Comparative genomics identified two conserved DNA modules in a corynebacterial plasmid family present in clinical isolates of the opportunistic human pathogen Corynebacterium jeikeium

Fatal respiratory diphtheria caused by β-lactam-resistant Corynebacterium diphtheriae

BACKGROUND

Diphtheria is a potentially fatal respiratory disease caused by toxigenic Corynebacterium diphtheriae. Although resistance to erythromycin has been recognised, β-lactam resistance in toxigenic diphtheria has not been described. Here, we report a case of fatal respiratory diphtheria caused by toxigenic C. diphtheriae resistant to penicillin and all other β-lactam antibiotics and describe a novel mechanism of inducible carbapenem resistance associated with the acquisition of a mobile resistance element.

METHODS

Long-read whole genome sequencing was performed using Pacific Biosciences SMRT sequencing to determine the genome sequence of C. diphtheriae BQ11 and mechanism of β-lactam resistance. To investigate phenotypic inducibility of meropenem resistance, short read sequencing was performed using an Illumina NextSeq500 sequencer on the strain with and without exposure to meropenem.

RESULTS

BQ11 demonstrated high-level resistance to penicillin (benzylpenicillin MIC ≥ 256 μg/ml), β-lactam/β-lactamase inhibitors and cephalosporins (amoxicillin/clavulanic acid MIC ≥ 256 μg/mL; ceftriaxone MIC ≥ 8 μg/L). Genomic analysis of BQ11 identified acquisition of a novel transposon carrying the penicillin binding protein Pbp2c, responsible for resistance to penicillin and cephalosporins. When strain BQ11 was exposed to meropenem, selective pressure drove amplification of the transposon in a tandem array and led to a corresponding change from a low level to high level meropenem resistant phenotype.

CONCLUSIONS

We have identified a novel mechanism of inducible antibiotic resistance whereby isolates that appear to be carbapenem susceptible on initial testing can develop in vivo resistance to carbapenems with repeated exposure. This phenomenon could have significant implications for treatment of C. diphtheriae infection and may lead to clinical failure.

Identification and characterization of smallest pore-forming protein in the cell wall of pathogenic Corynebacterium urealyticum DSM 7109

Background

Corynebacterium urealyticum, a pathogenic, multidrug resistant member of the mycolata, is known as causative agent of urinary tract infections although it is a bacterium of the skin flora. This pathogenic bacterium shares with the mycolata the property of having an unusual cell envelope composition and architecture, typical for the genus Corynebacterium. The cell wall of members of the mycolata contains channel-forming proteins for the uptake of solutes.

Results

In this study, we provide novel information on the identification and characterization of a pore-forming protein in the cell wall of C. urealyticum DSM 7109. Detergent extracts of whole C. urealyticum cultures formed in lipid bilayer membranes slightly cation-selective pores with a single-channel conductance of 1.75 nS in 1 M KCl. Experiments with different salts and non-electrolytes suggested that the cell wall pore of C. urealyticum is wide and water-filled and has a diameter of about 1.8 nm. Molecular modelling and dynamics has been performed to obtain a model of the pore. For the search of the gene coding for the cell wall pore of C. urealyticum we looked in the known genome of C. urealyticum for a similar chromosomal localization of the porin gene to known porH and porA genes of other Corynebacterium strains. Three genes are located between the genes coding for GroEL2 and polyphosphate kinase (PKK2). Two of the genes (cur_1714 and cur_1715) were expressed in different constructs in C. glutamicum ΔporAΔporH and in porin-deficient BL21 DE3 Omp8 E. coli strains. The results suggested that the gene cur_1714 codes alone for the cell wall channel. The cell wall porin of C. urealyticum termed PorACur was purified to homogeneity using different biochemical methods and had an apparent molecular mass of about 4 kDa on tricine-containing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

Conclusions

Biophysical characterization of the purified protein (PorACur) suggested indeed that cur_1714 is the gene coding for the pore-forming protein in C. urealyticum because the protein formed in lipid bilayer experiments the same pores as the detergent extract of whole cells. The study is the first report of a cell wall channel in the pathogenic C. urealyticum.

