How Do Fungi Survive in the Sea and Respond to Climate Change?

With the over 2000 marine fungi and fungal-like organisms documented so far, some have adapted fully to life in the sea, while some have the ability to tolerate environmental conditions in the marine milieu. These organisms have evolved various mechanisms for growth in the marine environment, especially against salinity gradients. This review highlights the response of marine fungi, fungal-like organisms and terrestrial fungi (for comparison) towards salinity variations in terms of their growth, spore germination, sporulation, physiology, and genetic adaptability. Marine, freshwater and terrestrial fungi and fungal-like organisms vary greatly in their response to salinity. Generally, terrestrial and freshwater fungi grow, germinate and sporulate better at lower salinities, while marine fungi do so over a wide range of salinities. Zoosporic fungal-like organisms are more sensitive to salinity than true fungi, especially Ascomycota and Basidiomycota. Labyrinthulomycota and marine Oomycota are more salinity tolerant than saprolegniaceous organisms in terms of growth and reproduction. Wide adaptability to saline conditions in marine or marine-related habitats requires mechanisms for maintaining accumulation of ions in the vacuoles, the exclusion of high levels of sodium chloride, the maintenance of turgor in the mycelium, optimal growth at alkaline pH, a broad temperature growth range from polar to tropical waters, and growth at depths and often under anoxic conditions, and these properties may allow marine fungi to positively respond to the challenges that climate change will bring. Other related topics will also be discussed in this article, such as the effect of salinity on secondary metabolite production by marine fungi, their evolution in the sea, and marine endophytes.

Escaping introns in COI through cDNA barcoding of mushrooms: Pleurotus as a test case.

DNA barcoding involves the use of one or more short, standardized DNA fragments for the rapid identification of species. A 648-bp segment near the 5' terminus of the mitochondrial cytochrome c oxidase subunit I (COI) gene has been adopted as the universal DNA barcode for members of the animal kingdom, but its utility in mushrooms is complicated by the frequent occurrence of large introns. As a consequence, ITS has been adopted as the standard DNA barcode marker for mushrooms despite several shortcomings. This study employed newly designed primers coupled with cDNA analysis to examine COI sequence diversity in six species of Pleurotus and compared these results with those for ITS. The ability of the COI gene to discriminate six species of Pleurotus, the commonly cultivated oyster mushroom, was examined by analysis of cDNA. The amplification success, sequence variation within and among species, and the ability to design effective primers was tested. We compared ITS sequences to their COI cDNA counterparts for all isolates. ITS discriminated between all six species, but some sequence results were uninterpretable, because of length variation among ITS copies. By comparison, a complete COI sequences were recovered from all but three individuals of Pleurotus giganteus where only the 5' region was obtained. The COI sequences permitted the resolution of all species when partial data was excluded for P. giganteus. Our results suggest that COI can be a useful barcode marker for mushrooms when cDNA analysis is adopted, permitting identifications in cases where ITS cannot be recovered or where it offers higher resolution when fresh tissue is. The suitability of this approach remains to be confirmed for other mushrooms.

Molecular divergence and species delimitation of the cultivated oyster mushrooms: integration of IGS1 and ITS.

Identification of edible mushrooms particularly Pleurotus genus has been restricted due to various obstacles. The present study attempted to use the combination of two variable regions of IGS1 and ITS for classifying the economically cultivated Pleurotus species. Integration of the two regions proved a high ability that not only could clearly distinguish the species but also served sufficient intraspecies variation. Phylogenetic tree (IGS1+ITS) showed seven distinct clades, each clade belonging to a separate species group. Moreover, the species differentiation was tested by AMOVA and the results were reconfirmed by presenting appropriate amounts of divergence (91.82% among and 8.18% within the species). In spite of achieving a proper classification of species by combination of IGS1 and ITS sequences, the phylogenetic tree showed the misclassification of the species of P. nebrodensis and P. eryngii var. ferulae with other strains of P. eryngii. However, the constructed median joining (MJ) network could not only differentiate between these species but also offer a profound perception of the species' evolutionary process. Eventually, due to the sufficient variation among and within species, distinct sequences, simple amplification, and location between ideal conserved ribosomal genes, the integration of IGS1 and ITS sequences is recommended as a desirable DNA barcode.

Green synthesis of silver nanoparticles using Ganoderma neo-japonicum Imazeki: a potential cytotoxic agent against breast cancer cells.

