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

Spiractinospora alimapuensis gen. nov., sp. nov., isolated from marine sediment of Valparaíso Bay (Chile) and proposal for reclassification of two species of the genus Nocardiopsis

An alkaliphilic actinobacterium, designated VN6-2T, was isolated from marine sediment collected from Valparaíso Bay, Chile. Strain VN6-2T formed yellowish-white branched substrate mycelium without fragmentation. Aerial mycelium was well developed, forming wavy or spiral spore chains. Strain VN6-2T exhibited a 16S rRNA gene sequence similarity of 93.9 % to Salinactinospora qingdaonensis CXB832T, 93.7 % to Murinocardiopsis flavida 14-Be-013T, and 93.7 % to Lipingzhangella halophila 14-Be-013T. Genome sequencing revealed a genome size of 5.9 Mb and an in silico G+C content of 69.3 mol%. Both of the phylogenetic analyses based on 16S rRNA gene sequences and the up-to-date bacterial core gene sequences revealed that strain VN6-2T formed a distinct monophyletic clade within the family Nocardiopsaceae . Chemotaxonomic assessment of strain VN6-2T showed that the major fatty acids were iso-C16 : 0, anteiso-C17 : 0 and 10-methyl-C18 : 0, and the predominant respiratory quinones were MK-9, MK-9(H2) and MK-9(H4). Whole-cell hydrolysates contained meso-diaminopimelic acid as the cell-wall diamino acid, and ribose and xylose as the diagnostic sugars. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, aminophospholipids, glycolipid and phospholipid. Based on the results of this polyphasic study, a novel genus, Spiractinospora gen. nov., is proposed within the family Nocardiopsaceae and the type species Spiractinospora alimapuensis gen. nov., sp. nov. The type strain is VN6-2T (CECT 30026T, CCUG 66258T). On the basis of the phylogenetic results herein, we also propose that Nocardiopsis arvandica and Nocardiopsis litoralis are later heterotypic synonyms of Nocardiopsis sinuspersici and Nocardiopsis kunsanensis , respectively, for which emended descriptions are given.

Streptomonospora litoralis sp. nov., a halophilic thiopeptides producer isolated from sand collected at Cuxhaven beach

Strain M2^T was isolated from the beach of Cuxhaven, Wadden Sea, Germany, in course of a program to attain new producers of bioactive natural products. Strain M2^T produces litoralimycin and sulfomycin-type thiopeptides. Bioinformatic analysis revealed a potential biosynthetic gene cluster encoding for the M2^T thiopeptides. The strain is Gram-stain-positive, rod shaped, non-motile, spore forming, showing a yellow colony color and forms extensively branched substrate mycelium and aerial hyphae. Inferred from the 16S rRNA gene phylogeny strain M2^T affiliates with the genus Streptomonospora. It shows 96.6% 16S rRNA gene sequence similarity to the type species Streptomonospora salina DSM 44593 ^T and forms a distinct branch with Streptomonospora sediminis DSM 45723 ^T with 97.0% 16S rRNA gene sequence similarity. Genome-based phylogenetic analysis revealed that M2^T is closely related to Streptomonospora alba YIM 90003 ^T with a digital DNA-DNA hybridisation (dDDH) value of 26.6%. The predominant menaquinones of M2^T are MK-10(H₆), MK-10(H₈), and MK-11(H₆) (> 10%). Major cellular fatty acids are iso-C_16:0, anteiso C_17:0 and C_18:0 10-methyl. The polar lipid profile consisted of diphosphatidylglycerol phosphatidyl glycerol, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, three glycolipids, two unknown phospholipids, and two unknown lipids. The genome size of type strain M2^T is 5,878,427 bp with 72.1 mol % G + C content. Based on the results obtained from phylogenetic and chemotaxonomic studies, strain M2^T (= DSM 106425 ^T = NCCB 100650 ^T) is considered to represent a novel species within the genus Streptomonospora for which the name Streptomonospora litoralis sp. nov. is proposed.

Streptomonospora halotolerans sp. nov., an actinomycete isolated from soil

A novel actinomycete, designated strain NEAU-Jh2-17(T), was isolated from muddy soil collected from a riverbank in Jilin Province, northern China, and characterized using a polyphasic approach. The 16S rRNA gene sequence of strain NEAU-Jh2-17(T) showed highest similarity to those of Streptomonospora nanhaiensis 12A09(T) (99.26%), Nocardiopsis rosea YIM 90094(T) (97.31%), Streptomonospora halophila YIM 91355(T )(97.24%) and Streptomonospora arabica S186(T) (97.02%). Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain NEAU-Jh2-17(T) fell within a cluster consisting of the type strains of species of the genus Streptomonospora and formed a stable clade with S. nanhaiensis 12A09(T) in trees generated with two algorithms. Key morphological and chemotaxonomic properties also confirmed the affiliation of strain NEAU-Jh2-17(T) to the genus Streptomonospora. The cell wall contained meso-diaminopimelic acid as the diagnostic diamino acid and whole-cell hydrolysates contained glucose, ribose and galactose. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylinositol mannoside (PIM), two unknown phospholipids (PLs) and two unknown glycolipids (GLs). The predominant menaquinones were MK-10(H2), MK-10(H8), MK-10(H6) and MK-10(H4). Major fatty acids were C18 : 0 10-methyl, anteiso-C17 : 0, C16 : 0 10-methyl, iso-C15 : 0, C17 : 0 10-methyl and C18 : 0. The DNA G+C content was 71.82 mol%. However, a combination of DNA-DNA hybridization results and some phenotypic characteristics demonstrated that strain NEAU-Jh2-17(T) could be distinguished from its closely related relatives. Therefore, strain NEAU-Jh2-17(T) is considered to represent a novel species of the genus Streptomonospora, for which the name Streptomonospora halotolerans sp. nov. is proposed. The type strain is NEAU-Jh2-17(T) ( = CGMCC 4.7218(T) = JCM 30347(T)).

