Nocardiopsis aegyptia sp. nov., isolated from marine sediment

An Overview on Nocardiopsis Species Originating From North African Biotopes as a Promising Source of Bioactive Compounds and In Silico Genome Mining Analysis of Three Sequenced Genomes

Actinobacteria are renowned for their prolific production of diverse bioactive secondary metabolites. In recent years, there has been an increasing focus on exploring "rare" genera within this phylum for biodiscovery purposes, notably the Nocardiopsis genus, which will be the subject of the present study. Recognizing the absence of articles describing the research process of finding bioactive molecules from the genus Nocardiopsis in North African environments. We, therefore, present a historical overview of the discoveries of bioactive molecules of the genus Nocardiopsis originating from the region, highlighting their biological activities and associated reported molecules, providing a snapshot of the current state of the field, and offering insights into future opportunities and challenges for drug discovery. Additionally, we present a genome mining analysis of three genomes deposited in public databases that have been reported to be bioactive. A total of 36 biosynthetic gene clusters (BGCs) were identified, including those known to encode bioactive molecules. Notably, a substantial portion of the BGCs showed little to no similarity to those previously described, suggesting the possibility that the analyzed strains could be potential producers of new compounds. Further research on these genomes is essential to fully uncovering their biotechnological potential. Moving forward, we discuss the experimental designs adopted in the reported studies, as well as new avenues to guide the exploration of the Nocardiopsis genus in North Africa.

Deinococcus arenicola sp. nov., a novel radiation-resistant bacterium isolated from sandy soil in Antarctica

A Gram-stain-positive, aerobic, non-mobile and spherical strain, designated ZS9-10T, belonging to the genus Deinococcus was isolated from soil sampled at the Chinese Zhong Shan Station, Antarctica. Growth was observed in the presence of 0-4 % (w/v) NaCl, at pH 7.0-8.0 and at 4-25 °C. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZS9-10T formed a lineage in the genus Deinococcus. It exhibited highest sequence similarity (97.4 %) to Deinococcus marmoris DSM 12784T. The major phospholipids of ZS9-10T were unidentified phosphoglycolipid, unidentified glycolipids and unidentified lipids. The major fatty acids were summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c), C16 : 0 and C16 : 1  ω7c. MK-8 was the predominant respiratory quinone. The digital DNA-DNA hybridization and average nucleotide identity values between strain ZS9-10T and its close relative D. marmoris DSM 12784T were 27.4 and 83.9 %, respectively. Based on phenotypic, phylogenetic and genotypic data, a novel species, named Deinococcus arenicola sp. nov., is proposed. The type strain iis ZS9-10T (=CCTCC AB 2019392T=KCTC43192T).

Genomic and Metabolomic Analyses of Nocardiopsis maritima YSL2 as the Mycorrhizosphere Bacterium of Suaeda maritima (L.) Dumort

Nine bacteria were isolated from the episphere of Suaeda maritima (L.) Dumort. Among them, the bacterial strain YSL2 displayed the highest antimicrobial activity on agar plates and exhibited significant novelty compared with other bacteria based on 16S rRNA analysis. Consequently, Nocardiopsis maritima YSL2T was subjected to phenotypic characterization and whole-genome sequencing. Phylogenetic analysis revealed its close association with Nocardiopsis aegyptia SNG49T. Furthermore, genomic analysis of strain YSL2T revealed the presence of various gene clusters, indicating its potential for producing antimicrobial secondary metabolites. Upon cultivation on a large scale, maritiamides A and B (1 and 2) were isolated and characterized as cyclic hexapeptides based on nuclear magnetic resonance, ultraviolet, infrared, and mass spectrometric data. The absolute configurations of the amino acid residues in the maritiamides were determined through chiral derivatization, utilizing FDAA and GITC. Maritiamides 1 and 2 exhibited promising antibacterial activities against Staphylococcus epidermidis and weakly inhibited the growth of Escherichia coli and Pseudomonas fluorescens.

Kaistella polysaccharea sp. nov., isolated from Antarctic intertidal sediment produces a novel extracellular polymeric substance

