Avidumicin, a novel cyclic bacteriocin, produced by Cutibacterium avidum shows anti-Cutibacterium acnes activity

The prevalence of antimicrobial-resistant Cutibacterium acnes in acne patients has increased owing to inappropriate antimicrobial use. Commensal skin bacteria may play an important role in maintaining the balance of the skin microbiome by producing antimicrobial substances. Inhibition of Cu. acnes overgrowth can prevent the development and exacerbation of acne vulgaris. Here, we evaluated skin bacteria with anti-Cu. acnes activity. Growth inhibition activity against Cu. acnes was tested using 122 strains isolated from the skin of healthy volunteers and acne patients. Comparative genomic analysis of the bacterium with or without anti-Cu. acnes activity was conducted. The anti-Cu. acnes activity was confirmed by cloning an identified gene cluster and chemically synthesized peptides. Cu. avidum ATCC25577 and 89.7% of the Cu. avidum clinical isolates (26/29 strains) inhibited Cu. acnes growth. The growth inhibition activity was also found against other Cutibacterium, Lactiplantibacillus, and Corynebacterium species, but not against Staphylococcus species. The genome sequence of Cu. avidum showed a gene cluster encoding a novel bacteriocin named avidumicin. The precursor protein encoded by avdA undergoes post-translational modifications, supposedly becoming a circular bacteriocin. The anti-Cu. acnes activity of avidumicin was confirmed by Lactococcus lactis MG1363 carrying avdA. The C-terminal region of the avidumicin may be essential for anti-Cu. acnes activity. A commensal skin bacterium, Cu. avidum, producing avidumicin has anti-Cu. acnes activity. Therefore, avidumicin is a novel cyclic bacteriocin with a narrow antimicrobial spectrum. These findings suggest that Cu. avidum and avidumicin represent potential alternative agents in antimicrobial therapy for acne vulgaris.

A New Pathway for Forming Acetate and Synthesizing ATP during Fermentation in Bacteria

Many bacteria and other organisms carry out fermentations forming acetate. These fermentations have broad importance for foods, agriculture, and industry. They also are important for bacteria themselves because they often generate ATP. Here, we found a biochemical pathway for forming acetate and synthesizing ATP that was unknown in fermentative bacteria. We found that the bacterium Cutibacterium granulosum formed acetate during fermentation of glucose. It did not use phosphotransacetylase or acetate kinase, enzymes found in nearly all acetate-forming bacteria. Instead, it used a pathway involving two different enzymes. The first enzyme, succinyl coenzyme A (succinyl-CoA):acetate CoA-transferase (SCACT), forms acetate from acetyl-CoA. The second enzyme, succinyl-CoA synthetase (SCS), synthesizes ATP. We identified the genes encoding these enzymes, and they were homologs of SCACT and SCS genes found in other bacteria. The pathway resembles one described in eukaryotes, but it uses bacterial, not eukaryotic, gene homologs. To find other instances of the pathway, we analyzed sequences of all biochemically characterized homologs of SCACT and SCS (103 enzymes from 64 publications). Homologs with similar enzymatic activity had similar sequences, enabling a large-scale search for them in genomes. We searched nearly 600 genomes of bacteria known to form acetate, and we found that 6% encoded homologs with SCACT and SCS activity. This included >30 species belonging to 5 different phyla, showing that a diverse range of bacteria encode the SCACT/SCS pathway. This work suggests the SCACT/SCS pathway is important for acetate formation in many branches of the tree of life. IMPORTANCE Pathways for forming acetate during fermentation have been studied for over 80 years. In that time, several pathways in a range of organisms, from bacteria to animals, have been described. However, one pathway (involving succinyl-CoA:acetate CoA-transferase and succinyl-CoA synthetase) has not been reported in prokaryotes. Here, we discovered enzymes for this pathway in the fermentative bacterium Cutibacterium granulosum. We also found >30 other fermentative bacteria that encode this pathway, demonstrating that it could be common. This pathway represents a new way for bacteria to form acetate from acetyl-CoA and synthesize ATP via substrate-level phosphorylation. It could be a target for controlling yield of acetate during fermentation, with relevance for foods, agriculture, and industry.

