell wall of the mycolic acid-containing actinomycete Corynebacterium glutamicum. Biochemical and electrophysiological investigations of the cell wall of the mutant strain revealed the presence of an alternative channel-forming protein. This porin was purified to homogeneity and studied in lipid bilayer membranes. It forms small anion-selective channels with a diameter of about 1.4 nm and an average single-channel conductance of about 700 pS in 1 M KCl. The PorBCglut channel could be blocked by citrate in a dose-dependent manner. This result was in agreement with growth experiments in citrate as sole carbon source where growth in citrate was impaired as compared with growth in other carbon sources. The PorBCglut protein was partially sequenced and based on the resulting amino acid sequence of the corresponding gene, which was designated as porB, was identified as an unannotated 381 bp long open reading frame (ORF) in the published genome sequence of C. glutamicum ATCC13032. PorBCglut contains 126 amino acids with an N-terminal extension of 27 amino acids. One hundred and thirty-eight base pairs downstream of porB, we found an ORF that codes for a protein with about 30% identity to PorBCglut, which was named PorCCglut. The arrangement of porB and porC on the chromosome suggested that both genes belong to the same cluster. RT-PCR from overlapping regions between genes from wild-type C. glutamicum ATCC 13032 and its ATCC 13032DeltaporA mutant demonstrated that this is the case and that porB and porC are cotranscribed. The gene products PorBCglut and PorCCglut represent obviously other permeability pathways for the transport of hydrophilic compounds through the cell wall of C. glutamicum.

Mycomembrane and S-layer: two important structures of Corynebacterium glutamicum cell envelope with promising biotechnology applications

Corynebacteria belong to a distinct Gram-positive group of bacteria including mycobacteria and nocardia, which are characterized by the presence of mycolic acids in their cell wall. These bacteria share the property of having an unusual cell envelope structural organization close to Gram-negative bacteria. In addition to the inner membrane, the cell envelope is constituted of a thick arabinogalactan-peptidoglycan polymer covalently linked to an outer lipid layer, which is mainly composed of mycolic acids and probably organized in an outer membrane like structure. In some species, the cell is covered by a crystalline surface layer composed of a single protein species, which is anchored in the outer membrane like barrier. An increasing number of reports have led to a better understanding of the structure of the cell wall of Corynebacterium glutamicum. These works included the characterization of several cell wall proteins like S-layer protein and porins, genetic and biochemical characterization of mycolic acids biosynthesis, ultrastructural description of the cell envelope, and chemical analysis of its constituents. All these data address new aspects regarding cell wall permeability towards macromolecules and amino acids but also open new opportunities for biotechnology applications.

Plasmids in Corynebacterium glutamicum and their molecular classification by comparative genomics

Endogenous plasmids and selectable resistance markers are a fundamental prerequisite for the development of efficient recombinant DNA techniques in industrial microorganisms. In this article, we therefore summarize the current knowledge about endogenous plasmids in amino acid-producing Corynebacterium glutamicum isolates. Screening studies identified a total of 24 different plasmids ranging in size from 2.4 to 95 kb. Although most of the C. glutamicum plasmids were cryptic, four plasmids carried resistance determinants against the antibiotics chloramphenicol, tetracycline, streptomycin-spectinomycin, and sulfonamides. Considerable information is now available on the molecular genetic organization of 12 completely sequenced plasmid genomes from C. glutamicum. The deduced mechanism of plasmid DNA replication and the degree of amino acid sequence similarity among replication initiator proteins was the basis for performing a classification of the plasmids into four distinct C. glutamicum plasmid families.

Phospholipid composition of several clinically relevant Corynebacterium species as determined by mass spectrometry: an unusual fatty acyl moiety is present in inositol-containing phospholipids of Corynebacterium urealyticum