BACKGROUND: Silver nanoparticles (AgNPs) are an important class of nanomaterial for a wide range of industrial and biomedical applications. AgNPs have been used as antimicrobial and disinfectant agents due their detrimental effect on target cells. The aim of our study was to determine the cytotoxic effects of biologically synthesized AgNPs using hot aqueous extracts of the mycelia of Ganoderma neo-japonicum Imazeki on MDA-MB-231 human breast cancer cells. METHODS: We developed a green method for the synthesis of water-soluble AgNPs by treating silver ions with hot aqueous extract of the mycelia of G. neo-japonicum. The formation of AgNPs was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. Furthermore, the toxicity of synthesized AgNPs was evaluated using a series of assays: such as cell viability, lactate dehydrogenase leakage, reactive oxygen species generation, caspase 3, DNA laddering, and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling in human breast cancer cells (MDA-MB-231). RESULTS: The ultraviolet-visible absorption spectroscopy results showed a strong resonance centered on the surface of AgNPs at 420 nm. The X-ray diffraction analysis confirmed that the synthesized AgNPs were single-crystalline, corresponding with the result of transmission electron microscopy. Treatment of MDA-MB-231 breast cancer cells with various concentrations of AgNPs (1-10 µg/mL) for 24 hours revealed that AgNPs could inhibit cell viability and induce membrane leakage in a dose-dependent manner. Cells exposed to AgNPs showed increased reactive oxygen species and hydroxyl radical production. Furthermore, the apoptotic effects of AgNPs were confirmed by activation of caspase 3 and DNA nuclear fragmentation. CONCLUSION: The results indicate that AgNPs possess cytotoxic effects with apoptotic features and suggest that the reactive oxygen species generated by AgNPs have a significant role in apoptosis. The present findings suggest that AgNPs could contribute to the development of a suitable anticancer drug, which may lead to the development of a novel nanomedicine for the treatment of cancers.

Phenelfamycins G and H, new elfamycin-type antibiotics produced by Streptomyces albospinus Acta 3619.

Phenelfamycins G and H are new members of the family of elfamycin antibiotics with the basic structure of phenelfamycins E and F, respectively, which are also well known as ganefromycins α and ß. Phenelfamycins G and H differ from phenelfamycins E and F by an additional hydroxy group at position C-30, which is not described so far for any of the elfamycin-type antibiotics. The actinomycete strain that produced phenelfamycins G and H was identified to be Streptomyces albospinus based on its 16S rRNA gene sequence. Phenelfamycins G and H exhibit a narrow antibacterial spectrum with a pronounced inhibitory activity against Propionibacterium acnes.

Gombapyrones, new alpha-pyrone metabolites produced by Streptomyces griseoruber Acta 3662.

Gombapyrones A-D, new members of the alpha-pyrone family of secondary metabolites, were produced by Streptomyces griseoruber Acta 3662, which was isolated from bamboo tree rhizosphere. The strain was characterized by its morphological and chemotaxonomical features and by 16S rDNA sequencing as S. griseobuber. The gombapyrone structures were determined by mass spectrometry and by NMR experiments, and were found to have an inhibitory activity against protein tyrosine phosphatase 1B and glycogen synthase kinase 3beta.

Nocardichelins A and B, siderophores from Nocardia strain acta 3026.

An actinomycete, strain Acta 3026, isolated from mangrove soil was characterized and found to belong to the genus Nocardia. The strain produces two new cytotoxic metabolites, nocardichelins A (1) and B (2). Each of the compounds strongly inhibited human cell lines from gastric adenocarcinoma, breast carcinoma, and hepatocellular carcinoma with GI50 values in a low micromolar to nanomolar range. The structural characterization of the compounds was performed by mass spectrometry and NMR spectroscopy. The nocardichelins represent a new group of siderophores that combine the structural elements of mycobactin-type siderophores from mycobacteria and hydroxamate-type siderophores (desferrioxamine B) produced by streptomycetes. The chromazurol S assay, characteristic for iron(III) complexation, was positive, confirming the role as a siderophore.

Pterulamides I-VI, linear peptides from a Malaysian Pterula sp.

Six new linear peptides, pterulamides I-VI (1-6), were isolated from the fruiting bodies of a Malaysian Pterula species. The structures were elucidated by MS and 2D NMR experiments, and the absolute configurations of the constituent amino acids established using Marfey's method. The pterulamides are mainly assembled from nonpolar N-methylated amino acids and, most interestingly, have non-amino-acid N-terminal groups, among them the unusual cinnamoyl, (E)-3-methylsulfinylpropenoyl, and (E)-3-methylthiopropenoyl groups. Furthermore, pterulamides I-V are the first natural peptides with a methylamide C-terminus. Pterulamides I and IV are cytotoxic against the P388 cell line with IC50 values of 0.55 and 0.95 microg/mL (0.79 and 1.33 microM), respectively.