中欧组织间合作研究项目MIX-UP助力实现“碳中和”

随着全球塑料循环体系的变革升级,提高塑料的回收利用不仅可以减少塑料在生命周期中的碳排放,还可以解决废塑料潜在的生态环境危害。文中介绍了2019年国家自然科学基金组织间国际 (地区) 合作研究项目“废塑料资源高效生物降解转化的关键科学问题与技术 (MIXed plastics biodegradation and UPcycling using microbial communities,MIX-UP)”。该项目聚焦“塑料污染”这一全球化的问题,围绕中欧双方确定的“塑料生物降解菌群”研究领域,联合中欧双方14家优势科研单位,开展实质性的重大前沿合作研究。针对废塑料生物降解中存在的解聚与重塑两个难题,项目以难降解石油基塑料 (PP、PE、PUR、PET和PS) 以及生物可降解塑料 (PLA和PHA) 的混合废塑料作为研究对象,从塑料微生物降解途径解析及关键元件的挖掘与改造、塑料高效降解混菌/多酶体系的构建与功能调控、塑料降解物的高值化炼制途径设计与利用策略3个方面展开研究。本项目将突破废塑料生物降解转化中高效降解元件挖掘、塑料降解物高值化利用的关键科学问题与技术,探索一条废塑料资源化、高值化、循环化、低碳化的新塑料循环路线,建立以“降塑再造”为核心理念的废塑料生物炼制体系,丰富我国固废资源化生物技术利用平台。项目的实施不仅有助于提升我国塑料 (生物) 循环经济的理论基础和关键技术水平,还可以推动我国与国际科研院所的多边交流与合作,促进我国在生物技术领域的创新发展,助力我国碳中和目标的实现。     

酞酸酯污染农田土壤生物修复研究进展

酞酸酯是目前世界上产量最大、应用面积最广的人工合成有机物,作为塑化剂被广泛应用于塑料制品中。近年来发现酞酸酯是一类典型的环境内分泌干扰物。随着生活中塑料制品日益增多,尤其是农用薄膜和有机肥的大量使用,农田土壤中酞酸酯污染日益加剧,酞酸酯污染土壤的修复逐渐引起国内外学者的广泛关注。生物修复具有价格低廉、效果良好和环境友好等特点,尤其适合于大面积污染农田土壤修复。从植物修复、微生物修复、植物微生物联合修复和动物修复等方面综述了国内外酞酸酯污染土壤生物修复的研究现状,并从高效修复植物筛选及机理探讨、实际污染土壤的降解菌修复研究、高效降解菌群的构建和作用机制等方面对该领域的研究进行了展望,以期为酞酸酯污染土壤的修复研究提供借鉴并拓展新的思路。     

VOCs-mediated hormonal signaling and crosstalk with plant growth promoting microbes

In the natural environment, plants communicate with various microorganisms (pathogenic or beneficial) and exhibit differential responses. In recent years, research on microbial volatile compounds (MVCs) has revealed them to be simple, effective and efficient groups of compounds that modulate plant growth and developmental processes. They also interfere with the signaling process. Different MVCs have been shown to promote plant growth via improved photosynthesis rates, increased plant resistance to pathogens, activated phytohormone signaling pathways, or, in some cases, inhibit plant growth, leading to death. Regardless of these exhibited roles, the molecules responsible, the underlying mechanisms, and induced specific metabolic/molecular changes are not fully understood. Here, we review current knowledge on the effects of MVCs on plants, with particular emphasis on their modulation of the salicylic acid, jasmonic acid/ethylene, and auxin signaling pathways. Additionally, opportunities for further research and potential practical applications presented.     

Relative importance of the effect of 2,4-D,glyphosate, and environmental variables on the soil microbial biomass

Two post-emergence herbicides (glyphosate and 2,4-D) were applied at field application levels to tilled field plots in a mixed cropping area in south-central Alberta. The effects of these chemicals on certain variables associated with microbial biomass and activity were monitored in these plots (as well as corresponding control plots) for 45 days. Glyphosate did not influence any of the microbial variables tested. Addition of 2,4-D significantly influenced all microbial variables investigated but these effects were transient, being detectable only within the first 1–5 days of herbicide addition. The effects of 2,4-D addition on the microbial variables tested, even when significant, were typically small and probably of little ecological consequence especially when spatial and temporal variation in these variables is taken into account.     

岷江干旱河谷优势灌丛对土壤微生物群落组成的影响

通过调查岷江干旱河谷两河口、飞虹、撮箕和牟托4个样地优势灌丛及其灌丛间空地的表土土壤物理化学性质和微生物群落组成,探讨植物灌丛群落对土壤微生物群落组成的影响。研究发现不同灌丛种类对土壤微生物群落组成以及土壤物理化学性质并没有显著影响,而同一样地灌丛与空地间的差异却较为显著。灌丛下比空地土壤中具有更高的有机质、养分含量,更高的土壤含水量和更低的容重,而灌丛下相对富集的养分资源是造成灌丛与空地间微生物群落组成差异的主要原因。不同样地影响微生物群落的主要因子存在一定差异,但与氮相关的因子(总氮、有效氮、碳/氮比)对土壤微生物群落着非常重要的影响,特别是对土壤微生物群落总生物量和细菌类群(革兰氏阳性菌、革兰氏阴性菌、细菌等)。虽然不同灌丛和空地下土壤中细菌群落都没有显著地变化,但真菌和菌根真菌却明显的在灌丛下富集。在飞虹和牟托样地,总磷和碳/磷比与真菌类群,主要指真菌和菌根真菌,表现出显著正相关性,这或许反映了真菌类群对于该区域磷循环的重要作用。研究结果揭示了灌丛植被在干旱河谷地区地下生态系统中的重要作用,以及氮、磷这两种养分元素对土壤微生物群落的重要影响。同时,未来对于干旱河谷地区植物-土壤关系的研究应该关注真菌和菌根真菌类群的作用。     