A comparative study on phospholipids of Corynebacterium amycolatum, Corynebacterium jeikeium and Corynebacterium urealyticum was carried out using fast-atom bombardment (FAB) and electrospray ionization (ESI) mass spectrometry. Data obtained indicate the presence of acylphosphatidylglycerol (APG), diphosphatidylglycerol, phosphatidylglycerol (PG), phosphatidylinositol (PI) and triacylphosphatidylinositol dimannosides (Ac(3)PIM(2)) in these bacteria. In general, octadecenoyl and hexadecanoyl fatty acyl moieties predominated in phospholipids of C. amycolatum, whereas high levels of hexadecenoyl were found in C. jeikeium and C. urealyticum. Mass spectra from purified APG and PG indicated that the sn-1 position of the glycerol was occupied by octadecenoyl in the three species studied. Notably, several major molecular species of PI and Ac(3)PIM(2) from C. urealyticum contained significant amounts of a moiety identified as 10-methyleneoctadecanoyl, located at the sn-1 position of these molecules. On the other hand, multiantibiotic resistant and susceptible strains of C. amycolatum differed in several minor phospholipid fatty acids of 19 carbon atoms, identified as 10-methyloctadecenoic, 10-methyloctadecanoic (tuberculostearic acid) and 10-methyleneoctadecanoic. The results demonstrate an overall similarity among the phospholipids of the different species studied but also significant differences related to the acyl chains of the glycerol moiety of these compounds, notably the high levels of an unusual fatty acyl moiety in inositol-containing phospholipids of C. urealyticum.

The putative transcriptional repressor McbR, member of the TetR-family, is involved in the regulation of the metabolic network directing the synthesis of sulfur containing amino acids in Corynebacterium glutamicum

In order to isolate transcriptional regulatory proteins involved in L-methionine-dependent repression in Corynebacterium glutamicum, proteins binding to the putative promoter region upstream of the metY gene were isolated by DNA affinity chromatography. One of the isolated proteins was identified as a putative transcriptional repressor of the TetR-family by a mass spectrometry fingerprint technique based on the complete C. glutamicum genome sequence. The respective gene, designated mcbR, was deleted in the mutant strain C. glutamicum DR1. Using 2D-PAGE, the protein contents of the C. glutamicum wild type and the mutant strain DR1 grown in media with or without L-methionine supplementation were compared and a set of six proteins was identified. Their abundance was drastically enhanced in the mutant strain and no longer influenced by L-methionine added to the growth medium. The corresponding genes were identified by mass spectrometry fingerprint analysis. They included metY encoding O-acetyl-L-homoserine sulfhydrylase, metK encoding S-adenosyl-methionine synthethase, hom encoding homoserine dehydrogenase, cysK encoding L-cysteine synthase, cysI encoding an NADPH dependant sulfite reductase, and ssuD encoding an alkanesulfonate monooxygenase. Evidently, the putative transcriptional repressor McbR is involved in the regulation of the metabolic network directing the synthesis of L-methionine in C. glutamicum. The C. glutamicum mcbR mutant can be considered to represent a first step in the construction of an L-methionine production strain.

Corynebacterium glaucum sp. nov

A bacterial strain, strain IMMIB R-5091(T), isolated from a cosmetic dye was characterized by phenotypic and molecular taxonomic methods. Chemotaxonomic investigations revealed the presence of cell-wall chemotype IV and short-chain mycolic acids consistent with the genus Corynebacterium. Comparative 16S rRNA gene sequencing showed that the isolate constitutes a distinct subline within the genus Corynebacterium, displaying > 2.6% sequence divergence from established species. The isolate could be distinguished from other members of the genus Corynebacterium by biochemical tests. Based on both phenotypic and phylogenetic evidence, it is proposed that strain IMMIB R-5091(T) (= DSM 44530T = NRRL B-24142(T)) be classified as the type strain of a novel species, Corynebacterium glaucum sp. nov.

Ion-trap mass spectrometry used in combination with gas chromatography for high-resolution metabolic flux determination

Metabolic fluxes provide a detailed metric of the cellular metabolic state. Fluxes are estimated indirectly from available measurements, and various methods have been developed for this purpose. Of particular interest are methods that make use of stable isotopic tracers because they enable flux estimation at a fine resolution. In this report, we present a protocol for the use of ion-trap mass spectrometry (MS) in combination with gas chromatography to measure the mass isotopomer distribution of biomass hydrolysates. At physiological steady-state, these measurements directly reflect the isotopic tracer distribution in the amino acid central carbon metabolism precursors. Because the extent to which a metabolic flux network can be accurately resolved strongly depends on the reliability and precision of the MS measurements and, in light of the current need for quantitative high-throughput biological analysis at the microscale, we discuss every step of the measurement process, indicate possible sources of error, and suggest solutions to avoid them. Potential advantages to using ion-trap versus quadrupole MS are also addressed. The final protocol requires 0.5 mg of dry biomass to detect the mass isotopomer distribution of 2-4 fragments of 13 amino acids, with a relative variance less than 1% for the most abundant peaks.

