Genus Nocardia Research Articles

Isolation and Characterization of Nocardiae Associated with Foaming Coastal Marine Waters.

Nocardiosis is an infectious disease caused by Nocardia species that occurs worldwide, albeit more prevalently in tropical/subtropical regions. It can appear as either acute, subacute or as a chronic infection mostly with those with a compromised/weakened immune system. Inhalation of spores and or mycelium fragments is the main transmission route for developing pulmonary nocardiosis. In contrast, cutaneous nocardiosis usually occurs via direct contact. In the subtropical region of the Sunshine Coast in Australia foaming events with thick and persistent and orange-brown color foam have been observed during summer seasons in the near shore marine environments. This study reports the existence of nocardiae in these near shore marine environments by the use of a novel isolation method which used the gas requirements of nocardiae as a selective battery. A total of 32 nocardiae were isolated with the use of this novel method and subsequently conducted molecular identification methods confirmed that the isolates belonged to the genus Nocardia. Twenty-one isolates out of the 32 were closely related to N. nova strains MGA115 and one was related to CBU 09/875, in addition when compared with human pathogenic nocardiae twenty of the isolates were found to be related to N. nova strain JCM 6044. Isolates displayed varied resistance against some of the antibiotics tested when interpretation threshold recommended the Comite de L’Antibiogramme de la Societe Francaise de Microbiologie were used. The highest level of resistance against cefotaxime (n = 27) and ceftriaxone (n = 24). Some of the isolates (n = 6) that displayed resistance to selected antibiotics also possessed potential human pathogenic characteristics such as adherence and translocation through human long epithelial cells as well as displaying phage resistance (n = 26). They might thus present a potential public health risk if frequently encountered through exposure to aerosols generated by the foam as well as direct contact through a wound. Preventative measures to control the growth of nocardiae in such environments such as the control of pollutants, might prevent potential infections that might be caused by these bacteria in humans as well as in marine animals.

Molecular characterization and improved diagnostics of Nocardia strains isolated over the last two decades at a German tertiary care center.

Nocardiosis is a rare but life-threatening infection caused by aerobic Actinomycetes of the genus Nocardia particularly affecting immunocompromised hosts. The identification of Nocardia ssp. and antibiotic susceptibility testing by standard microbiological methods are incomplete and molecular techniques may improve diagnostics. We studied 39 Nocardia strains isolated from 33 patients between 2000 and 2018. Twenty-four patients (72.7 %) were immunocompromised. Whole genome sequencing (WGS) revealed a broad taxonomic range of those isolates spanning 13 different species, including four strains that belonged to three novel species based on average nucleotide identity (ANI < 95 % with currently available genome sequences). 16S rRNA gene analyses mirrored WGS results. Conventional MALDI-TOF analysis correctly identified 29 isolates at the species level (74.4 %). Our advanced protocol with formic acid and acetonitrile treatment increased identification to 35 isolates (89.7 %). Antibiotic resistance was tested using both a microdilution method and MIC strip testing. Results were in good concordance with an overall trimethoprim-sulfamethoxazole (SXT) resistance rate of 13.5 %. WGS of a SXT resistant N. farcinica isolate showed a deletion of several amino acids in a homolog of dihydropteroate synthase (FolP2) that was not seen in sensitive members of this species. Diversity of Nocardia isolates was high and involved many different species, suggesting that this taxon has broadly distributed mechanisms for infecting individuals. Widely applicable diagnostic methods including MALDI-TOF and 16S rRNA gene analyses correctly identified most strains. WGS additionally revealed molecular insights into SXT resistance mechanisms of clinical Nocardia isolates highlighting the potential application of (meta)genomic-based diagnostics in the future.

Identification and Characterization of Mycobacterium smegmatis and Mycobacterium avium subsp. paratuberculosis Zinc Transporters.

