Salazar Alekseyeva Katherine, Mähnert Barbara, Berthiller Franz, Breyer Eva, Herndl Gerhard J, Baltar Federico
Department of Functional and Evolutionary Ecology, Microbial Oceanography Working Group, University of Vienna, 1030 Vienna, Austria.
Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), 3430 Tulln, Austria.
J Fungi (Basel). 2021 Aug 26;7(9):690. doi: 10.3390/jof7090690.
Ergosterol has traditionally been used as a proxy to estimate fungal biomass as it is almost exclusively found in fungal lipid membranes. Ergosterol determination has been mostly used for fungal samples from terrestrial, freshwater, salt marsh- and mangrove-dominated environments or to describe fungal degradation of plant matter. In the open ocean, however, the expected concentrations of ergosterol are orders of magnitude lower than in terrestrial or macrophyte-dominated coastal systems. Consequently, the fungal biomass in the open ocean remains largely unknown. Recent evidence based on microscopy and -omics techniques suggests, however, that fungi contribute substantially to the microbial biomass in the oceanic water column, highlighting the need to accurately determine fungal biomass in the open ocean. We performed ergosterol extractions of an oceanic fungal isolate () with biomass concentrations varying over nine orders of magnitude. While after the initial chloroform-methanol extraction ~87% of the ergosterol was recovered, a second extraction recovered an additional ~10%. Testing this extraction method on samples collected from the open Atlantic Ocean, we successfully determined ergosterol concentrations as low as 0.12 pM. Thus, this highly sensitive method is well suited for measuring fungal biomass from open ocean waters, including deep-sea environments.
传统上，麦角固醇一直被用作估算真菌生物量的替代指标，因为它几乎只存在于真菌的脂质膜中。麦角固醇测定主要用于来自陆地、淡水、盐沼和红树林为主的环境中的真菌样本，或用于描述植物物质的真菌降解。然而，在开阔海洋中，麦角固醇的预期浓度比陆地或大型植物为主的沿海系统低几个数量级。因此，开阔海洋中的真菌生物量在很大程度上仍然未知。然而，最近基于显微镜和组学技术的证据表明，真菌对海洋水柱中的微生物生物量有很大贡献，这凸显了准确测定开阔海洋中真菌生物量的必要性。我们对一种生物量浓度变化超过九个数量级的海洋真菌分离株进行了麦角固醇提取。虽然在最初的氯仿 - 甲醇提取后，约87%的麦角固醇被回收，但第二次提取又回收了约10%。在从开阔大西洋采集的样本上测试这种提取方法时，我们成功测定出低至0.12 pM的麦角固醇浓度。因此，这种高灵敏度方法非常适合测量开阔海洋水域（包括深海环境）中的真菌生物量。