Corynebacterium jeikeium jk0268 constitutes for the 40 amino acid long PorACj, which forms a homooligomeric and anion-selective cell wall channel

Corynebacterium jeikeium, a resident of human skin, is often associated with multidrug resistant nosocomial infections in immunodepressed patients. C. jeikeium K411 belongs to mycolic acid-containing actinomycetes, the mycolata and contains a channel-forming protein as judged from reconstitution experiments with artificial lipid bilayer experiments. The channel-forming protein was present in detergent treated cell walls and in extracts of whole cells using organic solvents. A gene coding for a 40 amino acid long polypeptide possibly responsible for the pore-forming activity was identified in the known genome of C. jeikeium by its similar chromosomal localization to known porH and porA genes of other Corynebacterium strains. The gene jk0268 was expressed in a porin deficient Corynebacterium glutamicum strain. For purification temporarily histidine-tailed or with a GST-tag at the N-terminus, the homogeneous protein caused channel-forming activity with an average conductance of 1.25 nS in 1M KCl identical to the channels formed by the detergent extracts. Zero-current membrane potential measurements of the voltage dependent channel implied selectivity for anions. This preference is according to single-channel analysis caused by some excess of cationic charges located in the channel lumen formed by oligomeric alpha-helical wheels. The channel has a suggested diameter of 1.4 nm as judged from the permeability of different sized hydrated anions using the Renkin correction factor. Surprisingly, the genome of C. jeikeium contained only one gene coding for a cell wall channel of the PorA/PorH type found in other Corynebacterium species. The possible evolutionary relationship between the heterooligomeric channels formed by certain Corynebacterium strains and the homooligomeric pore of C. jeikeium is discussed.

Transcriptional control of lipid metabolism by the MarR-like regulator FamR and the global regulator GlxR in the lipophilic axilla isolate Corynebacterium jeikeium K411

Corynebacterial fatty acid metabolism has been associated with human body odour, and is therefore discussed as a potential target for the development of new deodorant additives. For this reason, the transcription levels of fad genes associated with lipid metabolism in the axilla isolate Corynebacterium jeikeium were analysed during growth on different lipid sources. The transcription of several fad genes was induced two- to ninefold in the presence of Tween 60, including the acyl-CoA dehydrogenase gene fadE6. DNA affinity chromatography identified the MarR-like protein FamR as candidate regulator of fadE6. DNA band shift assays and in vivo reporter gene fusions confirmed the direct interaction of FamR with the mapped fadE6 promoter region. Moreover, DNA affinity chromatography and DNA band shift assays detected the binding of GlxR to the promoter regions of fadE6 and famR, revealing a hierarchical control of fadE6 transcription by a feed-forward loop. Binding of GlxR and FamR to additional fad gene regions was demonstrated in vitro by DNA band shift assays, resulting in the co-regulation of fadA, fadD, fadE and fadH genes. These results shed first light on the hierarchical transcriptional control of lipid metabolism in C. jeikeium, a pathway associated with the development of human axillary odour.

Complete genome sequence, lifestyle, and multi-drug resistance of the human pathogen Corynebacterium resistens DSM 45100 isolated from blood samples of a leukemia patient

BACKGROUND

Corynebacterium resistens was initially recovered from human infections and recognized as a new coryneform species that is highly resistant to antimicrobial agents. Bacteremia associated with this organism in immunocompromised patients was rapidly fatal as standard minocycline therapies failed. C. resistens DSM 45100 was isolated from a blood culture of samples taken from a patient with acute myelocytic leukemia. The complete genome sequence of C. resistens DSM 45100 was determined by pyrosequencing to identify genes contributing to multi-drug resistance, virulence, and the lipophilic lifestyle of this newly described human pathogen.

