1、适应玉米的溶磷细菌筛选及其对玉米生长的影响 *梅新兰 1 闪安琪 1 蒋 益 1 韦 中 1 王誉瑶 1 王世梅 1 沈其荣 1 徐阳春 1 刘 建 2（1 国家有机类肥料工程技术研究中心，江苏省有机固体废弃物资源化协同创新中心，南京农业大学资源与环境科学学院，南京 210095）（2 江苏省沿江地区农业科学研究所，江苏如皋 226541）摘 要 从石灰性土壤中分离获得 4 株高效溶磷细菌 X5、X6、Z4 和 Z8，研究其生物学特征，探索其单独及复合的溶磷促生潜能。研究发现菌株 X5、X6、Z4 和 Z8 均可以利用玉米根系分泌物作碳源生长。菌株 X6 和 Z4 均能产生 IAA 和铁载体，
2、菌株 Z8 可产生 IAA 不产生铁载体，菌株 X5 可产生铁载体不产生 IAA。盆栽试验结果表明，接种单一溶磷菌及 4 株菌复合处理均可促进玉米生长，但复合菌群的溶磷促生效果显著高于单一菌株。通过 16S rRNA 基因序列分析研究菌株的分类地位，初步鉴定X5、X6、Z4、Z8 分别为荧光假单孢菌（Pseudomonas fluorescens） 、草假单胞菌（Pseudomonas poae） 、巨大芽孢杆菌（Bacillus megaterium）和枯草芽孢杆菌（Bacillus subtilis） 。关键词 溶磷细菌；吲哚乙酸；铁载体；玉米根系分泌物；复合菌群；促生效果中图分类号 S1
3、44.9 文献标识码 A 在农业生态系统中土壤有效磷是作物生长及高产的限制因子，植物缺磷生长迟缓，植株矮小。农田土壤中 磷素蕴藏丰富，但主要以难溶性的矿物态磷存在 1。据全国土壤普查估算，我国约2/3的耕地缺磷，土壤有效态磷仅占全磷量的2%3% 2。尤其我国北方石灰性土壤以Ca-P磷为主，约占全磷量的80%左右 3。释放这些土壤中固定的磷对于提高土壤磷素有效性、减少磷肥施用量具有重要意义，也符合我国当前提出的“减肥、减药”重大战略目标及可持续发展的生态农业方向。土壤中存在一定量的溶磷菌，通过产酸等机制可将被固定的磷释放出来，但是溶磷菌在植物根际的数量级较低，溶磷活性不高。因此，有必要从土壤环境
4、中筛选高效解磷菌株，制备生物菌剂，再回接到植物根际，以提高溶磷效率及促进植物生长 4-5。目前普遍采用选择性培养基筛选溶磷菌 6，并根据产生溶磷圈的直径作为溶磷能力大小的指标，但是很多实验室获得的高效溶磷菌，在应用时效果不稳定 7。因为溶磷菌最终* 国家科技支撑计划项目（ 2013BAD20B05） 、农业部 948 项目（ 2011-G27）和公益性行业（农业）项目（201203001）资助 Supported by the National key technology R Drechsel H. Biotechnology (2nd edition), Chapter 5: Microb
5、ial Siderophores. 199925 李阜棣. 土壤微生物学. 北京：中国农业出版社, 1996Li F D. Soil Microbiology. Beijing: China agriculture press, 1996Screening of phosphate-solubilizing bacteria adaptable to corn and effects of the bacteria on the growth of cornMEI Xinlan1 SHAN Anqi1 JIANG Yi1 WANG Yuyao 1 WEI Zhong1 WANG Shimei1
6、 SHEN Qirong1 XU Yangchun1 LIU Jian2(1 National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China)(2 Institute
7、 of Agricultural Sciences of the Yangtze River Bank District, Rugao, Jiangsu 226541, China )Abstract Phosphate-solubilizing bacteria (PSB) are a group of beneficial bacteria capable of hydrolyzing organic and inorganic phosphorus from insoluble compounds. P-solubilization ability of the microorganis
8、ms is considered to be one of the most important traits associated with plant phosphate nutrition. A number of PSB strains have been screened out from soils in laboratory, however, few reports are available on their successful application in fields. More and more evidence suggests that root coloniza
9、tion of PSB is very important for phosphate solubilization; therefore, survivability of PSB in plant rhizosphere is one of the basic principles for PSB screening. In present study, 20 strains of PSB with phosphate solubilization halos ranging from 7.920 mm were isolated from the rhizosphere of the c
10、orn growing in calcareous soil with the Pikovskaya medium plate method. Ten of the 20 strains of PSB, coded as X3, X5, X6, Z2, Z3, Z4, Z5, Z7, Z8 and Z9, with bigger phosphate solubilization halos were further tested for phosphate-solubilizing capacity in the NBRIP medium. Results show that gram-neg
11、ative (G-) PSB (X3, X5, X6, Z2, Z3 and Z5) solubilized much more phosphate than gram-positive (G+) ones (Z4, Z7, Z8 and Z9) did. The mean phosphate concentration in the NBRIP medium of the G- PSB treatments was 449.7 g ml-1, with phosphate concentration in Treatment G- PSB Z3 being the highest, reac
12、hing to 562.2 g ml-1. However, the highest phosphate concentration obtained by G+ PSB was only 46.9 g ml-1. In further experiment, 8 strains of PSB (G+: Z4, Z7, Z8 and Z9; and G-: X5, X6, Z3 and Z5) were evaluated for corn root exudate utilization capacity. All of the 8 strains of PSB were found to
13、be able to utilize corn root exudate as sole carbon source and the G- PSB grew much better than G+ ones. Consistent with the findings in the culture in NBRIP medium, G- PSB solubilized much more phosphate than G+ PSB did when using corn root exudate as sole carbon source. Based on phosphate-solubili
14、zation and root exudate utilization capacities, two G- strains of PSB, X5 (Pseudomonas fluorescens) and X6 (Pseudomonas poae), and two G+ strains of PSB, Z4 (Bacillus megaterium) and Z8 (Bacillus subtilis) were selected for further experiment to test their IAA and siderophore production and phosphate solubilization capacities and effect on corn growth in greenhouse. X6 and Z4 was found to be able to produce both IAA and siderophore. Z8 was able to produce IAA but not siderophore, and X5 was able to produce
