土壤中抗生素抗性基因的环境行为与阻控研究进展

抗生素抗性基因(Antibiotic resistance genes,ARGs)的传播威胁着生态环境安全和人体健康,已成为一个全球性的问题。土壤中抗生素抗性基因的分布、来源、扩散传播以及消减技术已成为一个研究热点。本文在简要介绍自然环境和受人类活动干扰土壤中抗生素抗性基因分布水平的基础上,分析了土壤中抗生素抗性基因的主要来源,剖析了抗生素抗性基因由土壤向其他环境介质(水、植物)传播的规律及其影响因素,如土壤理化性质、农艺调控和环境中污染物等。进而探讨了环境中各种生物和非生物因素对土壤中抗生素抗性基因持久性的影响和环境中抗生素抗性基因的消减技术,包括好氧堆肥、厌氧发酵、水处理工艺等。最后,提出遵循“大健康(One Health)”准则,以跨学科的方法控制抗生素抗性基因在环境中的传播,以更全面地将抗生素抗性基因对人类的健康风险降低至最低水平。

两个分离菌株对2,4-D降解效率的微生态系统模拟

在微生态系统模拟条件下 ,2个分离菌株Sphingomonaspaucimobilis 92 56 ,Ralstoniaeu trophusJMP表现出对除草剂 2 ,4 D的高效降解性能 .但R eutrophusJMP能在更多的模拟条件下成为优势种群 .对 2个菌株的种群消长影响最大的生态因子是湿度和 2 ,4 D的浓度 .种群增长与 2 ,4 D降解有约 2 4h的时滞 ;种群的增长量不完全受底物 2 ,4 D消耗的多少制约 .多个生态因子的综合作用说明模拟的微生态系统离自然系统还有较大的差别 .

土壤中的生物多样性与生态系统功能

我们回顾了目前关于土壤生物多样性及其在生态系统过程中的作用、对于人类目标的重要性及对胁迫和扰动的恢复能力等的研究进展。现存物种的数量远远大于人们已经描述的数量,即使是对于肉眼可见的分类群也是如此。而且也普遍缺乏在生物地理学上的综合描述。迫切需要在分类学和对新一代系统科学家培训上做更大努力。尤其是应当集中致力于就我们所知。对生态系统功能起关键作用的土壤生物类群方面。为了确定这种类群,需要对土壤生物区系的影响圈(sphere of Influence,SOI),如根的生物区系、有机物质破碎者(shredder)和土壤生物扰动者(bioturbator)加以识别,这些影响圈比如可能通过与植物的相互作用而控制着生态系统的过程。在这些SOI中,我们分析出了土壤有机体的功能类群。最迫切需要研究的问题是将物种按功能类群进行区分,并确定功能类群中的物种冗余。这种迫切性是根据为阐述与集约化农业、森林扰动、环境污染和全球环境变化有关的土壤功能丧失程度的需要而确定的。目前认为最处于危险的土壤生物区系是那些大型动物群的有机物破碎者、土壤生物扰动者、某些专门的细菌(如硝化细菌和固氮菌)以及形成真菌的菌根中贫乏物种的功能类群。在开展这些优先性研究时,需要使用长期的和大尺度的田间试验,以及地理统计学和地理信息系统等现代方法进行试验研究。

Ranking environmental and edaphic attributes driving soil microbial community structure and activity with special attention to spatial and temporal scales

The incredibly complex soil microbial communities at small scales make their analysis and identification of reasons for the observed structures challenging.Microbial community structure is mainly a result of the inoculum(dispersal),the selective advantages of those organisms under the habitat-based environmental attributes,and the ability of those colonizers to sustain themselves over time.Since soil is protective,and its microbial inhabitants have long adapted to varied soil conditions,significant portions of the soil microbial community structure are likely stable.Hence,a substantial portion of the community will not correlate to often measured soil attributes.We suggest that the drivers be ranked on the basis of their importance to the fundamental needs of the microbes:(i)those that supply energy,i.e.,organic carbon and electron acceptors;(i)environmental effectors or stressors,i.e.,pH,salt,drought,and toxic chemicals;(ii)macro-organism associations,i.e.,plants and their seasonality,animals and their fecal matter,and soil fauna;and(iv)nutrients,in order,N,P,and probably of lesser importance,other micronutrients,and metals.The relevance of drivers also varies with spatial and time scales,for example,aggregate to field to regional,and persistent to dynamic populations to transcripts,and with the extent of phylogenetic difference,hence phenotypic differences in organismal groups.We present a summary matrix to provide guidance on which drivers are important for particular studies,with special emphasis on a wide range of spatial and temporal scales,and illustrate this with genomic and population(rRNA gene)data from selected studies.

