Comparative genomic analysis of the Dietzia genus: an insight into genomic diversity, and adaptation

Dietzia strains are widely distributed in the environment, presenting an opportunistic role, and some species have undetermined taxonomic characteristics. Here, we propose the existence of errors in the classification of species in this genus using comparative genomics. We performed ANI, dDDH, pangenome and genomic plasticity analyses better to elucidate the phylogenomic relationships between Dietzia strains. For this, we used 55 genomes of Dietzia downloaded from public databases that were combined with a newly sequenced. Sequence analysis of a phylogenetic tree based on genome similarity comparisons and dDDH, ANI analyses supported grouping different Dietzia species into four distinct groups. The pangenome analysis corroborated the classification of these groups, supporting the idea that some species of Dietzia could be reassigned in a possible classification into three distinct species, each containing less variability than that found within the global pangenome of all strains. Additionally, analysis of genomic plasticity based on groups containing Dietzia strains found differences in the presence and absence of symbiotic Islands and pathogenic islands related to their isolation site. We propose that the comparison of pangenome subsets together with phylogenomic approaches can be used as an alternative for the classification and differentiation of new species of the genus Dietzia.

The Roles of the Two-Component System, MtrAB, in Response to Diverse Cell Envelope Stresses in Dietzia sp. DQ12-45-1b

Two-component systems (TCSs) act as common regulatory systems allowing bacteria to detect and respond to multiple environmental stimuli, including cell envelope stress. The MtrAB TCS of Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance, and thus is found to be highly conserved across this phylum. However, how precisely the MtrAB TCS regulates cellular homeostasis in response to environmental stress remains unclear. Here, we show that the MtrAB TCS plays an important role in the tolerance to different types of cell envelope stresses, including environmental stresses (i.e., oxidative stress, lysozyme, SDS, osmotic pressure, and alkaline pH stresses) and envelope-targeting antibiotics (i.e., isoniazid, ethambutol, glycopeptide, and β-lactam antibiotics) in Dietzia sp. DQ12-45-1b. An mtrAB mutant strain exhibited slower growth compared to the wild-type strain and was characterized by abnormal cell shapes when exposed to various environmental stresses. Moreover, deletion of mtrAB resulted in decreased resistance to isoniazid, ethambutol, and β-lactam antibiotics. Further, Cleavage under targets and tagmentation sequencing (CUT&Tag-seq) and electrophoretic mobility shift assays (EMSAs) revealed that MtrA binds the promoters of genes involved in peptidoglycan biosynthesis (ldtB, ldtA, murJ), hydrolysis (GJR88_03483, GJR88_4713), and cell division (ftsE). Together, our findings demonstrated that the MtrAB TCS is essential for the survival of Dietzia sp. DQ12-45-1b under various cell envelope stresses, primarily by controlling multiple downstream cellular pathways. Our work suggests that TCSs act as global sensors and regulators in maintaining cellular homeostasis, such as during episodes of various environmental stresses. The present study should shed light on the understanding of mechanisms for bacterial adaptivity to extreme environments.

IMPORTANCE The multilayered cell envelope is the first line of bacterial defense against various extreme environments. Bacteria utilize a large number of sensing and regulatory systems to maintain cell envelope homeostasis under multiple stress conditions. The two-component system (TCS) is the main sensing and responding apparatus for environmental adaptation. The MtrAB TCS highly conserved in Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance. However, how MtrAB works with regard to signals impacting changes to the cell envelope is not fully understood. Here, we found that in the Actinobacterium Dietzia sp. DQ12-45-1b, a TCS named MtrAB is pivotal for ensuring normal cell growth as well as maintaining proper cell morphology in response to various cell envelope stresses, namely, by regulating the expression of cell envelope-related genes. Our findings should greatly advance our understanding of the adaptive mechanisms responsible for maintaining cell integrity in times of sustained environmental shocks.