Characterization of the human skin resistome and identification of two microbiota cutotypes

BACKGROUND

The human skin microbiota is considered to be essential for skin homeostasis and barrier function. Comprehensive analyses of its function would substantially benefit from a catalog of reference genes derived from metagenomic sequencing. The existing catalog for the human skin microbiome is based on samples from limited individuals from a single cohort on reference genomes, which limits the coverage of global skin microbiome diversity.

RESULTS

In the present study, we have used shotgun metagenomics to newly sequence 822 skin samples from Han Chinese, which were subsequently combined with 538 previously sequenced North American samples to construct an integrated Human Skin Microbial Gene Catalog (iHSMGC). The iHSMGC comprised 10,930,638 genes with the detection of 4,879,024 new genes. Characterization of the human skin resistome based on iHSMGC confirmed that skin commensals, such as Staphylococcus spp, are an important reservoir of antibiotic resistance genes (ARGs). Further analyses of skin microbial ARGs detected microbe-specific and skin site-specific ARG signatures. Of note, the abundance of ARGs was significantly higher in Chinese than Americans, while multidrug-resistant bacteria ("superbugs") existed on the skin of both Americans and Chinese. A detailed analysis of microbial signatures identified Moraxella osloensis as a species specific for Chinese skin. Importantly, Moraxella osloensis proved to be a signature species for one of two robust patterns of microbial networks present on Chinese skin, with Cutibacterium acnes indicating the second one. Each of such "cutotypes" was associated with distinct patterns of data-driven marker genes, functional modules, and host skin properties. The two cutotypes markedly differed in functional modules related to their metabolic characteristics, indicating that host-dependent trophic chains might underlie their development.

CONCLUSIONS

The development of the iHSMGC will facilitate further studies on the human skin microbiome. In the present study, it was used to further characterize the human skin resistome. It also allowed to discover the existence of two cutotypes on the human skin. The latter finding will contribute to a better understanding of the interpersonal complexity of the skin microbiome. Video abstract.

Regulatory relationship between quality variation and environment of Cistanche deserticola in three ecotypes based on soil microbiome analysis

The environment affects the composition and function of soil microbiome, which indirectly influences the quality of plants. In this study, 16S amplicon sequencing was used to reveal the differences in soil microbial community composition of Cistanche deserticola in three ecotypes (saline-alkali land, grassland and sandy land). Through the correlation analysis of microbial community abundance, phenylethanoid glycoside contents and ecological factors, the regulatory relationship between microbial community and the quality variation of C. deserticola was expounded. The metabolic function profile of soil microbiome was predicted using Tax4Fun. Data showed that the soil microbial communities of the three ecotypes were significantly different (AMOVA, P < 0.001), and the alpha diversity of grassland soil microbial community was the highest. Core microbiome analysis demonstrated that the soil microbial communities of C. deserticola were mostly have drought, salt tolerance, alkali resistance and stress resistance, such as Micrococcales and Bacillales. The biomarkers, namely, Oceanospirillales (saline-alkali land), Sphingomonadales (grassland) and Propionibacteriales (sandy land), which can distinguish three ecotype microbial communities, were excavated through LEfSe and random forest. Correlation analysis results demonstrated that 2'-acetylacteoside is positively correlated with Oceanospirillales in saline-alkali land soil. The metabolic function profiles displayed highly enriched metabolism (carbohydrate and amino acid metabolisms) and environmental information processing (membrane transport and signal transduction) pathways. Overall, the composition and function of soil microbiomes were found to be important factors to the quality variation of C. deserticola in different ecotypes. This work provided new insight into the regulatory relationship amongst the environment, soil microbial community and plant quality variation.