RESULTS

The genome of C. resistens DSM 45100 consists of a circular chromosome of 2,601,311 bp in size and the 28,312-bp plasmid pJA144188. Metabolic analysis showed that the genome of C. resistens DSM 45100 lacks genes for typical sugar uptake systems, anaplerotic functions, and a fatty acid synthase, explaining the strict lipophilic lifestyle of this species. The genome encodes a broad spectrum of enzymes ensuring the availability of exogenous fatty acids for growth, including predicted virulence factors that probably contribute to fatty acid metabolism by damaging host tissue. C. resistens DSM 45100 is able to use external L-histidine as a combined carbon and nitrogen source, presumably as a result of adaptation to the hitherto unknown habitat on the human skin. Plasmid pJA144188 harbors several genes contributing to antibiotic resistance of C. resistens DSM 45100, including a tetracycline resistance region of the Tet W type known from Lactobacillus reuteri and Streptococcus suis. The tet(W) gene of pJA144188 was cloned in Corynebacterium glutamicum and was shown to confer high levels of resistance to tetracycline, doxycycline, and minocycline in vitro.

CONCLUSIONS

The detected gene repertoire of C. resistens DSM 45100 provides insights into the lipophilic lifestyle and virulence functions of this newly recognized pathogen. Plasmid pJA144188 revealed a modular architecture of gene regions that contribute to the multi-drug resistance of C. resistens DSM 45100. The tet(W) gene encoding a ribosomal protection protein is reported here for the first time in corynebacteria. Cloning of the tet(W) gene mediated resistance to second generation tetracyclines in C. glutamicum, indicating that it might be responsible for the failure of minocycline therapies in patients with C. resistens bacteremia.

Complete genome sequence of Corynebacterium variabile DSM 44702 isolated from the surface of smear-ripened cheeses and insights into cheese ripening and flavor generation

Background

Corynebacterium variabile is part of the complex microflora on the surface of smear-ripened cheeses and contributes to the development of flavor and textural properties during cheese ripening. Still little is known about the metabolic processes and microbial interactions during the production of smear-ripened cheeses. Therefore, the gene repertoire contributing to the lifestyle of the cheese isolate C. variabile DSM 44702 was deduced from the complete genome sequence to get a better understanding of this industrial process.

Results

The chromosome of C. variabile DSM 44702 is composed of 3, 433, 007 bp and contains 3, 071 protein-coding regions. A comparative analysis of this gene repertoire with that of other corynebacteria detected 1, 534 predicted genes to be specific for the cheese isolate. These genes might contribute to distinct metabolic capabilities of C. variabile, as several of them are associated with metabolic functions in cheese habitats by playing roles in the utilization of alternative carbon and sulphur sources, in amino acid metabolism, and fatty acid degradation. Relevant C. variabile genes confer the capability to catabolize gluconate, lactate, propionate, taurine, and gamma-aminobutyric acid and to utilize external caseins. In addition, C. variabile is equipped with several siderophore biosynthesis gene clusters for iron acquisition and an exceptional repertoire of AraC-regulated iron uptake systems. Moreover, C. variabile can produce acetoin, butanediol, and methanethiol, which are important flavor compounds in smear-ripened cheeses.

Conclusions

The genome sequence of C. variabile provides detailed insights into the distinct metabolic features of this bacterium, implying a strong adaption to the iron-depleted cheese surface habitat. By combining in silico data obtained from the genome annotation with previous experimental knowledge, occasional observations on genes that are involved in the complex metabolic capacity of C. variabile were integrated into a global view on the lifestyle of this species.

Molecular basis of human body odour formation: insights deduced from corynebacterial genome sequences

During the past few decades, there has been an increased interest in the essential role of commensal skin bacteria in human body odour formation. It is now generally accepted that skin bacteria cause body odour by biotransformation of sweat components secreted in the human axillae. Especially, aerobic corynebacteria have been shown to contribute strongly to axillary malodour, whereas other human skin residents seem to have little influence. Analysis of odoriferous sweat components has shown that the major odour-causing substances in human sweat include steroid derivatives, short volatile branched-chain fatty acids and sulphanylalkanols. In this mini-review, we describe the molecular basis of the four most extensively studied routes of human body odour formation, while focusing on the underlying enzymatic processes. Considering the previously reported role of β-oxidation in odour formation, we analysed the genetic repertoire of eight Corynebacterium species concerning fatty acid metabolism. We particularly focused on the metabolic abilities of the lipophilic axillary isolate Corynebacterium jeikeium K411.

