Nocardiopsis alkaliphila sp. nov., a novel alkaliphilic actinomycete isolated from desert soil in Egypt

Actinobacteria From Desert: Diversity and Biotechnological Applications

Deserts, as an unexplored extreme ecosystem, are known to harbor diverse actinobacteria with biotechnological potential. Both multidrug-resistant (MDR) pathogens and environmental issues have sharply raised the emerging demand for functional actinobacteria. From 2000 to 2021, 129 new species have been continuously reported from 35 deserts worldwide. The two largest numbers are of the members of the genera Streptomyces and Geodermatophilus, followed by other functional extremophilic strains such as alkaliphiles, halotolerant species, thermophiles, and psychrotolerant species. Improved isolation strategies for the recovery of culturable and unculturable desert actinobacteria are crucial for the exploration of their diversity and offer a better understanding of their survival mechanisms under extreme environmental stresses. The main bioprospecting processes involve isolation of target actinobacteria on selective media and incubation and selection of representatives from isolation plates for further investigations. Bioactive compounds obtained from desert actinobacteria are being continuously explored for their biotechnological potential, especially in medicine. To date, there are more than 50 novel compounds discovered from these gifted actinobacteria with potential antimicrobial activities, including anti-MDR pathogens and anti-inflammatory, antivirus, antifungal, antiallergic, antibacterial, antitumor, and cytotoxic activities. A range of plant growth-promoting abilities of the desert actinobacteria inspired great interest in their agricultural potential. In addition, several degradative, oxidative, and other functional enzymes from desert strains can be applied in the industry and the environment. This review aims to provide a comprehensive overview of desert environments as a remarkable source of diverse actinobacteria while such rich diversity offers an underexplored resource for biotechnological exploitations.

Actinobacteria from Extreme Niches in Morocco and Their Plant Growth-Promoting Potentials

The objectives of this study were to assess actinobacterial diversity in five Moroccan extreme habitats and to evaluate their plant growth-promoting (PGP) activities. The soil samples were collected from different locations, including soils contaminated with heavy metals, from a high altitude site, from the desert, and from a marine environment. In total, 23 actinobacteria were isolated, 8 from Merzouga sand soil; 5 from Cannabis sativa rhizospheric soil; 5 from Toubkal mountain; 4 from a Draa sfar mining site; and 1 from marine soil. Based on their genotypic classification using 16S rRNA gene sequences, 19 of all belonged to the genus Streptomyces (82%) while the rest are the members of the genera Nocardioides (4.5%), Saccharomonospora (4.5%), Actinomadura (4.5%), and Prauserella (4.5%). Isolates Streptomyces sp. TNC-1 and Streptomyces sp. MNC-1 showed the highest level of phosphorus solubilization activity with 12.39 and 8.56 mg/mL, respectively. All 23 isolates were able to solubilize potassium, and 91% of them could grow under nitrogen-free conditions. The ability of the isolated actinobacteria to form indole-3-acetic acid (IAA) ranged from 6.70 to 75.54 μg/mL with Streptomyces sp. MNC-1 being the best IAA producer. In addition, all of the actinobacteria could produce siderophores, with Saccharomonospora sp. LNS-1 synthesizing the greatest amount (138.92 μg/mL). Principal coordinate analysis revealed that Streptomyces spp. MNC-1, MNT-1, MNB-2, and KNC-5; Saccharomonospora sp. LNS-1; and Nocardioides sp. KNC-3 each showed a variety of high-level plant growth-promoting activities. The extreme environments in Morocco are rich with bioactive actinobacteria that possess a variety of plant growth-promoting potentials that can further benefit green and sustainable agriculture.

