Bengtsson Göran
Laboratory of Ecological Chemistry, University of Lund, Ecology Building, S-223 62, Lund, Sweden.
Oecologia. 1982 Dec;55(3):355-363. doi: 10.1007/BF00376923.
The utilization of amino acids in leaf protein and leaf leachate by aquatic hyphomycetes was studied during decomposition in a combined field and laboratory experiment. Leaves were sampled from a stream which exhibited a seasonal variation in free amino acid concentration in surface water, reaching peaks in autumn and winter. In the leaf drift environment the concentration of amino acids was approximately two orders of magnitude higher than in surface water. Protein amino acid content, which was higher in alder leaves than in beech leaves, decreased exponentially and faster in alder leaves, so that protein amino acid content was similar in the two leaf types after 9-10 weeks decomposition. From 55% to 75% of leaf amino acids were used instantaneously by attached fungi, which grew well, especially on alder leaves, regardless of the presence of a grazing amphipod. If nitrogen was a limiting nutrient source for fungi, it appeared to be more advantageous to colonize alder leaves. Four times more fungal species were found on alder leaves than on beech leaves. The changes in concentration of amino acids in leaves and water was described by a set of differential equations. Rate constants for the transfer of amino acids from leaves and water were estimated from experimental data and the preference in fungi for protein-bound and free amino acids evaluated.The amounts of free amino acids in water absorbed by fungi varied between leaf types and leaves at different stages of decay. Experimental data showed a switching behaviour in fungal absorption of dissolved amino acids so that absorption became superproportional at a certain proportion of free amino acids available in the water.
在一项结合了野外和实验室的实验中，研究了水生真菌对叶片蛋白质和叶片浸出液中氨基酸的利用情况，该实验是在树叶分解过程中进行的。树叶取自一条溪流，该溪流地表水的游离氨基酸浓度呈现季节性变化，在秋季和冬季达到峰值。在树叶漂流环境中，氨基酸浓度比地表水高出约两个数量级。桤木叶中的蛋白质氨基酸含量高于山毛榉叶，且呈指数下降，桤木叶下降得更快，因此在分解9 - 10周后，两种树叶的蛋白质氨基酸含量相似。附着的真菌能立即利用55%至75%的叶片氨基酸，这些真菌生长良好，尤其是在桤木叶上，无论是否存在食草性端足类动物。如果氮是真菌的限制营养源，那么在桤木叶上定殖似乎更具优势。在桤木叶上发现的真菌种类是山毛榉叶上的四倍。用一组微分方程描述了树叶和水中氨基酸浓度的变化。根据实验数据估算了氨基酸从树叶和水中转移的速率常数，并评估了真菌对蛋白质结合型和游离型氨基酸的偏好。真菌吸收的水中游离氨基酸量因树叶种类和树叶腐烂的不同阶段而异。实验数据显示，真菌对溶解氨基酸的吸收存在转换行为，即在水中一定比例的游离氨基酸存在时，吸收变得超比例。