Co-extraction during reactive extraction of phenylalanine using Aliquat 336: interfacial mass transfer

Reactive liquid-liquid extraction can be used to separate hydrophilic fermentation products that would not otherwise partition into nonpolar solvents. However, during extraction of the target solute other compounds present in the extraction medium will also react with the ion exchange reagent and are thus co-extracted. In this study the effect of co-extraction on the interfacial flux of the target solute phenylalanine has been investigated for reactive extraction using Aliquat 336. The effect of co-extracting compounds has been included in a new interfacial flux balance, and experimental results reveal that the interfacial concentrations are equal to the final equilibrium conditions of the system. Using this information a simple mass transfer model has been developed from which film mass transfer coefficients may be determined. Co-extraction of other compounds present in the feed was found to reduce the interfacial flux of the target solute by reducing the driving force. Co-extraction did not affect the value of the film mass transfer coefficient, and therefore, co-extraction does not effect the transport properties of the solute to the interface. Extraction from a multicomponent fermentation broth resulted in a reduced flux, which arises from a reduction in the driving force caused by high levels of co-extraction. Furthermore, the flux was also reduced as the result of a mass transfer resistance caused by soluble surface-active compounds present in the fermentation broth adsorbing to the interface. The biomass associated with the fermentation broth was also found to reduce the solute flux, and it is believed that this is due to blockage of the interfacial area.

Molecular and biochemical characterization of mechanosensitive channels in Corynebacterium glutamicum

Database searches in the Corynebacterium glutamicum genome sequence revealed homologs of the mechanosensitive channels MscL and YggB of Escherichia coli. To elucidate the physiological role of these putative channels deletion mutants were constructed. Betaine efflux induced by osmotic downshock of the mscL deletion mutant was nearly identical to that of the wild-type, whereas the yggB deletion mutant showed a reduced efflux rate. Interestingly, the double deletion strain, which was expected to have an even more decreased capability of betaine excretion, had only a slightly reduced efflux rate compared to the wild-type and did not show an increased mortality after osmotic downshift. These results led to the hypothesis that C. glutamicum may possess a third type of mechanosensitive channel not related to the MscL and YggB/KefA families. Furthermore it is unlikely that an MscM-like activity is responsible for the betaine efflux, because of the high transport capacity detected in the double deletion mutant.

Dynamic calibration and dissolved gas analysis using membrane inlet mass spectrometry for the quantification of cell respiration

A membrane inlet mass spectrometer connected to a miniaturized reactor was applied for dynamic dissolved gas analysis. Cell samples were taken from 7 mL shake flask cultures of Corynebacterium glutamicum ATCC 13032, and transferred to the 12 mL miniaturized reactor. There, oxygen uptake and carbon dioxide and its mass isotopomer production rates were determined using a new experimental procedure and applying nonlinear model equations. A novel dynamic method for the calibration of the membrane inlet mass spectrometer using first-order dynamics was developed. To derive total dissolved concentration of all carbon dioxide species (C(T)) from dissolved carbon dioxide concentration ([CO(2)](aq)), the ratio of C(T) to [CO(2)](aq) was determined by nonlinear parameter estimation, whereas the mass transfer coefficient of CO(2) was determined by the Wilke-Chang correlation. Subsequently, the suitability of the model equations for respiration measurements was examined using residual analysis and the Jarque-Bera hypothesis test. The resulting residuals were found to be random with normal distribution, which proved the adequacy of the application of the model for cell respiration analysis. Hence, dynamic changes in respiration activities could be accurately analyzed using membrane inlet mass spectrometry with the novel calibration method.

Determination of the absolute configurations of the anteiso acid moieties of glycoglycerolipid S365A isolated from Corynebacterium aquaticum

The absolute configurations of the two acid moieties, 12-methyltetradecanoate and 14-methylhexadecanoate, of glycoglycerolipid S365A isolated from Corynebacterium aquaticum were determined by an HPLC analysis after their conversion with the chiral fluorescent labeling reagents, (1S,2S)- and (1R,2R)-2-(2,3-anthracenedicarboximido)cyclohexanol. Both anteiso acids had the S configuration.