Nasal Dysbiosis in Cutaneous T-Cell Lymphoma Is Characterized by Shifts in Relative Abundances of Non-Staphylococcus Bacteria

The nasal microbiome of patients with cutaneous T-cell lymphoma (CTCL) remains unexplored despite growing evidence connecting nasal bacteria to skin health and disease. Nasal swabs from 45 patients with CTCL (40 with mycosis fungoides, 5 with Sézary syndrome) and 20 healthy controls from the same geographical region (Chicago Metropolitan Area, Chicago, IL) were analyzed using sequencing of 16S ribosomal RNA and tuf2 gene amplicons. Nasal α-diversity did not differ between mycosis fungoides/Sézary syndrome and healthy controls (Shannon index, genus level, P = 0.201), but distinct microbial communities were identified at the class (R2 = 0.104, P = 0.023) and order (R2 = 0.0904, P = 0.038) levels. Increased relative abundance of the genera Catenococcus, Vibrio, Roseomonas, Acinetobacter, and unclassified Clostridiales was associated with increased skin disease burden (P < 0.005, q < 0.05). Performed to accurately resolve nasal Staphylococcus at the species level, tuf2 gene amplicon sequencing revealed no significant differences between mycosis fungoides/Sézary syndrome and healthy controls. Although S. aureus has been shown to worsen CTCL through its toxins, no increase in the relative abundance of this taxon was observed in nasal samples. Despite the lack of differences in Staphylococcus, the CTCL nasal microbiome was characterized by shifts in numerous other bacterial taxa. These data add to our understanding of the greater CTCL microbiome and provide context for comprehending nasal-skin and host‒tumor‒microbial relationships.

Investigation of Age-Related Changes in the Skin Microbiota of Korean Women

The microbiota of human skin is influenced by host and environmental factors. To determine if chronological age influences the composition of the skin microbiota on the forehead and hands, 73 Korean women were sorted into one of three age groups: (1) 10-29 years (n = 24), (2) 30-49 years (n = 21), and (3) 50-79 years (n = 28). From the 73 women, 146 skin samples (two skin sites per person) were collected. 16S rRNA gene amplicon sequencing was then conducted to analyze the skin microbiota. The overall microbial distribution varied on the forehead but was similar on the hands across the three age groups. In addition, the composition of the skin microbiota differed between the forehead and hands. Commensal microbiota, such as Streptococcus, Staphylococcus, Cutibacterium, and Corynebacterium, which contribute to maintaining skin health via dominant occupation, were affected by increasing age on forehead and hand skin. Alpha diversity indices increased significantly with age on forehead skin. This study indicates that older people may be more susceptible to pathogenic invasions due to an imbalanced skin microbiota resulting from age-related changes. The results of our study may help develop new strategies to rebalance skin microbiota shifted during aging.

Pan-genomic analysis reveals that the evolution of Dietzia species depends on their living habitats

The bacterial genus Dietzia is widely distributed in various environments. The genomes of 26 diverse strains of Dietzia, including almost all the type strains, were analysed in this study. This analysis revealed a lipid metabolism gene richness, which could explain the ability of Dietzia to live in oil related environments. The pan-genome consists of 83,976 genes assigned into 10,327 gene families, 792 of which are shared by all the genomes of Dietzia. Mathematical extrapolation of the data suggests that the Dietzia pan-genome is open. Both gene duplication and gene loss contributed to the open pan-genome, while horizontal gene transfer was limited. Dietzia strains primarily gained their diverse metabolic capacity through more ancient gene duplications. Phylogenetic analysis of Dietzia isolated from aquatic and terrestrial environments showed two distinct clades from the same ancestor. The genome sizes of Dietzia strains from aquatic environments were significantly larger than those from terrestrial environments, which was mainly due to the occurrence of more gene loss events during the evolutionary progress of the strains from terrestrial environments. The evolutionary history of Dietzia was tightly coupled to environmental conditions, and iron concentrations should be one of the key factors shaping the genomes of the Dietzia lineages.

Skin diseases of the breast and nipple: Inflammatory and infectious diseases

Certain dermatologic conditions are unique to the breast and nipple, whereas others may incidentally involve these structures. All require a nuanced approach to diagnosis and treatment because of the functional, sexual, and aesthetic importance of this area. The lactating patient requires special management because certain treatment options are contraindicated. All dermatologic conditions involving the breast and nipple require careful evaluation because malignancy of the breast can be mistaken for a benign condition or may trigger the development of certain dermatologic conditions. The second article in this continuing medical education series reviews common and uncommon inflammatory and infectious conditions of the breast and nipple and provides insight into both the diagnosis and the treatment of this heterogeneous group of diseases. For the purposes of this article, these conditions are divided into 4 distinct categories: 1) dermatitis; 2) radiation-induced changes; 3) mastitis; and 4) miscellaneous dermatologic conditions of the breast and nipple.

