T-RFLP技术及其在微生物群落结构研究中的应用

作者介绍了末端限制性片段长度多态性（T-RFLP）分析技术的基本原理和操作方法,并就该方法在生态环境中、动物和人体内微生物群落结构的研究应用情况做了综述。由于T-RFLP分析技术不依赖于细菌培养,并且整合了自动测序仪的高分辨率和高通量特征,因此,对于分析复杂的群落结构比其它的指纹识别技术具有更明显的优势,最后分析了此种技术的不足之处并对它的应用前景做出了展望。     

Characteristics of Salmonella contamination of broilers and slaughterhouses in the region of Constantine (Algeria)

The present study provides the first data about the prevalence of Salmonella contamination of broilers and slaughterhouses in the region of Constantine, Algeria. The serotypes and anti-microbial resistance phenotypes of the isolates were determined, and risk factors contributing to the contamination were evaluated. A total of 2490 samples, 1800 originating from 30 broiler farms and 690 from 15 slaughterhouses, were taken during two periods: March 2005-June 2006 and September 2006-March 2007. Salmonella contamination concerned 37% of the broiler farms and 53% of the slaughterhouses. Among the 55 isolates recovered, 10 different serotypes were identified. The most frequently recovered serotypes in both slaughterhouses and breeder farms were S. Hadar (36%, n = 20), S. Virchow (16%, n = 9), S. Infantis (10.9%, n = 6), S. Albany (11%, n = 6) and S. Carnac (7%, n = 4). Isolates belonging to S. Heidelberg (2%, n = 1) and S. Rissen (2%, n = 1) were found only in farms, while those belonging to S. Typhimurium (9%, n = 5), S. Enteritidis (4%, n = 2) and S. Montevideo (2%, n = 1) were recovered only from slaughterhouses. Thirty-nine isolates (80%) were resistant to at least one anti-microbial and 51% were multi-resistant, i.e. resistant to two or more anti-microbial molecules. About 58% (n = 32) were resistant to streptomycin, 36% (n = 20) to tetracyclines, 27% (n = 15) to nalidixic acid, 13% (n = 7) to ofloxacin and one isolate to enrofloxacin. Finally, seven distinct anti-microbial resistance profiles were identified. In parallel, four risk factors were found to be significantly associated with Salmonella contamination. Together with the huge spread of Salmonella in the broiler production chain in Constantine, Algeria, these risk factors highlight the hazards of the broiler channels, particularly linked to poor technical and hygiene practices.     

不同类型的污泥对土壤微生物性质的影响: 地中海退化土的田间试验研究

The recycling of suitable organic wastes can enhance soil fertility via effects on soil physical, chemical and biological properties. To compare the effects of digested (DS), thermally dried (TDS) and composted dewatered (CDS) sewage sludge on soil microbiological properties, an experiment was conducted at field sites for more than one year (401 d) when applied to two Mediterranean degraded soils (loam and loamy sand soils). All three types of sewage sludge had a significant effect on measured parameters. I...     

Structural and functional diversity of soil bacterial and fungal communities following woody plant encroachment in the southern Great Plains

In the southern Great Plains (USA), encroachment of grassland ecosystems by Prosopis glandulosa (honey mesquite) is widespread. Mesquite encroachment alters net primary productivity, enhances stores of C and N in plants and soil, and leads to increased levels of soil microbial biomass and activity. While mesquite’s impact on the biogeochemistry of the region is well established, it effects on soil microbial diversity and function are unknown. In this study, soils associated with four plant types (C₃ perennial grasses, C₄ midgrasses, C₄ shortgrasses, and mesquite) from a mesquite-encroached mixed grass prairie were surveyed to in an attempt to characterize the structure, diversity, and functional capacity of their soil microbial communities. rRNA gene cloning and sequencing were used in conjunction with the GeoChip functional gene array to evaluate these potential differences. Mesquite soil supported increased bacterial and fungal diversity and harbored a distinct fungal community relative to other plant types. Despite differences in composition and diversity, few significant differences were detected with respect to the potential functional capacity of the soil microbial communities. These results may suggest that a high level of functional redundancy exists within the bacterial portion of the soil communities; however, given the bias of the GeoChip toward bacterial functional genes, potential functional differences among soil fungi could not be addressed. The results of this study illustrate the linkages shared between above- and belowground communities and demonstrate that soil microbial communities, and in particular soil fungi, may be altered by the process of woody plant encroachment.     