An exopolysaccharide-producing bacterial strain GW4-15T, belonging to the genus Kaistella, was isolated from intertidal sediment from King George Island, Antarctic. The strain was Gram-stain-negative, aerobic, rod-shaped, non-motile and yellow-pigmented. The strain was able to grow in the presence of 0-2 % (w/v) NaCl (optimum, 0 %), at 4-30 °C (optimum, 20-28 °C) and at pH 5.0-10.0 (optimum, pH 8.0). A phylogenetic tree based on 16S rRNA gene sequences showed that strain GW4-15T formed a lineage within the genus Kaistella with the closest phylogenetic neighbours Kaistella carnis NCTC 13525T (98.3 %), Kaistella gelatinilytica G5-32T (97.7 %), Kaistella antarctica LMG 24720T (97.4 %) and Kaistella yonginensis HMD1043T (96.9 %). Digital DNA-DNA hybridization values of strain GW4-15T with K. carnis NCTC 13525T, K. antarctica LMG 24720T, K. gelatinilytica G5-32T and K. yonginensis HMD1043T were 22.8, 22.0, 21.7 and 21.6 %, respectively. The average nucleotide identity values between strain GW4-15T and K. carnis NCTC 13525T , K. antarctica LMG 24720T, K. gelatinilytica G5-32T and K. yonginensis HMD1043T were 79.3, 78.6, 77.5 and 77.2 %, respectively. The G+C content of the genome was 36.2 mol%. The major phospholipids were phosphatidylethanolamine and aminophospholipid. The predominant menaquinone was MK-6. The major fatty acids were anteiso-C15 : 0 (28.7 %), iso-C16 : 0 3-OH (15.7 %), iso-C16 : 0 H (10.0 %), iso-C16 : 0 (5.4 %), summed feature 9 (comprising iso-C17 : 1  ω9c and/or 10-methyl C16 : 0; 5.2 %) and iso-C15 : 0 (5.1 %). The monosaccharide composition of the new type of extracellular polymeric of GW4-15T was Glc, GalN, GlcN, Rha, Man and Gal with a molar ratio of 3.14 : 3.83 : 8.38 : 5.16 : 1 : 2.82. Based on phenotypic, phylogenetic and genotypic data, a novel species, Kaistella polysaccharea sp. nov., is proposed with the type strain GW4-15T (=CGMCC 1.19368T=KCTC 92753T).

Cryobacterium zhongshanensis sp. nov., an actinobacterium isolated from Antarctic soil

A Gram-staining-positive, heterotrophic, non-spore-forming, non-motile, rod-shaped, strain ZS14-85^T belonging to the genus Cryobacterium was isolated from soil in Antarctica. Growth was observed in the presence of 0-2% (w/v) NaCl, at pH 7.0-9.0 (optimum, pH 7.0) and 4-30 ℃ (optimum, 20 ℃). Phylogenetic analysis showed that strain ZS14-85^T formed a lineage in the genus Cryobacterium. The digital DNA-DNA hybridization (dDDH) values between strain ZS14-85^T and its close relatives Cryobacterium psychrotolerans CGMCC 1.5382^T, Cryobacterium soli MCCC 1K03549^T and Cryobacterium breve NBRC 113800^T were 22.5, 22.3 and 22.2%, respectively. Orthologous Average Nucleotide Identity (OrthoANI) scores between strain ZS14-85^T and C. psychrotolerans CGMCC 1.5382^T, C. breve NBRC 113800^T and C. soli MCCC 1K03549^T were 78.7, 78.1 and 77.7%, respectively. The polar lipids of strain ZS14-85^T were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), one unidentified glycolipid (GL) and two unidentified lipids (L). The major fatty acids were anteiso-C_15:0 (60.7%), iso-C_16:0 (17.0%) and anteiso-C_17:0 (15.2%). MK-10, MK-11 and MK-9 were the predominant respiratory menaquinones. Based on phenotypic, phylogenetic and genotypic data, a novel species, Cryobacterium zhongshanensis sp. nov. is proposed. The type strain is ZS14-85^T (= CCTCC AB 2019396^T = KCTC 49384^T).

Arthrobacter terrae sp. nov., a psychrophilic actinobacterium with multi copies of capA gene isolated from Antarctic soil

A Gram-staining-positive, non-spore-forming, non-flagellated, ellipsoidal, strain Z1-20 ^T belonging to the genus Arthrobacter was isolated from a soil sample collected from the Zhongshan station, Antarctic. Phylogenetic analysis of the 16S rRNA gene sequences and phylogenetic analysis revealed that strain Z1-20 ^T formed a unique single cluster in the genus Arthrobacter and shared high 16S rRNA sequence similarities of 97.1% and 96.9% with A. glacialis HLT2-12-2 ^T and A. psychrochitiniphilus GP3^T, respectively. Values of Digital DNA-DNA hybridization (dDDH) between strain Z1-20 ^T against A. glacialis HLT2-12-2 ^T and A. psychrochitiniphilus GP3^T were 20.3% and 13.8%, respectively. Average nucleotide identity (ANI) score between strain Z1-20 ^T against A. glacialis HLT2-12-2 ^T and A. psychrochitiniphilus GP3^T were 72.5% and 72.1%, respectively. Genes for the synthesis of the osmoprotectant glycine betaine and higher copies of capA gene encoding cold shock protein were found in genome of Z1-20 ^T that may help Z1-20 ^T in cold-adaptation. Strain Z1-20 ^T comprised lysine as the diagnostic diamino acid. Based on the results of phylogenetic, phenotypic and chemotaxonomic features, strain Z1-20 ^T represents a novel species of a novel taxon of genus Arthrobacter, for which the name Arthrobacter terrae gen. nov., sp. nov. is proposed.