Nisin J, a Novel Natural Nisin Variant, Is Produced by Staphylococcus capitis Sourced from the Human Skin Microbiota

The skin microbiota is thought to play a key role in host protection from infection. Nisin J is a novel nisin variant produced by Staphylococcus capitis APC 2923, a strain isolated from the toe web space area in a screening study performed on the human skin microbiota. Whole-genome sequencing and mass spectrometry of the purified peptide confirmed that S. capitis APC 2923 produces a 3,458-Da bacteriocin, designated nisin J, which exhibited antimicrobial activity against a range of Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and Cutibacterium acnes The gene order in the nisin J gene cluster (nsjFEGBTCJP) differs from that of other nisin variants in that it is lacking the nisin regulatory genes, nisRK, as well as the nisin immunity gene nisI Nisin J has 9 amino acid changes compared to prototypical nisin A, with 8 amino acid substitutions, 6 of which are not present in other nisin variants (Ile4Lys, Met17Gln, Gly18Thr, Asn20Phe, Met21Ala, Ile30Gly, Val33His, and Lys34Thr), and an extra amino acid close to the C terminus, rendering nisin J the only nisin variant to contain 35 amino acids. This is the first report of a nisin variant produced by a Staphylococcus species and the first nisin producer isolated from human skin.IMPORTANCE This study describes the characterization of nisin J, the first example of a natural nisin variant, produced by a human skin isolate of staphylococcal origin. Nisin J displays inhibitory activity against a wide range of bacterial targets, including MRSA. This work demonstrates the potential of human commensals as a source for novel antimicrobials that could form part of the solution to antibiotic resistance across a broad range of bacterial pathogens.

Classification of Cutibacterium acnes at phylotype level by MALDI-MS proteotyping

Cutibacterium acnes is a major commensal human skin bacteria. It is a producer of propionic acids that maintain skin acidic pH to inhibit the growth of pathogens. On the other hand, it is also associated with diseases such as acne vulgaris and sarcoidosis. C. acnes strains have been classified into six phylotypes using DNA-based approaches. Because several characteristic features of C. acnes vary according to the phylotype, the development of a practical method to identify these phylotypes is needed. For rapid identification of phylotypes for C. acnes strains, a matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) fingerprinting technique has been applied; however, some phylotypes have not been discriminated. We developed a high-throughput protein purification method to detect biomarker proteins by ultrafiltration. MALDI-MS proteotyping using profiling of identified biomarker peaks was applied for the classification of 24 strains of C. acnes, and these were successfully classified into the correct phylotypes. This is a promising method that allows the discrimination of C. acnes phylotypes independent of a DNA-based approach.

Structural and biochemical characterization of the Cutibacterium acnes exo-β-1,4-mannosidase that targets the N-glycan core of host glycoproteins

Commensal and pathogenic bacteria have evolved efficient enzymatic pathways to feed on host carbohydrates, including protein-linked glycans. Most proteins of the human innate and adaptive immune system are glycoproteins where the glycan is critical for structural and functional integrity. Besides enabling nutrition, the degradation of host N-glycans serves as a means for bacteria to modulate the host's immune system by for instance removing N-glycans on immunoglobulin G. The commensal bacterium Cutibacterium acnes is a gram-positive natural bacterial species of the human skin microbiota. Under certain circumstances, C. acnes can cause pathogenic conditions, acne vulgaris, which typically affects 80% of adolescents, and can become critical for immunosuppressed transplant patients. Others have shown that C. acnes can degrade certain host O-glycans, however, no degradation pathway for host N-glycans has been proposed. To investigate this, we scanned the C. acnes genome and were able to identify a set of gene candidates consistent with a cytoplasmic N-glycan-degradation pathway of the canonical eukaryotic N-glycan core. We also found additional gene sequences containing secretion signals that are possible candidates for initial trimming on the extracellular side. Furthermore, one of the identified gene products of the cytoplasmic pathway, AEE72695, was produced and characterized, and found to be a functional, dimeric exo-β-1,4-mannosidase with activity on the β-1,4 glycosidic bond between the second N-acetylglucosamine and the first mannose residue in the canonical eukaryotic N-glycan core. These findings corroborate our model of the cytoplasmic part of a C. acnes N-glycan degradation pathway.

[Research progress on the genus Microlunatus]

Members of the genus Microlunatus exhibit many potential advantages in managing the environmental pollution caused by phosphorus. The genus was proposed by Nakamura and co-workers with the name Microlunatus phosphovorus as the type species in 1995. Up to date, the genus Microlunatus encompasses seven validly described species, which were isolated from various environments. Members of the genus Microlunatus share the following genus-specific characteristics, possessing LL-2, 6-diaminopimelic acid in the cell wall peptidoglycan, MK-9(H4) as the predominant menaquinone and diphosphatidylglycerol and phosphatidylglycerol as the phospholipid pattern. Based on the taxonomic results of two newly isolated strains of the genus Microlunatus and the related reference reports, this review summarizes the research advances of the genus Microlunatus, including the genus establishment, taxonomic characteristics, their distribution in the environments, as well as the application prospect in chemical and medical industry.