Zinc uptake in bacteria is essential to maintain cellular homeostasis and survival. ZnuABC is an important zinc importer of numerous bacterial genera, which is expressed to restore zinc homeostasis when the cytosolic concentration decreases beyond a critical threshold. Upon zinc limitation the fast-growing nonpathogenic organism Mycobacterium smegmatis (MSMEG) as well as the ruminant pathogen M. avium subsp. paratuberculosis (MAP) increases expression of genes encoding ZnuABC homologues, but also of genes encoding other transporters. This suggests an involvement of these transporters in zinc homeostasis. Here we characterized the putative zinc transporters of MSMEG (ZnuABC and ZnuABC2) and MAP (ZnuABC, MptABC, and MAP3774-76). Deletion of either ZnuABC or ZnuABC2 in MSMEG did not lead to growth defects, but to an increased expression of zinc marker genes in MSMEGΔznuABC, indicating cytosolic zinc limitation. However, chromatin immunoprecipitation proved direct binding of the global zinc regulator Zur to promoter regions of both znuABC and znuABC2. Simultaneous deletion of both transporters caused severe growth defects, which could be restored either by homologous complementation with single ZnuABC transporters or supplementation of growth media with zinc but not iron, manganese, cobalt, or magnesium. Heterologous complementation of the double mutant with MAP transporters also resulted in reconstitution of growth. Nonradioactive FluoZinTM-3AM zinc uptake assays directly revealed the competence of all transporters to import zinc. Finally, structural and phylogenetic analyses provided evidence of a novel class of ZnuABC transporters represented by the ZnuABC2 of MSMEG, which is present only in actinobacteria, mainly in the genera Nocardia, Streptomyces and fast growing Mycobacteria IMPORTANCEZinc is necessary for bacterial growth but simultaneously toxic when in excess. Hence, bacterial cells have developed systems to alter intracellular concentration. Regulation of these systems is primarily executed at transcriptional level by regulator proteins which sense femtomolar changes in the zinc level. In environmental and pathogenic mycobacteria zinc starvation induces expression of common zinc import systems such as the ZnuABC transporter, but also of other additional not yet characterized transport systems. In this study, we characterized the role of such systems in zinc transport. We showed that transport systems of both species whose transcription is induced upon zinc starvation can exchangeably restore cellular zinc homeostasis in transporter deficient mutants by transporting zinc into the cell.

Disseminated Nocardiosis Masquerading as Metastatic Malignancy

Nocardiosis is an uncommon Gram-Positive bacterial infection caused by aerobic Actinomycetes of the genus Nocardia. It can be local-ized or systemic and is regarded as an opportunistic infection that is commonly seen in immunocompromised patients. We report a case of disseminated Nocardiosis in a patient on immunosuppressant therapy in whom the clinical presentation was highly suggestive of a meta-static disease.

1557. First Report of Nocardia veterana Soft Tissue Abscess

BackgroundMembers of the genus Nocardia are filamentous, gram-positive, aerobic bacteria and exist ubiquitously in most environments. In 2001, the species Nocardia veterana was first isolated, and it predominantly causes pulmonary infections in immunocompromised hosts.MethodsWe present the first report of a soft tissue abscess caused by N. veterana in a 59-year-old woman being treated for chronic cutaneous graft-versus-host disease.ResultsAfter failing to improve with empiric treatment, two incision and drainage procedures were required. She subsequently completed a one-year course of oral antibiotic therapy consisting of trimethoprim-sulfamethoxazole then azithromycin. No relapse occurred. To better characterize N. veterana infections, we performed a systematic literature review and summarized all previously reported cases.Nocardia veterana abscess ConclusionThe rising prevalence of immunocompromising conditions warrants increased vigilance for N. veterana infections and other atypical or opportunistic pathogens.Disclosures All Authors: No reported disclosures

Characterization and function study of a glutamyl endopeptidase homolog from Nocardia seriolae.

Glutamic endopeptidases (Glu), belonging to the class of serine proteases, are a subfamily of chymotrypsin-like proteolytic enzymes, which are regarded as important virulence factors in bacteria. However, the roles of glutamic endopeptidases of Nocardia seriolae in pathogenic process still remain uncertain. Here, a glutamic endopeptidase homolog from N. seriolae (GluNS) was cloned and its function was elucidated. GluNS encoded a 414-aa protein which shared 93% identity to N. concava. In the phylogenetic tree, the glutamic endopeptidases of genus Nocardia clustered together firstly and then clustered with Streptomyces species. Moreover, GluNS was identified to be a secreted protein of N. seriolae and localized in the mitochondria of FHM cells. The transient overexpression of GluNS significantly induced increase in caspase-3 activity and decrease in ΔΨm values in FHM cells. The number of apoptotic bodies was remarkably higher than that in control group. Taken together, GluNS overexpression induced apoptotic characteristics in FHM cells. This study provided new insights into the function of glutamic endopeptidase from N. seriolae.