Rare actinobacteria isolated from the hypersaline Ojo de Liebre Lagoon as a source of novel bioactive compounds with biotechnological potential

The Ojo de Liebre Lagoon is a Marine Protected Area that lies within a UNESCO World Heritage Site and is a critical habitat for important migratory species such as the grey whale and bird species. Unique hypersaline environments, such as the Ojo de Liebre Lagoon, are underexplored in terms of their bacterial and chemical diversity, representing a potential source for new bioactive compounds with pharmacological properties. Actinobacteria are one of the most diverse and prolific taxonomic bacterial groups in terms of marine bioactive compounds. This study aimed to identify the culturable actinobacterial community inhabiting the Lagoon, as well as to test their potential as new sources of anticancer compounds with pharmacological potential. A selective isolation approach focused on spore-forming bacteria from 40 sediment samples generated a culture collection of 64 strains. The 16S rRNA gene analyses identified three phyla in this study, the Actinobacteria, Firmicutes and Proteobacteria, where the phylum Actinobacteria dominated (57%) the microbial community profiles. Within the Actinobacteria, nine different genera were isolated including the Actinomadura, Micromonospora, Nocardiopsis, Plantactinospora and Streptomyces sp. We observed seasonal differences on actinobacteria recovery. For instance, Micromonospora strains were recovered during the four sampling seasons, while Arthrobacter and Pseudokineococcus were only isolated in February 2018, and Blastococcus, Rhodococcus and Streptomyces were uniquely isolated in June 2018. Ethyl acetate crude extracts derived from actinobacterial cultures were generated and screened for cytotoxic activity against six cancer cell lines. Strains showed promising low percentages of viability on lung (H1299), cervical (SiHa), colon (Caco-2) and liver (HepG2) cancer lines. Molecular networking results suggest many of the metabolites produced by these strains are unknown and they might harbour novel chemistry. Our results showed the Ojo de Liebre Lagoon is a novel source for isolating diverse marine actinobacteria which produce promising bioactive compounds for potential biotechnological use as anticancer agents.

Lacisediminihabitans changchengi sp. nov., an actinobacterium isolated from Antarctic swamplands mud

A Gram-staining-positive, heterotrophic, non-spore-forming, non-motile, short rod-shaped, strain G11-30^T belonging to the genus Lacisediminihabitans was isolated from a swampland mud in Antarctica. The strain was identified using a polyphasic taxonomic approach. The strain grew well on R2A agar media and formed no aerial mycelia and no diffusible pigments on any media tested. The chemotaxonomic results showed 2, 4-diaminobutyric acid (DAB) is the diagnostic diamino acid of the peptidoglycan. MK-10 was the predominant respiratory menaquinone. The major phospholipids were phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), unidentified lipid (L) and unidentified glycolipid (GL). The major fatty acids were anteiso-C15:0 (64.5%) and iso-C15:0 (18.7%). A phylogenetic tree based on 16S rRNA gene sequences showed that strain G11-30^T formed a lineage in the genus Lacisediminihabitans with the closest phylogenetic Lacisediminihabitans profunda CHu50b-6-2^T and Glaciihabitans tibetensis MP203^T (97.9%, 97.5% 16S rRNA gene sequence similarity). A phylogenomic tree based on genome sequence of G11-30^T, conferred by Type Strain Genome Server (TYGS), separated it from L. profunda CHu50b-6-2^T. Strain G11-30^T has a complete genome size of 2.59 Mb, with a G + C content of 66.2 mol%. The digital DNA-DNA hybridization (dDDH) score between strain G11-30^T and reference strains L. profunda CHu50b-6-2^T and G. tibetensis MP203^T were 20.1 and 20.3%, respectively. Concurrently, Average Nucleotide Identity (ANI) score between strain G11-30 ^T against. profunda CHu50b-6-2^T and G. tibetensis MP203^T were 76.2 and72.5%, respectively. Based on phenotypic, phylogenetic and genotypic data, a novel species, Lacisediminihabitans changchengi sp. nov. is proposed. The type strain is G11-30^T (= CCTCC AA 2019080^T = KCTC49359^T).

Saliniquinone Derivatives, Saliniquinones G-I and Heraclemycin E, from the Marine Animal-Derived Nocardiopsis aegyptia HDN19-252

Four new anthraquinone derivatives, namely saliniquinones G-I (1-3) and heraclemycin E (4), were obtained from the Antarctic marine-derived actinomycete Nocardiopsis aegyptia HDN19-252, guided by the Global Natural Products Social (GNPS) molecular networking platform. Their structures, including absolute configurations, were elucidated by extensive NMR, MS, and ECD analyses. Compounds 1 and 2 showed promising inhibitory activity against six tested bacterial strains, including methicillin-resistant coagulase-negative staphylococci (MRCNS), with MIC values ranging from 3.1 to 12.5 μM.