[Reactivating factor of Luteococcus japonicus subsp. casei: isolation and characterization]

It has been shown that a producer strain of reactivating factor (RF) is identical to a typical strain of Luteococcus japonicus DSM 10546 from the Propionibacteriaceae family according to the physiological and biochemical properties and the sequencing of 16S rRNA fragments. A number of phenotypical differences from the model strain allowed the producer strain to be considered a subspecies of Luteococcus japonicus, and it was named Luteococcus japonicus subsp. casei. At cultivation of the producer, RF is secreted into the medium and plays the role of a signaling molecule. RF antioxidant activities towards various organic radicals may be a possible mechanism of its protective and reactivating effects. Metabolites secreted by the L. casei producer strain into the culture medium were separated by a combination of liquid chromatographies. Four components possessing biological activities were found. The most active one was studied by MALDI-TOF mass spectrometry, which revealed that it is a polypeptide. Primary identification of some amino acid residues was performed. Sugar residues were found in the structure.

Microlunatus cavernae sp. nov., a novel actinobacterium isolated from Alu ancient cave, Yunnan, South-West China

A Gram-positive, coccoid, non-endospore-forming actinobacterium, designated YIM C01117(T), was isolated from a soil sample collected from Alu ancient cave, Yunnan province, south-west China. Based on the 16S rRNA gene sequence analysis, strain YIM C01117(T) was shown to belong to the genus Microlunatus, with highest sequence similarity of 97.4 % to Microlunatus soli DSM 21800(T). The whole genomic DNA relatedness as shown by the DNA-DNA hybridization study between YIM C01117(T) and M. soli DSM 21800(T) had a low value (47 ± 2 %). Strain YIM C01117(T) was determined to contain LL-diaminopimelic acid with Gly, Glu and Ala amino acids (A3γ' type) in the cell wall. Whole-cell hydrolysates were found to contain glucose, galactose, mannose and ribose. The major polar lipids were determined to be phosphatidylglycerol and diphosphatidylglycerol. The predominant menaquinone system present is MK-9(H4), while the major fatty acids were identified to be anteiso-C15:0 (24.1 %), iso-C16:0 (22.3 %) and iso-C15:0 (11.4 %). The G+C content of the genomic DNA was determined to be 65.9 mol%. The chemotaxonomic and genotypic data support the affiliation of the strain YIM C01117(T) to the genus Microlunatus. The results of physiological and biochemical tests allow strain YIM C01117(T) to be differentiated phenotypically from recognized Microlunatus species. Strain YIM C01117(T) is therefore considered to represent a novel species of the genus Microlunatus, for which the name Microlunatus cavernae sp. nov. is proposed. The type strain is YIM C01117(T) (= DSM 26248(T) = JCM 18536(T)).

Microlunatus ginsengisoli sp. nov., isolated from soil of a ginseng field

A Gram-positive, aerobic, coccus-shaped, non-endospore-forming bacterium (Gsoil 633(T)) was isolated from soil from a ginseng field in Pocheon province in South Korea. The novel isolate was characterized in order to determine its taxonomic position. On the basis of 16S rRNA gene sequence similarities, strain Gsoil 633(T) was shown to belong to the family Propionibacteriaceae. The closest phylogenetic relative was Microlunatus phosphovorus DSM 19555(T), with 96.1 % sequence similarity; the sequence similarity to other members of the family was less than 95.4 %. The isolate was characterized chemotaxonomically as having ll-2,6-diaminopimelic acid in the cell-wall peptidoglycan, MK-9(H(4)) as the predominant menaquinone and anteiso-C(15 : 0), iso-C(15 : 0) and iso-C(16 : 0) as the major fatty acids. The G+C content of the genomic DNA was 69.8 mol%. The morphological and chemotaxonomic properties of the isolate were consistent with those of M. phosphovorus, but the results of physiological and biochemical tests allowed the phenotypic differentiation of strain Gsoil 633(T) from this species. Therefore, strain Gsoil 633(T) represents a novel species, for which the name Microlunatus ginsengisoli sp. nov. is proposed. The type strain is Gsoil 633(T) (=KCTC 13940(T)=DSM 17942(T)).