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.

Nocardiopsis species as potential sources of diverse and novel extracellular enzymes

Members of the genus Nocardiopsis are generally encountered in locations that are inherently extreme. They are present in frozen soils, desert sand, compost, saline or hypersaline habitats (marine systems, salterns and soils) and alkaline places (slag dumps, lake soils and sediments). In order to survive under these severe conditions, they produce novel and diverse enzymes that allow them to utilize the available nutrients and to thrive. The members of this genus are multifaceted and release an assortment of extracellular hydrolytic enzymes. They produce enzymes that are cold-adapted (α-amylases), thermotolerant (α-amylases and xylanases), thermoalkalotolerant (cellulases, β-1,3-glucanases), alkali-tolerant thermostable (inulinases), acid-stable (keratinase) and alkalophilic (serine proteases). Some of the enzymes derived from Nocardiopsis species act on insoluble polymers such as glucans (pachyman and curdlan), keratin (feathers and prion proteins) and polyhydroxyalkanoates. Extreme tolerance exhibited by proteases has been attributed to the presence of some amino acids (Asn and Pro) in loop structures, relocation of multiple salt bridges to outer regions of the protein or the presence of a distinct polyproline II helix. The range of novel enzymes is projected to increase in the forthcoming years, as new isolates are being continually reported, and the development of processes involving such enzymes is envisaged in the future.

Description of Streptomonospora sediminis sp. nov. and Streptomonospora nanhaiensis sp. nov., and reclassification of Nocardiopsis arabia Hozzein & Goodfellow 2008 as Streptomonospora arabica comb. nov. and emended description of the genus Streptomonospora

Two actinomycete strains isolated from marine sediment samples, designated YIM M11335(T) (from the Indian Ocean) and 12A09(T) (from the South China Sea), were obtained and examined by a polyphasic approach. The two Gram-staining-positive, aerobic strains produced branched substrate mycelia and aerial hyphae that were not fragmented, and no diffusible pigment was produced on the media tested. At maturity, spore chains and single spores were formed on aerial hyphae and substrate mycelium, respectively. Whole-organism hydrolysates of both strains contained meso-diaminopimelic acid and the diagnostic sugars glucose and galactose. Their predominant menaquinones were MK-10(H4), MK-10(H6), MK-11(H4), MK-11(H6) and MK-11(H8) for strain YIM 11335(T) and MK-10(H4), MK-10(H6), MK-11(H4), MK-11(H6) and MK-11(H8) for strain 12A09(T). The polar lipids detected in the two strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, phosphatidylcholine, an unknown phosphoglycolipid and several unknown glycolipids, phospholipids and polar lipids. The major fatty acids (>10%) were iso-C16 : 0 and C16:0 for strain YIM 11335(T) and iso-C16:0 for strain 12A09(T). The G+C contents of the genomic DNA of strains YIM 11335(T) and 12A09(T) were 70.7% and 74.4%, respectively. DNA-DNA hybridization relatedness values of these two isolates with the type strains Nocardiopsis arabia DSM 45083(T) and Streptomonospora halophila YIM 91355(T) supported the hypothesis they are representatives of two different species. Based on phylogenetic analysis, phenotypic and genotypic data, it is concluded that the two isolates belong to the genus Streptomonospora of the family Nocardiopsaceae and that the type strain of N. arabia should be reclassified as a representative of Streptomonospora arabica comb. nov. The names proposed for the two novel species are Streptomonospora sediminis sp. nov. (type strain YIM M11335(T) = DSM 45723(T) = CCTCC AB 2012051(T)) and Streptomonospora nanhaiensis sp. nov. (type strain 12A09(T) = KCTC 29145(T) = CCTCC AB 2013140(T)), respectively. An emended description of the genus Streptomonospora is also proposed in the light of the new data.

Systematic and biotechnological aspects of halophilic and halotolerant actinomycetes

More than 70 species of halotolerant and halophilic actinomycetes belonging to at least 24 genera have been validly described. Halophilic actinomycetes are a less explored source of actinomycetes for discovery of novel bioactive secondary metabolites. Degradation of aliphatic and aromatic organic compounds, detoxification of pollutants, production of new enzymes and other metabolites such as antibiotics, compatible solutes and polymers are other potential industrial applications of halophilic and halotolerant actinomycetes. Especially new bioactive secondary metabolites that are derived from only a small fraction of the investigated halophilic actinomycetes, mainly from marine habitats, have revealed the huge capacity of this physiological group in production of new bioactive chemical entities. Combined high metabolic capacities of actinomycetes and unique features related to extremophilic nature of the halophilic actinomycetes have conferred on them an influential role for future biotechnological applications.

