Abstract: A strain of nitrogen-fixing bacteria, W11, isolated from the root of sugar cane has been identificated as Pantoea agglomeras using an auto-identificat ion system for bacterium based on 96 biochemical test data. W11 has the properties of tolerance to acid(pH3.5) and high sucrose concentration (30%), A amount of acid was formed and reduced the acidity of medium to pH of 4.41, the nitrogenase activity was inhibited in presence of 3.1mmol NH₄NO₃ or 58.5mmol NaNO₃. The optimum growth and maximum nitrogenase activity of W11 occurs at the medium containing 10% sucrose and 0.25g/L sodium glutamate, pH5.5, 28-30^oC. Its behaviours of tolerance to acid and high sucrose concentration, acid production and the use of carbon substrates is simiiar to that the Acetobacter diazotrophicus has. The strain W11 was inferred to have a nitrogen-fixing relationship associated with the root of sugar cane.

Key words: nitrogen fixation, root of sugar cane, identification of strain, biochemical test, Pantoea agglomera

摘要： 从甘蔗根部分离的固氮菌株W11，经细菌自动鉴定系统根据96个生化试验指标，鉴定为成团泛菌。该菌株耐酸(pH3.5)，耐高蔗糖浓度(30%)，产酸使培养基的酸度降低到pH4.41，3.1mmol NH₄NO₃或58.8mmol NaNO₃能抑制固氮酶活性。在培养基的蔗糖浓度为10%，谷氨酸钠0.25g/L, pH5.5，28～30℃条件下，该菌株生长最佳，固氮酶活性最高。在耐高蔗糖浓度，耐酸，碳源利用，产酸方面与固氮醋酸杆菌相似。

关键词: 固氮, 甘蔗根部, 菌种鉴定, 生化试验, 成团泛菌