Antisense-RNA-mediated plasmid copy number control in pCG1-family plasmids, pCGR2 and pCG1, in Corynebacterium glutamicum

pCGR2 and pCG1 belong to different subfamilies of the pCG1 family of Corynebacterium glutamicum plasmids. Nonetheless, they harbour homologous putative antisense RNA genes, crrI and cgrI, respectively. The genes in turn share identical positions complementary to the leader region of their respective repA (encoding plasmid replication initiator) genes. Determination of their precise transcriptional start- and end-points revealed the presence of short antisense RNA molecules (72 bp, CrrI; and 73 bp, CgrI). These short RNAs and their target mRNAs were predicted to form highly structured molecules comprising stem–loops with known U-turn motifs. Abolishing synthesis of CrrI and CgrI by promoter mutagenesis resulted in about sevenfold increase in plasmid copy number on top of an 11-fold (CrrI) and 32-fold (CgrI) increase in repA mRNA, suggesting that CrrI and CgrI negatively control plasmid replication. This control is accentuated by parB, a gene that encodes a small centromere-binding plasmid-partitioning protein, and is located upstream of repA. Simultaneous deactivation of CrrI and parB led to a drastic 87-fold increase in copy number of a pCGR2-derived shuttle vector. Moreover, the fact that changes in the structure of the terminal loops of CrrI and CgrI affected plasmid copy number buttressed the important role of the loop structure in formation of the initial interaction complexes between antisense RNAs and their target mRNAs. Similar antisense RNA control systems are likely to exist not only in the two C. glutamicum pCG1 subfamilies but also in related plasmids across Corynebacterium species.

Complete genome sequence and lifestyle of black-pigmented Corynebacterium aurimucosum ATCC 700975 (formerly C. nigricans CN-1) isolated from a vaginal swab of a woman with spontaneous abortion

Background

Corynebacterium aurimucosum is a slightly yellowish, non-lipophilic, facultative anaerobic member of the genus Corynebacterium and predominantly isolated from human clinical specimens. Unusual black-pigmented variants of C. aurimucosum (originally named as C. nigricans) continue to be recovered from the female urogenital tract and they are associated with complications during pregnancy. C. aurimucosum ATCC 700975 (C. nigricans CN-1) was originally isolated from a vaginal swab of a 34-year-old woman who experienced a spontaneous abortion during month six of pregnancy. For a better understanding of the physiology and lifestyle of this potential urogenital pathogen, the complete genome sequence of C. aurimucosum ATCC 700975 was determined.

Results

Sequencing and assembly of the C. aurimucosum ATCC 700975 genome yielded a circular chromosome of 2,790,189 bp in size and the 29,037-bp plasmid pET44827. Specific gene sets associated with the central metabolism of C. aurimucosum apparently provide enhanced metabolic flexibility and adaptability in aerobic, anaerobic and low-pH environments, including gene clusters for the uptake and degradation of aromatic amines, L-histidine and L-tartrate as well as a gene region for the formation of selenocysteine and its incorporation into formate dehydrogenase. Plasmid pET44827 codes for a non-ribosomal peptide synthetase that plays the pivotal role in the synthesis of the characteristic black pigment of C. aurimucosum ATCC 700975.

Conclusions

The data obtained by the genome project suggest that C. aurimucosum could be both a resident of the human gut and possibly a pathogen in the female genital tract causing complications during pregnancy. Since hitherto all black-pigmented C. aurimucosum strains have been recovered from female genital source, biosynthesis of the pigment is apparently required for colonization by protecting the bacterial cells against the high hydrogen peroxide concentration in the vaginal environment. The location of the corresponding genes on plasmid pET44827 explains why black-pigmented (formerly C. nigricans) and non-pigmented C. aurimucosum strains were isolated from clinical specimens.

