东南极企鹅和海豹粪土层细菌群落的变化特征

海洋动物粪土是南极陆地生态系统养分的重要来源，粪土层细菌群落对南极苔原碳、氮循环过程起重要作用，但目前对南极海洋动物粪土层中细菌群落的变化特征却鲜有报道。本文采集了东南极四个企鹅、海豹粪土剖面样品，通过酶活性、微生物量碳、微生物熵、土壤呼吸和DNA浓度测定以及16 S r DNA-DGGE分析，探讨了粪土层中细菌群落变化特征及其与环境因子的关系。土壤转化酶、脲酶和磷酸酶活性、微生物量碳、土壤呼吸和微生物熵随深度增加而递减，而代谢熵增加，表明随深度增加，微生物生存环境恶劣，造成细菌丰度和酶分泌量减小，需更多有机碳进行能量代谢。土壤DNA浓度与pH、含水率、TOC、TN、微生物量碳、土壤呼吸以及酶活性呈高度正相关，表明这些因子对粪土层中细菌种群的丰度有重要影响。DGGE图谱分析证实：东南极海洋动物粪土中含丰富的细菌群落结构，随深度增加泳道带型数量和亮度递减，表明细菌多样性和丰度递减。聚类分析表明：四个剖面随深度泳道带型差异明显，细菌遗传相似性为46%，企鹅、海豹粪土细菌群落差异性尤为明显；发现四个粪土剖面中，细菌丰度与企鹅、海豹粪的相对含量呈协调一致性变化，且表层5cm粪土层细菌丰度最高，表明东南极企鹅和海豹排泄物对土壤中细菌群落多样性变化起重要作用。

CHANGING CHARACTERISTICS OF BACTERIAL COMMUNITIES IN SOILS IMPACTED BY PENGUIN AND SEAL EXCRETA,EAST ANTARCTICA

Antarctic tundra soils impacted by sea animal excreta are an important source of nutrients in terrestrial ecosystem. The bacterial community in the Antarctic tundra soils plays an important role in carbon and nitrogen cycles, but at present changing characteristics of bacterial community in the soils influenced by sea animal excreta have received little attention. In this paper, we investigated four penguin and seal colony soil profiles (DA1, DMG and DS, HS) from east Antarctica. Soil enzyme activity, microbial biomass C, microbial quotient, soil respiration, metabolic quotient and DNA concentration were measured from all the soil horizons and the composition of bacterial communities were simultaneously assessed through 16 S r DNA-DGGE. The objectives were to study changing characteristics of soils bacterial community and their relationships with environmental factors. Soil invertase, urease, phosphatase activities, microbial biomass, soil respiration and microbial quotient decreased with depths, however, metabolic quotient increased, indicating that the microbial environment became worse, which caused bacteria species, quantity, enzyme secretion decreases, and the energy required by the microbial community for its growth and maintenance increased from the surface to the deeper horizons. Soil DNA concentrations were highly relevant with pH, moisture content, TOC, TN, microbial biomass C, soil respiration and enzyme activity, indicating that those environmental factors greatly affects bacteria abundance. DGGE analysis reflected the high bacterial community structure in East Antarctic tundra soils, lane numbers and type brightness decreased with depths. Clustering analysis showed that the differences between lane types were significant in four profiles with the depth, bacteria genetic similarity was 46%, and bacterial community in penguins, seals colony soil showed a significant difference.Penguins and seals excreta play an important role in the change of soil bacteria community diversity in east Antarctica.