Ferreira Carlos M H, Vilas-Boas Ângela, Sousa Cátia A, Soares Helena M V M, Soares Eduardo V
REQUIMTE/LAQV, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
Bioengineering Laboratory-CIETI, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, rua Dr António Bernardino de Almeida, 431, 4249-015, Porto, Portugal.
AMB Express. 2019 May 28;9(1):78. doi: 10.1186/s13568-019-0796-3.
Iron deficiency is one of the main causes of chlorosis in plants, which leads to losses in field crops quality and yield. The use of synthetic chelates to prevent or correct iron-deficiency is not satisfactory mainly due to their poor biodegradability. The present work aimed to search suitable microorganisms to produce alternative, environment-friendly iron-chelating agents (siderophores). For this purpose, the performance of five bacteria (Azotobacter vinelandii, Bacillus megaterium, Bacillus subtilis, Pantoea allii and Rhizobium radiobacter) was evaluated, regarding siderophore production kinetics, level of siderophore production (determined by chrome azurol S, CAS method), type of siderophore produced (using Arnow and Csaky's tests) and iron-chelating capacity at pH 9.0. All bacteria were in stationary phase at 24 h, except A. vinelandii (at 72 h) and produced the maximum siderophore amount (80-140 µmol L) between 24 and 48 h, with the exception of A. vinelandii (at 72 h). The analysis of culture filtrates revealed the presence of catechol-type siderophores for B. subtilis and R. radiobacter and hydroxamate-type siderophores for B. megaterium and P. allii. In the case of A. vinelandii, both siderophore-types (catechol and hydroxamates) were detected. The highest iron-chelating capacity, at pH 9.0, was obtained by B. megaterium followed by B. subtilis and A. vinelandii. Therefore, these three bacteria strains are the most promising bacteria for siderophore production and chlorosis correction under alkaline conditions.
缺铁是植物黄化病的主要原因之一，会导致大田作物的品质和产量下降。使用合成螯合物来预防或纠正缺铁情况并不理想，主要是因为它们的生物降解性较差。目前的工作旨在寻找合适的微生物来生产替代性的、环境友好型铁螯合剂（铁载体）。为此，评估了五种细菌（棕色固氮菌、巨大芽孢杆菌、枯草芽孢杆菌、葱头泛菌和放射形根瘤菌）在铁载体生产动力学、铁载体生产水平（通过铬天青S，即CAS法测定）、所产生铁载体的类型（使用阿诺和恰基试验）以及在pH 9.0时的铁螯合能力方面的表现。所有细菌在24小时时进入稳定期，除了棕色固氮菌（在72小时时），并且在24至48小时之间产生了最大量的铁载体（80 - 140微摩尔/升），棕色固氮菌除外（在72小时时）。对培养滤液的分析表明，枯草芽孢杆菌和放射形根瘤菌产生邻苯二酚型铁载体，巨大芽孢杆菌和葱头泛菌产生异羟肟酸型铁载体。对于棕色固氮菌，检测到了两种铁载体类型（邻苯二酚和异羟肟酸）。在pH 9.0时，巨大芽孢杆菌的铁螯合能力最高，其次是枯草芽孢杆菌和棕色固氮菌。因此，这三株细菌是在碱性条件下生产铁载体和纠正黄化病最有前景的细菌。
