One of the limiting factors of soil fertility is contamination with petroleum hydrocarbons, which has affected soil fertility's effective biological activity, such as the symbiosis of nitrogen fixing bacteria with legumes. In this study, some petroleum hydrocarbons' effect on the nodulation of Rhizobium sp. in alfalfa roots under greenhouse conditions was evaluated. For this purpose, 25 bacterial isolates were isolated from alfalfa surface-sterilized root nodules, 5 of which could grow in yeast mannitol media containing crude oil up to 5%. These strains also had the ability to coexist with alfalfa roots and form nodules under in-vitro condition. Isolate B20 formed the highest number of nodules on alfalfa roots at concentrations of 1, 3, and 5% crude oil, which according to the 16S rRNA gene sequencing result, belonged to Ensifer meliloti. Then the effect of different concentration of crude oil (1-3-5% v/w), paraffin (1-3-5% v/w), toluene (50-100-200 ppm), naphthalene (50-100-200 ppm), and phenanthrene (50-100-200 ppm) was investigated on alfalfa growth in the presence of Ensifer meliloti. According to the results, the highest number of nodules (53.33) was observed in the control treatment, and the lowest number of nodules (14.66) was observed at the concentration of 200 mg/kg of phenanthrene. As the number of benzene rings increased, or the pollutant concentration increased, plant growth decreased as assayed by root and shoot biomass, plant nitrogen, number of root nodules, and soil microbial respiration. Contaminants or metabolites produced by the activity of soil microorganisms may inhibit the nodulation activity of Ensifer meliloti.

土壤肥力的限制因素之一是石油烃的污染，这影响了土壤肥力的有效生物活性，例如固氮菌与豆类的共生。在这项研究中，一些石油烃对根瘤菌根瘤的影响。在温室条件下对苜蓿根系中的植物进行了评估。为此，从苜蓿表面灭菌的根瘤中分离出25种细菌分离株，其中5种可以在含高达5％原油的酵母甘露醇培养基中生长。这些菌株还具有与苜蓿根共存并在体外形成结节的能力。健康）状况。分离物B20在浓度分别为1、3和5％的原油上，在苜蓿根上形成的根瘤数量最多，根据16S rRNA基因测序结果，该菌株属于甜叶菊（Ensifer meliloti）。然后影响不同浓度的原油（1-3-5％v / w），石蜡（1-3-5％v / w），甲苯（50-100-200 ppm），萘（50-100- 200 ppm）和菲（50-100-200 ppm）在Ensifer meliloti存在下对苜蓿生长的影响进行了研究。根据该结果，在200mg / kg的菲浓度下，在对照处理中观察到最大数量的结节（53.33），而观察到最低数量的结节（14.66）。随着苯环数的增加或污染物浓度的增加，通过根和茎生物量，植物氮，根瘤数和土壤微生物呼吸分析，植物生长下降。土壤微生物的活动所产生的污染物或代谢产物可能会抑制旋毛虫的结瘤活性。