Nocardia terrae sp. nov., an actinomycete isolated from soil in Thailand.

A novel actinomycete strain ET3-3T isolated from soil collected from Chachoengsao province, Thailand was taxonomic evaluated using a polyphasic approach. Chemotaxonomic analysis indicated that meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. Mycolic acids were present. Ribose, arabinose, and galactose were detected in its whole-cell hydrolysates. The strain comprised C16:0 and TBSA 10-methyl C18:0 as the main fatty acids and MK-8(H4ω-cycl) as the predominant menaquinone. Major polar lipids were phosphatidylinositol, phosphatidylinositol mannoside, phosphatidylethanolamine, and diphosphatidylglycerol. The results of 16S rRNA gene sequence analysis showed that strain ET3-3T was closely related to Nocardia seriolae JCM 30082T (99.2%), Nocardia yunnanensis JCM 30082T (98.4%), and Nocardia concava JCM 12351T (98.2%). The draft genome of ET3-3T was 9.31Mb with 8826 coding sequences with an average G + C content of 68.0%. The comparison of the draft genome of strain ET3-3T and N. seriolae NBRC 15557T showed theANIb, ANIm and the digital DNA-DNA hybridization values of 86.3%, 88.5% and 32.9%, respectively. The results of the taxonomic analysis suggested that strain ET3-3T represented a novel species of the genus Nocardia for which the name Nocardia terrae sp. nov. is proposed. The type strain is ET3-3T (= JCM 33776T = TISTR 2837T).

Phylogenetic and Physiological Diversity of Cultivable Actinomycetes Isolated From Alpine Habitats on the Qinghai-Tibetan Plateau.

Actinomycetes in extreme alpine habitat have attracted much attention due to their unique physiological activities and functions. However, little is known about their ecological distribution and diversity. Here, we explored the phylogenetic relationship and physiological heterogeneity of cultivable actinomycetes from near-root soils of different plant communities in the Laohu Ditch (2200 – 4200 m) and Gaize County area (5018 – 5130 m) on the Qinghai-Tibetan Plateau. A total of 128 actinomycete isolates were obtained, 16S rDNA-sequenced and examined for antimicrobial activities and organic acid, H2S, diffusible pigments, various extracellular enzymes production. Seventy three isolates of the total seventy eight isolates from the Laohu Ditch, frequently isolated from 2200 to 4200 m, were closely related to Streptomyces spp. according to the 16S rDNA sequencing, while four isolates within the genus Nocardia spp. were found at 2200, 2800, and 3800 m. In addition, one potential novel isolate with 92% sequence similarity to its nearest match Micromonospora saelicesensis from the GenBank database, was obtained at 2200 m. From the Gaize County area, fifty Streptomyces isolates varied in diversity at different sites from 5018 to 5130 m. The investigation of phenotypic properties of 128 isolates showed that 94.5, 78.9, 68, 64.8, 53, 51.6, 50, 36.7, 31.2, and 22.7% of the total isolates produced catalase, lipase 2, urease, protease, H2S, lipase 3, amylase, lipase 1, diffusible pigment and organic acid, respectively. The antimicrobial assays of the total isolates revealed that 5, 28, 19, and 2 isolates from Streptomyces spp. exhibited antimicrobial activity against Escherichia coli, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa, respectively. This study intends to bring helpful insights in the exploitation and utilization of alpine actinomycetes for novel bioactive compounds discovery.

A survey of intact low-density polyethylene film biodegradation by terrestrial Actinobacterial species.

