Abstract

The contribution of fungi to carbon (C) and nitrogen (N) cycling is related to their growth efficiency (amount of biomass produced per unit of substrate utilized). The concentration and availability of N influence the activity and growth efficiency of saprotrophic fungi. When N is scarce in soils, fungi have to invest more energy to obtain soil N, which could result in lower growth efficiencies. Yet, the effect of N on the growth efficiencies of individual species of fungi in soil has not been studied extensively. In this study, we investigated the influence of different concentrations of mineral N on the growth efficiency of two common soil fungi, Trichoderma harzianum and Mucor hiemalis in a soil-like environment. We hypothesized that a higher N availability will coincide with higher biomass production and growth efficiency. We measured fungal biomass production and respiration fluxes in sand microcosms amended with cellobiose and mineral N at different C:N ratios. For both fungal species lower C:N ratios resulted in the highest biomass production as well as the highest growth efficiency. This may imply that when N is applied concurrently with a degradable C source, a higher amount of N will be temporarily immobilized into fungal biomass.

摘要

真菌对碳（C）和氮（N）循环的贡献与它们的生长效率（单位使用的底物产生的生物量）有关。氮的浓度和有效性影响腐养真菌的活性和生长效率。当土壤中氮缺乏时，真菌必须投入更多的能量来获取土壤N，这可能会导致生长效率降低。但是，尚未广泛研究氮对土壤中单个真菌物种生长效率的影响。在这项研究中，我们调查了不同浓度的矿质氮对两种常见土壤真菌哈茨木霉和毛霉菌生长效率的影响。在类似土壤的环境中 我们假设更高的氮利用率将与更高的生物量生产和生长效率相吻合。我们在不同的C：N比率下，用纤维二糖和矿物质N修正了沙子微观世界中真菌生物量的产生和呼吸通量。对于这两种真菌，较低的C：N比值​​导致最高的生物量生产以及最高的生长效率。这可能意味着，当将N与可降解的C源同时施用时，大量N会暂时固定在真菌生物质中。