Sustainable Soils & Grassland Systems Department, Rothamsted Research, North Wyke, Okehampton EX20 2SB, UK.
Rapid Commun Mass Spectrom. 2011 Jun 15;25(11):1479-84. doi: 10.1002/rcm.4888.
Many studies utilise enrichment of stable isotopes as tracers to follow the interactions occurring within soil food webs and methods have been developed to enrich bacteria, soil fauna and plant litter, Here for the first time we attempt to enrich a soil fungus to 99 atom% with (13)C and (15)N stable isotopes. In this study our objectives were to (a) assess whether the saprotrophic zygomycete fungus Absidia cylindrospora could grow on a medium enriched to 99 atom% with (13)C-glucose and (15)N-ammonium chloride, (b) to determine the level of enrichment obtained, and (c) to examine the change in growth rate of this fungus while it was growing on the dually enriched medium. To achieve this, the fungus was grown on agar enriched with (13)C and (15)N to 99 atom% and its growth rate monitored. The results showed that A. cylindrospora would grow on the highly labelled growth medium, but that its rate of growth was affected compared with the rate on either natural abundance media or media highly enriched with a single isotope ((13)C or (15)N). The implications of these results is that although the fungus is able to utilise these heavier isotopes, the biochemical processes involved in growth are affected, and consideration should be given to these differences when using stable isotope tracers in, for example, soil food web studies.
许多研究利用稳定同位素的富集作为示踪剂来追踪土壤食物网中发生的相互作用，并且已经开发出了富集细菌、土壤动物和植物凋落物的方法。在这里，我们首次尝试将土壤真菌富集到 99 原子%的 (13)C 和 (15)N 稳定同位素。在这项研究中，我们的目标是：(a) 评估腐生接合菌 Absidia cylindrospora 是否可以在富含 (13)C-葡萄糖和 (15)N-氯化铵的培养基上生长；(b) 确定获得的富集水平；(c) 研究该真菌在双重富集培养基上生长时生长速率的变化。为了实现这一目标，我们将真菌在富含 (13)C 和 (15)N 的琼脂上培养，并监测其生长速度。结果表明，A. cylindrospora 可以在高度标记的生长培养基上生长，但与在自然丰度培养基或单一同位素（(13)C 或 (15)N）高度富集的培养基上的生长速度相比，其生长速度受到了影响。这些结果的含义是，尽管真菌能够利用这些较重的同位素，但参与生长的生化过程受到了影响，因此在例如在土壤食物网研究中使用稳定同位素示踪剂时，应该考虑到这些差异。
