Department of Botany, University of Auckland, Auckland, New Zealand.
Appl Environ Microbiol. 1985 Apr;49(4):955-9. doi: 10.1128/aem.49.4.955-959.1985.
Nitrogenase activity in mangrove forests at two locations in the North Island, New Zealand, was measured by acetylene reduction and N(2) uptake. Nitrogenase activity (C(2)H(2) reduction) in surface sediments 0 to 10 mm deep was highly correlated (r = 0.91, n = 17) with the dry weight of decomposing particulate organic matter in the sediment and was independent of light. The activity was not correlated with the dry weight of roots in the top 10 mm of sediment (r = -0.01, n = 13). Seasonal and sample variation in acetylene reduction rates ranged from 0.4 to 50.0 mumol of C(2)H(4) m h under air, and acetylene reduction was depressed in anaerobic atmospheres. Nitrogen fixation rates of decomposing leaves from the surface measured by N(2) uptake ranged from 5.1 to 7.8 nmol of N(2) g (dry weight) h, and the mean molar ratio of acetylene reduced to nitrogen fixed was 4.5:1. Anaerobic conditions depressed the nitrogenase activity in decomposing leaves, which was independent of light. Nitrogenase activity was also found to be associated with pneumatophores. This activity was light dependent and was probably attributable to one or more species of Calothrix present as an epiphyte. Rates of activity were generally between 100 and 500 nmol of C(2)H(4) pneumatophore h in summer, but values up to 1,500 nmol of C(2)H(4) pneumatophore h were obtained.
在新西兰北岛的两个地点的红树林中，通过乙炔还原和 N(2) 吸收来测量固氮酶活性。0 到 10 毫米深的表层沉积物中的固氮酶活性（C(2)H(2)还原）与沉积物中分解的颗粒有机物质的干重高度相关（r = 0.91，n = 17），与光照无关。该活性与沉积物中表层 10 毫米内的干重根（r = -0.01，n = 13）无关。乙炔还原率的季节性和样本变化范围为空气中 0.4 至 50.0 μmol 的 C(2)H(4) m h，而在厌氧环境中，乙炔还原受到抑制。通过 N(2) 吸收测量的表面分解叶片的固氮率范围为 5.1 至 7.8 nmol 的 N(2) g（干重）h，乙炔还原与固定氮的平均摩尔比为 4.5:1。厌氧条件抑制了分解叶片中的固氮酶活性，该活性与光照无关。还发现固氮酶活性与呼吸根有关。这种活性依赖于光照，可能归因于作为附生植物存在的一种或多种 Calothrix 物种。活性速率通常在夏季为 100 至 500 nmol 的 C(2)H(4) 呼吸根 h，但可获得高达 1500 nmol 的 C(2)H(4) 呼吸根 h。