退化喀斯特植被恢复对土壤微生物数量及群落功能多样性的影响

采集不同恢复阶段的土壤样品,采用微生物培养法研究了退化喀斯特植被恢复对土壤微生物数量、群落功能多样性的影响。研究结果表明随着退化喀斯特植被的恢复,土壤微生物数量增加,表现为乔木群落阶段灌木群落阶段草本群落阶段裸地阶段。土壤微生物群落代谢功能分析表明:植被恢复往往导致较高的平均颜色变化率、物种丰富度和功能多样性。乔木群落阶段的平均诱导底物利用率最高,明显地与其他3个恢复阶段不同。总之,植被恢复使得土壤微生物数量增加,碳源平均利用率增强。因此,创造了更好的土壤条件更有利于退化喀斯特植被的恢复。     

抗线虫基因番茄秸秆对土壤生物活性的影响

采用室内模拟培养的方法,研究了不同用量(2%,4%)转抗线虫基因番茄秸秆和普通番茄秸秆分解对土壤酶活性及微生物量碳的影响。结果表明:与普通番茄秸秆相比,添加低量(2%)秸秆,23d前,抗线虫处理土壤脲酶活性显著提高,9d时土壤碱性磷酸酶活性显著提高,23d时则显著降低,23d后,土壤微生物量碳含量显著提高。添加高量(4%)秸秆,4d时抗线虫处理土壤脲酶活性显著提高,91d时则显著降低,9d时,土壤碱性磷酸酶活性显著提高,23d,42d时则显著降低,9d,23d时,抗线虫处理土壤微生物量碳含量显著提高。抗线虫处理与普通处理间土壤蔗糖酶活性的差异在秸秆添加量为2%和4%时都不显著。     

Biogeochemical interfaces in soil: The interdisciplinary challenge for soil science

Soil, the “Earth's thin skin” serves as the delicate interface between the biosphere, hydrosphere, atmosphere, and lithosphere. It is a dynamic and hierarchically organized system of various organic and inorganic constituents and organisms, the spatial structure of which defines a large, complex, and heterogeneous interface. Biogeochemical processes at soil interfaces are fundamental for the overall soil development, and they are the primary driving force for key ecosystem functions such as plant productivity and water quality. Ultimately, these processes control the fate and transport of contaminants and nutrients into the vadose zone and as such their biogeochemical cycling. The definite objective in biogeochemical‐interface research is to gain a mechanistic understanding of the architecture of these biogeochemical interfaces in soils and of the complex interplay and interdependencies of the physical, chemical, and biological processes acting at and within these dynamic interfaces in soil. The major challenges are (1) to identify the factors controlling the architecture of biogeochemical interfaces, (2) to link the processes operative at the individual molecular and/or organism scale to the phenomena active at the aggregate scale in a mechanistic way, and (3) to explain the behavior of organic chemicals in soil within a general mechanistic framework. To put this in action, integration of soil physical, chemical, and biological disciplines is mandatory. Indispensably, it requires the adaption and development of characterization and probing techniques adapted from the neighboring fields of molecular biology, analytical and computational chemistry as well as materials and nano‐sciences. To shape this field of fundamental soil research, the German Research Foundation (DFG) has granted the Priority Program “Biogeochemical Interfaces in Soil”, in which 22 individual research projects are involved.     