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.

Aestuariimicrobium kwangyangense gen. nov., sp. nov., an ll-diaminopimelic acid-containing bacterium isolated from tidal flat sediment

Four Gram-positive, catalase-positive, short rod- or coccoid-shaped bacterial strains, R27T, R44, R45 and R47, were isolated from an enrichment culture with diesel oil-degradation activity and their taxonomic positions were investigated using a polyphasic approach. Phenotypic, phylogenetic and genetic similarities indicated that strains R27T, R44, R45 and R47 belong to the same species. Phylogenetic analysis based on 16S rRNA gene sequences showed that the four strains form a distinct evolutionary lineage within the family Propionibacteriaceae. The novel four strains had cell-wall peptidoglycan based on ll-diaminopimelic acid, MK-9(H4) as the predominant menaquinone and anteiso-C15 : 0 as the major cellular fatty acid. The DNA G+C contents were 68.8–69.2 mol%. These chemotaxonomic properties, together with phylogenetic distinctiveness, distinguish the four novel strains from recognized members of the family Propionibacteriaceae. On the basis of phenotypic, chemotaxonomic, phylogenetic and genetic data, strains R27T, R44, R45 and R47 are classified as representatives of a new genus and novel species, Aestuariimicrobium kwangyangense gen. nov., sp. nov., within the family Propionibacteriaceae. The type strain of Aestuariimicrobium kwangyangense sp. nov. is R27T (=KCTC 19182T=JCM 14204T).

Identification of polypeptides expressed in response to vinyl chloride, ethene, and epoxyethane in Nocardioides sp. strain JS614 by using peptide mass fingerprinting

Enzymes expressed in response to vinyl chloride, ethene, and epoxyethane by Nocardioides sp. strain JS614 were identified by using a peptide mass fingerprinting (PMF) approach. PMF provided insight concerning vinyl chloride biodegradation in strain JS614 and extends the use of matrix-assisted laser desorption-ionization time of flight mass spectrometry as a tool to enhance characterization of biodegradation pathways.

A Genetic Insight Into Peptide and Amino-Acid Utilization by Propionibacterium freudenreichii LMG 16415

In this note the genetic characterization of the peptide degrading system of Propionibacterium freudenreichii was addressed. Genomic fragments of P. freudenreichii subsp. freudenreichii LMG 16415 were cloned in Escherichia coli XL1 Blue, and those leading to an increase in peptidase-like activity using chromogenic substrates aminoacyl-beta-naphtylamides (aminoacyl-betaNA) were isolated and sequenced. This strategy allowed the identification of partial gene regions of P. freudenreichii LMG 16415 with significant similarity to proteins directly or indirectly involved in peptide and amino acid metabolism, i.e., an oligopeptide transporter, a D-amino acid oxidase, a muropeptidase, and an ABC transporter involved in osmoregulation similar to glycine betaine transporters.

Evaluation of recA gene as a phylogenetic marker in the classification of dairy propionibacteria

The aim of this study was to investigate the validity of recA gene as a molecular marker for the reliable discrimination and classification of dairy propionibacteria and the closely related species. Regions of the recA gene, varying in size between 613 and 677 nucleotides, were sequenced for Propionibacterium acidipropionici, P. cyclohexanicum, P. freudenreichii, P. jensenii, P. microaerophilum and P. thoenii using degenerate consensus primers constructed by aligning recA sequences of some actinobacteria. The 16S rRNA encoding genes for the type and reference strains of the species P. acidipropionici, P. jensenii and P. thoenii were also sequenced to remove ambiguous positions present in the current database reports, such to improve the classification scheme of reference. As found for other bacterial species, recA sequences permitted a better distinction among the dairy propionibacteria considered than 16S rRNA gene. However, the topology of phylogenetic trees constructed on the recA gene regions sequenced and their putative translations appeared rather different and less statistically valid than the 16S rRNA gene tree. In addition, the possibility of designing PCR-based identification and detection tests on the new recA sequences was demonstrated by assessing specific amplification protocols for P. cyclohexanicum and P. microaerophilum.