Corynebacterium appendicis sp. nov

A lipophilic, coryneform bacterium isolated from a human clinical specimen was characterized by phenotypic and molecular-taxonomic methods. Chemotaxonomic investigations revealed the presence of cell-wall chemotype IV and short-chain mycolic acids consistent with the genus Corynebacterium. The isolate could be distinguished from other members of the genus Corynebacterium by positive urease and catalase tests as well as its failure to produce acid from carbohydrates. Comparative 16S rRNA gene sequencing showed that this isolate constitutes a distinct subline within the genus Corynebacterium, displaying >3.0% sequence divergence from other known Corynebacterium species. Based on both phenotypic and phylogenetic evidence, it is proposed that this isolate be classified as a novel species, Corynebacterium appendicis sp. nov., represented by strain IMMIB R-3491T (= DSM 44531T = NRRL B-24151T).

Differentiation of Corynebacterium amycolatum, C. minutissimum, C. striatum and related species by pyrolysis-gas-liquid chromatography with atomic emission detection

We report here the application of pyrolysis-gas chromatography followed by atomic emission detection (AED) for the characterisation of Corynebacterium amycolatum and related species (i.e., C. striatum, C. minutissimum, C. xerosis and the recently described C. freneyi). This phenotypic method, which analyses the whole chemical composition of bacteria, clearly separates C. amycolatum from other species. Moreover, this C. amycolatum group is subdivided into two distinct subgroups. We cannot differentiate the C. minutissimum strains from those of C. striatum. On the other hand, C. freneyi and C. xerosis are clearly distinct from the other species.

Charting and unzipping the surface layer of Corynebacterium glutamicum with the atomic force microscope

Bacterial surface layers (S-layers) are extracellular protein networks that act as molecular sieves and protect a large variety of archaea and bacteria from hostile environments. Atomic force microscopy (AFM) was used to asses the S-layer of Coryne-bacterium glutamicum formed of PS2 proteins that assemble into hexameric complexes within a hexagonal lattice. Native and trypsin-treated S-layers were studied. Using the AFM stylus as a nanodissector, native arrays that adsorbed to mica as double layers were separated. All surfaces of native and protease-digested S-layers were imaged at better than 1 nm lateral resolution. Difference maps of the topographies of native and proteolysed samples revealed the location of the cleaved C-terminal fragment and the sidedness of the S-layer. Because the corrugation depths determined from images of both sides span the total thickness of the S-layer, a three-dimensional reconstruction of the S-layer could be calculated. Lattice defects visualized at 1 nm resolution revealed the molecular boundaries of PS2 proteins. The combination of AFM imaging and single molecule force spectroscopy allowed the mechanical properties of the Corynebacterium glutamicum S-layer to be examined. The results provide a basis for understanding the amazing stability of this protective bacterial surface coat.

Corynebacterium aurimucosum sp. nov. and emended description of Corynebacterium minutissimum Collins and Jones (1983)

Two coryneform bacteria isolated from human clinical specimens were characterized by phenotypic and molecular taxonomic methods. Chemotaxonomic investigations revealed the presence of cell-wall chemotype IV and short-chain mycolic acids consistent with the genus Corynebacterium sensu stricto. Comparative 16S rRNA gene sequence analysis showed that the two strains are genealogically highly related (99.8% sequence similarity) and constitute a new subline within the genus Corynebacterium, with Corynebacterium minutissimum as their nearest phylogenetic neighbours (98.8% sequence similarity). However, DNA-DNA hybridization experiments demonstrated unambiguously that the isolates are genealogically distinct from Corynebacterium minutissimum (42% homology). Biochemical testing indicated that the two isolates were hardly differentiated from Corynebacterium minutissimum. Based on both phenotypic and phylogenetic evidence it is proposed that these isolates be classified as a new species, Corynebacterium aurimucosum sp. nov. The type strain of Corynebacterium aurimucosum is represented by strain IMMIB D-1488T (= DSM 44532T = NRRL B-24143T).

