Nitrogen sources alter ligninase and cellulase activities of thermophilic fungi isolated from compost and vermicompost.

Fungi harboring lignocellulolytic activity accelerate the composting process of agricultural wastes; however, using thermophilic fungal isolates for this process has been paid little attention. Moreover, exogenous nitrogen sources may differently affect fungal lignocellulolytic activity. A total of 250 thermophilic fungi were isolated from local compost and vermicompost samples. First, the isolates were qualitative assayed for ligninase and cellulase activities using Congo red (CR) and carboxymethyl cellulose (CMC) as substrates, respectively. Then, twenty superior isolates harboring higher ligninase and cellulase activities were selected and quantitatively assayed for both enzymes in basic mineral (BM) liquid medium supplemented with the relevant substrates and nitrogen sources including (NH4)2SO4 (AS), NH4NO3 (AN), urea (U), AS + U (1:1), or AN + U (1:1) with final nitrogen concentration of 0.3 g/L. The highest ligninase activities of 99.94, 89.82, 95.42, 96.25, and 98.34% of CR decolorization were recorded in isolates VC85, VC94, VC85, C145, and VC85 in the presence of AS, U, AS + U, AN, and AN + U, respectively. Mean ligninase activity of 63.75% in superior isolates was achieved in the presence of AS and ranked the highest among other N compounds. The isolates C200 and C184 exhibited the highest cellulolytic activity in the presence of AS and AN + U by 8.8 and 6.5 U/ml, respectively. Mean cellulase activity of 3.90 U/mL was achieved in AN + U and ranked the highest among other N compounds. Molecular identification of twenty superior isolates confirmed that all of them are belonging to Aspergillus fumigatus group. Focusing on the highest ligninase activity of the isolate VC85 in the presence of AS, the combination can be recommended as a potential bio-accelerator for compost production.

Cytotoxic, anti-biofilm and antimicrobial polyketides from the plant associated fungus Chaetosphaeronema achilleae.

From extracts of the plant associated fungus Chaetosphaeronema achilleae collected in Iran, a previously unreported isoindolinone named chaetosisoindolinone (1) and a previously undescribed indanone named chaetosindanone (2) were isolated in addition to five known metabolites, 2-(2-acetyl-3,5-dihydroxyphenyl) acetic acid (3), vulculic acid (4), 2-(2-acetyl-3-hydroxy-5-methoxyphenyl)acetic acid (5), curvulin (6), and curvulol (7). Their structures were elucidated on the basis of extensive spectroscopic analysis and high-resolution mass spectrometry. The isolated compounds were tested for their antimicrobial, anti-biofilm, and nematicidal activities. Compound 2 exhibited cytotoxicity against the human breast adenocarcinoma MCF-7 cells with an IC50 value of 1.5 µg/mL. Furthermore, compounds 4 and 7 almost completely inhibited biofilm formation in Staphylococcus aureus at 256 µg/mL. Weak antimicrobial activities were also observed for some of the isolated compounds against Mucor hiemalis, Rhodoturula glutinis, Chromobacterium violaceum, and Staphylococcus aureus.

Cytotoxic, antimicrobial and antiviral secondary metabolites produced by the plant pathogenic fungus Cytospora sp. CCTU A309.

Chemical analysis of extracts from cultures of the plant pathogenic fungus Cytospora sp. strain CCTU A309 collected in Iran led to the isolation of two previously unreported heptanedioic acid derivatives namely (2R,3S) 2-hydroxy-3-phenyl-4-oxoheptanedioic acid (1) and (2S,3S) 2-hydroxy-3-phenyl-4-oxoheptanedioic acid (2) as diastereomers, four previously undescribed prenylated p-terphenyl quinones 3-6 in addition to five known metabolites. Their structures were elucidated on the basis of extensive spectroscopic analysis and high-resolution mass spectrometry. For metabolites 1 and 2, the absolute configurations at C-2 were deduced from comparison of the 1H NMR difference of their (S)- and (R)-phenylglycine methyl ester derivatives while the relative configurations were tentatively assigned by a J-based analysis and confirmed by comparison of 13C chemical shifts to literature data. The isolated compounds were tested for their cytotoxic, antimicrobial (including biofilm inhibition), antiviral, and nematicidal activities. While only moderate antimicrobial effects were observed, the terphenyl quinone derivatives 3-6 and leucomelone (10) exhibited significant cytotoxicity against the mouse fibroblast L929 and cervix carcinoma KB-3-1 cell lines with IC50 values ranging from 2.4 to 26 µg/mL. Furthermore, metabolites 4-6 showed interesting antiviral activity against hepatitis C virus (HCV).

Diversity of culturable fungi inhabiting petroleum-contaminated soils in Southern Iran.

The present study was aimed at characterising species diversity of fungi inhabiting petroleum-contaminated soils of oil fields in a southern region of Iran. Two different techniques were used for fungal isolation including enrichment on atmospheres of phenolic hydrocarbons and crude oil as substrate. Phylogenetic analysis of the internal transcribed spacer of ribosomal DNA was used for taxonomic identification with additional information from the ß-tubulin gene for selected taxa. Overall, 183 strains from 14 genera and five orders were obtained: Pleosporales (Alternaria, Curvularia, Stemphylium, Ulocladium), Chaetothyriales (Exophiala), Eurotiales (Aspergillus), Hypocreales (Acremonium, Emericellopsis, Sarocladium, Stachybotrys, Fusarium, Trichoderma, Beauveria), and Capnodiales (Cladosporium). The most frequently isolated strains belonged to the genera Alternaria, Exophiala and Aspergillus. The crude oil substrate was the most successful isolation method, and among the four hydrocarbon enrichments, toluene substrate yielded the highest number of strains. Enrichment on xylene and benzene also yielded herpotrichiellaceous and other filamentous fungi.