Exploring Structural Diversity of Microbe Secondary Metabolites Using OSMAC Strategy: A Literature Review

Microbial secondary metabolites (MSMs) have played and continue to play a highly significant role in the drug discovery and development process. Genetically, MSM chemical structures are biologically synthesized by microbial gene clusters. Recently, however, the speed of new bioactive MSM discovery has been slowing down due to consistent employment of conventional cultivation and isolation procedure. In order to alleviate this challenge, a number of new approaches have been developed. The strategy of one strain many compounds (OSMAC) has been shown as a simple and powerful tool that can activate many silent biogenetic gene clusters in microorganisms to make more natural products. This review highlights important and successful examples using OSMAC approaches, which covers changing medium composition and cultivation status, co-cultivation with other strain(s), adding enzyme inhibitor(s) and MSM biosynthetic precursor(s). Available evidences had shown that variation of cultivation condition is the most effective way to produce more MSMs and facilitate the discovery of new therapeutic agents.

Antimicrobial potential of haloalkaliphilic Nocardiopsis sp. AJ1 isolated from solar salterns in India

Antagonistic haloalkaliphilic Nocardiopsis sp. AJ1 (GenBank JX575136.1), isolated and identified from the saline soil of Kovalam solar salterns was able to produce antimicrobial secondary metabolites and effectively suppressed several bacterial and fungal pathogens. The metabolite extracted from ethyl acetate precipitation suppressed the bacterial and fungal pathogens to the range between 2.14 and 20.14 mm and also controlled the shrimp killer virus WSSV by 83% than the control and significantly (p < 0.05) differed. GC-MS analysis revealed that, the ethyl acetate precipitation contains pyrrolo (1,2-A(pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl)-) and actinomycin C2. Non ribosomal peptide synthetase (NRPS) was amplified by PCR with the amplicon size of 750-800 bp length and further predicted the secondary structure by Iterative Threading Assembly Refinement (I-TASSER) bioinformatics approach. I-TASSER prediction helped to find out the secondary, 3-D structure, and ligand binding sites. The top ten modelling concluded that, the NRPS gene is closely similar to surfactin synthesizing gene, surfactin A synthetase C (SRFA-C). The findings revealed that, the active compounds from the secondary metabolites effectively suppressed the pathogenic bacteria, fungi, and virus and useful to develop antimicrobials.

Genome-Based Taxonomic Classification of the Phylum Actinobacteria

The application of phylogenetic taxonomic procedures led to improvements in the classification of bacteria assigned to the phylum Actinobacteria but even so there remains a need to further clarify relationships within a taxon that encompasses organisms of agricultural, biotechnological, clinical, and ecological importance. Classification of the morphologically diverse bacteria belonging to this large phylum based on a limited number of features has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees. Here, draft genome sequences of a large collection of actinobacterial type strains were used to infer phylogenetic trees from genome-scale data using principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families, and genera, as well as many species and a few subspecies were shown to be in need of revision leading to proposals for the recognition of 2 orders, 10 families, and 17 genera, as well as the transfer of over 100 species to other genera. In addition, emended descriptions are given for many species mainly involving the addition of data on genome size and DNA G+C content, the former can be considered to be a valuable taxonomic marker in actinobacterial systematics. Many of the incongruities detected when the results of the present study were compared with existing classifications had been recognized from 16S rRNA gene trees though whole-genome phylogenies proved to be much better resolved. The few significant incongruities found between 16S/23S rRNA and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences. Similarly good congruence was found between the discontinuous distribution of phenotypic properties and taxa delineated in the phylogenetic trees though diverse non-monophyletic taxa appeared to be based on the use of plesiomorphic character states as diagnostic features.

Effect of amino acids on the repression of alkaline protease synthesis in haloalkaliphilic Nocardiopsis dassonvillei

A newly isolated salt-tolerant alkaliphilic actinomycete, Nocardiopsis dassonvillei strain OK-18 grows on mineral salts medium with glucose as carbon source. It also grows and produces protease with amino acids as sole carbon source. The synthesis of extracellular alkaline protease parallel to growth was repressible by substrate concentrations. The absolute production of the protease was delinked with growth under nutritional stress, as protease production was high, despite poor growth. When amino acids served as the sole source of carbon and nitrogen, the enzyme production was significantly controlled by the number of amino acids. Maximal protease production was achieved with proline, asparagine, tyrosine, alanine, methionine and valine as sole source of carbon and nitrogen in minimal medium. With the increasing number of different amino acids in the presence and absence of glucose, the protease production was synergistically lower as compared to complex medium.