Characterization of the cell surface protein gene of Corynebacterium ammoniagenes

Three dominant cell surface proteins of Corynebacterium ammoniagenes ATCC 6872 were identified in the cell wall fraction. The cspA gene, which encodes one of the major cell surface proteins, was cloned using the N-terminal amino acid sequence of the protein. Then the cloned chromosomal fragment containing the cspA gene was sequenced and was shown to encode a mature polypeptide of 333 amino acids with a molecular mass of 36654 Da. The amino acid sequence of the cspA gene showed similarity to the amino acid sequence of C. glutamicum CspA, one of the two major secreted proteins of C. glutamicum, although C. ammoniagenes CspA and C. glutamicum CspA differed in size. Northern blot analysis and primer extension analysis respectively revealed a 1.1 kb transcript and a promoter sequence resembling that of the C. ammoniagenes fatty acid synthase B (fasB) gene.

Corynebacterium freneyi sp. nov., alpha-glucosidase-positive strains related to Corynebacterium xerosis

Three coryneform strains from clinical specimens were studied. They belonged to the genus Corynebacterium, since they had type IV cell walls containing corynemycolic acids. They had phenotypic characteristics that included alpha-glucosidase, pyrazinamidase and alkaline phosphatase activities and fermentation of glucose, ribose, maltose and sucrose. These are the characteristics of Corynebacterium xerosis. Since this species is very rare in human pathology, the strains were studied in more detail by comparing the 16S-23S intergenic spacers, rDNA sequences and levels of DNA similarity of these three strains and those of the reference strains C. xerosis ATCC 373T and Corynebacterium amycolatum CIP 103452T. According to DNA-DNA hybridization data, the three novel strains are members of the same species (level of DNA similarity >72%). Phylogenetic analysis revealed that these strains are closely related to C. xerosis and C. amycolatum, but DNA-relatedness experiments showed clearly that they constitute a distinct new species, with levels of DNA relatedness of less than 23% to C. xerosis ATCC 373T and less than 5% to C. amycolatum CIP 103452T. Two other alpha-glucosidase-positive strains presenting the same biochemical characteristics were included in the study and proved to be C. amycolatum. This new species can be differentiated from C. xerosis and C. amycolatum strains by carbon source utilization, intergenic spacer region length profiles and some biochemical characteristics such as glucose fermentation at 42 degrees C and growth at 20 degrees C. The name Corynebacterium freneyi sp. nov. is proposed with the type strain ISPB 6695110T (= CIP 106767T = DSM 44506T).

Structure of the cell envelope of corynebacteria: importance of the non-covalently bound lipids in the formation of the cell wall permeability barrier and fracture plane

With the recent success of the heterologous expression of mycobacterial antigens in corynebacteria, in addition to the importance of these bacteria in biotechnology and medicine, a better understanding of the structure of their cell envelopes was needed. A combination of molecular compositional analysis, ultrastructural appearance and freeze-etch electron microscopy study was used to arrive at a chemical model, unique to corynebacteria but consistent with their phylogenetic relatedness to mycobacteria and other members of the distinctive suprageneric actinomycete taxon. Transmission electron microscopy and chemical analyses showed that the cell envelopes of the representative strains of corynebacteria examined consisted of (i) an outer layer composed of polysaccharides (primarily a high-molecular-mass glucan and arabinomannans), proteins, which include the mycoloyltransferase PS1, and lipids; (ii) a cell wall glycan core of peptidoglycan-arabinogalactan which may contain other sugar residues and was usually esterified by corynomycolic acids; and (iii) a typical plasma membrane bilayer. Freeze-etch electron microscopy showed that most corynomycolate-containing strains exhibited a main fracture plane in their cell wall and contained low-molecular-mass porins, while the fracture occurred within the plasma membrane of strains devoid of both corynomycolate and pore-forming proteins. Importantly, in most strains, the amount of cell wall-linked corynomycolates was not sufficient to cover the bacterial surface; interestingly, the occurrence of a cell wall fracture plane correlated with the amount of non-covalently bound lipids of the strains. Furthermore, these lipids were shown to spontaneously form liposomes, indicating that they may participate in a bilayer structure. Altogether, the data suggested that the cell wall permeability barrier in corynebacteria involved both covalently linked corynomycolates and non-covalently bound lipids of their cell envelopes.