Kaistella gelatinilytica sp. nov., a flavobacterium isolated from Antarctic soil

A Gram-stain-negative, aerobic, non-spore-forming, rod-shaped, non-motile, yellow-pigmented bacteria, designated strain G5-32^T, belonging to the genus Kaistella was isolated from soil collected in the Antarctic. The strain was identified using a polyphasic taxonomic approach. The strain grew in the presence of 0-5% (w/v) NaCl (optimum, 1%), at pH 6.0-9.0 (optimum, pH 8.0) and at 4-28 °C (optimum, 20 °C). The predominant menaquinone was MK-6 (99.4%). The major fatty acids were anteiso-C_15:0 (28.2%), iso-C_15:0 (16.4%), summed feature 9 (comprising iso-C_17:1 ω9c and/or 10-methyl C_16:0; 10.6%) and iso-C_16:0 (5.9%). A phylogenetic tree based on 16S rRNA gene sequences showed that strain G5-32^T formed a lineage within the genus Kaistella with the closest phylogenetic neighbours Kaistella yonginensis HMD1043^T, Kaistella chaponensis DSM 23145^T, Kaistella jeonii DSM 17048^T and Kaistella carnis NCTC 13525^T (97.9, 97.8, 97.8 and 98.0 % 16S rRNA gene sequence similarity, respectively). The ANI values between strain G5-32^T and K. jeonii DSM 17048^T, K. chaponensis DSM 23145^T, K. carnis NCTC 13525^T and K. yonginensis HMD1043^T were 90.9, 82.6, 77.1 and 76.3%. Concurrently, digital DNA-DNA hybridization values of strain G5-32^T assessed against K. jeonii DSM 17048^T, K. chaponensis DSM 23145^T, K. carnis NCTC 13525^T and K. yonginensis HMD1043^T were 42.3, 25.9, 21.7 and 21.3%, respectively. Based on phenotypic, phylogenetic and genotypic data, a novel species, Kaistella gelatinilytica sp. nov., is proposed. The type strain is G5-32^T (=CCTCC AA 2019083^T=KCTC 72766^T).

Chryseolinea flava sp. nov., a new species of Chryseolinea isolated from soil

A pale yellow bacterial strain, designated SDU1-6^T, was isolated from a soil sample collected in the Jinan campus of Shandong University, Shandong Province, PR China. The strain was aerobic, motile, Gram-stain-negative and rod-shaped. Cellular growth occurred at 13-37 °C, pH 5.0-10.0 and with 0-0.1 % (w/v) NaCl, and the optimal growth was at 25 °C and pH 7.5. SDU1-6^T had the highest 16S rRNA gene similarity of 95.42 % with Chryseolinea serpens DSM 24574^T. The genome was 6 542 746 bp in length with 43.5 mol% DNA G+C content. The major fatty acids of SDU1-6^T were C16 : 1ω5 and iso-C15 : 0, the major menaquinone was menaquinone-7 (MK-7) and the major polar lipid was phosphatidylethanolamine. On the basis of the polyphasic evidence and the 16S rRNA gene sequence, SDU1-6^T represents a novel species of the genus Chryseolinea, for which the name Chryseolineaflava sp. nov. is proposed. The type strain is SDU1-6^T (=CGMCC 1.13492^T=JCM 32520^T).

New bioactive compounds from the marine-derived actinomycete Nocardiopsis lucentensis sp. ASMR2

In the search for new bioactive compounds from extremophilic actinomycetes, a new marine actinomycete strain, Nocardiopsis lucentensis sp. ASMR2 has been isolated and taxonomically identified from marine plants collected in the Red Sea at Hurghada coasts. A large-scale fermentation of the strain on modified rice solid medium was performed, followed by work-up and purification of the obtained extract using a series of chromatographic purifications, delivering the novel butenolide system 3′-hydroxy-N-(2-oxo-2,5-dihydrofuran-4-yl)propionamide (1a) along with the naturally new 4-methoxy-2H-isoquinolin-1-one (2). Furthermore, eight known bioactive compounds are also reported, namely, indole-3-carboxylic acid, indole-3-acetic acid, indole-3-acetic acid methyl ester, furan-2,5-dimethanol, tyrosol, glycerol linoleate, cyclo-(Tyr, Pro), and adenosine. The chemical structures of the new compounds (1a, 2) were confirmed by extensive one- and two-dimensional (1D and 2D) nuclear magnetic resonance (NMR) spectroscopy, electron ionization high resolution (EI-HR) mass spectrometry, and by comparison with literature data. The antimicrobial activity of the strain extract, as well as of compounds 1a and 2, were studied using a panel of pathogenic microorganisms. The in vitro cytotoxicity of the bacterial extract and compounds 1a and 2 were studied against the human cervix carcinoma cell line (KB-3-1) and its multidrug-resistant subclone (KB-V1).

