Draft Genome Sequence of Marine-Derived Actinomycete Nocardiopsis sp. Strain TP-A0876, a Producer of Polyketide Pyrones

Diketopiperazine derivative from marine actinomycetes Nocardiopsis sp. SCA30 with antimicrobial activity against MRSA

Actinobacteria isolated from marine sources are a potential source of novel natural products. In this study, we report isolation, biological activity and characterization of secondary metabolites from strain Nocardiopsis sp. SCA30, isolated from marine sediments of Havelock Islands, Andaman and Nicobar, India. The ethyl acetate extracts of the isolate on screening for biological activity demonstrated antibacterial potency and antiproliferative activity. The extracts showed anticancer activity in a panel of cell lines, including HCT 15, HT 29, MCF 7 and MDA-MB 468, at concentrations ranging from 62.5 to 1000 µg/ml. A dose-dependent reduction in cell viability was observed in all the tested cell lines. The extract at 15 µg/ml and 30 µg/ml inhibited growth of methicillin-resistant Staphylococcus aureus ATCC NR-46071 and NR-46171 with MIC's of 15.62 and 7.81 µg/ml, respectively. LC-MS and NMR studies revealed that the antibacterial and anticancer compound isolated from Nocardiopsis sp. SCA30 is 1-acetyl-4-4(hydroxyphenyl)piperazine.

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.

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.

Draft Genome Sequence of Marine-Derived Streptomyces sp. TP-A0873, a Producer of a Pyrrolizidine Alkaloid Bohemamine

Streptomyces sp. TP-A0873, isolated from deep-sea water, produces three different classes of secondary metabolites: antimycin, bohemamine, and alkylated butenolides. In order to assess the biosynthetic potential of this strain, draft genome sequencing was carried out. The genome contained at least 14 gene clusters for polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS).

Draft Genome Sequence of Streptomyces albus Strain NBRC 13014T, the Type Species of the Genus Streptomyces

Streptomyces albus is the type species of the genus Streptomyces. Here, we report the draft genome sequence of S. albus strain NBRC 13014^T. The genome contains at least seven orphan polyketide synthase and nonribosomal peptide synthetase gene clusters. The genome sequence will also serve as a valuable reference for Streptomyces taxonomy.

Taxonomic affiliation of new genomes should be verified using average nucleotide identity and multilocus phylogenetic analysis

The average nucleotide identity (ANI) determines if two genomes belong to the same species. Using ANI, we detected mislabeled genomes and recommend verifying with ANI and multilocus phylogenetic analysis the species affiliations of the announced genomes. The slightly different results obtained with different ANI calculation software can potentially mislead taxonomic inferences.

Nocapyrones: α- and γ-pyrones from a marine-derived Nocardiopsis sp

One new α-pyrone (nocapyrone R (1)), and three known γ-pyrones (nocapyrones B, H and L (2-4)) were isolated from the culture extract of a Nocardiopsis strain collected from marine sediment. Structures of these compounds were determined on the basis of spectroscopic data including NMR and MS. γ-Pyrones 2-4 were found to induce adiponectin production in murine ST-13 preadipocyte cells but the α-pyrone 1 had no activity. The absolute configuration of the anteiso-methyl branching in 4 was determined by HPLC comparison of a degraded product of 4 with standard samples as a 2:3 enantiomeric mixture of (R)- and (S)-isomers.