Characterization of Yuhushiella sp. TD-032 from the Thar Desert and its antimicrobial activity

During a screening program for antimicrobial compounds from underexplored habitats, a Gram-positive bacterium TD-032, was isolated from arid soil, Thar Desert (India), and analyzed for its morphological, physicochemical, and antimicrobial properties. The 16S ribosomal DNA (rDNA) sequence of the isolate was further studied for the novelty of γ-hyper variable region. TD-032 was grown in large-scale culture, and aqueous and organic solvent extracts analyzed for antimicrobial activity. Culture characteristics showed a lack of diffusible and melanoid pigments. The morphological features were pale yellow aerial mycelium colony color with brownish yellow substrate mycelium and leathery texture. The isolate could grow at 1% concentration of sodium chloride, temperature of 40°C, and a wide range of pH (7.0–12.0). An evaluation for extracellular enzymatic activities showed secretion of gelatinase(s), cellulase(s), and lipase(s). The γ-hyper variable region of 16S rDNA sequence of TD-032 showed 98.33% relatedness to Yuhushiella deserti, indicating a potential new species. Aqueous and ethyl acetate extracts showed antimicrobial activity against Gram-positive and Gram-negative bacteria inclusive clinical isolates. Inhibition of both test bacteria suggests that TD-032 produces a broad spectrum of antimicrobial substances.

Nocardiopsis species: Incidence, ecological roles and adaptations

Members of the genus Nocardiopsis are ecologically versatile and biotechnologically important. They produce a variety of bioactive compounds such as antimicrobial agents, anticancer substances, tumor inducers, toxins and immunomodulators. They also secrete novel extracellular enzymes such as amylases, chitinases, cellulases, β-glucanases, inulinases, xylanases and proteases. Nocardiopsis species are aerobic, Gram-positive, non-acid-fast, catalase-positive actinomycetes with nocardioform substrate mycelia and their aerial mycelia bear long chains of spores. Their DNA possesses high contents of guanine and cytosine. There is a marked variation in properties of the isolates obtained from different ecological niches and their products. An important feature of several species is their halophilic or halotolerant nature. They are associated with a variety of marine and terrestrial biological forms wherein they produce antibiotics and toxins that help their hosts in evading pathogens and predators. Two Nocardiopsis species, namely, N. dassonvillei and N. synnemataformans (among the thirty nine reported ones) are opportunistic human pathogens and cause mycetoma, suppurative infections and abscesses. Nocardiopsis species are present in some plants (as endophytes or surface microflora) and their rhizospheres. Here, they are reported to produce enzymes such as α-amylases and antifungal agents that are effective in warding-off plant pathogens. They are prevalent as free-living entities in terrestrial locales, indoor locations, marine ecosystems and hypersaline habitats on account of their salt-, alkali- and desiccation-resistant behavior. In such natural locations, Nocardiopsis species mainly help in recycling organic compounds. Survival under these diverse conditions is mediated by the production of extracellular enzymes, antibiotics, surfactants, and the accumulation of compatible solutes. The accommodative genomic features of Nocardiopsis species support their existence under the diverse conditions where they prevail.

Allosalinactinospora lopnorensis gen. nov., sp. nov., a new member of the family Nocardiopsaceae isolated from soil