Ultrafast pyrosequencing of Corynebacterium kroppenstedtii DSM44385 revealed insights into the physiology of a lipophilic corynebacterium that lacks mycolic acids

Corynebacterium kroppenstedtii is a lipophilic corynebacterial species that lacks in the cell envelope the characteristic alpha-alkyl-beta-hydroxy long-chain fatty acids, designated mycolic acids. We report here the bioinformatic analysis of genome data obtained by pyrosequencing of the type strain C. kroppenstedtii DSM44385 that was initially isolated from human sputum. A single run with the Genome Sequencer FLX system revealed 560,248 shotgun reads with 110,018,974 detected bases that were assembled into a contiguous genomic sequence with a total size of 2,446,804bp. Automatic annotation of the complete genome sequence resulted in the prediction of 2122 coding sequences, of which 29% were considered as specific for C. kroppenstedtii when compared with predicted proteins from hitherto sequenced pathogenic corynebacteria. This comparative content analysis of the genome data revealed a large repertoire of genes involved in sugar uptake and central carbohydrate metabolism and the presence of the mevalonate route for isoprenoid biosynthesis. The lack of mycolic acids and the lipophilic lifestyle of C. kroppenstedtii are apparently caused by gene loss, including a condensase gene cluster, a mycolate reductase gene, and a microbial type I fatty acid synthase gene. A complete beta-oxidation pathway involved in the degradation of fatty acids is present in the genome. Evaluation of the genomic data indicated that lipophilism is the dominant feature involved in pathogenicity of C. kroppenstedtii.

The lifestyle of Corynebacterium urealyticum derived from its complete genome sequence established by pyrosequencing

Corynebacterium urealyticum is a lipid-requiring, urealytic bacterium of the human skin flora that has been recognized as causative agent of urinary tract infections. We report the analysis of the complete genome sequence of C. urealyticum DSM7109, which was initially recovered from a patient with alkaline-encrusted cystitis. The genome sequence was determined by a combination of pyrosequencing and Sanger technology. The chromosome of C. urealyticum DSM7109 has a size of 2,369,219bp and contains 2024 predicted coding sequences, of which 78% were considered as orthologous with genes in the Corynebacterium jeikeium K411 genome. Metabolic analysis of the lipid-requiring phenotype revealed the absence of a fatty acid synthase gene and the presence of a beta-oxidation pathway along with a large repertoire of auxillary genes for the degradation of exogenous fatty acids. A urease locus with the gene order ureABCEFGD may play a pivotal role in virulence of C. urealyticum by the alkalinization of human urine and the formation of struvite stones. Multidrug resistance of C. urealyticum DSM7109 is mediated by transposable elements, conferring resistances to macrolides, lincosamides, ketolides, aminoglycosides, chloramphenicol, and tetracycline. The complete genome sequence of C. urealyticum revealed a detailed picture of the lifestyle of this opportunistic human pathogen.

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.

ef1097 and ypkK encode enterococcin V583 and corynicin JK, members of a new family of antimicrobial proteins (bacteriocins) with modular structure from Gram-positive bacteria

Unlike the colicins, microcins and related peptide antibiotics, little is known about antibiotic proteins (M(r)>10,000) from Gram-positive bacteria, since only few examples have been described to date. In this study we used heterologous expression of recombinant proteins to access the 17 kDa antibiotic protein SA-M57 from Streptococcus pyogenes, along with two proteins of unknown function identified in publicly available databases: EF1097 from Enterococcus faecalis and YpkK from Corynebacterium jeikeium. Here we show that all three are antibiotic proteins with different spectra of antimicrobial activity that kill sensitive bacteria at nanomolar concentrations. In silico structure predictions indicate that although the three proteins share little sequence similarity, they may be composed of conserved secondary structural elements: a relatively unstructured, acidic N-terminal portion and a basic C-terminal portion characterized by two helical elements separated by a loop structure and stabilized by an essential disulphide. Expression of individual segments as well as protein chimaeras revealed that, at least in the case of YpkK, the C-terminal portion is responsible for the killing action of the protein, whereas the role of the N-terminal portion remains unclear. Both scnM57 and ef1097 appear to be widely distributed in Strep. pyogenes and Ent. faecalis (respectively), whereas ypkK is found only rarely amongst clinical isolates of C. jeikeium. Finally, we determined that the proteins kill sensitive bacteria without lysis, a feature that distinguishes them from known murolytic proteins.

