韩美哲, 王小显, 刘常宏, 薛雅蓉, 卜元卿, 张明. 苏云金芽孢杆菌菌剂对棉花根际土壤细菌数量及多样性的影响[J]. 中国生态农业学报(中英文), 2013, 21(10): 1277-1283. DOI: 10.3724/SP.J.1011.2013.30128
引用本文: 韩美哲, 王小显, 刘常宏, 薛雅蓉, 卜元卿, 张明. 苏云金芽孢杆菌菌剂对棉花根际土壤细菌数量及多样性的影响[J]. 中国生态农业学报(中英文), 2013, 21(10): 1277-1283. DOI: 10.3724/SP.J.1011.2013.30128
HAN Mei-Zhe, WANG Xiao-Xian, LIU Chang-Hong, XUE Ya-Rong, BU Yuan-Qing, ZHANG Ming. Effects of Bacillus thuringiensis agent on bacterial population and diversity in cotton rhizosphere soil[J]. Chinese Journal of Eco-Agriculture, 2013, 21(10): 1277-1283. DOI: 10.3724/SP.J.1011.2013.30128
Citation: HAN Mei-Zhe, WANG Xiao-Xian, LIU Chang-Hong, XUE Ya-Rong, BU Yuan-Qing, ZHANG Ming. Effects of Bacillus thuringiensis agent on bacterial population and diversity in cotton rhizosphere soil[J]. Chinese Journal of Eco-Agriculture, 2013, 21(10): 1277-1283. DOI: 10.3724/SP.J.1011.2013.30128

苏云金芽孢杆菌菌剂对棉花根际土壤细菌数量及多样性的影响

Effects of Bacillus thuringiensis agent on bacterial population and diversity in cotton rhizosphere soil

  • 摘要: 采用稀释平板培养法与PCR-DGGE技术, 以阿维菌素为阳性对照, 水为阴性对照, 研究了大田喷施推荐剂量(0.1 kg·hm-2)和高剂量(10 kg·hm-2)苏云金芽孢杆菌(Bt)菌剂对棉花根际土壤细菌种群数量及结构的影响。结果表明, 喷雾处理后1~3 d, 不同处理组土壤细菌数量间无显著性差异, 在3 d时细菌数量均值达到最大, 之后开始下降, 12 d后清水对照、推荐剂量Bt菌剂、高剂量Bt菌剂处理组土壤细菌数量均值维持在4.0×107 CFU·g-1左右; 推荐剂量Bt菌剂处理样品土壤细菌数量在6 d时显著高于清水对照, 其余时间与清水对照间无显著性差异; 高剂量Bt菌剂处理与清水对照在整个试验期间均无显著性差异; 阿维菌素处理组土壤细菌数量在0~6 d内与清水对照无显著性差异, 而在12~45 d内显著低于其他3个处理组。DGGE图谱显示, Bt菌剂处理对棉花根际土壤17种细菌均无显著抑制作用。聚类分析结果表明, Bt菌剂对土壤细菌群落结构的扰动在12 d后得到恢复。与阴性对照组相比, Bt菌剂对土壤细菌多样性指数无显著影响, 而阳性对照阿维菌素对土壤细菌种群消长和多样性指数有较强的影响。对DGGE图谱中17条电泳条带的序列分析, 证明棉花根际土壤中存在起固氮作用的慢生根瘤菌属细菌和具有污染修复与净化活性的鞘脂菌属、鞘氨醇单胞菌属和红球菌属细菌。Bt菌剂与阿维菌素处理均对这些土壤有益菌群无明显不利影响。总体结果表明, Bt菌剂无论是在正常推荐剂量下还是在较高剂量(推荐剂量的100倍)下使用, 对棉花根际土壤微生态环境产生的冲击都较小, 是一种生态安全性较高的生物农药。

     

    Abstract: Bacillus thuringiensis (Bt) is a gram-positive and soil-dwelling bacterium widely used as biological pesticide with broad insecticidal spectra. Most Bt strains can produce Cry proteins which have specific activities against insect species of the orders Lepidoptera, Diptera, Coleoptera, Hymenoptera and Nematodes. Because of the specificity against target insects, Bt has been regarded as an environmentally friendly biopesticide with little or no effect on mammals, birds, amphibians, reptiles and most other beneficial insects. In fact, it has so far not been conclusively studied whether Bt was really safe to natural microbial communities in agricultural ecosystems. In this study, the influence of Bt on soil bacterial population and diversity in cotton fields was investigated by using traditional plating method and PCR-DGGE technique after application of two dosages 0.1 kg·hm-2 (recommended dosage) and 10 kg·hm-2 (hgih dosage) of Bt agent. Avermectins and water were respectively used as positive and negative controls. Result indicated that 3 days after treatment, Bt had no significant effect on bacterial abundance in soils. Bacterial abundance reached the maximum 3 days after treatment and began to decline thereafter. Then 12 days after treatment, bacterial abundance in soils treated with water, commercial recommended dosage and high dosage Bt was 4.0×107 CFU·g-1. Bacterial abundance in soils treated with recommended dosage Bt was not significantly different from that treated with water. Sixth days into the experiment, there was a significantly high bacterial abundance in soils treated with recommended dosage Bt. There was also no significant difference in soil bacterial abundance between high dosage Bt and water during the whole experiment. Six days after treatment, bacterial abundance of soil treated with avermectins was not significantly different from that treated with water. However, bacterial abundance of avermectins treatment was significantly lower than that of the other 3 treatments 12 45 days after treatment. DGGE spectrogram analyses showed that Bt agent had no significant harmful effects on cotton rhizosphere soil bacterial community structures. Based on analyses of bacterial structures of different treatments, electrophoresis bands of samples treated with given dosages Bt and negative control were in the same branch cluster after 12 days of treatment. This indicated that Bt agent had no influence on bacterial community structure after 12 days. The diversity indexes of Bt treatments were same as that of negative control. Compared with Bt agent, avermectins significantly suppressed bacterial abundance in cotton rhizosphere soils. Following DGGE analysis, 17 different sequences (B1 B17) retrieved from the GenBank using BLAST program were isolated. Sequences with 100% homology of Bt were observed only in Bt treatment dosages of 10 kg·hm-2. This suggested that Bt could not replace native species in agricultural ecosystems if applied at commercial recommended dosage. In addition, beneficial-role bacteria in soils (e.g., Bradyrhizobium sp. which helped Leguminosae to fix nitrogen into soils; Sphingobium sp., Sphingomonas sp. and Rhodococcus sp. which acted as pollution remediation species) were retrieved from the GenBank. Bt had no influence on these functional species in soils at the given dosages. In conclusion, the study provided an evaluation of the effects of Bt on microbial population and community structure using culture-dependent/independent techniques. The study suggested that Bt biocontrol agent was environmentally friendly with no significant effect on natural bacterial communities in soil ecologies.

     

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