A novel actinomycete, designated strain CA15-2T, was isolated from a soil sample collected from the rhizosphere of tamarisk in the Lop Nor region, Xinjiang, China, and was characterized by using a polyphasic taxonomic approach. Optimal growth occurred at 37 °C and pH 7.5–8.0 and with 5 % (w/v) NaCl. Strain CA15-2T formed white to pale-yellow branched substrate mycelium without fragmentation and sparse aerial mycelium with wavelike curves. Whole-cell hydrolysates of the isolate contained meso-diaminopimelic acid as the diagnostic diamino acid of the cell wall but no diagnostic sugars. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylmethylethanolamine, phosphatidylethanolamine, one unidentified glycolipid, one unidentified phospholipid and other unidentified lipids. MK-9(H8), MK-10(H8) and MK-10(H6) were the predominant menaquinones. The major fatty acids were iso-C16 : 0 and C16 : 0. The G+C content of the genomic DNA was 69.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CA15-2T formed a distinct subclade in the family Nocardiopsaceae , with less than 95 % 16S rRNA gene sequence similarity to all known members of the family Nocardiopsaceae . On the basis of the evidence from our polyphasic study, a novel genus, Allosalinactinospora gen. nov., is proposed, with the type species Allosalinactinospora lopnorensis gen. nov., sp. nov. The type strain of Allosalinactinospora lopnorensis is strain CA15-2T ( = DSM 45697T = CGMCC 4.7074T).

Actinobase: Database on molecular diversity, phylogeny and biocatalytic potential of salt tolerant alkaliphilic actinomycetes

Actinobase is a relational database of molecular diversity, phylogeny and biocatalytic potential of haloalkaliphilic actinomycetes. The main objective of this data base is to provide easy access to range of information, data storage, comparison and analysis apart from reduced data redundancy, data entry, storage, retrieval costs and improve data security. Information related to habitat, cell morphology, Gram reaction, biochemical characterization and molecular features would allow researchers in understanding identification and stress adaptation of the existing and new candidates belonging to salt tolerant alkaliphilic actinomycetes. The PHP front end helps to add nucleotides and protein sequence of reported entries which directly help researchers to obtain the required details. Analysis of the genus wise status of the salt tolerant alkaliphilic actinomycetes indicated 6 different genera among the 40 classified entries of the salt tolerant alkaliphilic actinomycetes. The results represented wide spread occurrence of salt tolerant alkaliphilic actinomycetes belonging to diverse taxonomic positions. Entries and information related to actinomycetes in the database are publicly accessible at http://www.actinobase.in. On clustalW/X multiple sequence alignment of the alkaline protease gene sequences, different clusters emerged among the groups. The narrow search and limit options of the constructed database provided comparable information. The user friendly access to PHP front end facilitates would facilitate addition of sequences of reported entries.

AVAILABILITY

The database is available for free at http://www.actinobase.in.

Nocardiopsis flavescens sp. nov., an actinomycete isolated from marine sediment

A Gram-positive, aerobic bacterium, strain SA6T, was isolated from marine sediment taken at a depth of 20 cm on the seashore of Lianyungang, Jiangsu Province, China. Strain SA6T contained meso-diaminopimelic acid, no diagnostic sugars, type PIII phospholipids, and MK-10(H2) and MK-10(H4) as the predominant menaquinones. The organism showed a range of chemical and morphological properties consistent with its classification in the genus Nocardiopsis. The almost-complete 16S rRNA gene sequence of strain SA6T was aligned with corresponding sequences of representatives of the genus Nocardiopsis and related taxa by using two tree-making algorithms. Strain SA6T formed a distinct phyletic line within the evolutionary radiation occupied by the genus Nocardiopsis and was related most closely to the type strain of Nocardiopsis lucentensis. Strain SA6T could be distinguished from its nearest phylogenetic relatives in the genus Nocardiopsis based on DNA–DNA relatedness data and a combination of phenotypic properties. Strain SA6T should therefore be assigned to the genus Nocardiopsis as a representative of a novel species, for which the name Nocardiopsis flavescens sp. nov. is proposed. The type strain is SA6T ( = CGMCC 4.5723T  = JCM 17424T).

