摘要：With the rapid expansion of GEPs(genetically engineered plants), people are more and more concerned about the ecological risks brought by their release. Assessing the effect of GEPs on soil microbial ecology is indispensable to study their ecological risks. In our study, the phospholipids fatty acid(plfa) method was used to analyze the microbial community of soil samples collected from fields with two types of GEPs_Bt transgenic corn and PVY(potato virus Y) cell protein gene transgenic potato. The principal components analysis(PCA) showed all controls were on the right of related GEPs samples along the PC1 (the first principal component) axis, which means a decrease of fungi in soils with genetically engineered crop since most of plfas that are strongly positively correlated with PC1 represent fungi. For samples collected from Bt transgenic cornfield, the ratios of gram_positive to gram_negative bacteria were less than those of controls. For samples of transgenic potato field, these ratios were lower than those of controls when soils were collected from deep layer(20—40 cm), but were higher when soils collected from surface layer(0—20 cm). For soils collected from 0—20 cm, the ratios of fungi to bacteria for all GEPs samples were at the same level. So were such rations for all controls. Changes of soil microbial community in two types of GEPs fields were detected in our study, but the causes and more information still needs further study.

摘要：由于桉树对原生生态系统具有潜在的破坏性影响,随着桉树人工林面积的不断扩大,桉树种植对森林生态系统的影响越来越受到社会的关注。围绕引进种桉树造林对土壤微生物群落的影响,应用成对试验设计,采用磷脂脂肪酸(plfa)和BIOLOG微平板培养等技术手段探讨土壤微生物群落结构和功能如何响应桉树人工林取代天然次生林这一变化,主要结果为:桉树人工林取代天然次生林导致:(1)土壤微生物生物量减少,包括:生物量碳、氮和磷脂脂肪酸丰度显著下降;(2)反映土壤微生物群落生理胁迫状况的指标:饱和直链脂肪酸/单不饱和脂肪酸、革兰氏阳性菌/革兰氏阴性菌、支链异构/反异构脂肪酸以及cy19:0/18:1ω7c的比值显著增加;(3)土壤微生物群落碳代谢强度和多样性显著降低;(4)桉树人工林取代天然次生林导致土壤微生物群落结构变化和功能退化的主要环境因素包括:植物物种丰富度和覆盖度的降低以及土壤资源(碳、氮和水分)可获得性的降低。综上所述,引进种桉树人工林取代天然次生林降低了植物物种丰富度和覆盖度以及土壤资源的可获得性,进而显著增强了土壤微生物群落生理胁迫、显著降低了土壤微生物群落功能。