Identification of Dietzia Species in a Patient with Endophthalmitis following Penetrating Injury with Retained Intraocular Metallic Foreign Body

To the best of our knowledge, we report the first case of Dietzia species in a patient with endophthalmitis. A 47-year-old man presented to the ophthalmology department with decreased vision, redness, and minimal pain in his right eye after a foreign body struck his eye following working using a hammer and chisel. Broad-spectrum polymerase chain reaction (PCR) and deoxyribonucleic acid (DNA) sequencing targeting 16S ribosomal ribonucleic acid-(rRNA-) encoding gene on an undiluted vitreous sample revealed 100% identity with GenBank sequences of Dietzia species including D. natronolimnaea, D. dagingensis, and D. cercidiphylli. The culture of the vitreous samples demonstrated the growth of Gram-positive cocci and polymorphic rods. The isolate from the culture was identified as D. natronolimnaea using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). The combination of surgical and medical treatment (pars plana vitrectomy and systemic and topical antibiotics) eradicated the infection successfully.

Complete Genome Sequence of Dietzia sp. Strain WMMA184, a Marine Coral-Associated Bacterium

Dietzia sp. strain WMMA184 was isolated from the marine coral Montastraea faveolata as part of ongoing drug discovery efforts. Analysis of the 4.16-Mb genome provides information regarding interspecies interactions as it pertains to the regulation of secondary metabolism and natural product biosynthesis potential.

Identification of Dietzia spp. from Cardiac Tissue by 16S rRNA PCR in a Patient with Culture-Negative Device-Associated Endocarditis: A Case Report and Review of the Literature

The genus Dietzia was recently distinguished from other actinomycetes such as Rhodococcus. While these organisms are known to be distributed widely in the environment, over the past decade several novel species have been described and isolated from human clinical specimens. Here we describe the identification of Dietzia natronolimnaea/D. cercidiphylli by PCR amplification and sequencing of the 16S rRNA encoding gene from cardiac tissue in a patient with culture-negative device-associated endocarditis.

Confluent and reticulated papillomatosis: diagnostic and treatment challenges

Confluent and reticulated papillomatosis (CRP) of Gougerot and Carteaud was first typified in 1927. With the help of electron microscopy, it has been elucidated that CRP arises due to aberrant keratinization. However, till date, there is no clear consensus on the etiologic trigger for CRP. Prevailing postulates include a bacterial trigger by Dietzia papillomatosis (type strain N 1280(T)), an exaggerated cutaneous response to Malassezia furfur, an endocrine basis stemming from insulin resistance, ultraviolet light-induced epidermal change, amyloid deposition, and a loss-of-function mutation in keratin 16. CRP typically presents as asymptomatic hyperpigmented papules and plaques with peripheral reticulation over the nape, axillae, upper chest, and upper back, occasionally with extension superior to the forehead and inferior to the pubic region. Dermoscopy may be used in the evaluation of CRP, but its diagnosis is made on clinical grounds given its nonspecific histopathological findings. Although successful treatment with topical keratolytics, retinoids, or antifungals has been reported, antibiotics, such as minocycline, at anti-inflammatory doses have emerged as a preferred therapeutic option. In this article, we review the diagnostic considerations in CRP and its therapeutic options.

Clinicopathological and diagnostic characterization of confluent and reticulate papillomatosis of Gougerot and Carteaud: a retrospective study in a South-East Asian population

BACKGROUND

Confluent and reticulate papillomatosis of Gougerot and Carteaud (CRP) is a rare dermatological condition, which has not been reported widely in Asian populations.

AIM

To characterize the clinicopathological and diagnostic features of CRP in a South-East Asian population.

METHODS

The medical records of 29 patients accorded the diagnosis of CRP at the National Skin Centre, Singapore, from 1990 to 2011, were analyzed.