Nocardiopsissediminis sp. nov., isolated from mangrove sediment

A filamentous actinomycete, designated strain 1SS5-02T, was isolated from mangrove sediment collected from Ranong province, Thailand. The strain formed aerial and substrate mycelia composed of long, branched hyphae. Aerial mycelia differentiated into non-motile, rod-shaped spores. The organism contained meso-diaminopimelic acid and no diagnostic sugars in whole-cell hydrolysates. The predominant menaquinones were MK-11(H4), MK-11(H6) and MK-11(H8). Polar lipids comprised phosphatidylcholine, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, two unidentified phospholipids and four unidentified lipids. The major fatty acids were iso-C16 : 0, C18 : 1ω9c, 10-methyl C18 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 73.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 1SS5-02T belonged to the genus Nocardiopsis. The strain showed the highest degree of 16S rRNA gene sequence similarity with 'Nocardiopsis mangrovei' HA11166 (97.9 %) and Nocardiopsis trehalosi VKM Ac-942T (97.8 %). However, strain 1SS5-02T could be distinguished from its nearest phylogenetic relatives in the genus Nocardiopsis on the basis of DNA-DNA relatedness values and the combination of phenotypic properties. On the basis of polyphasic taxonomy, strain 1SS5-02T is considered to represent a novel species of the genus Nocardiopsis, for which the name Nocardiopsis sediminis sp. nov. is proposed. The type strain is 1SS5-02T (=BCC 75410T=NBRC 110934T).

Nocardiopsis oceani sp. nov. and Nocardiopsis nanhaiensis sp. nov., actinomycetes isolated from marine sediment of the South China Sea

Two actinomycete strains, designated 10A08AT and 10A08BT, were isolated from marine sediment samples of the South China Sea and their taxonomic positions were determined by a polyphasic approach. The two Gram-stain-positive, aerobic strains produced branched substrate mycelium and aerial hyphae, and no diffusible pigment was produced in the media tested. At maturity, spore chains were formed on aerial hyphae and all mycelium fragmented with age. Whole-cell hydrolysates of both strains contained meso-diaminopimelic acid and no diagnostic sugars. Their predominant menaquinones (>10 %) were MK-9(H4), MK-9(H6) and MK-10(H6) for strain 10A08AT and MK-9(H4), MK-9(H6), MK-10(H4) and MK-10(H6) for strain 10A08BT. The polar lipids detected from the two strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and unknown phosphoglycolipids and phospholipids. The major fatty acids (>10 %) of both strains were iso-C16 : 0 and summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B). The genomic DNA G+C contents of strains 10A08AT and 10A08BT were 70.9 and 71.6 mol%, respectively. On the basis of 16S rRNA gene sequence similarities, the two strains were shown to be most closely related to species of the genus Nocardiopsis. DNA–DNA hybridization relatedness values of < 70 % between these two isolates and their closest neighbour, Nocardiopsis terrae YIM 90022T, and between the two strains supported the conclusion that they represent two novel species. Based on phylogenetic analysis and phenotypic and genotypic data, it is concluded that the two isolates belong to the genus Nocardiopsis, and the names Nocardiopsis oceani sp. nov. (type strain 10A08AT = DSM 45931T = BCRC 16951T) and Nocardiopsis nanhaiensis sp. nov. (type strain 10A08BT = CGMCC 47227T = BCRC 16952T) are proposed.

Agromyces binzhouensis sp. nov., an actinobacterium isolated from a coastal wetland of the Yellow River Delta

A Gram-stain-positive, heterotrophic, non-spore-forming, rod-shaped strain, designated OAct353T, belonging to the genus Agromyces was isolated from a soil sample collected from a coastal wetland of the Yellow River delta, PR China. The strain was identified using a polyphasic taxonomic approach. The strain grew in the presence of 0-10 % (w/v) NaCl (optimum 2-3 %), at pH 5.0-8.0 (optimum pH 7.0) and 12-36 °C (optimum 28 °C). The isolate contained 2,4-diaminobutyric acid, glutamic acid and glycine in its peptidoglycan. The acyl type of the cell-wall muramic acid was N-acetyl. The whole-cell sugars of this novel strain were glucose, xylose and rhamnose. The predominant menaquinones were MK-12 (74 %) and MK-11 (21 %). The major phospholipids were phosphatidylglycerol, one unknown phospholipid, three unknown glycolipids and three unknown polar lipids. The major fatty acids were iso-C16:0, anteiso-C15:0 and anteiso-C17:0. The DNA G+C content was 69.6 mol %. DNA-DNA relatedness clearly separated strain OAct353T from its closest relatives. On the basis of phenotypic, phylogenetic and chemotaxonomic data, a novel species, Agromyces binzhouensis sp. nov., is proposed. The type strain is OAct353T (=CGMCC4.7180T=DSM 28305T=NRRL B-59115T).