Genomics of Actinobacteria: tracing the evolutionary history of an ancient phylum

Actinobacteria constitute one of the largest phyla among bacteria and represent gram-positive bacteria with a high G+C content in their DNA. This bacterial group includes microorganisms exhibiting a wide spectrum of morphologies, from coccoid to fragmenting hyphal forms, as well as possessing highly variable physiological and metabolic properties. Furthermore, Actinobacteria members have adopted different lifestyles, and can be pathogens (e.g., Corynebacterium, Mycobacterium, Nocardia, Tropheryma, and Propionibacterium), soil inhabitants (Streptomyces), plant commensals (Leifsonia), or gastrointestinal commensals (Bifidobacterium). The divergence of Actinobacteria from other bacteria is ancient, making it impossible to identify the phylogenetically closest bacterial group to Actinobacteria. Genome sequence analysis has revolutionized every aspect of bacterial biology by enhancing the understanding of the genetics, physiology, and evolutionary development of bacteria. Various actinobacterial genomes have been sequenced, revealing a wide genomic heterogeneity probably as a reflection of their biodiversity. This review provides an account of the recent explosion of actinobacterial genomics data and an attempt to place this in a biological and evolutionary context.

Nitrogen Metabolism and Nitrogen Control in Corynebacteria: Variations of a Common Theme

The published genome sequences of Corynebacterium diphtheriae, Corynebacterium efficiens, Corynebacterium glutamicum and Corynebacterium jeikeium were screened for genes encoding central components of nitrogen source uptake, nitrogen assimilation and nitrogen control systems. Interestingly, the soil-living species C. efficiens and C. glutamicum exhibit a broader spectrum of genes for nitrogen transport and metabolism than the pathogenic species C. diphtheriae and C. jeikeium. The latter are characterized by gene decay and loss of functions like urea metabolism and nitrogen-dependent transcription control. The global regulator of nitrogen regulation AmtR and its DNA-binding motif are conserved in C. diphtheriae, C. efficiens and C. glutamicum, while in C. jeikeium, an AmtR-encoding gene as well as putative AmtR-binding motifs are missing.

Dysgalacticin: a novel, plasmid-encoded antimicrobial protein (bacteriocin) produced by Streptococcus dysgalactiae subsp. equisimilis

Dysgalacticin is a novel bacteriocin produced by Streptococcus dysgalactiae subsp. equisimilis strain W2580 that has a narrow spectrum of antimicrobial activity directed primarily against the principal human streptococcal pathogen Streptococcus pyogenes. Unlike many previously described bacteriocins of Gram-positive bacteria, dysgalacticin is a heat-labile 21.5 kDa anionic protein that kills its target without inducing lysis. The N-terminal amino acid sequence of dysgalacticin [Asn-Glu-Thr-Asn-Asn-Phe-Ala-Glu-Thr-Gln-Lys-Glu-Ile-Thr-Thr-Asn-(Asn)-Glu-Ala] has no known homologue in publicly available sequence databases. The dysgalacticin structural gene, dysA, is located on the indigenous plasmid pW2580 of strain W2580 and encodes a 220 aa preprotein which is probably exported via a Sec-dependent transport system. Natural dysA variants containing conservative amino acid substitutions were also detected by sequence analyses of dysA elements from S. dysgalactiae strains displaying W2580-like inhibitory profiles. Production of recombinant dysgalacticin by Escherichia coli confirmed that this protein is solely responsible for the inhibitory activity exhibited by strain W2580. A combination of in silico secondary structure prediction and reductive alkylation was employed to demonstrate that dysgalacticin has a novel structure containing a disulphide bond essential for its biological activity. Moreover, dysgalacticin displays similarity in predicted secondary structure (but not primary amino acid sequence or inhibitory spectrum) with another plasmid-encoded streptococcal bacteriocin, streptococcin A-M57 from S. pyogenes, indicating that dysgalacticin represents a prototype of a new class of antimicrobial proteins.

