Gibson Brian R, Mitchell Derek T
Department of Botany, University College Dublin, Dublin 4, Ireland.
Mycol Res. 2005 Apr;109(Pt 4):478-86. doi: 10.1017/s095375620400214x.
Ericoid endomycorrhizal fungi (two isolates of Hymenoscyphus ericae obtained from unpolluted heathlands and two H. ericae-type endophytes isolated from Calluna vulgaris growing on Cu-contaminated mine spoil) were grown for 14 d on 10% Rorison's solution containing sodium phytate as the sole P source and either trace (0.16 microM) or elevated (0.25 mM) concentrations of Cu. The elevated levels of Cu in the medium had no effect on the growth of the two H. ericae-type endophytes from mine spoil sites but caused a significant reduction in growth of the two H. ericae isolates from unpolluted sites. Wall, cytoplasmic and extracellular fractions were assayed for phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activity. K(m) and V(max) values varied between the different endophytes and both were highest in the wall fractions. Wall-bound phosphatase activity, excluding PDEase of one H. ericae-type endophyte, was generally unaffected after the isolates had been grown on medium containing 0.25 mM Cu. Extracellular PDEase of the two H. ericae-type endophytes from mine spoil sites was stimulated by 0.25 mM Cu in the growth medium. Cu concentrations up to 5.0 mM in the assay medium did not inhibit wall-bound phosphatase activity whereas three of the isolates showed a stimulation of extracellular activity with increasing Cu. The results are discussed in relation to phosphatase activity of ericoid endophytes on Cu-contaminated substrates.
石楠状内生菌根真菌（从未受污染的石南荒原分离得到的两种欧石楠菌根菌分离物，以及从生长在铜污染矿渣上的普通石南中分离得到的两种欧石楠菌根菌型内生菌）在含有植酸钠作为唯一磷源的10%罗里森溶液中培养14天，铜浓度分别为痕量（0.16微摩尔）或升高（0.25毫摩尔）。培养基中升高的铜水平对来自矿渣场地的两种欧石楠菌根菌型内生菌的生长没有影响，但导致来自未受污染场地的两种欧石楠菌根菌分离物的生长显著降低。对细胞壁、细胞质和细胞外部分进行磷酸单酯酶（PMEase）和磷酸二酯酶（PDEase）活性测定。不同内生菌之间的米氏常数（K(m)）和最大反应速度（V(max)）值有所不同，且两者在细胞壁部分中最高。在分离物在含有0.25毫摩尔铜的培养基上生长后，除一种欧石楠菌根菌型内生菌的磷酸二酯酶外，细胞壁结合的磷酸酶活性通常不受影响。生长培养基中0.25毫摩尔铜刺激了来自矿渣场地的两种欧石楠菌根菌型内生菌的细胞外磷酸二酯酶活性。测定培养基中高达5.0毫摩尔的铜浓度并未抑制细胞壁结合的磷酸酶活性，而其中三种分离物随着铜含量增加细胞外活性受到刺激。结合石楠状内生菌在铜污染底物上的磷酸酶活性对结果进行了讨论。