Low-density polyethylene (LDPE) polymer is mainly used in the production of plastic bags and food packaging making up the largest volume of plastic pollutions. These polymers are potential substrates for bacteria in the bioremediation process. In this study, soil samples were collected from different plastic landfills in Iran and subsequently enriched in specific media (polyethylene as carbon source) to increase the population of LDPE-degrading bacteria. Seventeen PE-degrading bacteria, some novel, were isolated from Iranian soil samples and identified using 16S rDNA gene sequencing. These isolates were capable of degrading PE in a limited incubation period without the need for physicochemical pretreatments and comprise mostly of Actinobacteria which include the three genera of Streptomyces, Nocardia, and Rhodococcus. The isolates belonged to 17 different species of gram-positive Actinobacteria. In all, 11 species of the genus Streptomyces, 3 species of the genus Rhodococcus, and 3 species of the genus Nocardia were identified. The isolates with less than 99% 16S rRNA gene similarity to previously known species were suspected to be new species. Various analyses (weight loss, SEM, FTIR, and tensile strength test) to determine polyethylene biodegradation rate were carried out after a 60-day incubation period. Analysis of polyethylene biodegradation elucidates that Actinobacteria have a high ability for biodegradation of polyethylene-based plastics. Streptomyces sp. IR-SGS-T10 showed the highest reduction in weight of the LDPE film (1.58mg/g/day) after 60days of incubation without any pretreatments. Rhodococcus sp. IR-SGS-T11 shows the best reduction in the tensile property of LDPE film, while results from FTIR study for Streptomyces sp. IR-SGS-Y1 indicated a significant change in structural analysis.

Nocardia spp.: A Rare Cause of Pneumonia Globally.

Members of the Nocardia genus are ubiquitous in the environment. These aerobic, gram-positive organisms can lead to life-threatening infection, typically in immunocompromised hosts such as solid organ transplant recipients or those receiving immunosuppressive medications for other reasons. This current review discusses the microbiology of nocardiosis, risk factors for infection, clinical manifestations, methods for diagnosis, and treatment. Nocardiosis primarily affects the lung but may also cause skin and soft tissue infection, cerebral abscess, bloodstream infection, or infection involving other organs. Although rare as a cause of community-acquired pneumonia, Nocardia can have severe morbidity and mortality, particularly in patients with comorbidities or compromised immunity. Early diagnosis and timely initiation of therapy are critical to optimizing patient outcomes. Species identification is important in determining treatment, as is in vitro susceptibility testing. Sulfonamide therapy is usually indicated, although a variety of other antimicrobials may be useful, depending on the species and susceptibility testing. Prolonged therapy is usually indicated, for 6 to 12 months, and in some cases surgical debridement may be required to resolve infection.

A clinical case report of brain abscess caused by Nocardia brasiliensis in a non-immunocompromised patient and a relevant literature review

BackgroundBrain abscess due to the Nocardia genus is rare and usually found in immunocompromised patients. The most common subtype implicated is Nocardia farcinica while brain abscess due to Nocardia brasiliensis is comparatively rare. Diagnosis of brain abscess is based mainly on bacteriological culture from pus collected at the site of infection, and brain imaging. Stereotaxic aspiration or surgical resection combined with adequate duration of treatment with antibiotics to which the bacteria are sensitive represent effective treatment strategies.Case presentationWe report a rare case of brain abscess caused by Nocardia brasiliensis in a non-immunocompromised patient. He admitted to our hospital twice with a headache. Stereotaxic aspiration was performed at the patient’s first appointment at the hospital, and a craniotomy was used to excise the lesion during subsequent abscess recurrence.ConclusionEarly diagnosis, reasonable surgical intervention, and adequate duration of treatment with effective antibiotics are critical for treating brain abscess.

Nocardia colli sp. nov., a new pathogen isolated from a patient with primary cutaneous nocardiosis.