Diversity within reference strains of Corynebacterium matruchotii includes Corynebacterium durum and a novel organism

Corynebacterium matruchotii has been the subject of numerous dental pathogenesis studies. The purpose of the present study was to resolve concerns about diversity within the reference strains of C. matruchotii through analysis of seven strains procured from the American Type Culture Collection (ATCC). Analysis of whole-cell fatty acid profiles with the library generation software of Microbial ID Inc. revealed that three types of organisms have been deposited in the ATCC as C. matruchotii. These three groups of organisms were also distinguishable by DNA-DNA dot blot hybridization, by sequences of two hypervariable regions of the 16S rRNA gene, and by the pyrrolidonyl arylamidase test. These studies indicate that two C. matruchotii reference strains, ATCC 33449 and ATCC 33822, are members of the recently proposed species, Corynebacterium durum. The colonial morphology and biochemical reactions of the C. durum strains are more diverse than originally reported. Strain ATCC 43833 is unique and represents a novel species. In addition to the type strain, ATCC 14266, true members of the species C. matruchotii include ATCC strains 14265, 33806, and 43832 plus two reference strains, L2 and Richardson 13, which comprise the vast majority of strains used in dental pathogenesis research with this species.

Isolation and characterization of a black-pigmented Corynebacterium sp. from a woman with spontaneous abortion

An unusual black-pigmented coryneform bacterium was isolated from the urogenital tract of a woman who experienced a spontaneous abortion during month 6 of pregnancy. Biochemical and chemotaxonomic analyses demonstrated that the unknown bacterium belonged to the genus Corynebacterium. Phylogenetic analysis based on 16S rRNA sequences (GenBank accession no. AF220220) revealed that the organism was a member of a distinct subline which includes uncultured Corynebacterium MTcory 1P (GenBank accession no. AF115934), derived from prostatic fluid, and Corynebacterium CDC B8037 (GenBank accession no. AF033314), an uncharacterized black-pigmented coryneform bacterium. On the basis of chemotaxonomic and phylogenetic evidence, this organism probably represents a new species and is most closely related to the uncharacterized Centers for Disease Control and Prevention group 4 coryneforms. Our strain is designated CN-1 (ATCC 700975).

Isolation and characterization of Corynebacterium ulcerans from cephalic implants in macaques

To determine the prevalence of colonization by Corynebacterium ulcerans, we cultured samples from the cephalic implant-skin margin and pharynx of 26 rhesus macaques and one pig-tailed macaque. All but one of the samples from the cephalic implants yielded a mixed population of bacteria. C. ulcerans grew from the cephalic implants in 56% and from the pharynx in 3% of the implanted animals. We screened nine of these isolates for diphtheria toxin (DT) and phospholipase D (PLD). Polymerase chain reactions (PCR) failed to identify DT in any of the tested isolates, which also lacked DT activity in Elek tests. However, all nine isolates tested had PLD toxin activity as determined by conjoint hemolysis on sheep blood agar plates in the presence of equi factor (Rhodococcus equi). In addition, PCR assays and Southern blot hybridization confirmed the presence of pld in the isolates. The role of the PLD toxin in promoting colonization of cephalic implants by C. ulcerans is unknown. We found C. ulcerans to be a frequent contaminant of the cephalic implant-skin margin. Further studies are necessary to investigate the relative clinical importance of this organism and the efficacy of various implant maintenance protocols in preventing infection.

Pulsed high-field gradient in vivo NMR spectroscopy to measure diffusional water permeability in Corynebacterium glutamicum