Emerging contaminants:A One Health perspective

Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health.Despite global efforts to mitigate legacy pollutants,the continuous introduction of new substances remains a major threat to both people and the planet.In response,global initiatives are focusing on risk assessment and regulation of emerging contaminants,as demonstrated by the ongoing efforts to establish the UN’s Intergovernmental Science-Policy Panel on Chemicals,Waste,and Pollution Prevention.This review identifies the sources and impacts of emerging contaminants on planetary health,emphasizing the importance of adopting a One Health approach.Strategies for monitoring and addressing these pollutants are discussed,underscoring the need for robust and socially equitable environmental policies at both regional and international levels.Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.

Gut microbiota research nexus:One Health relationshipbetween human,animal,and environmental resistomes

The emergence and rapid spread of antimicrobial resistance is of global public health concern.The gut microbiota harboring diverse commensal and opportunistic bacteria that can acquire resistance via horizontal and vertical gene transfers is considered an important reservoir and sink of antibiotic resistance genes(ARGs).In this review,we describe the reservoirs of gut ARGs and their dynamics in both animals and humans,use the One Health perspective to track the transmission of ARG-containing bacteria between humans,animals,and the environment,and assess the impact of antimicrobial resistance on human health and socioeconomic development.The gut resistome can evolve in an environment subject to various selective pressures,including antibiotic administration and environmental and lifestyle factors(e.g.,diet,age,gender,and living conditions),and interventions through probiotics.Strategies to reduce the abundance of clinically relevant antibiotic-resistant bacteria and their resistance determinants in various environmental niches are needed to ensure the mitigation of acquired antibiotic resistance.With the help of effective measures taken at the national,local,personal,and intestinal management,it will also result in preventing or minimizing the spread of infectious diseases.This review aims to improve our understanding of the correlations between intestinal microbiota and antimicrobial resistance and provide a basis for the development of management strategies to mitigate the antimicrobial resistance crisis.

地下水铀污染的原位微生物还原与固定：在美国能源部田纳西橡树岭放射物污染现场的试验

总结了美国斯坦福大学和橡树岭国家实验室等在美国能源部田纳西州橡树岭综合试验基地进行的铀污染原位微生物修复阶段性试验结果.本试验利用微生物以乙醇为电子供体还原地下水和沉积物中的六价铀为不溶解的四价铀,使之原位固定化.随后通过加入溶解氧和硝酸盐来试验微生物还原后的地下水层中还原固定态铀的稳定性.通过预处理和长期间隔注入乙醇溶液,地下水中铀浓度从40～60mg·L-1降至0.03mg·L-1以下,达到了美国环保署饮用水的标准.还原的四价铀主要以U(Ⅳ)-Fe复合物的形态存在.结果表明,固定化后的四价铀只有在厌氧条件下才是稳定的,溶解氧和硝酸盐侵入地下水层后会使固定化的四价铀重新氧化为溶解态的六价铀.在试验过程中,采用多种分子生物学方法检测了微生物种群的变化和与铀氧化还原反应有关的功能微生物.本研究表明,在维持试验系统无氧和无硝酸盐的条件下,通过添加乙醇为电子供体可有效地促进地下水中土著功能微生物的活性,从而实现铀的原位还原固定与稳定.

A buried Neolithic paddy soil reveals loss of microbial functional diversity after modern rice cultivation

It has been documented that human activities are causing the rapid loss of taxonomic, phylogenetic, genetic and functional diversity in soils. However, it remains unclear how modern intensive rice cultivation impacts the soil microbiome and its functionality. Here we examined the microbial composition and function differences between a buried Neolithic paddy soil and an adjacent, currently-cultivated paddy soil using high throughput metagenomics technologies. Our results showed that the currently cultivated soil contained about 10-fold more microbial biomass than the buried one. Analyses based on both 16S rRNA genes and functional gene array showed that the currently cultivated soil had significantly higher phylogenetic diversity, but less functional diversity than the buried Neolithic one. The community structures were significantly different between modern and ancient soils, with functional structure shifting towards accelerated organic carbon （C） degradation and nitrogen （N） transfor- mation in the modem soils. This study implies that, modern intensive rice cultivation has substantially altered soil microbial functional structure, leading to functional homogenization and the promotion of soil ecological functions related to the acceleration of nutrient cycling which is necessary for high crop yields.

In Memoriam:David D.Myrold(1955–2021)

David D.Myrold,65,Professor of Soil Microbiology in the Department of Crop and Soil Science at Oregon State University,passed away in Corvallis,Oregon,USA on July 15,2021.Dave was well known to many soil scientists for his work on soil nitrogen cycling,a career of research work that was summarized in his latest 2021 publication—Transformation of Nitrogen.