A novel nocardioform strain, CICC 11023T, was isolated from a tissue biopsy of neck lesions of a patient with primary cutaneous nocardiosis and characterized to establish its taxonomic position. The morphological, biochemical, physiological and chemotaxonomic properties of strain CICC 11023T were consistent with classification in the genus Nocardia . Whole-cell hydrolysates were rich in meso-diaminopimelic acid, galactose, arabinose and fructose. Mycolic acids were present. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid and two unidentified lipids, and the predominant menaquinone was cyclo MK-8 (H4, ω-cyclo). The main fatty acids (>5 %) were C18 : 0 10-methyl (TBSA), C16 : 0, summed feature 4 (C16 : 1 trans 9/C15 : 0 iso 2OH), C15 : 0 and C17 : 0 10-methyl. Phylogenetic analyses based on 16S rRNA gene sequences revealed that the isolate is most closely related (>98 % similarity) to the type strains Nocardia ninae OFN 02.72T, Nocardia iowensis UI 122540T and Nocardia alba YIM 30243T, and phylogenetic analysis of gyrB gene sequences showed similarity (89.1–92.2 %) to Nocardia vulneris NBRC 108936T, Nocardia brasiliensis IFM 0236T and Nocardia exalbida IFM 0803T. DNA–DNA hybridization results for strain CICC 11023T compared to Nocardia type strains ranged from 20.4 to 35.4 %. The genome of strain CICC 11023T was 8.78 Mbp with a G+C content of 67.4 mol% overall. The average nucleotide identity (ANI) values between strain CICC 11023T and N. alba YIM 30243T were low (OrthoANIu=77.47 %), and the ANI values between strain CICC 11023T and N. vulneris NBRC 108936 T were low (OrthoANIu=83.75 %). Consequently, strain CICC 11023T represents a novel Nocardia species on the basis of this polyphasic study, for which the name Nocardia colli sp. nov. is proposed. The type strain is CICC 11023T (=KCTC 39837T).

Taxonomic Structure of Bacterial Communities of Rhizospheric Soil under Bogs’ Plants

For the first time, the ratio of large taxa and the genera spectrum of the prokaryotic community of the rhizosphere soil under typical plants of bogs were studied using high-throughput sequencing. The predominance of Acidobacteria and Alpha-proteobacteria and a low proportion of other taxa (less than 10%) were established. Representatives of the phyla Acidobacteria and Actinobacteria, as well as the class Alpha-proteobacteria class predominated among the 24 bacterial genera found. Common bacterial genera were identified in rhizospheric soil under plants and surface layers of peat. Representatives of most of these bacteria are adapted to grow in an acidic environment at low temperatures and consume various sugars, polysaccharides, aromatic compounds, and organic and amino acids. Bacteria of the genera Cytophaga and Acidothermus, widely distributed in bacterial communities, are capable of cellulose destruction, while representatives of the genus Occallatibacter utilize chitin and bacteria of the genus Nocardia consume humic substances and lignin.

Isolation and 16S rRNA gene sequences analysis of thermophilic Actinobacteria isolated from soil in Cisolok geothermal area, West Java, Indonesia

The thermophilic Actinobacteria are known not only as producers of pharmaceutically important bioactive compounds, but also commercially important enzymes, yet their diversity in geothermal area in Indonesia have been rarely reported. In our previous study, a new thermophilic Actinobacteria genus belonging to the family Pseudonocardiaceae has been isolated from soil in Cisolok geothermal area. This current study reports the taxonomy and findings of potentially new taxa of thermophilic Actinobacteria, based on phylogenetic analysis of 16S rRNA gene sequences. Twenty-five isolates of thermophilic Actinobacteria were isolated from soil samples and maintained using previously described methods. The 16S rRNA gene sequence-similarity search against all related species was performed using EzTaxon-e database. The sequences of 25 isolates showed similarity to member of family Streptomycetaceae (genus Streptomyces; 10 isolates), Thermomonosporaceae (genus Actinomadura; 3 isolates), Streptosporangiaceae (genus Microbispora; 6 isolates), Micromonosporaceae (genus Micromonospora; 2 isolates), Pseudonocardiaceae (genus Amycolatopsis; 3 isolates), and Nocardiaceae (genus Nocardia; 1 isolate). Fifteen out of 25 isolates are belong to non-Streptomycetaceae family, thus regarded as rare Actinobacteria. Nineteen out of 25 isolates showed 16S rRNA gene sequence-similarity values 97 – 99% to their closely related species, suggested the potential for findings novel taxa of thermophilic Actinobacteria from Cisolok geothermal area.

Nocardia stercoris sp. nov., a novel actinomycete isolated from the cow dung.