Nocardioides alkalitolerans sp. nov., isolated from an alkaline serpentinite soil in Korea

Four Gram-positive, rod- or coccus-shaped bacterial strains, KSL-1T, KSL-9, KSL-10 and KSL-12, were isolated from an alkaline serpentinite soil in Korea, and their taxonomic positions were investigated in a polyphasic study. The four strains exhibited no difference in their 16S rRNA gene sequences. Phylogenetic analyses based on 16S rRNA gene sequences showed that the four strains were phylogenetically affiliated to the genus Nocardioides. The four strains had cell-wall peptidoglycan based on ll-diaminopimelic acid as the diamino acid, indicating wall chemotype I. The predominant menaquinone detected in the four strains was MK-8(H4). The major fatty acid components were iso-C16 : 0, 10-methyl-C18 : 0, C18 : 1 ω9c and C17 : 1 ω6c. The DNA G+C contents were 72·4–73·6 mol%. The four strains exhibited 16S rRNA gene sequence similarity levels of 94·0–96·3 % to the type strains of Nocardioides species with validly published names. DNA–DNA relatedness levels between the four strains were 85–91 %. On the basis of phenotypic properties, phylogenetic distinctiveness and genotypic relatedness, strains KSL-1T, KSL-9, KSL-10 and KSL-12 were classified in the genus Nocardioides as members of a novel species, Nocardioides alkalitolerans sp. nov. The type strain is strain KSL-1T (=KCTC 19037T=DSM 16699T).

Transfer of Hongia koreensis Lee et al. 2000 to the genus Kribbella Park et al. 1999 as Kribbella koreensis comb. nov

The taxonomic status of Hongia koreensis was investigated by molecular systematic methods. On the basis of 16S rDNA phylogeny, H. koreensis was closely associated with Kribbella flavida and Kribbella sandramycini and formed a monophyletic clade with these species. These three taxa shared over 98% 16S rDNA sequence similarity and many chemotaxonomic properties, which strongly indicates that they belong to the same genus. DNA-DNA pairing was employed to elucidate the genomic relatedness among these taxa. H. koreensis represented a distinct genomic species that can be differentiated from members of the genus Kribbella. Physiological characteristics and phospholipid and cellular fatty acid compositions can be also used to separate H. koreensis from species of the genus Kribbella. On the basis of data presented in this and earlier studies, it is proposed that H. koreensis Lee et al. 2000 should be transferred to the genus Kribbella Park et al. 1999 as Kribbella koreensis comb. nov.

Propionimicrobium gen. nov., a new genus to accommodate Propionibacterium lymphophilum (Torrey 1916) Johnson and Cummins 1972, 1057AL as Propionimicrobium lymphophilum comb. nov

Based upon significant differences in chemotaxonomic properties, i.e., amino acid composition of peptidoglycan, fatty acids and base composition of DNA, and supported by the phylogenetic position of the 165 rDNA sequence the species Propionibacterium lymphophilum was reclassified as Propionimicrobium lymphophilum comb. nov.

Detection of transposon Tn5432-mediated macrolide-lincosamide-streptogramin B (MLSB) resistance in cutaneous propionibacteria from six European cities

Forty-five cutaneous propionibacterial isolates from six European cities were found to be highly resistant to all macrolide-lincosamide-streptogramin B antibiotics, including the ketolide telithromycin. This contrasts with previously documented phenotypes associated with 23S rRNA mutations. Sequencing of the resistance determinant showed it to be erm(X) of corynebacterial origin located on the composite transposon Tn5432.