Nocardiopsis sp. SD5: A potent feather degrading rare actinobacterium isolated from feather waste in Tamil Nadu, India

Feather waste, generated in large quantities as a byproduct of commercial poultry processing, is nearly pure keratin protein, and keratin in its native state is not degradable by common proteolytic enzymes. The aim of the study was to find a potent feather degrading actinobacteria from feather waste soil. Out of 91 actinobacterial isolates recorded from feather waste soil in Tiruchirappalli and Nammakkal District, Tamil Nadu, India, isolate SD5 was selected for characterization because it exhibited significant keratinolytic activity. On the basis of the phenotypic, biochemical characterization and 16S rRNA gene-sequencing studies, the isolate was identified as Nocardiopsis sp. SD5. Protease and keratinase activity of Nocardiopsis sp. SD5 were analyzed. The enzyme was more stable over the neutral pH and the temperature of 40 °C. The optimum temperature and pH for both proteolytic and keratinolytic activity was determined at 50 °C and pH 9, respectively. Enzyme inhibitors, detergents and chelator declined the enzyme activity with increasing concentration. Non denaturing poly acrylamide gel electrophoresis and zymogram elucidated the presence of 30 kda and 60 kda protease enzymes. These findings indicated that thermo alkaliphilic feather degrading strain Nocardiopsis sp. SD5 could be used to control the feather waste pollution and to convert keratin rich feather waste into useful feedstock for poultry industry. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Salinactinospora qingdaonensis gen. nov., sp. nov., a halophilic actinomycete isolated from a salt pond

A novel halophilic, filamentous, actinomycete strain, designated CXB832T, was isolated from a salt pond in Qingdao, China. Optimal growth occurred at 37 °C, pH 7.0–8.0 and 9–12 % (w/v) NaCl. Strain CXB832T formed pale yellow to deep yellow branched substrate mycelium without fragmentation. Abundant white aerial mycelium differentiated into long chains of spores and the spores were rod-shaped with smooth surfaces. Strain CXB832T contained meso-diaminopimelic acid as the diagnostic diamino acid of the cell-wall peptidoglycan, and glucose and xylose as the major whole-cell sugars. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phospholipids, glycolipid and unidentified lipids. MK-10(H8), MK-9(H8), MK-10(H2) and MK-10(H6) were the predominant menaquinones. The major fatty acids were i-C16 : 0 (30.71 %), ai-C17 : 0 (13.31 %) and C16 : 0 (11.28 %). The G+C content of the DNA was 60.1 mol%. Comparative analysis of 16S rRNA gene sequences showed that the novel strain was most closely related to genera within the family Nocardiopsaceae , but formed a separate lineage. The highest sequence similarities were to Nocardiopsis arabia DSM 45083T (95.4 %) and Haloactinospora alba DSM 45015T (94.9 %). On the basis of phenotypic, chemotaxonomic and phylogenetic distinctiveness, strain CXB832T represents a new genus and novel species in the family Nocardiopsaceae , for which the name Salinactinospora qingdaonensis gen. nov., sp. nov. is proposed. The type strain of the type species is CXB832T ( = DSM 45442T = LMG 25567T).

Nocardiopsis nikkonensis sp. nov., isolated from a compost sample

An actinomycete strain, designated YU1183-22T, was isolated from a compost sample collected in Nikko, Japan. The isolate formed white aerial mycelium with relatively long aerial hyphae showing chains of arthrospores. Strain YU1183-22T grew with 0–10 % (w/v) NaCl, at pH 6–11 and at 10–37 °C (optimum 30 °C). Strain YU1183-22T contained meso-diaminopimelic acid and no diagnostic sugars. The predominant menaquinones were MK-10(H10) and MK-10(H8). The polar lipids were phosphatidylcholine and phosphatidylglycerol. The major cellular fatty acids were iso-C16 : 0, anteiso-C17 : 0 and tuberculostearic acid. The G+C content of the DNA was 72.3 mol%. Chemotaxonomic and morphological characterization clearly demonstrated that strain YU1183-22T belonged to the genus Nocardiopsis. Phylogenetic analysis using 16S rRNA gene sequences showed that the isolate was closely related to Nocardiopsis salina YIM 90010T (98.0 % 16S rRNA gene sequence similarity), Nocardiopsis xinjiangensis YIM 90004T (97.9 %) and Nocardiopsis kunsanensis HA-9T (97.3 %). However, DNA–DNA relatedness as well as physiological and biochemical analyses showed that strain YU1183-22T could be differentiated from its closest phylogenetic relatives. It is proposed that this strain be classified as a representative of a novel species of the genus Nocardiopsis, with the name Nocardiopsis nikkonensis sp. nov. The type strain is YU1183-22T (=NBRC 102170T =KCTC 19666T).

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)).