Murinocardiopsis flavida gen. nov., sp. nov., an actinomycete isolated from indoor walls

Two Gram-stain-positive, mycelium-forming actinobacteria (strains 14-Be-013T and 02-Gi-014) were isolated from walls colonized with moulds and studied taxonomically. The isolates formed yellowish-pigmented substrate mycelium showing no fragmentation. Comparative analysis of 16S rRNA gene sequences showed that these bacteria are most closely related to genera within the family Nocardiopsaceae, but form a separate lineage within this family. Highest sequence similarities were to the type strains of Marinactinospora thermotolerans (96.0 % to 14-Be-013T), Nocardiopsis dassonvillei subsp. albirubida and Nocardiopsis lucentensis (both 95.3 % to 14-Be-013T). Whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid of the cell wall and no diagnostic sugars. Mycolic acids were absent. The major menaquinones were MK-10(H4), MK-11(H4) and MK-12(H2). The polar lipid profile consisted of phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and unknown lipids. Major fatty acids iso-C16 : 0, anteiso-C17 : 0 and C18 : 1 ω9c supported the affiliation of these isolates to the family Nocardiopsaceae. Phenotypic analysis (including chemotaxonomy) further differentiated strains 14-Be-013T and 02-Gi-014 from the most closely related members of the genera Marinactinospora and Nocardiopsis. Since the two strains form a distinct lineage in the 16S rRNA gene sequence-based phylogenetic tree, the novel genus Murinocardiopsis gen. nov. with the type species Murinocardiopsis flavida sp. nov. is proposed. The type strain of Murinocardiopsis flavida is 14-Be-013T (=DSM 45312T =CCM 7612T).

Nocardiopsis litoralis sp. nov., a halophilic marine actinomycete isolated from a sea anemone

A Gram-positive, moderately halophilic, alkalitolerant, filamentous, aerobic actinomycete, designated strain JSM 073097(T), was isolated from a sea anemone collected from a tidal flat in the South China Sea. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the new isolate was a member of the genus Nocardiopsis and was most closely related to Nocardiopsis kunsanensis HA-9(T), Nocardiopsis xinjiangensis YIM 90004(T) and Nocardiopsis salina YIM 90010(T) (99.6, 98.5 and 98.1 % similarity, respectively). Phenotypic characteristics and chemotaxonomic data also indicated that strain JSM 073097(T) was a member of the genus Nocardiopsis. The strain grew well on most of the media tested, producing white to yellow-white substrate mycelium and white aerial mycelium and straight to flexuous hyphae. The substrate mycelium was well developed and fragmented with age; the aerial mycelium produced long, straight to flexuous spore chains with non-motile, smooth-surfaced, rod-shaped spores. The strain grew in the presence of 1-15 % (w/v) total salts and at pH 6.0-10.5 and 20-35 degrees C; optimum growth occurred in the presence of 5-7 % (w/v) total salts and at pH 8.5 and 25 degrees C. Whole-cell hydrolysates of strain JSM 073097(T) contained meso-diaminopimelic acid and no diagnostic sugars. The predominant menaquinones were MK-10(H(4)), MK-10(H(6)) and MK-10(H(8)). The major cellular fatty acids were iso-C(15 : 0), iso-C(16 : 0), anteiso-C(16 : 0) and 10-methyl C(18 : 0). Polar lipids comprised diphosphatidylglycerol, phosphatidylcholine and phosphatidylglycerol. The DNA G+C content of strain JSM 073097(T) was 70.4 mol%. The combination of phylogenetic analysis, DNA-DNA relatedness data, phenotypic characteristics and chemotaxonomic data supported the suggestion that strain JSM 073097(T) represents a novel species of the genus Nocardiopsis, for which the name Nocardiopsis litoralis sp. nov. is proposed. The type strain is JSM 073097(T) (=DSM 45168(T)=KCTC 19473(T)).

Nocardiopsis arabia sp. nov., a halotolerant actinomycete isolated from a sand-dune soil

The taxonomic status of an unknown actinomycete isolated from a sand-dune soil was established using a polyphasic approach. Isolate S186(T) had chemotaxonomic and morphological properties consistent with its classification in the genus Nocardiopsis, grew on agar plates at NaCl concentrations of up to 15 % (w/v) and formed a distinct phyletic line in the Nocardiopsis 16S rRNA gene sequence tree. Its closest phylogenetic neighbours were Nocardiopsis chromatogenes, Nocardiopsis composta, Nocardiopsis gilva and Nocardiopsis trehalosi, with sequence similarity to the various type strains of 96.9 %, but it was readily distinguished from the type strains of these and related species using a range of phenotypic properties. It is apparent from the genotypic and phenotypic data that strain S186(T) belongs to a novel species of the genus Nocardiopsis, for which the name Nocardiopsis arabia sp. nov. is proposed. The type strain is S186(T) (=CGMCC 4.2057(T) =DSM 45083(T)).