RESULTS

The male to female ratio was 2.6:1. Eight patients were Indians. The mean age at the onset of skin eruptions was 29.1 years (range 16-55 years), while the mean duration was 19.9 months (range 0.5-120 months). CRP itself was the most common preliminary diagnosis. Fungal smears were negative in all 22 instances. All 29 patients had received a trial of antifungal therapy before being seen at our center. Antifungal therapy was repeated in three subjects, and the response was uniformly poor. Conversely, the treatment response with tetracyclines was excellent, yielding more than a 50% response in all 14 patients. Four patients suffered recurrence of CRP. According to the diagnostic criteria set forth by Davis et al., 25/29 patients (86.2%) and 19/29 patients (65.6%) fulfilled at least three and four criteria, respectively.

CONCLUSION

A predilection for male gender and Indian ethnicity were noted in our study. The diagnosis of CRP was often made clinically, and investigations were mainly ancillary. The treatment response was poor with antifungal agents but excellent with tetracyclines. The diagnostic criteria proposed by Davis et al. were found to be useful in our cohort of patients.

Reticulate dermatoses

The term "reticulate" is used for clinical description of skin lesions that are configured in a net-like pattern. Many primary and secondary dermatoses present in such patterns involving specific body sites. Certain cutaneous manifestations of systemic diseases or genodermatoses also present in such manner. This review classifies and describes such conditions with reticulate lesions and briefly, their associated features.

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

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

High efficiency degradation crude oil by a novel mutant irradiated from Dietzia strain by 12C6+ heavy ion using response surface methodology

Crude oil is an extremely complex mixture of hydrocarbons; also contaminate environmental, leading to carcinogenic, teratogenic and mutagenic. Petroleum hydrocarbons degradation Dietzia strain DMYR9 was isolated from oilfield. Response surface methodology was applied for statistical designing of process parameters for dry weight of biomass production in the process of degradation. The optimization process parameters were successfully employed for degradation crude oil and confirmed through confirmatory experiments. On 28th day, analysis was done by GC-MS, These data show that the crude oil samples of n-Hexadecane, Octadecane, n-Nonadecanec, n-Pentacosane, n-Hexacosane, n-Heneicosane, n-Docosane, n-Tetracosane, n-Octacosane and Tetraethyl removal efficiency could reach up to 0%. RSM optimization and use of effective (12)C(6+)-ion irradiation methods can considerably enhance ability to degradation of microbial. Hence, bioresource Dietzia strain DMYR9, high ability to degradation, can be further used for subsequent repair hydrocarbons polluted of environment.

Dietzia papillomatosis bacteremia

The clinical significance of Dietzia papillomatosis is for the moment limited to the rare skin disease confluent and reticulated papillomatosis. We present a case of infection with D. papillomatosis in a 2-year-old boy with known syringomyelia. The microbiological diagnosis was done using 16S rRNA gene sequencing. This is the first report of bacteremia with D. papillomatosis.

First isolation of Dietzia cinnamea from a dog bite wound in an adult patient

We report the first case of deep-wound colonization by Dietzia cinnamea in a patient who had been bitten by a dog.

Biodegradation of aniline in an alkaline environment by a novel strain of the halophilic bacterium, Dietzia natronolimnaea JQ-AN

Dietzia natronolimnaea JQ-AN was isolated from industrial wastewater containing aniline. Under aerobic conditions, the JQ-AN strain degraded 87% of the aniline in a 300 mg L(-1) aniline solution after 120 h of shake flask incubation in a medium containing sodium acetate. This strain had an unusually high salinity tolerance in minimal medium (0-6% NaCl, w/v). The optimal pH for microbial growth and aniline biodegradation was pH 8.0. Two liters of simulated aniline wastewater was created in a reactor at pH 8.0 and 3% NaCl (w/v), and biodegradation of aniline was tested over 7 days at 30 °C. For the initial concentrations of 100, 300, and 500 mg L(-1), 100%, 80.5% and 72% of the aniline was degraded, respectively. Strain JQ-AN may use an ortho-cleavage pathway for dissimilation of the catechol intermediate.

