Jančič Sašo, Frisvad Jens C, Kocev Dragi, Gostinčar Cene, Džeroski Sašo, Gunde-Cimerman Nina
Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, Ljubljana, Slovenia.
Department of System Biology, Technical University of Denmark, Søltofts Plads, Building 221, Kgs. Lyngby, Denmark.
PLoS One. 2016 Dec 30;11(12):e0169116. doi: 10.1371/journal.pone.0169116. eCollection 2016.
The food- and airborne fungal genus Wallemia comprises seven xerophilic and halophilic species: W. sebi, W. mellicola, W. canadensis, W. tropicalis, W. muriae, W. hederae and W. ichthyophaga. All listed species are adapted to low water activity and can contaminate food preserved with high amounts of salt or sugar. In relation to food safety, the effect of high salt and sugar concentrations on the production of secondary metabolites by this toxigenic fungus was investigated. The secondary metabolite profiles of 30 strains of the listed species were examined using general growth media, known to support the production of secondary metabolites, supplemented with different concentrations of NaCl, glucose and MgCl2. In more than two hundred extracts approximately one hundred different compounds were detected using high-performance liquid chromatography-diode array detection (HPLC-DAD). Although the genome data analysis of W. mellicola (previously W. sebi sensu lato) and W. ichthyophaga revealed a low number of secondary metabolites clusters, a substantial number of secondary metabolites were detected at different conditions. Machine learning analysis of the obtained dataset showed that NaCl has higher influence on the production of secondary metabolites than other tested solutes. Mass spectrometric analysis of selected extracts revealed that NaCl in the medium affects the production of some compounds with substantial biological activities (wallimidione, walleminol, walleminone, UCA 1064-A and UCA 1064-B). In particular an increase in NaCl concentration from 5% to 15% in the growth media increased the production of the toxic metabolites wallimidione, walleminol and walleminone.
食品源和空气传播的真菌属——威克海姆酵母属包含七个嗜旱和嗜盐物种：西氏威克海姆酵母、蜂蜜威克海姆酵母、加拿大威克海姆酵母、热带威克海姆酵母、穆里威克海姆酵母、常春藤威克海姆酵母和食鱼威克海姆酵母。所有列出的物种都适应低水分活度，并且能够污染用大量盐或糖保存的食品。关于食品安全，研究了高盐和高糖浓度对这种产毒真菌次生代谢产物产生的影响。使用已知支持次生代谢产物产生的通用生长培养基，并添加不同浓度的氯化钠、葡萄糖和氯化镁，检测了所列物种的30个菌株的次生代谢产物谱。使用高效液相色谱 - 二极管阵列检测（HPLC - DAD）在两百多种提取物中检测到约一百种不同的化合物。尽管对蜂蜜威克海姆酵母（以前的广义西氏威克海姆酵母）和食鱼威克海姆酵母的基因组数据分析显示次生代谢产物簇数量较少，但在不同条件下检测到大量次生代谢产物。对所得数据集的机器学习分析表明，氯化钠对次生代谢产物产生的影响高于其他测试溶质。对选定提取物的质谱分析表明，培养基中的氯化钠会影响一些具有重要生物活性的化合物（威克海姆二酮、威克海姆醇、威克海姆酮、UCA 1064 - A和UCA 1064 - B）的产生。特别是在生长培养基中氯化钠浓度从5％增加到15％会增加有毒代谢产物威克海姆二酮、威克海姆醇和威克海姆酮的产生。