Nocarimidazoles A and B from a Marine-Derived Actinomycete of the Genus Nocardiopsis

Chemical investigation of a marine-derived actinomycete isolated from marine sediments collected off the coast of southern California and identified as a Nocardiopsis sp. (strain CNQ115) led to the isolation of two new 4-aminoimidazole alkaloids, nocarimidazoles A (1) and B (2). The chemical structures of nocarimidazoles A and B were assigned by interpretation of NMR spectroscopic data and through methylation to yield monomethyl and dimethyl derivatives. Nocarimidazoles A and B possess a 4-aminoimidazole ring combined with a conjugated carbonyl side chain, which is rarely found in microbial secondary metabolites.

Biogeography of Nocardiopsis strains from hypersaline environments of Yunnan and Xinjiang Provinces, western China

The genus Nocardiopsis is a widespread group within the phylum Actinobacteria and has been isolated from various salty environments worldwide. However, little is known about whether biogeography affects Nocardiopsis distribution in various hypersaline environments. Such information is essential for understanding the ecology of Nocardiopsis. Here we analyzed 16S rRNA, gyrB, rpoB and sodA genes of 78 Nocardiopsis strains isolated from hypersaline environments in Yunnan and Xinjiang Provinces of western China. The obtained Nocardiopsis strains were classified into five operational taxonomic units, each comprising location-specific phylo- and genotypes. Statistical analyses showed that spatial distance and environmental factors substantially influenced Nocardiopsis distribution in hypersaline environments: the former had stronger influence at large spatial scales, whereas the latter was more influential at small spatial scales.

Microbacterium nanhaiense sp. nov., an actinobacterium isolated from sea sediment

A Gram-staining-positive, heterotrophic, anaerobic, non-spore-forming, non-motile, rod-shaped strain, OAct400T, belonging to the genus Microbacterium was isolated from a sediment collected from a depth of 2093 m in the South China Sea, China. The strain was identified using a polyphasic taxonomic approach. The strain grew well on yeast extract/malt extract agar (ISP 2) and nutrient agar media, and formed no aerial mycelium and no diffusible pigments on any media tested. The strain grew in the presence of 0-8 % (w/v) NaCl (optimum, 2-4 %), at pH 5.0-10.0 (optimum, pH 7.0) and at 4-37 °C (optimum, 28 °C). Strain OAct400T contained ornithine as the diagnostic diamino acid. The whole-cell sugars were dominated by glucose and galactose. The predominant menaquinones were MK-11 (51 %) and MK-10 (24 %). The major phospholipids were phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were anteiso-C15 : 0 (59.35 %), iso-C16 : 0 (17.89 %) and anteiso-C17 : 0 (16.09 %). DNA-DNA relatedness with Microbacterium amylolyticum DSM 24221T and Microbacterium gubbeenense CIP 107184T, the nearest phylogenetic relatives (97.73 and 97.44 % 16S rRNA gene sequence similarity, respectively) was 31.3 ± 2.1 and 28.7 ± 1.2 %, respectively. On the basis of phenotypic, phylogenetic and genotypic data, a novel species, Microbacterium nanhaiense sp. nov., is proposed. The type strain is OAct400T ( = CGMCC 4.7181T = DSM 26811T = KCTC 29185T).

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).

Nocardiopsis fildesensis sp. nov., an actinomycete isolated from soil

A filamentous actinomycete strain, designated GW9-2T, was isolated from a soil sample collected from the Fildes Peninsula, King George Island, West Antarctica. The strain was identified using a polyphasic taxonomic approach. The strain grew slowly on most media tested, producing small amounts of aerial mycelia and no diffusible pigments on most media tested. The strain grew in the presence of 0–12 % (w/v) NaCl (optimum, 2–4 %), at pH 9.0–11.0 (optimum, pH 9.0) and 10–37 °C (optimum, 28 °C). The isolate contained meso-diaminopimelic acid, no diagnostic sugars and MK-9(H4) as the predominant menaquinone. The major phospholipids were phosphatidylglycerol, phosphatidylcholine and phosphatidylmethylethanolamine. The major fatty acids were iso-C16 : 0, anteiso-C17 : 0, C18 : 1ω9c, iso-C15 : 0 and iso-C17 : 0. DNA–DNA relatedness was 37.6 % with Nocardiopsis lucentensis DSM 44048T, the nearest phylogenetic relative (97.93 % 16S rRNA gene sequence similarity). On the basis of the results of a polyphasic study, a novel species, Nocardiopsis fildesensis sp. nov., is proposed. The type strain is GW9-2T ( = CGMCC 4.7023T = DSM 45699T = NRRL B-24873T).

Nocardiopsis coralliicola sp. nov., isolated from the gorgonian coral, Menella praelonga

An actinobacterial strain, SCSIO 10427T, was isolated from a gorgonian coral sample collected from Weizhou Island, Guangxi province, China, and its taxonomic position was investigated using a polyphasic approach. The organism was found to have a range of chemical and morphological properties consistent with its classification in the genus Nocardiopsis . Phylogenetic analysis indicated that 16S rRNA gene sequence similarity between strain SCSIO 10427T and type strains of other recognized members of the genus Nocardiopsis was lower than 98.4 %. Furthermore, phenotypic characteristics revealed that the strain differed from the currently recognized species of the genus Nocardiopsis . Therefore, strain SCSIO 10427T represents a novel species of the genus Nocardiopsis , for which the name Nocardiopsis coralliicola sp. nov. is proposed. The type strain is SCSIO 10427T ( = CCTCC AA 2011010T = DSM 45611T).

