The need to study the holobiome for gainful uses of endophytes

It is established that endophytes (bacteria and fungi) affect positively several traits of their host plants including growth, nutrient acquisition, and tolerance to abiotic and biotic stressors. Owing to this, endophytes are envisaged as a route to improve sustainable agricultural production. However, such effects of endophytes on crops although evident under lab conditions, are devoid of consistency under field conditions. The main reason for this could be the lack of our understanding of the functioning of the endophytes as a consortium within the plant (holobiome). It is essential to study the complex web of interactions which operate in the inner tissues of plants harboring endophytes. I highlight here, alluding to the work on foliar fungal endophytes, the importance of studying endophytes as a consortium rather than merely as one species in isolation to better appreciate their role in the plant holobiome. Such an approach should aid in harnessing the technological potential of endophytes.     

微生物“暗物质”研究曙光

微生物是地球上生命的主体之一,拥有极为丰富多彩的代谢途径,在很大程度上塑造了使人类宜居的地球。由于绝大部分环境中的微生物无法被分离和培养,微生物被喻为生命物质中的"暗物质"。近年来,迅猛发展的基因组学技术有力地推动了微生物"暗物质"的研究,使我国微生物生态学科发展从"诞生期"和"启蒙期"跨越式发展到"暴发期",乐观预测未来可能进入一个具有鲜明特色的"领航期"。     

微生物生态学驱动社会与经济“绿色高效发展”

面对物种数量繁多、生态分布广泛、生态功能强大的微生物资源,微生物生态学的任务一方面在于不断发现和认识这类生命"暗物质"及其存在机制,另一方面要充分挖掘和利用这些微生物资源。微生物生态学的应用从最早的混合发酵发展到极端微生物资源利用、微生物生态制剂开发逐渐拓展到合成微生物生态等多个领域。2019年10月在湖南省长沙市举行的"中国生态学学会微生物生态专业委员会学术年会"设立了3个与微生物生态学应用相关的分会场,本期《微生物学通报》也开辟了"人工生态系统微生物"栏目,凸显了我国微生物生态学在资源、能源和环境等应用领域的成果,让我们看到了其成为社会与经济"绿色高效发展"重要驱动力的希望。     

大庆油田微生物采油现场试验进展

本文介绍近十几年以来大庆油田利用具有产气、降解原油、产生物表面活性剂及堵调性能的菌剂,通过地下发酵,开展微生物采油现场试验取得的进展.分析了该项技术适用的油藏条件和应用特点.截止到2012年底,应用微生物采油技术增产原油达12×104 t.其中微生物单井吞吐518口,累计增油6.3×104t,实施微生物驱和调驱项目10项(45个井组),累计增油5.7×104 t,为大庆油田稳产发挥了重要作用.     

Changes in microbial nutrient status during secondary succession and its modification by earthworms

Summary Microbial biomass, nutrient (N and P) status, and carbon and nutrient limitation of the microflora were investigated in soils from five different sites (field, 5-, 12-, and about 50-year-old fallow, beechwood), which represent different stages of a secondary succession from a wheat field to the climax ecosystem of a beechwood on limestone. In addition, the effect of faeces production by the substrate feeding earthworm species Octolasion lacteum (Örley) on the nutrient status of the soil microflora of these sites was studied. Humus had accumulated in the soil of the third fallow site, with an enhanced biomass of microflora. However, in the beechwood soil, which had the highest humus content, microbial biomass was lower than in the soil of the third fallow site and similar to that of the field and the two younger fallow sites. In general, soil microbial biomass was little affected by the passage of soil through the gut of O. lacteum. The soil microflora of the field, the 5-, 12-, and about 50-year-old fallow was limited by carbon, whereas in the beechwood soil phosphorus limited microbial growth. NItrogen availability to the soil microflora was low in the two younger fallow sites and high in the field and the third fallow. In the beechwood soil nitrogen supply did not affect microbial carbon utilization. Application of phosphorus stimulated glucose mineralization in the soil of the field, the third fallow, and the beechwood, but not in the two younger fallow sites. Therefor, the nutrient status of the soil microflora seems to have changed during secondary succession: presumably, during the first phase the availability of nitrogen decreased, whereas during the second phase microbial phosphorus supply became more important, which resulted in phosphorus limitation of the soil microflora in the climax ecosystem. The passage of soil through the gut of O. lacteum caused an alteration in the microbial nutrient status. Generally, microbial growth in earthworm casts was limited by carbon. The relative effect of the gut passage of the soils on microbial carbon utilization seems to increase during succession. Therefore, the effect of decomposer invertebrates on microbial nutrient supply seems to increase during secondary succession. In general, nitrogen did not limit microbial carbon utilization in earthworm casts. Phosphorus requirements of the soil microflora were lowered by the gut passage of the soil of the third fallow site and the beechwood, which indicates an increased phosphorus supply in earthworm casts. Howerver, this additional supply was not sufficient to enable optimal carbon utilization by the soil microflora. The results indicate that the effect of decomposer invertebrates on the soil microflora depends on the nutrient status of the ecosystem.     

