Phylogenetic evaluation of the genus Nostoc and description of Nostoc neudorfense sp. nov., from the Czech Republic.

Cyanobacterial strain ARC8 was isolated from seepage coming into the river Dracice, Frantiskov, Czech Republic, and was characterized using a polyphasic approach. Strain ARC8 showed a typical Nostoc-like morphology and in-depth morphological characterization indicated that it is a member of the genus Nostoc. Furthermore, in the 16S rRNA gene phylogeny inferred using Bayesian inference, maximum likelihood and neighbour joining methods, strain ARC8 clustered within the Nostoc sensu stricto clade. The phylogenetic distance and the positioning of strain ARC8 also indicated that it is a member of the genus Nostoc. Furthermore, the rbcL gene phylogeny along with the 16S-23S ITS secondary structure analysis also supported the findings from the 16S rRNA gene tree. In accordance with the International Code of Nomenclature for Algae, Fungi and Plants we describe a novel species of Nostoc with the name Nostoc neudorfense sp. nov.

Desikacharya gen. nov., a phylogenetically distinct genus of Cyanobacteria along with the description of two new species, Desikacharya nostocoides sp. nov. and Desikacharya soli sp. nov., and reclassification of Nostoc thermotolerans to Desikacharya thermotolerans comb. nov.

Two Nostoc-like strains have been isolated, purified, cultured and identified on the basis of the polyphasic approach using morphological, ecological, molecular and phylogenetic methods. Both strains were found to have morphology similar to the genus Nostoc, but clustered strongly in a group distant from the Nostocsensu stricto clade. Further analysis, using the folded structures of the 16S-23S ITS region revealed strong differences from closely related members of the genus Nostoc. Distinct phylogenetic clustering and strong tree topologies using Bayesian inference, maximum-likelihood and maximum-parsimony methods indicated the need to revisit the taxonomy of the members of this particular clade with a clear need for giving a generic status distinct from the genus Nostoc. In accordance with the International Code of Nomenclature for Algae, Fungi and Plants, the name Desikacharya gen. nov. is proposed for the new genus along with the description of two new species, Desikacharya nostocoides sp. nov. and Desikacharya soli sp. nov., and reclassification of Nostoc thermotolerans to Desikacharya thermotolerans comb. nov.

Description of two new species of Aliinostoc and one new species of Desmonostoc from India based on the Polyphasic Approach and reclassification of Nostoc punensis to Desmonostoc punense comb. nov.

Three heterocytous cyanobacterial strains were isolated from different habitats of Central India, and initial morphological studies indicated them to be members of the genus Nostoc or other closely related genera. Subsequent studies using morphological, ecological, molecular and phylogenetic methods indicated the three strains to be new members of the genera Aliinostoc and Desmonostoc. Folding of the D1-D1' helix of the ITS region clearly differentiated the three strains from the other closely related strains, thus providing final indications of the strains being different and new additions to the genera Aliinostoc and Desmonostoc. In accordance with the International Code of Nomenclature for algae, fungi and plants, we establish three new species: Aliinostoc tiwarii sp. nov, Aliinostoc soli sp. nov. and Desmonostoc magnisporum sp. nov. along with reclassifying Nostoc punensis as Desmonostoc punense comb. nov.

Antifungal compounds from cyanobacteria.

Cyanobacteria are photosynthetic prokaryotes found in a range of environments. They are infamous for the production of toxins, as well as bioactive compounds, which exhibit anticancer, antimicrobial and protease inhibition activities. Cyanobacteria produce a broad range of antifungals belonging to structural classes, such as peptides, polyketides and alkaloids. Here, we tested cyanobacteria from a wide variety of environments for antifungal activity. The potent antifungal macrolide scytophycin was detected in Anabaena sp. HAN21/1, Anabaena cf. cylindrica PH133, Nostoc sp. HAN11/1 and Scytonema sp. HAN3/2. To our knowledge, this is the first description of Anabaena strains that produce scytophycins. We detected antifungal glycolipopeptide hassallidin production in Anabaena spp. BIR JV1 and HAN7/1 and in Nostoc spp. 6sf Calc and CENA 219. These strains were isolated from brackish and freshwater samples collected in Brazil, the Czech Republic and Finland. In addition, three cyanobacterial strains, Fischerella sp. CENA 298, Scytonema hofmanni PCC 7110 and Nostoc sp. N107.3, produced unidentified antifungal compounds that warrant further characterization. Interestingly, all of the strains shown to produce antifungal compounds in this study belong to Nostocales or Stigonematales cyanobacterial orders.

Anti-MRSA-acting carbamidocyclophanes H-L from the Vietnamese cyanobacterium Nostoc sp. CAVN2.

The methanol extract of the Vietnamese freshwater cyanobacterium Nostoc sp. CAVN2 exhibited cytotoxic effects against MCF-7 and 5637 cancer cell lines as well as against nontumorigenic FL and HaCaT cells and was active against methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae. High-resolution mass spectrometric analysis indicated the presence of over 60 putative cyclophane-like compounds in an antimicrobially active methanol extract fraction. A paracyclophanes-focusing extraction and separation methodology led to the isolation of 5 new carbamidocyclophanes (1-5) and 11 known paracyclophanes (6-16). The structures and their stereochemical configurations were elucidated by a combination of spectrometric and spectroscopic methods including HRMS, 1D and 2D NMR analyses and detailed comparative CD analysis. The newly described monocarbamoylated [7.7]paracyclophanes (1, 2, 4 and 5) differ by a varying degree of chlorination in the side chains. Carbamidocyclophane J (3) is the very first reported carbamidocyclophane bearing a single halogenation in both butyl residues. Based on previous studies a detailed phylogenetic examination of cyclophane-producing cyanobacteria was carried out. The biological evaluation of 1-16 against various clinical pathogens highlighted a remarkable antimicrobial activity against MRSA with MICs of 0.1-1.0 µM, and indicated that the level of antibacterial activity is related to the presence of carbamoyl moieties.