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).

Spinactinospora alkalitolerans gen. nov., sp. nov., an actinomycete isolated from marine sediment

A novel marine actinomycete, designated CXB654T, was isolated from marine sediment collected at a depth of 17.5 m near the Yellow Sea Cold Water Mass, China. Optimal growth occurred at 37.0 °C, at pH 7.0–8.0 and in 3–8 % (w/v) NaCl. Strain CXB654T formed branched substrate mycelium without fragmentation. Abundant aerial mycelium differentiated into long or short chains of spores and spores were elliptical and cylindrical with spiny surfaces. Strain CXB654T contained meso-diaminopimelic acid as the diagnostic diamino acid, and ribose and glucose as the major whole-cell components. Phospholipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol and phosphatidylinositol. MK-10(H8), MK-10(H6) and MK-9(H8) were the predominant menaquinones. The major fatty acids were i-C16 : 0 (24.46 %), ai-C17 : 0 (20.66 %) and C18 : 0 (20.14 %). The DNA G+C content was 71.1 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. Highest sequence similarities were to Murinocardiopsis flavida DSM 45312T (96.6 %), Thermobifida halotolerans YIM 90462T (96.5 %) and Marinactinospora thermotolerans DSM 45154T (96.1 %). On the basis of phenotypic, chemotaxonomic and phylogenetic distinctiveness, strain CXB654T was considered to represent a novel species in a new genus in the family Nocardiopsaceae, and the name Spinactinospora alkalitolerans gen. nov., sp. nov. is proposed; the type strain is CXB654T ( = DSM 45414T = LMG 25485T).

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).

Nocardiopsis sinuspersici sp. nov., isolated from sandy rhizospheric soil

A polyphasic taxonomic study of a halotolerant bacterium, isolated from sandy rhizospheric soil in Sarbandar, Persian Gulf, Iran, revealed that strain HM6T represents a novel species within the genus Nocardiopsis. Results of the 16S rRNA gene sequence comparison revealed that strain HM6T clustered with strains of the genus Nocardiopsis, showing the highest degree of 16S rRNA gene sequence similarity to Nocardiopsis quinghaiensis (99.2 %), Nocardiopsis aegyptia (98.5 %) and Nocardiopsis halotolerans (98.3 %). However, DNA–DNA hybridization studies with these type strains revealed less than 39.6 % similarity. Rather than genotypic differences, there are some phenotypic discrepancies between strain HM6T and closely related species of the genus Nocardiopsis. Main morphological and chemotaxonomical features of strain HM6T include: (i) growth characteristics, i.e. the formation of a scant light-yellow to white aerial mycelium and the typical zig-zag form of the hyphae, which fragment during ageing into smooth rod-shaped spores; (ii) the presence of meso-diaminopimelic acid and glucose plus ribose in whole-cell hydrolysates; (iii) the presence of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and phosphatidylinositol, together with three unknown Nocardiopsis-specific phospholipids (close to diphosphatidylglycerol in position) in polar lipid extracts; (iv) the presence of the major menaquinones MK-10(H0), MK-10(H2) and MK-9(H0) in the non-polar fraction; (v) the presence of iso/anteiso-branched plus 10-methyl-branched fatty acids, showing the diagnostic combination for species of the genus Nocardiopsis of iso-16 : 0 (31.1 %), anteiso-17 : 0 (19.2 %), 10-methyl-17 : 0 (5.8 %) and tuberculostearic acid (8.8 %); and (vi) the absence of mycolic acids. Analysis of the 16S rRNA gene sequence revealed that strain HM6T represents a distinct taxon within the genus Nocardiopsis. Based upon genotypic and phenotypic differences from other members of the genus, a novel species, Nocardiopsis sinuspersici sp. nov., is proposed. The type strain is HM6T (=UTMC 00102T =DSM 45277T =CCUG 57624T).

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)).

Lucentamycins A-D, cytotoxic peptides from the marine-derived actinomycete Nocardiopsis lucentensis

Four new 3-methyl-4-ethylideneproline-containing peptides, lucentamycins A-D (1-4), have been isolated from the fermentation broth of a marine-derived actinomycete identified by phylogenetic methods as Nocardiopsis lucentensis (strain CNR-712). The planar structures of the new compounds were assigned on the basis of 1D and 2D NMR spectroscopic techniques, while the absolute configurations of the amino acid residues were determined by application of the advanced Marfey method. Lucentamycins A (1) and B (2) showed significant in vitro cytotoxicity against HCT-116 human colon carcinoma.