Dietzia aurantiaca sp. nov., isolated from a human clinical specimen

A Gram-positive, coccoid, non-endospore-forming actinobacterium (strain CCUG 35676T) was isolated from cerebrospinal fluid from a 24-year-old woman in Gothenborg, Sweden. Based on pairwise 16S rRNA gene sequence similarity studies, strain CCUG 35676T was shown to belong to the genus Dietzia and was most closely related to the type strains of Dietzia aerolata (99.3 %), Dietzia lutea (98.8 %), Dietzia schimae (98.5 %), Dietzia maris (98.5 %), Dietzia alimentaria (98.3 %) and Dietzia cercidiphylli (98.0 %). The major menaquinone was MK-8(H2). Major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, an unidentified aminophospholipid (APL1), an unidentified phospholipid (PL1) and unidentified glycolipids (GL1 and GL3). Numerous other lipids were also detected. The fatty acid profile, comprising C16 : 0, C17 : 0, C18 : 1ω9c and 10-methyl-C18 : 0 as major fatty acids, supported the affiliation of strain CCUG 35676T to the genus Dietzia. On the basis of the results of physiological and biochemical tests and DNA–DNA hybridizations, a clear phenotypic and genotypic differentiation of strain CCUG 35676T from the most closely related Dietzia species is possible. Strain CCUG 35676T represents a novel species, for which the name Dietzia aurantiaca sp. nov. is proposed, with CCUG 35676T ( = JCM 17645T) as the type strain.

Draft genome sequence of Dietzia alimentaria 72T, belonging to the family Dietziaceae, isolated from a traditional Korean food

Actinobacterial strain 72(T), named Dietzia alimentaria, which belongs to the family Dietziaceae, was isolated from a traditional Korean food made from clams. The draft genome sequence of D. alimentaria 72(T) contains 3,352,817 bp, with a G+C content of 67.34%.

Dietzia alimentaria sp. nov., isolated from a traditional Korean food

An actinobacterial strain, designated 72T, was isolated from a traditional salt-fermented seafood in Korea. Colonies were coral red and cells were Gram-reaction-positive, non-motile rods. Strain 72T grew with 0–10 % (w/v) NaCl, at pH 7–10 and at 15–37 °C. Optimum growth conditions were 2 % NaCl, pH 7.0 and 30 °C. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain 72T belonged to the genus Dietzia. The major cellular fatty acids (>5 %) were C16 : 0, summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), 10-methyl C18 : 0, C17 : 0, C19 : 0 and C18 : 1ω9c. 16S rRNA gene sequence analysis and DNA–DNA hybridization, coupled with physiological and biochemical tests, revealed genotypic and phenotypic differences between strain 72T and other members of the genus Dietzia. Based on these data, strain 72T represents a novel species, for which the name Dietzia alimentaria sp. nov. is proposed. The type strain is 72T ( = JCM 16360T  = KACC 21126T).

Diversity of metabolic shift in response to oxygen deprivation in Corynebacterium glutamicum and its close relatives

Oxygen-deprived Corynebacterium glutamicum R cells remain metabolically active, producing considerable amounts of organic acids even when not actively growing. We compared the proficiencies of C. glutamicum and close relatives grown under aerobic conditions to metabolize glucose when deprived of oxygen. Eight strains that readily consumed glucose without cell growth subsequently produced organic acids. Among these, the glucose consumption rates of the two C. glutamicum strains (>40 mM/h) and Corynebacterium efficiens (>12 mM/h) were an order of magnitude higher than those of the other five strains. The resultant organic acid yields of these three strains (>86%) consequently exceeded those of the other five (<60%). This difference is probably rooted in the comparatively inferior activities of glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and malate dehydrogenase observed in the five strains. Moreover, under oxygen deprivation, phosphoenolpyruvate carboxylase (PEPC) activity of C. efficiens was elevated tenfold, but its lack of fumarase activity meant that no succinic acid could be produced. The metabolic shift occasioned by addition of the PEPC substrate sodium bicarbonate resulted in a doubling of the glucose consumption rate of the two C. glutamicum strains but not that of the other six close relatives.

Genetic manipulation tools for Dietzia spp

AIM

To develop an applicable vector system and a transformation method for the manipulation of Dietzia spp.