Nocardiopsis quinghaiensis sp. nov., isolated from saline soil in China

A previously unknown Gram-positive, obligately aerobic actinomycete, YIM 28A4(T), was isolated from a sample of saline soil collected from the Qaidam Basin in Qinghai Province, north-west China, and was investigated using a polyphasic taxonomic approach. The strain grew well on most of the media tested, producing white to pale-yellow substrate mycelium, white aerial mycelium and straight to flexuous hyphae. The substrate mycelium was well developed and fragmented with age; the aerial mycelium produced long, straight spore chains. The spore chains were composed of non-motile, smooth-surfaced, rod-shaped spores. No diffusible pigments were produced on any of the media tested. The strain grew in the presence of 0-10 % (w/v) NaCl and at pH 6.0-8.0, with optimum growth occurring at 3 % (w/v) NaCl and pH 7.0. It grew at 10-37 degrees C, the optimum growth temperature being 28 degrees C. Whole-cell hydrolysates of strain YIM 28A4(T) contained meso-diaminopimelic acid and no diagnostic sugars. The predominant phospholipids were phosphatidylcholine, phosphatidylglycerol and diphosphatidylglycerol. The predominant menaquinones were MK-10, MK-10(H(2)), MK-11 and MK-11(H(2)). The major cellular fatty acids were iso-C(16 : 0), anteiso-C(15 : 0) and anteiso-C(17 : 0). The DNA G+C content was 67.1 mol%. The morphological and chemotaxonomic characteristics of the isolate matched those described for Nocardiopsis species. A phylogenetic analysis based on 16S rRNA gene sequence comparisons confirmed that strain YIM 28A4(T) was a member of the genus Nocardiopsis and most closely related to the type strains Nocardiopsis aegyptia DSM 44442(T) and Nocardiopsis halotolerans DSM 44410(T), showing 98.1 and 97.8 % 16S rRNA gene sequence similarity, respectively. Strain YIM 28A4(T) can be differentiated from these type strains by using phenotypic, phylogenetic and DNA-DNA hybridization data. On the basis of the polyphasic evidence, strain YIM 28A4(T) represents a novel species of the genus Nocardiopsis, for which the name Nocardiopsis quinghaiensis sp. nov. is proposed. The type strain is YIM 28A4(T) (=DSM 44739(T) =CGMCC 4.3494(T)).

Production of alkaline protease from an alkaliphilic actinomycete

The repression of alkaline protease synthesis from alkaliphilic actinomycete was studied by using glucose, peptone, yeast extract, KH2PO4 and amino acids; tyrosine, tryptophan, lysine, and arginine. There was a critical limit of stimulation of enzyme production by these components. Crude components such as molasses, wheat flour, and wheat bran were found to be effective for growth and enzyme production. The high level of enzyme production using agro-industrial by-products is commercially significant due to cheap nature of these sources. The findings are quite attractive, as only few actinomycetes, particularly alkaliphilic ones, have so far been explored for their enzymatic potential and regulation of enzyme synthesis.