A novel actinobacterial strain, designated NEAU-LL90T, was isolated from cow dung collected from Shangzhi, Heilongjiang Province, north-east PR China and characterized by using a polyphasic approach. Morphological and chemotaxonomic characteristics were consistent with those members of the genus Nocardia. The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The predominant menaquinone detected was MK-8(H4, ω-cycl). Major fatty acids (>10 %) were identified as C16:0, C18:1ω9c, C18:0 and 10-methyl C19:0. Mycolic acids were present. The results of 16S rRNA gene sequence analysis showed that strain NEAU-LL90T belongs to the genus Nocardia with high sequence similarity to Nocardia niigatensis JCM11894T (98.1 %), similarities to other type strains of species of the genus Nocardia were found to be lower than 98.0 %. Furthermore, a combination of DNA-DNA hybridization results and some phenotypic characteristics demonstrated that strain NEAU-LL90T could be distinguished from its closest relative. Therefore, it is proposed that strain NEAU-LL90T represents a novel species of the genus Nocardia, for which the name Nocardia stercoris sp. nov. is proposed. The type strain is NEAU-LL90T (=CGMCC 4.7500T=JCM 32663T).

General characteristics and clinical significance of Nocardia and Gordonia genera

Over the last years, an increasing attention in modern medical microbiology has been paid to examining Actinomycetaceae, Corynebacteriaceae, Mycobacteriaceae, Nocardiaceae, Gordoniaceae sps. Members of the Mycobacteriaceae family are increasingly examined in research and real-life practice, whereas bacteria belonging to families such as Nocardiaceae and Gordoniaceae remain poorly investigated despite novel methods emerging in practical microbiology that allow to more accurately identify microorganisms. According to the current classification, the genus Nocardia includes over 80 species, most of which rarely result in human disease development. Most often, members of the genus Nocardia cause lesions in bronchopulmonary system, which, however, may also cause development of pathological processes in other anatomical sites. Likewise, members of the genus Gordonia may also trigger infectious lesions in human, which were previously often incorrectly identified as other actinomycetes or mycobacteria. Owing to use of 16S rRNA sequencing, it substantially improved identification of these bacteria. Currently, an increasing number of microorganisms with potential clinical significance has been recorded. In addition, similar to nocardiosis, diverse primary and secondary immunodeficiencies play a primary role in gordonii-associated development of pathological processes. However, an additional risk factor may be represented by pathological conditions associated with ingestion of foreign bodies colonized by such microorganisms. Most often, members the genus Nocardia cause lesions in the bronchopulmonary system able, however, affect other anatomical areas. Half of all cases of pulmonary nocardiosis are accompanied by pathological processes of extrapulmonary localization, whereas as low as 20% of patients manifest with extrapulmonary form of the disease usually occurring when the pathogen spreads hematogenously or via other routes also highlighted by primary pulmonary lesion. Moreover, members of the genus Gordonia may result in similar infectious lesions. Currently, the number of aerobic actinomycetes of potential clinical significance is increasing that may be due to their role in diverse pathological processes of various etiologies, which have been more often reported in scientific publications. Few reports regarding infections caused by the genus Gordonia ara available which may be due to a paucity of microorganisms isolated from clinical material or false identification as mycobacteria or Nocardia. Similar to nocardiosis, diverse immunodeficiencies play a primary role in the development of pathological processes associated with Gordonia. However, an additional risk factor may be linked to pathological conditions associated with the ingestion of foreign bodies colonized by these microorganisms. Available publications allows to underline etiological significance of Gordonia in development of cholecystitis, granulomatous skin lesions, eyelid abscess of other soft tissues, granulomatous mastitis, brain abscess and meningitis, as well as external otitis, bronchitis, endocarditis and mediastinitis. In addition, all these microorganisms can cause bacteremia associated with use of a central venous catheter. Owing to emergence of new detection methods as well as elevated rate of immunocompromised patients, and subsequently increased amount of new cases caused by members of the Nocardiaceae and Gordoniaceae families, an interest they rise will grow progressively.

Identification and Mobilization of a Cryptic Antibiotic Biosynthesis Gene Locus from a Human-Pathogenic Nocardia Isolate.

The genus Nocardia contains >50 human pathogenic species that cause a range of illnesses from skin and soft tissue infections to lung and brain infections. However, despite their membership in the most prominent family of secondary metabolite producers (the Actinomycetes), the ability of Nocardia species, especially those that cause human infections, to produce secondary metabolites has not been as well studied. Using genome mining, we have investigated cryptic secondary metabolite biosynthesis gene clusters from Nocardia species and identified a conserved locus within human pathogenic strains of Nocardia brasiliensis and Nocardia vulneris. Direct capture and heterologous expression in a Streptomyces host activated the biosynthetic locus, revealing it to be the source of the brasiliquinones, benz[a]anthraquinone antibiotics whose biosynthetic pathway has remained hidden for over two decades, until now. Our findings highlight these hitherto neglected human pathogenic Nocardia as a source of diverse and important natural products.