接种菌剂对鸡粪堆肥腐殖酸的影响

以鸡粪和稻草为原料进行条垛式堆肥,接种芽孢杆菌菌剂,堆肥共持续42 d。堆肥过程中接种菌剂处理和对照的总腐殖酸含量呈现先下降然后上升趋势。堆肥前3 d接种菌剂处理和对照的总腐殖酸含量基本相同,第7d接种菌剂处理总腐殖酸含量开始大于对照,堆肥结束时接种菌剂堆肥的总腐殖酸含量为23.1%,而对照的为17.2%。游离腐殖酸、水溶性腐殖酸、胡敏酸含量与总腐殖酸含量的变化趋势基本一致,呈现先降后升的趋势。富里酸含量呈先升后降趋势。堆肥结束时接种菌剂处理的各种腐殖酸含量均显著高于对照,说明接种菌剂可以促进堆肥中腐殖酸的产生。     

长期施肥对土壤微生物生物量碳、氮及矿质态氮含量动态变化的影响

利用位于陕西杨凌的17年长期定位试验研究了长期不施肥(CK)、单施化肥(F)、化肥配施有机肥(F+M)和化肥加秸秆还田(F+S)处理对小麦-玉米轮作体系中作物不同生长时期土壤微生物生物量碳、氮(SMBC、SMBN)和矿质态氮含量的影响。结果表明,0—10 cm土层土壤SMBC、SMBN和矿质态氮含量的变化范围分别为264.8~752.2、37.51~14.8和3.83~8.5 mg/kg。不同处理相比,F+M处理中各采样时期(小麦苗期、拔节期、灌浆期及玉米播种期、大喇叭口期、灌浆期和收获后)土壤SMBC和SMBN含量均为最高,分别为不施肥对照的1.382~.65和1.892~.50倍;F+S处理矿质态氮含量最高,SMBC和SMBN也高于F和CK处理,大部分采样时期的差异达显著水平(P0.05);与CK相比,长期单施化肥也使各时期SMBC和SMBN含量提高。在小麦拔节期到灌浆期的旺盛生长阶段各施肥处理土壤SMBN含量均下降,而矿质态氮含量变化不大,处于较低水平;在玉米大喇叭口期到灌浆期的旺盛生长阶段,F+M、F+S和F处理土壤矿质态氮含量显著下降,而SMBN含量均有所升高。表明在土壤矿质态氮含量较高时,作物首先利用矿质态氮,而在土壤矿质态氮含量处于较低水平时,微生物固持的氮素可能会释放出来供作物吸收利用。     

燕沟流域土壤微生物学性质对植被恢复过程的响应

以黄土高原丘陵区陕北延安燕沟流域为例,研究了退耕地土壤微生物生物量对植被恢复过程的响应。结果表明,随植被恢复年限的增加,植被盖度、多度和物种数均呈现先增加后减少然后又增加的趋势。同对照农地相比,表层(0—5 cm)土壤呼吸速率和土壤微生物生物量均明显增加。表层土壤呼吸速率和微生物量碳、氮、磷分别比对照农地增加31.61%3~60.75%和15.19%5~12.81%、122.91%6~97.15%、193.5%2~068.17%。表层土壤呼吸速率对植被恢复的响应是在植被恢复初期(02~9年),随植被恢复年限的增加而增加;植被恢复305~5年期间,随植被恢复年限的增加而减少;而植被恢复55年以后,又随植被恢复年限的增加而增加。植被恢复过程中,土壤微生物量碳、氮和磷的变化与土壤呼吸速率变化趋势类似。除植被恢复8和16年外,植被恢复年限间的土壤呼吸速率、呼吸熵和微生物量碳、氮、磷均有显著性差异。表层土壤呼吸速率与土壤微生物量氮、磷呈极显著相关,土壤微生物量碳与土壤微生物量氮呈显著相关;而土壤呼吸熵与呼吸速率和微生物量碳、氮、磷相关性不明显。