Five novel species of the genus Nocardiopsis isolated from hypersaline soils and emended description of Nocardiopsis salina Li et al. 2004

Five novel Nocardiopsis strains isolated from hypersaline soils in China were subjected to a polyphasic analysis to determine their taxonomic position. All of the novel isolates could grow on agar plates at NaCl concentrations of up to 18 % (w/v), with optimum growth at 5-8 %. The DNA G+C contents of the novel strains ranged from 67.9 to 73.2 mol%. The morphological and chemotaxonomic characteristics of the isolates matched those described for members of the genus Nocardiopsis. Based on their 16S rRNA gene sequence analysis, DNA-DNA hybridization values and phenotypic characteristics, including the composition of cell-wall amino acids and sugars, menaquinones, polar lipids and cellular fatty acids, the isolates are proposed as representing five novel species of the genus Nocardiopsis. The novel species are proposed as Nocardiopsis gilva sp. nov. [type strain YIM 90087T (=KCTC 19006T=CCTCC AA 2040012T=DSM 44841T)], Nocardiopsis rosea sp. nov. [type strain YIM 90094T (=KCTC 19007T=CCTCC AA 2040013T=DSM 44842T), Nocardiopsis rhodophaea sp. nov. [type strain YIM 90096T (=KCTC 19049T=CCTCC AA 2040014T=DSM 44843T), Nocardiopsis chromatogenes sp. nov. [type strain YIM 90109T (=KCTC 19008T=CCTCC AA 2040015T=DSM 44844T) and Nocardiopsis baichengensis sp. nov. [type strain YIM 90130T (=KCTC 19009T=CCTCC AA 2040016T=DSM 44845T). On the basis of the chemotaxonomic data, the description of the recently described species Nocardiopsis salina Li et al. 2004 is emended.

Nocardiopsis salina sp. nov., a novel halophilic actinomycete isolated from saline soil in China

A moderately halophilic actinomycete strain, designated YIM 90010T, was isolated from a soil sample collected from a hypersaline habitat in Xinjiang Province, China, and then investigated using a polyphasic taxonomic approach. The strain produced abundant aerial mycelia and fragmented substrate mycelia on most media tested; the optimum NaCl concentration for growth was 10 % (w/v) and the optimum growth temperature and pH were 28 degrees C and 7.2, respectively. Chemotaxonomically and phylogenetically, the strain was related to members of the genus Nocardiopsis. The isolate contained chemotaxonomic markers that were diagnostic for the genus Nocardiopsis, i.e. meso-diaminopimelic acid, no diagnostic sugars, and MK-10(H6), MK-10(H8) and MK-12 as the predominant menaquinones. The major fatty acids were iso- and anteiso-branched acids combined with tuberculostearic acid (Me C(18 : 0)), straight-chain saturated fatty acids and unsaturated fatty acids. The G + C content was 73.1 mol%. Phylogenetic analysis confirmed that strain YIM 90010T was a member of the genus Nocardiopsis and most closely related to Nocardiopsis kunsanensis (97.6 % similarity) and Nocardiopsis xinjiangensis (98.1 % similarity). It can be differentiated from these species by using phenotypic characteristics, phylogenetic analysis and DNA-DNA hybridization results. On the basis of the polyphasic evidence, a novel species, Nocardiopsis salina sp. nov., is proposed. The type strain of the species is YIM 90010T (= KCTC 19003T = CCTCC AA 204009T).

Nesterenkonia sandarakina sp. nov. and Nesterenkonia lutea sp. nov., novel actinobacteria, and emended description of the genus Nesterenkonia

Two novel actinobacteria isolates, designated YIM 70009T and YIM 70081T, were characterized in order to determine their taxonomic position. Cells of strains YIM 70009T and YIM 70081T were cocci, although only the latter were motile. The G+C contents of their DNAs were 64·0 and 64·5 mol%, respectively. On the basis of chemotaxonomic characteristics and 16S rRNA gene sequence analysis, the two isolates were classified in the genus Nesterenkonia. DNA–DNA hybridization and comparison of phenotypic characteristics revealed that strains YIM 70009T and YIM 70081T differed from each other and from known species. Therefore, it is proposed that they represent two separate novel species of the genus Nesterenkonia: Nesterenkonia sandarakina sp. nov. (type strain, YIM 70009T=CCTCC AA 203007T=DSM 15664T=KCTC 19011T) and Nesterenkonia lutea sp. nov. (type strain, YIM 70081T=CCTCC AA 203010T=DSM 15666T=KCTC 19013T).