微生物菌剂在难降解有机污染治理的研究进展

大量的难降解有机污染物被排放到环境中,因其蓄积性、持久性和生物毒性,对人类健康和生态环境造成严重危害。近年来,利用微生物菌剂治理难降解有机污染物的研究已取得较好的进展。综述微生物菌剂在国内外的发展历程,介绍微生物菌剂制备中常用的固定化技术及载体材料,并分析总结微生物菌剂在酚类物质、多环芳烃和多氯联苯等有机污染物治理中的研究进展。在此基础上,提出治理难降解有机污染物的微生物菌剂研发所存在的主要问题及其展望。     

A comprehensive review of microbial electrochemical systems as a platform technology

Microbial electrochemical systems (MESs) use microorganisms to covert the chemical energy stored in biodegradable materials to direct electric current and chemicals. Compared to traditional treatment-focused, energy-intensive environmental technologies, this emerging technology offers a new and transformative solution for integrated waste treatment and energy and resource recovery, because it offers a flexible platform for both oxidation and reduction reaction oriented processes. All MESs share one common principle in the anode chamber, in which biodegradable substrates, such as waste materials, are oxidized and generate electrical current. In contrast, a great variety of applications have been developed by utilizing this in situ current, such as direct power generation (microbial fuel cells, MFCs), chemical production (microbial electrolysis cells, MECs; microbial electrosynthesis, MES), or water desalination (microbial desalination cells, MDCs). Different from previous reviews that either focus on one function or a specific application aspect, this article provides a comprehensive and quantitative review of all the different functions or system constructions with different acronyms developed so far from the MES platform and summarizes nearly 50 corresponding systems to date. It also provides discussions on the future development of this promising yet early-stage technology.     

Electroactive mixed culture derived biofilms in microbial bioelectrochemical systems: the role of pH on biofilm formation, performance and composition

The pH-value played a crucial role for the development and current production of anodic microbial electroactive biofilms. It was demonstrated that only a narrow pH-window, ranging from pH 6 to 9, was suitable for growth and operation of biofilms derived from pH-neutral wastewater. Any stronger deviation from pH neutral conditions led to a substantial decrease in the biofilm performance. Thus, average current densities of 151, 821 and 730 μA cm(-2) were measured for anode biofilms grown and operated at pH 6, 7 and 9 respectively. The microbial diversity of the anode chamber community during the biofilm selection process was studied using the low cost method flow-cytometry. Thereby, it was demonstrated that the pH value as well as the microbial inocula had an impact on the resulting anode community structure. As shown by cyclic voltammetry the electron transfer thermodynamics of the biofilms was strongly depending on the solution's pH-value.     