Pulsed high-field gradient in vivo NMR spectroscopy was used to measure diffusional water permeability in cell suspensions of the Gram-positive bacterium Corynebacterium glutamicum. Two different regions of H2O mobility were detected. One was characterized by the apparent coefficient of self-diffusion, D(1 app) = (4.6-12.7)x10(-8) cm(2) s(-1), depending on the observation time t. The other region was characterized by D(2) = 1.4x10(-5) cm(2) s(-1). The value of D(2) was similar to the diffusion coefficient of H2O in free water and in extracellular biological fluids. Restricted diffusion could be demonstrated for the slower process (D(1)). It was attributed to the cytoplasm of the cells. The membrane permeability, P(d H2O), for C. glutamicum was (4.8+/-0.4)x10(-3) cm s(-1). It compared favorably with values reported for human erythrocytes and was higher by a factor of about 100 compared to the diffusional permeability for ethanol, P(d ethanol), in Zymomonas mobilis. Addition of HgCl2, a water channel inhibitor in eukaryotes, decreased P(d H2O) in C. glutamicum by a factor of approximately 8. To our knowledge, these are the first functional studies of water transport in prokaryotes that yielded quantitative data, viz., transmembrane water permeability expressed through D(H2O) and P(d H2O).

Influenza A virus-binding activity of glycoglycerolipids of aquatic bacteria

As the aqueous sphere has been proposed to be an important source medium for the virus infection of land animals, the glycolipids of some aquatic organisms were examined for human influenza A virus-binding activity. Active compounds were not found among the eight echinoderm gangliosides, but two active non-sialylated glycoglycerolipids were isolated from an aquatic bacterium, Corynebacterium aquaticum. The structural formula of one of them, H632A, was elucidated to be 1-14-methyl-hexadecanoyl-3-alpha-D-galactopyranosyl-(1-->3)-6-(12-met hyl-tetradecanoyl)-1-alpha-D-mannopyranosyl]-sn-glycerol. The latter together with reported one elsewhere, S365A, 1-14-methyl-hexadecanoyl-3-[alpha-D-mannopyranosyl-(1-->3)-6-(12-meth yl-tetradecanoyl)-1-alpha-D-mannopyranosyl]-sn-glycerol, apparently bound to three human influenza viruses, A/PR/8/34 (H1N1), A/Aichi/2/68 (H3N2), and A/Memphis/1/71 (H3N2), exhibiting 7-12% (H632A) and 10-22% (S365A) of the activities of the control substances (Neu5Acalpha2-3-paragloboside and Neu5Acalpha2-6- paragloboside). Additionally, these glycolipids were assumed to have virus-neutralizing activities for the following two reasons: (i) The hemagglutination and hemolysis activities of the viruses were inhibited by the glycolipid. (ii) The leakage of a cytosolic enzyme (lactate dehydrogenase) from Madin-Darby canine kidney cells on virus infection was prevented by the glycolipids to nearly the same extent as by fetuin. This is the first evidence of the binding- and neutralizing-abilities of native glycoglycerolipids as to influenza viruses.

A new type of glycoglycerolipids from Corynebacterium aquaticum

A new type of glycoglycerolipids, S361A and S365A, were obtained from Corynebacterium aquaticum strains, S361 and S365, newly isolated from soils, and were identified as (2R)-1-[alpha-glucopyranosyl-(1alpha-3)-(6O-acyl-alpha-manno pyranosyl)]-3-O-acylglycerol and (2R)-1-[alpha-mannopyranosyl-(1alpha-3)-(6-O-acyl-alpha-mannopyran osyl)]-3-O-acylglycerol, respectively. S365A was identical to a novel glycoglycerolipid recently isolated from some bacteria, but S361A was a new analog having a glucosylmannosyl in place of the dimannosyl group. Our results indicate that this sn-2 lysotype of glyceroglycolipids may be widely distributed in bacteria.

Two-dimensional electrophoretic analysis of Corynebacterium glutamicum membrane fraction and surface proteins

An improved protocol for the two-dimensional analysis of proteins of the Corynebacterium glutamicum cytoplasmic membrane fraction is described. By use of increased 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) concentrations (2-4%) and an optimized electrophoresis protocol, horizontal streaking of proteins of the cytoplasmic membrane fraction was almost completely avoided. More important, in contrast to a previously published method, both a sample tray and IPG-phor isoelectric focusing unit can be used for the in-gel application of proteins. The described protocol was also found to be suitable for hydrophilic cytoplasmic proteins. Additionally, the preparation and analysis of C. glutamicum cell surface proteins is described. Proteins were extracted with lauroyl sarcosinate and 100-120 spots were separated on two-dimensional (2-D) gels in comparison to 18-20 spots observed previously by standard sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). C. glutamicum proteins can now be separated into three distinct fractions resembling different functional units of the bacterial cell.