Cutaneous nocardiosis: A great imitator

Nocardiosis is caused by Gram-positive aerobic bacilli of the Nocardia genus, which are saprophytes living in the soil. It is a rare and opportunist disease with a localized or disseminated infection. When occurring in patients who are immunocompromised, involvement is usually systemic, most commonly represented by pulmonary disease. It can also be acquired through direct inoculation, entailing primary skin and subcutaneous tissue infections, frequently presenting as a localized nodular process. Cutaneous nocardiosis can manifest as a lymphocutaneous infection, actinomycetoma, superficial skin infection, or secondary infection from hematogenic dissemination. Diagnosis is made by identification of the organism in the culture of a clinical sample. Staining for acid-alcohol–resistant bacteria and, especially, Gram staining, is particularly relevant to obtain a rapid and presumptive diagnosis, while awaiting culture results. First-line medication is sulfamethoxazole-trimethoprim, which may be used with other antimicrobials, if necessary. Nocardiosis may be considered a major mimicker of several cutaneous diseases that present difficult, and often, delayed diagnoses.

Nocardia yunnanensis sp. nov., an actinomycete isolated from a soil sample.

A novel actinomycete strain, designated CFH S0054T, was isolated from a soil sample collected from Xiaokongshan in Tengchong, Yunnan Province, in south-west PR China. Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain CFH S0054T belonged to the genus Nocardia. Based on the results of 16S rRNA gene sequence analysis, strain CFH S0054T was most closely related to Nocardia concava IFM 0354T (98.3 %), Nocardia inohanensis NBRC 100128T (97.9 %), Nocardia otitidiscaviarum NBRC 14405T (97.9 %) and Nocardia heshunensis CFH S0067T (97.8 %). Strain CFH S0054T contained C16 : 0, C18 : 1 ω9c, C18 : 0 10-methyl (TBSA) and summed feature 3 as major cellular fatty acids and MK-8 (H4ω-cycl) as the major respiratory quinone. The polar lipid profile included phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and unknown phospholipids. The cell wall contained meso-diaminopimelic acid, and the whole-cell hydrolysates were arabinose, galactose, glucose, fructose, ribose and mannose. The genome of strain CFH S0054T was 7.9 Mbp with a G+C content of 68.4 mol%, the average nucleotide identity (ANI) values between strain CFH S0054T and N. concava IFM0354T were low (ANIm<87.7 % and ANIb=84.1 %). On the basis of phylogenetic, physiological and chemotaxonomic data, strain CFHS0054T is considered to represent a novel species of the genus Nocardia, for which the name Nocardiayunnanensis sp. nov. is proposed, The type strain is CFH S0054T (DSM 46763T=JCM 30082T).

Nocardia panacis sp. nov., a novel actinomycete with antiphytopathogen activity isolated from the rhizosphere of Panax notoginseng.

Strain YIM PH21724T was isolated from the rhizosphere of Panax notoginseng. Phylogenetic analyses based on 16S rRNA gene sequences showed that the strain exhibits close phylogenetic relatedness to Nocardia kroppenstedtii N1286T (97.70%), Nocardia farcinica NCTC 11134T (97.67%) and Nocardia puris DSM 44599T (97.40%). The menaquinones were identified as MK-9 (H4), MK-8 (H4, ω-cyclo) and MK-8 (H4), and the major fatty acids (> 10%) were identified as C16:0, C18:1 ω9c and C18:0 10-methyl. The polar lipids were found to be composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and an unidentified lipid. The G + C content of the genomic DNA was determined to be 67.01mol%. The phenotypic, chemotaxonomic, phylogenetic and genomic results clearly show strain YIM PH21724T should be classified in the genus Nocardia and represents a novel species, for which the name Nocardia panacis sp. nov. is proposed. The type strain is YIM PH21724T (= DSM 105904T = KCTC 49030T = CCTCC AA 2017043T).