Long-term cathode performance and the microbial communities that develop in microbial fuel cells fed different fermentation endproducts

To better understand how cathode performance and substrates affected communities that evolved in these reactors over long periods of time, microbial fuel cells were operated for more than 1 year with individual endproducts of lignocellulose fermentation (acetic acid, formic acid, lactic acid, succinic acid, or ethanol). Large variations in reactor performance were primarily due to the specific substrates, with power densities ranging from 835 ± 21 to 62 ± 1 mW/m³. Cathodes performance degraded over time, as shown by an increase in power of up to 26% when the cathode biofilm was removed, and 118% using new cathodes. Communities that developed on the anodes included exoelectrogenic families, such as Rhodobacteraceae, Geobacteraceae, and Peptococcaceae, with the Deltaproteobacteria dominating most reactors. Pelobacter propionicus was the predominant member in reactors fed acetic acid, and it was abundant in several other MFCs. These results provide valuable insights into the effects of long-term MFC operation on reactor performance.     

DGGE/TGGE技术及其在微生物分子生态学中的应用

变性梯度凝胶电泳(DGGE)和温度梯度凝胶电泳(TGGE)是近些年微生物分子生态学研究中的热点技术之一。由于DGGE／TGGE技术具有可靠性强、重现性高、方便快捷等优点,被广泛地应用于微生物群落多样性和动态性分析。文章对DGGE／TGGE技术原理与关键环节、局限性和应用前景进行了综述。     

Symposium Introductory Remarks: A Brief History of Aquatic Microbial Ecology

ABSTRACT This report serves to introduce the symposium on food chains and food webs that is jointly sponsored by the Society of Protozoologists and the Phycological Society of America. A brief history of the field of aquatic microbial ecology is presented with an emphasis on the development of theoretical models that have directed the course of research — research that has shaped the development of new and more complex models of the present. the paper aims to provide historical background for all symposium participants and an introduction to the specific presentations of the four guest speakers.     

Efficient salt removal in a continuously operated upflow microbial desalination cell with an air cathode

Microbial desalination cells (MDCs) hold great promise for drinking water production because of potential energy savings during the desalination process. In this study, we developed a continuously operated MDC - upflow microbial desalination cell (UMDC) for the purpose of salt removal. During the 4-month operation, the UMDC constantly removed salts and generated bio-electricity. At a hydraulic retention time (HRT) of 4 days (salt solution) and current production of ∼62 mA, the UMDC was able to remove more than 99% of NaCl from the salt solution that had an initial salt concentration of 30 g total dissolved solids (TDS)/L. In addition, the TDS removal rate was 7.50 g TDS L⁻¹ d⁻¹ (salt solution volume) or 5.25 g TDS L⁻¹ d⁻¹ (wastewater volume), and the desalinated water met the drinking water standard, in terms of TDS concentration. A high charge transfer efficiency of 98.6% or 81% was achieved at HRT 1 or 4 d. The UMDC produced a maximum power density of 30.8 W/m³. The phenomena of bipolar electrodialysis and proton transport in the UMDC were discussed. These results demonstrated the potential of the UMDC as either a sole desalination process or a pre-desalination reactor for downstream desalination processes.     

Application of biocathode in microbial fuel cells: cell performance and microbial community

Instead of the utilization of artificial redox mediators or other catalysts, a biocathode has been applied in a two-chamber microbial fuel cell in this study, and the cell performance and microbial community were analyzed. After a 2-month startup, the microorganisms of each compartment in microbial fuel cell were well developed, and the output of microbial fuel cell increased and became stable gradually, in terms of electricity generation. At 20 ml/min flow rate of the cathodic influent, the maximum power density reached 19.53 W/m3, while the corresponding current and cell voltage were 15.36 mA and 223 mV at an external resistor of 14.9 Omega, respectively. With the development of microorganisms in both compartments, the internal resistance decreased from initial 40.2 to 14.0 Omega, too. Microbial community analysis demonstrated that five major groups of the clones were categorized among those 26 clone types derived from the cathode microorganisms. Betaproteobacteria was the most abundant division with 50.0% (37 of 74) of the sequenced clones in the cathode compartment, followed by 21.6% (16 of 74) Bacteroidetes, 9.5% (7 of 74) Alphaproteobacteria, 8.1% (6 of 74) Chlorobi, 4.1% (3 of 74) Deltaproteobacteria, 4.1% (3 of 74) Actinobacteria, and 2.6% (2 of 74) Gammaproteobacteria.     