METHODS AND RESULTS

The pNV18 Nocardia-E. coli shuttle vector was tested and found to be a replicating plasmid in Dietzia sp. E1. With the use of pNV18, an electroporation method was optimized for the transformation of Dietzia sp. E1, and a transformation efficiency suitable for genetic manipulations was achieved (2·18×10(4) transformants μg(-1) DNA). The method was also applied for the transformation of Dietzia cinnamea, D. maris, D. natronolimnaea and D. psychralcaliphila.

CONCLUSIONS

The first applicable vectors and a simple electroporation protocol enabling the manipulation of several Dietzia spp. are presented.

SIGNIFICANCE AND IMPACT OF THE STUDY

Dietzia spp. have clinical, industrial and great environmental importance; however, the analysis of the Dietzia genus is currently hampered by the lack of manipulation techniques. The presented basic tools allow the genetic analysis of several Dietzia species, including the human disease-associated Dietzia maris.

Identification of atypical Rhodococcus-like clinical isolates as Dietzia spp. by 16S rRNA gene sequencing

Rhodococcus equi and Dietzia spp. are closely related actinomycetes that show similar phenotypic properties. In humans, R. equi is an opportunistic pathogen associated with severe immunodeficiency. Dietzia spp. are environmental bacteria that have been isolated recently from clinical material and are presumptively associated with human infections. During the last 5 years, 15 bacterial isolates from human clinical samples collected at the Hospital Marqués de Valdecilla, Santander, Spain, were identified as R. equi by the API Coryne test. 16S rRNA gene sequencing confirmed seven isolates to be true R. equi strains, whereas the other eight were identified as members of the genus Dietzia, including Dietzia maris (four isolates), Dietzia natronolimnaea (two isolates), and Dietzia timorensis and Dietzia sp. (one isolate each). The eight Dietzia isolates were highly sensitive to 12 antimicrobial compounds.

Dietzia aerolata sp. nov., isolated from the air of a duck barn, and emended description of the genus Dietzia Rainey et al. 1995

A Gram-stain-positive, coccoid, non-endospore-forming actinobacterium (Sj14aT) was isolated from the air of a duck barn on tryptone soy agar after filter sampling. On the basis of 16S rRNA gene sequence similarity studies, strain Sj14aT was shown to belong to the genus Dietzia and was most closely related to Dietzia schimae (98.7 %), Dietzia cercidiphylli (98.4 %) and Dietzia maris (98.6 %). The major menaquinone was MK-8 (H2). The polar lipid profile included the major components diphosphatidylglycerol, phosphatidylglycerol, an unknown polar lipid and two unknown glycolipids. Phosphatidylinositol and two phosphatidylinositol mannosides, as well as several other unknown lipids, were also detected. The polyamine pattern contained the major compounds spermine and spermidine. The fatty acid profile, containing C16 : 0, C17 : 0, C18 : 1 ω9c and 10-methyl C18 : 0 as major fatty acids, supported the affiliation of strain Sj14aT to the genus Dietzia. The results of physiological and biochemical tests and DNA–DNA hybridizations allowed a clear phenotypic differentiation of strain Sj14aT from the most closely related species of the genus Dietzia. Strain Sj14aT represents a novel species, for which the name Dietzia aerolata sp. nov. is proposed, with the type strain Sj14aT (=DSM 45334T =CCM 7659T).

Williamsia faeni sp. nov., an actinomycete isolated from a hay meadow

The taxonomic status of an actinomycete isolated from soil collected from a hay meadow was determined using a polyphasic approach. The strain, designated N1350(T), had morphological and chemotaxonomic properties consistent with its classification in the genus Williamsia and formed a distinct phyletic line within the clade comprising the type strains of species of the genus Williamsia in the 16S rRNA gene tree. Strain N1350(T) shared highest 16S rRNA gene sequence similarities with Williamsia marianensis MT8(T) (98.1 %) and Williamsia muralis MA140-96(T) (98.3 %). However, strain N1350(T) was readily distinguished from the type strains of Williamsia species using a combination of phenotypic properties. On the basis of these data, strain N1350(T) is considered to represent a novel species of the genus Williamsia. The name proposed for this taxon is Williamsia faeni sp. nov., with the type strain N1350(T) (=DSM 45372(T) =NCIMB 14575(T) =NRRL B-24794(T)).