Under the influence of the active deodorant ingredient 4-hydroxy-3-methoxybenzyl alcohol, the skin bacterium Corynebacterium jeikeium moderately responds with differential gene expression

A 70mer oligonucleotide microarray was constructed to analyze genome-wide expression profiles of Corynebacterium jeikeium, a skin bacterium that is predominantly present in the human axilla and involved in axillary odor formation. Oligonucleotides representing 100% of the predicted coding regions of the C. jeikeium K411 genome were designed and spotted in quadruplicate onto epoxy-coated glass slides. The quality of the printed microarray was demonstrated by co-hybridization with fluorescently labeled cDNA probes obtained from exponentially growing C. jeikeium cultures. Accordingly, genes detected with different intensities resulting in log(2) transformed ratios greater than 0.8 or smaller than -0.8 can be regarded as differentially expressed with a confidence level greater than 99%. In an application example, we measured global changes of gene expression during growth of C. jeikeium in the presence of different concentrations of the deodorant component 4-hydroxy-3-methoxybenzyl alcohol that is active in preventing body odor formation. Global expression profiling revealed that low concentrations of 4-hydroxy-3-methoxybenzyl alcohol (0.5 and 2.5mg/ml) had almost no detectable effect on the transcriptome of C. jeikeium. A slightly higher concentration of 4-hydroxy-3-methoxybenzyl alcohol (5mg/ml) resulted in differential expression of 95 genes, 86 of which showed an enhanced expression when compared to a control culture. Besides many genes encoding proteins that apparently participate in transcription and translation, the drug resistance determinant cmx and the predicted virulence factors sapA and sapD showed significantly enhanced expression levels. Differential expression of relevant genes was validated by real-time reverse transcription PCR assays.

Complete genome sequence and analysis of the multiresistant nosocomial pathogen Corynebacterium jeikeium K411, a lipid-requiring bacterium of the human skin flora

Corynebacterium jeikeium is a "lipophilic" and multidrug-resistant bacterial species of the human skin flora that has been recognized with increasing frequency as a serious nosocomial pathogen. Here we report the genome sequence of the clinical isolate C. jeikeium K411, which was initially recovered from the axilla of a bone marrow transplant patient. The genome of C. jeikeium K411 consists of a circular chromosome of 2,462,499 bp and the 14,323-bp bacteriocin-producing plasmid pKW4. The chromosome of C. jeikeium K411 contains 2,104 predicted coding sequences, 52% of which were considered to be orthologous with genes in the Corynebacterium glutamicum, Corynebacterium efficiens, and Corynebacterium diphtheriae genomes. These genes apparently represent the chromosomal backbone that is conserved between the four corynebacteria. Among the genes that lack an ortholog in the known corynebacterial genomes, many are located close to transposable elements or revealed an atypical G+C content, indicating that horizontal gene transfer played an important role in the acquisition of genes involved in iron and manganese homeostasis, in multidrug resistance, in bacterium-host interaction, and in virulence. Metabolic analyses of the genome sequence indicated that the "lipophilic" phenotype of C. jeikeium most likely originates from the absence of fatty acid synthase and thus represents a fatty acid auxotrophy. Accordingly, both the complete gene repertoire and the deduced lifestyle of C. jeikeium K411 largely reflect the strict dependence of growth on the presence of exogenous fatty acids. The predicted virulence factors of C. jeikeium K411 are apparently involved in ensuring the availability of exogenous fatty acids by damaging the host tissue.