膜生物反应器中的生物学特征

由于在膜生物反应器内膜的截留作用 ,使膜生物反应器内的一些生物学特征与传统的活性污泥过程有所不同。本文系统地阐述了膜生物反应器内的微生物群落、活性污泥及微生物产物的生理生化特征。     

海洋微生物学：新机遇，新挑战

海洋占地球表面积的71%,海洋微生物对海洋及人类的生活有重大影响。由于特殊的生存环境,海洋微生物能产生陆栖微生物所不能产生的结构新颖、作用特殊的生物活性物质,有潜力应用于医疗、食品、环境保护等各个领域。海洋微生物研究充满了新的机遇,同时也面临着新的挑战。《微生物学通报》本期推出了"海洋微生物学主题刊",旨在展现我国海洋微生物学研究的最新进展和成果,促进我国海洋微生物学的交流和发展。     

宏基因组学与动物病原微生物检测

宏基因组学（ metagenome）是直接从土壤、海水、人及动物胃肠道、口腔、呼吸道、皮肤等环境中获取样品DNA,利用载体将其克隆到替代宿主细胞中构建宏基因文库,以高通量检测为主要技术来研究特定环境中全部微生物的基因组及筛选活性物质和基因的新兴学科。利用宏基因组学技术不仅能够有效地检测特定环境的微生物群落结构,扩展了微生物资源的利用空间,发展了新兴的高通量检测技术,丰富了生物信息学内容。基于宏基因组学研究方法在环境微生物研究中的优势,对近年来相关领域、方法及其在人及动物病原微生物研究中的应用进行综述,以期将此方法用于实验动物病原微生物的调查分析及动物疫情、生物安全的监测。     

Insecticidal and nematicidal properties of microbial metabolites

Summary Metabolites from 942 microbial isolates were screened for insecticidal and nematicidal properties. The isolates included 302 streptomycetes, 502 novel actinomycetes including representatives of 18 genera, 28 unidentified aerobic actinomycetes, 70 fungi and 40 bacteria other than actinomycetes. When diluted 10-fold, the metabolites from 55 isolates caused nearly 100% mortality in mosquito larvae (Aedes aegypti) within 24 h. These isolates included 27 isolates ofStreptomyces, four ofActinoplanes, three isolates each ofActinomadura andStreptoverticillium, two isolates each ofMicromonospora, Bacillus andPaecilomyces, and one isolate each ofMicropolyspora, Nocardiopsis, Streptosporangium, Oerskovia, Thermomonospora, Chainia, Pseudomonas, Fusarium, Monilia andSyncephalestrum. Two fungal isolates could not be identified to the generie level. Extracts from the culture broth of 18 isolates caused 100% mortality in mosquito larvae within 15 min to 24 h at a concentration of 1000 ppm. The LC₅₀ of partially purified products from two isolates was 1–2.5 ppm and that of the semipurified preparations from four other isolates was 50 ppm. Valinomycin was identified as an active component in the culture broth from one isolate. The culture broth from 15 isolates of aerobic actinomycetes and 4 of fungi were toxic toPanagrellus redivivus (Nematoda); these included 12 isolates with selective nematicidal properties.Michigan Agriculture Experiment Station, Journal Article No. 12321.     

Microbial decomposition of leaf litter as influenced by fertilizers

Summary A urea and NPK-mixture at concentration of 5, 10 and 15 mg g^–1 air dry litter stimulated microbial populations, microbial activity and rate of decomposition of the litter. The stimulation was more pronounced as the concentration of the fertilizers was increased. However, this trend was reverse after two months in case of urea except for bacterial population. Fewer fungal species were isolated from the fertilizer-treated litter, together with a certain degree of alteration in the composition of mycoflora.