Effects of Ultraviolet Radiation on the Gram-Positive Marine Bacterium Microbacterium maritypicum

Although extensive information is available on the effect ultraviolet (UV) radiation has on Gram-negative marine bacteria, there is a scarcity of data concerning UV radiation and Gram-positive marine bacteria. The focus of this paper is on Microbacterium maritypicum, with the Gram-negative Vibrio natriegens being used as a standard of comparison. M. maritypicum exhibited growth over a NaCl range of 0-1000 mM: , with optimum growth occurring between 0 and 400 mM: NaCl. In contrast, V. natriegens grew over a NaCl span of 250-1000 mM: , with best growth being observed between 250 and 600 mM: NaCl. UV radiation experiments were done using the medium with 250 mM: NaCl. For solar (UV-A and B) radiation and log-phase cells, M. maritypicum was determined to be three times more resistant than V. natriegens. For germicidal (UV-C) radiation, the pattern of resistance of the log-phase cells to the lethal effects of the radiation was even more pronounced, with the Gram-positive bacterium being more than 12 to 13 times more resistant. Similar data to the solar and germicidal log-phase UV kill curves were obtained for stationary-phase cells of both organisms. Photoreactivation was observed for both types of cells exposed to UV-C but none for cells treated with UV-A and B. When log phase cells of M.maritypicum were grown at 0.0 and 0.6 M: NaCl and exposed to UV-C radiation, no difference in survivorship patterns was noted from that of 0.25 M: NaCl grown cells. Although this study has only focused on two marine bacteria, our results indicate that the Gram-positive M. maritypicum could have a built-in advantage for survival in some marine ecosystems.

Culturable actinobacteria from the marine sponge Hymeniacidon perleve: isolation and phylogenetic diversity by 16S rRNA gene-RFLP analysis

A total of 106 actinobacteria associated with the marine sponge Hymeniacidon perleve collected from the Yellow Sea, China were isolated using eight different media. The number of species and genera of actinobacteria recovered from the different media varied significantly, underlining the importance of optimizing the isolation conditions. The phylogenetic diversity of the actinobacteria isolates was assessed using 16S rRNA gene amplification-restriction fragment length polymorphism (RFLP) analysis of the 106 strains with different morphologies. The RFLP fingerprinting of selected strains by HhaI-digestion of the 16S rRNA genes resulted in 11 different patterns. The HhaI-RFLP analysis gave good resolution for the identification of the actinobacteria isolates at the genus level. A phylogenetic analysis using 16S rRNA gene sequences revealed that the isolates belonged to seven genera of culturable actinobacteria including Actinoalloteichus, Micromonospora, Nocardia, Nocardiopsis, Pseudonocardia, Rhodococcus, and Streptomyces. The dominant genus was Streptomyces, which represented 74% of the isolates. Three of the strains identified are candidates for new species.

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).

Degradation of polyesters by a novel marine Nocardiopsis aegyptia sp. nov.: Application of Plackett-Burman experimental design for the improvement of PHB depolymerase activity

This is the first report on the degradation of poly(3-hydroxybutyrate) (PHB), and its copolymers poly(3-hydroxyvalerate) P(3HB-co-10-20% HV) by Nocardiopsis aegyptia, a new species isolated from marine seashore sediments. The strain excreted an extracellular PHB depolymerase and grew efficiently on PHB or its copolymers as the sole carbon sources. The degradation activity was detectable by the formation of a transparent clearing zone around the colony on an agar Petri plate after 25 days, or a clearing depth under the colony in test tubes within 3 weeks. The previous techniques proved that the bacterium was able to assimilate the monomeric components of the shorter alkyl groups of the polymers. Nocardiopsis aegyptia hydrolyzed copolymers 10-20% PHBV more rapidly than the homopolymer PHB. The bacterial degradation of the naturally occurring sheets of poly(3-hydroxybutyrate), and its copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was observed by scanning electron microscopy (SEM). The samples were degraded at the surface and proceeded to the inner part of the materials. Clear morphological alterations of the polymers were noticed, indicating the degradative capability of the bacterium. Plackett-Burman statistical experimental design has been employed to optimize culture conditions for maximal enzyme activity. The main factors that had significant positive effects on PHB depolymerase activity of Nocardiopsis aegyptia were sodium gluconate, volume of medium/flask and age of inoculum. On the other hand, MgSO4.7H2O, KH2PO4, K2HPO4 and NH4NO3 exhibited negative effects. Under optimized culture conditions, the highest activity (0.664 U/mg protein) was achieved in a medium predicted to be near optimum containing (in g/L): PHB, 0.5; C6H11O7Na, 7.5; MgSO4.7H2O, 0.35; K2HPO4, 0.35; NH4NO3, 0.5; KH2PO4, 0.35; malt extract, 0.5 and prepared with 50% seawater. The medium was inoculated with 1% (v/v) spore suspension of 7 days old culture. Complete clarity of the medium was achieved after 3 days at 30 degrees C.