Characterization of genes for enzymes involved in the phenanthrene degradation in Nocardioides sp. KP7

The nucleotide sequence of the gene cluster, phdEFABGHCD, encoding enzymes responsible for the transformation of phenanthrene to 1-hydroxy-2-naphthoate in Nocardioides sp. strain KP7 was determined. This gene cluster, which may constitute a single operon, resided at 6.1-kb downstream of the phdIJK gene cluster encoding the enzymes for the transformation of 1-hydroxy-2-naphthoate to o-phthalate. In general, the phd products exhibited moderate degrees of homology with isofunctional enzymes found in pathways for the degradation of other aromatic compounds. Remarkably, the phdC gene product had features of the [3Fe-4S] type ferredoxin, which has not been found so far as a component of the ring-hydroxylating dioxygenase. Escherichia coli carrying the genes for phenanthrene dioxygenase, phdABCD, was capable to oxidize phenanthrene.

Nocardioides pyridinolyticus sp. nov., a pyridine-degrading bacterium isolated from the oxic zone of an oil shale column

A bacterial strain which is able to degrade pyridine was previously isolated from the oxic zone of an oil shale column and described as Pimelobacter sp. strain OS4T. However, Pimelobacter species have been transferred to the genera Nocardioides and Terrabacter. Strain OS4T was identified as a member of the genus Nocardioides on the basis of chemotaxonomic analysis and phylogenetic inference based on 16S ribosomal DNA (rDNA) sequence analysis. The G+C content of strain OS4T is 72.5 mol%. The cell wall peptidoglycan contains LL-diaminopimelic acid as the diamino acid. The predominant menaquinone is MK-8(H4). The cellular fatty acid profile of strain OS4T is similar to that of the genus Nocardioides. The 16S rDNA similarity of strain OS4T with previously described Nocardioides species is 94.5% +/- 0.7%, and a phylogenetic tree based on 16S rDNA sequences revealed a distinct lineage for strain OS4T within the evolutionary radiation enclosed by the genus Nocardioides. Therefore, on the basis of our data, we propose that strain OS4T should be placed in the genus Nocardioides as a member of a new species, Nocardioides pyridinolyticus. The type strain of the new species is strain OS4 (= KCTC 0074BP).

Description of Nocardiopsis synnemataformans sp. nov., elevation of Nocardiopsis alba subsp. prasina to Nocardiopsis prasina comb. nov., and designation of Nocardiopsis antarctica and Nocardiopsis alborubida as later subjective synonyms of Nocardiopsis dassonvillei

Data from chemotaxonomic and 16S ribosomal DNA sequence analyses of an isolate obtained from the sputum of a kidney transplant patient identified the isolate as a member of the genus Nocardiopsis. DNA-DNA hybridization data, as well as physiological characteristics, indicated that the isolate represents a new species of the genus Nocardiopsis, designated Nocardiopsis synnemataformans; the type strain is strain IMMIB D-1215 (= DSM 44143). In addition, DNA-DNA hybridization data, as well as the results of biochemical tests, indicated that Nocardiopsis alborubida DSM 40465T, Nocardiopsis antarctica DSM 43884T, and Nocardiopsis dassonvillei DSM 43111T represent a single species designated N. dassonvillei. We also found that Nocardiopsis alba subsp. alba DSM 43377T and N. alba subsp. prasina DSM 43845T are genetically different and therefore propose that N. alba subsp. prasina be elevated to species status as Nocardiopsis prasina comb. nov., whose type strain is strain DSM 43845.

[Propionic acid cocci and their taxonomic position]

In order to determine the taxonomic position of propionic cocci, the authors studied their morphological, cultural and biochemical properties, the fatty acid composition of cells, and established the degree of homology for the DNAs of cocci and classical propionic bacteria using the method of molecular hybridization. The cocci were found to have the activities of catalase and superoxide dismutase which were higher than in the studied propionic bacteria. The propionic cocci and propionic bacteria were shown to be similar in terms of their fatty acid composition and to contain the C15-saturated acid in the form of anteiso isomer as the main type of fatty acids. Their fatty acid composition was most similar to that of the species Propionibacterium jensenii (P. technicum). The propionic cocci and bacteria are related in the structure of their genomes, particularly, in the case of the bacterium P. jensenii (P. raffinosaceum)--49%. On the basis of studying the phenotypic characteristics, the fatty acid composition, the nucleotide composition of DNA, and the high degree of homology between the DNAs of the cocci and the bacterial species P. jensenii (P. raffinosaceum), the authors propose to assign the cocci to the genus Propionibacterium as a new species Propionibacterium coccoides.