The detected new natural lipoheptapeptide compounds with modified structures have significant potential for biotechnological and biocontrol applications. The complementary ITMS(2) data as well as the described internal fragmentation mechanism obtained from the sodiated surfactin molecules may further facilitate the structural elucidation of cyclic lipopeptides in the future. Copyright © 2016 John Wiley & Sons, Ltd.

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Prostaglandins are C20 fatty acid metabolites with diverse biological functions. In mammalian cells, prostaglandins are produced from arachidonic acid (AA) via cyclooxygenases (COX1 and COX2). Although fungi do not possess cyclooxygenase homologues, several pathogenic species are able to produce prostaglandins from host-derived arachidonic acid. In this study, we characterized the prostaglandin profile of the emerging human pathogen Candida parapsilosis with HPLC-MS and compared it to that of C. albicans. We found that both species synthesized prostaglandins (mainly PGD 2 and PGE 2 ) from exogenous AA. Furthermore, as OLE2 has been associated with prostaglandin synthesis in C. albicans, we generated homozygous OLE2 deletion mutants in C. parapsilosis and examined their PGE 2 production. However, the PGE 2 production of the OLE2 KO strain was similar to that of wild type (WT), indicating that OLE2 is not required for prostaglandin synthesis in C. parapsilosis. Interestingly, analyses of the fatty acid composition of WT and OLE2 KO cells by gas chromatography (GC) highlighted the accumulation of palmitoleic and oleic acid in the OLE2 deletion mutant. The OLE2 KO cells were killed more efficiently by human monocytes-derived macrophages (MDMs) as well as induced higher interleukin-10 (IL-10) secretion, indicating that OLE2 affects the virulence of C. parapsilosis. Taken together, these results contribute to the better understanding of fatty acid biosynthesis pathways in C. parapsilosis.

Surfactins are cyclic lipopeptides consisting of a β-hydroxy fatty acid of various chain length and a peptide ring of seven amino acids linked together by a lactone bridge, forming the cyclic structure of the peptide chain. These compounds are produced mainly by Bacillus species and possess numerous biological effects such as antimicrobial (antiviral, antibacterial, and antifungal) activities. A mixture of surfactins extracted from Bacillus subtilis strain SZMC 6179J was examined by HPLC-ESI-IT-MS technique, enhancing their separation to reveal novel lipopeptide varieties with higher masses and to characterize their structures. During the MS2 spectra analyses of their sodiated molecular ions [M + Na]+, a previously rarely encountered group of surfactins was detected and two novel types of the group were discovered containing methyl esterified aspartic acid residue in their fifth amino acid position. The relative amounts of these monomethyl isoforms exceeded 35% of the produced surfactin in total. In the m/z value of 1114, all the detected isoforms possessed aspartic acid 4-methyl ester residue in their fifth amino acid position (C17-[Lxx4, AME5], C18-[AME5]), offering an opportunity to separate a pure fraction of the compound and to study its biological activities in the future.

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Aspergilli section Flavi, originally isolated from air samples collected from inhabited apartments (AP), unoccupied basements (BS), and processing facilities of a grain mill (GM), were analyzed for their potential to produce aflatoxin B 1 (AFB 1) on solid media. The isolates were further characterized with regard to their cytotoxic, genotoxic, and pro-inflammatory properties in vitro. Aspergilli were identified based on partial calmodulin (CaM) gene sequencing; the producing capacities of isolates were analyzed by HPLC/FLD and confirmed by genes in biosynthesis (aflR, norA, omtA). In the grain mill, the Aspergilli section Flavi (up to 1.3 × 10 6 cfu/m 3) dominated by AFB 1-producing Aspergillus flavus (71%, 4.5-5254 ng/ml) which showed a serious health risk for workers. Living environments were not relevant sources of exposure. After 24 h, AFB 1 (1-100 μmol/l) reduced cell viability (MTT test) in both A549 cells and THP-1 macrophage-like cells without reaching IC 50. In A549 cells, the extract of the AFB 1producing A. flavus significantly decreased cell viability but not below 50%. THP-1 macrophage-like cells were more sensitive to both extracts, but IC 50 was obtained only for the AFB 1-producing strain (0.37 mg/ml; AFB 1 2.78 μmol/l). AFB 1 (1 and 10 μmol/ l) induced significant DNA damage (tail intensity, alkaline comet assay) in A549 cells in contrast to Aspergilli extracts. AFB 1 elevated IL-6 and IL-8, while Aspergilli extracts increased IL-1β, TNF-α, and IL-17 release in THP-1 macrophages (ELISA). Chronic exposure to AFB 1 and/or other metabolites in airborne A. flavus from occupational environments may stimulate epithelial damage of airways accompanied by lowered macrophage viability.