Bakhshandeh Esmaeil, Rahimian Heshmatollah, Pirdashti Hematollah, Nematzadeh Ghorban Ali
Department of Plant Molecular Physiology, Genetics and Agricultural Biotechnology Institute of Tabarestan, Sari Agricultural Sciences and Natural Resources University, 4813181344, Sari, Iran,
World J Microbiol Biotechnol. 2014 Sep;30(9):2437-47. doi: 10.1007/s11274-014-1669-1. Epub 2014 Jun 4.
The purposes of this study were to evaluate the phosphate solubilization activity of bacteria isolated from the rhizosphere of rice paddy soil in northern Iran, and to study the effect of temperature, NaCl and pH on the growth of these isolates by modeling. Three of the most effective strains from a total of 300 isolates were identified and a phylogenetic analysis was carried out by 16S rDNA sequencing. The isolates were identified as Pantoea ananatis (M36), Rahnella aquatilis (M100) and Enterobacter sp. (M183). These isolates showed multiple plant growth-promoting attributes such as phosphate solubilization activity and indole-3-acetic acid (IAA) production. The M36, M100 and M183 isolates were able to solubilize 172, 263 and 254 µg ml(-1) of Ca3(PO4)2 after 5 days of growth at 28 °C and pH 7.5, and to produce 8.0, 2.0 and 3.0 μg ml(-1) of IAA when supplemented with L-tryptophan (1 mg ml(-1)) for 72 h, at 28 °C and pH 7.0, respectively. The solubilization of insoluble phosphate was associated with a drop in the pH of the culture medium and there was an inverse relationship between pH and solubilized P (r = -0.98, P < 0.0952). There were no significant differences among isolates in terms of acidity tolerance based on their confidence limits as assessed by segmented model analysis and all isolates were able to grow at pH 4.3-11 (with optimum at 7.0-7.5). Based on a sigmoidal trend of a three-parameter logistic model, the salt concentration required for 50 % inhibition was 8.15, 6.30 and 8.23 % NaCl for M36, M100 and M183 isolates, respectively. Moreover, the minimum and maximum growth temperatures estimated by the segmented model were 5.0 and 42.75 °C for M36, 12.76 and 40.32 °C for M100, and 10.63 and 43.66 °C for M183. The three selected isolates could be deployed as inoculants to promote plant growth in an agricultural environment.
本研究的目的是评估从伊朗北部稻田土壤根际分离出的细菌的解磷活性，并通过建模研究温度、NaCl和pH对这些分离菌株生长的影响。从总共300株分离菌株中鉴定出3株最有效的菌株，并通过16S rDNA测序进行系统发育分析。这些分离菌株被鉴定为菠萝泛菌（M36）、水生拉恩菌（M100）和肠杆菌属（M183）。这些分离菌株表现出多种促进植物生长的特性，如解磷活性和吲哚-3-乙酸（IAA）的产生。M36、M100和M183分离菌株在28℃和pH 7.5条件下生长5天后，能够溶解172、263和254μg ml⁻¹的Ca₃(PO₄)₂，并且在28℃和pH 7.0条件下，分别添加L-色氨酸（1mg ml⁻¹）72小时后，能够产生8.0、2.0和3.0μg ml⁻¹的IAA。不溶性磷酸盐的溶解与培养基pH值的下降有关，并且pH值与溶解的磷之间存在负相关关系（r = -0.98，P < 0.0952）。根据分段模型分析评估的置信限，分离菌株在耐酸性方面没有显著差异，所有分离菌株都能够在pH 4.3 - 11的条件下生长（最适pH为7.0 - 7.5）。基于三参数逻辑模型的S形趋势，M36、M100和M183分离菌株50%抑制所需的盐浓度分别为8.15%、6.30%和8.23% NaCl。此外，分段模型估计的M36的最低和最高生长温度分别为5.0和42.75℃，M100为12.76和40.32℃，M183为10.63和43.66℃。这三株选定的分离菌株可作为接种剂用于促进农业环境中的植物生长。