Dietzia timorensis sp. nov., isolated from soil

An actinomycete strain, ID05-A0528(T), was isolated using the SDS-yeast extract pre-treatment method from soil under mahogany (Swietenia mahogani) trees in West Timor, Indonesia, and was examined by using a polyphasic taxonomic approach. Chemotaxonomic and phylogenetic characterizations demonstrated that the novel strain belongs to the genus Dietzia. 16S rRNA gene sequencing studies showed that the strain was related to Dietzia cinnamea (97.2 %). Results of phenotypic and phylogenetic analyses determined that strain ID05-A0528(T) is different from the known species of the genus Dietzia. It is proposed that the isolate should be classified as a representative of a novel species of the genus Dietzia, with the name Dietzia timorensis sp. nov. The type strain is ID05-A0528(T) (=BTCC B-560(T) =NBRC 104184(T)).

Hydrocarbon degradation by Dietzia sp. A14101 isolated from an oil reservoir model column

The hydrocarbon-degrading strain Dietzia sp. A14101 was isolated from an oil reservoir model column inoculated with oil-field bacteria. The column was continuously injected with nitrate (0.5 mM) from the start of water flooding, which lead to a gradual development of nitrate reduction in the column. Strain A14101 was able to utilize a range of aliphatic hydrocarbons as sole carbon and energy source during aerobic growth. Whole oil gas chromatography analysis of the crude oil phase from aerobic pure cultures showed that strain A14101 utilized the near complete range of aliphatic components and aromatic components toluene and xylene. Longer n-alkanes >/=C(17) were utilized simultaneously with the shorter C(10) and C(15). After 120 days aerobic incubation, the whole oil gas chromatography profile of the crude oil phase was similar to that of heavily biodegraded oils. Anaerobic degradation of hydrocarbons with nitrate was not observed. Nitrate reduction was, however, observed during anaerobic growth on propionate, which suggests that strain A14101 grows on fatty acids in the column rather than on hydrocarbons.

Dietzia schimae sp. nov. and Dietzia cercidiphylli sp. nov., from surface-sterilized plant tissues

Two actinobacterial strains, YIM 65001(T) and YIM 65002(T), were isolated from surface-sterilized plant tissues collected from Yunnan Province, south-west China, and their taxonomic positions were determined by using a polyphasic approach. The DNA G+C contents of strains YIM 65001(T) and YIM 65002(T) were 71.9 and 72.6 mol%, respectively. The two strains had chemotaxonomic markers that were consistent with their classification in the genus Dietzia. Phylogenetic analysis based on almost-complete 16S rRNA gene sequences indicated that strain YIM 65001(T) was related most closely to Dietzia maris DSM 43672(T) and that strain YIM 65002(T) was related most closely to Dietzia natronolimnaea CBS 107.95(T). Levels of 16S rRNA gene sequence similarity between strains YIM 65001(T) and YIM 65002(T) and the type strains of other recognized members of the genus Dietzia were 95.8-99.8 %. DNA-DNA hybridization experiments confirmed the separate genomic status of strains YIM 65001(T) and YIM 65002(T). Strains YIM 65001(T) and YIM 65002(T) showed significant phenotypic differences between each other and their closest recognized neighbours. On the basis of their phenotypic and phylogenetic distinctiveness, the two novel isolates were identified as representing two novel species of the genus Dietzia, for which the names Dietzia schimae sp. nov. (type strain YIM 65001(T)=CCTCC AA 207015(T)=DSM 45139(T)) and Dietzia cercidiphylli sp. nov. (type strain YIM 65002(T)=CCTCC AA 207016(T)=DSM 45140(T)) are proposed.

The genus Dietzia: a new home for some known and emerging opportunist pathogens

The genus Dietzia has only been established fairly recently. The Gram morphology and colony appearance of the species of this genus is remarkably similar to Rhodococcus equi. In the absence of simple, accurate methods for their identification, Dietzia spp. might have been misidentified as a Rhodococcus spp. and/or considered to be contaminants only. This MiniReview is designed to summarize current evidence on the clinical significance of Dietzia species, to consider their potential role as human pathogens, and to outline approaches that can be used to accurately classify and identify members of the genus, with the overall aim of alerting the medical microbiological community to a little known genus that contains clinically significant organisms.