Effects of fire on soil respiration,ATP content and enzyme activities in Mediterranean maquis

Question: Do low or high intensity fires affect micro‐organism activity in the upper soil layer of Mediterranean maquis? Location: 600 m from the sea in the Nature Reserve of Castel Volturno (Campania, southern Italy, 40°57’N; 13°55’E). Methods: Soil respiration was measured in situ on intact soil; enzyme activity (cellulase, xylanase, invertase, trehalase and protease) and ATP content were measured on soil samples collected under three species of maquis vegetation: Phillyrea angustifolia L., Myrtus communis L. and Cistus incanus L. Results: Soil microbial respiration showed no significant differences in CO₂ flux in treated and untreated plots, but the ATP content in the soil under C. incanus and M. communis was lower in the treated plots for most of the study period. In the soil under Ph. angustifolia, ATP content was low only for one week after fire. The reduction was more marked in the samples from ‘high fire intensity’ than from ‘low fire intensity’ plots. Soil respiration and ATP content exhibited seasonal variations linked to soil water content. Among the enzyme activity measured in the soil under the three plant covers, only invertase declined in burned plots throughout the study period, particularly in the ‘high fire intensity’ plots. Activity of the enzymes cellulase, xylanase, trehalase and protease had a different sensitivity depending on the respective shrub cover. Conclusions: Impact of fire on soil microbial activity is largely dependent on vegetation mosaic and species identity.     

Evaluation of candidate probiotic strains for gilthead sea bream larvae (Sparus aurata) using an in vivo approach

AIMS: The aim of this study was to evaluate the effect of six bacterial strains on gilthead sea bream larvae (Sparus aurata). METHODS AND RESULTS: Six bacterial strains isolated from well-performing live food cultures were identified by sequencing fragments of their 16s rDNA genome to the genus level as Cytophaga sp., Roseobacter sp., Ruergeria sp., Paracoccus sp., Aeromonas sp. and Shewanella sp. Survival rates of gilthead sea bream larvae transferred to seawater added these bacterial strains at concentrations of 6 +/- 0.3 x 10(5) bacteria ml(-1) were similar to those of larvae transferred to sterilized seawater and showed an average of 86% at 9 days after hatching, whereas, survival rates of larvae transferred to filtered seawater were lower (P < 0.05), and showed an average of 39%, 9 days after hatching. CONCLUSION: Several bacterial strains isolated from well-performing live food cultures showed a positive effect for sea bream larvae when compared with filtered seawater. SIGNIFICANCE AND IMPACT OF THE STUDY: The approach used in this study could be applied as an in vivo evaluation method of candidate probiotic strains used in the rearing of marine fish larvae.     

微生物菌剂在农业废弃物堆肥腐熟过程中的应用及其田间试验效果

以农村生活垃圾中的可堆肥腐熟成分和蘑菇渣为堆肥原料,通过添加微生物菌剂进行堆肥试验,研究其在农业废弃物堆肥腐熟过程中的作用,并通过田间试验研究堆肥腐熟后肥料样品对黄瓜和青椒的增产效果,以验证其肥效。结果表明添加微生物菌剂有助于堆肥腐熟后样品的氮、磷、钾的保全和有机质的增加,促进养分均衡。添加微生物菌剂的堆肥腐熟肥料样品在田间试验中对黄瓜和青椒的增产效果最为显著,分别为22.21%和19.87%。     

Suppression of Pythium ultimum by Biowaste Composts in Relation to Compost Microbial Biomass, Activity and Content of Phenolic Compounds

Seventeen composts from separately collected organic household waste plus one bark compost and one compost from grape marc were analysed for suppression of Pythium ultimum, phytotoxicity, microbial biomass and activity, substrate-induced respiration, extractible phenolic compounds and other physical and chemical parameters. Nine of the samples were mildly suppressive to P. ultimum, the others were conducive. The bark compost sample was strongly suppressive. Therefore of the examined composts, only the bark could be used to exert an economically relevant control of P. ultimum in horticultural media. A large part of the compost samples was slightly phytotoxic. Microbial biomass and SIR had only weak correlations with disease incidence. Microbial activity and content of extractible phenolics were positively correlated with disease incidence. None of the tested parameters were therefore suitable as a predictive test for suppression of P. ultimum with the compost samples used in this study.     

Single particle reconstructions of the transferrin-transferrin receptor complex obtained with different specimen preparation techniques

The outcome of three-dimensional (3D) reconstructions in single particle electron microscopy (EM) depends on a number of parameters. We have used the well-characterized structure of the transferrin (Tf)-transferrin receptor (TfR) complex to study how specimen preparation techniques influence the outcome of single particle EM reconstructions. The Tf-TfR complex is small (290kDa) and of low symmetry (2-fold). Angular reconstitution from images of vitrified specimens does not reliably converge on the correct structure. Random conical tilt reconstructions from negatively stained specimens are reliable, but show variable degrees of artifacts depending on the negative staining protocol. Alignment of class averages from vitrified specimens to a 3D negative stain reference model using FREALIGN largely eliminated artifacts in the resulting 3D maps, but not completely. Our results stress the need for critical evaluation of structures determined by single particle EM.