Development of Biological Methods for Controlling the Aerobic Microorganism–Induced Corrosion of Carbon Steel

Cocultivation of destructor microorganisms and their antagonists decreases the corrosion loss of carbon steel by 20 to 80%. It was found that a microorganism can either accelerate or inhibit corrosion, depending on the nutrient. The magnitude of the effect on corrosion depends on the ability of the microorganism to respond to changes in the nutrient medium composition by releasing acidic or alkaline metabolites.     

Initial stages of steel biocorrosion

Initial stages of corrosion of mild steel induced by Klebsiela rhinoscleromatis BO2 were studied in various media. The effect of the microorganism was detected 8-10 h after inoculation. The number of viable cells were virtually unchanged within one month in all media, but the corrosive activity of the strain decreased. The corrosive activity of microorganisms can be determined by spectrophotometry even only after incubation for 24 h. At a low level of organic substrate, even strong colonization with microorganisms does not inevitably result in a significant damage to metals.     

Studies of Initial Stages of Biocorrosion of Steel

Initial stages of corrosion of mild steel induced by Klebsiela rhinoscleromatis BO2 were studied in various media. The effect of the microorganism was detected 8–10 h after inoculation. The number of viable cells was virtually unchanged over one month in all media, but the corrosive activity of the strain decreased. The corrosive activity of microorganisms can be determined by spectrophotometry even after incubation for only 24 h. At a low level of organic substrate, even strong colonization with microorganisms does not inevitably result in significant damage to metals.     

微生物诱导的植物系统抗性

综述了由植物病原菌和非病原性的根际促生菌诱导产生的两种植物系统抗性:系统获得性抗性(SAR)和系统诱导抗性(ISR),比较了两类系统抗性的诱导、信号分子和机理的异同点,阐述了信号分子水杨酸在系统获得性抗性诱导过程中的作用及茉莉酸和乙烯在系统诱导抗性产生过程中的作用。     

Slime problems in the paper and board industry

 The latest trends in the paper industry have been towards manufacturing by a neutral or alkaline process, greater consumption of secondary fibres and the closing-up of the process water systems. Under these conditions of papermaking, the problems of deposits, corrosion and odours due to the microbiological activity increase considerably and therefore, runnability and production problems occur. To help our understanding of the current situation in the paper industry, this paper presents a review of the microorganism sources, the consequences of the microbiological activity upon the actual systems of manufacturing paper and board, and the current state of the different alternatives for its prevention and control, as well as the future trends to address environmental considerations. Received: 20 March 1996/Received revision: 23 May 1996/Accepted: 28 May 1996     

微生物对植物源中药有效成分形成的影响

植物体内外生长着大量微生物,它们主要从表皮侵入植物体.植物识别侵入的微生物后,会形成次生代谢产物来抵抗微生物的侵入,这些代谢产物为我们提供了丰富的药源.血竭、沉香、皮用中药、组培生产药用成分及一些栽培中药中有效成分的形成都与微生物有密切关系.微生物在中药上的应用有很多问题急待解决,深入研究微生物对中药的影响对提高中药质量具有重要作用.     

不同栽培时间三叶赤楠根际微生物多样性及其PCR-DGGE分析

应用聚合酶链式反应—变性梯度凝胶电泳（PCR-DGGE）研究了不同栽培时间三叶赤楠根际微生物多样性特征。结果表明：采用改进的蛋白酶K-CTAB法提取的三叶赤楠土壤DNA经PCR扩增的产物经DGGE检测后得到的电泳条带清晰且分离效果好,可以明显反映出三叶赤楠生长过程中土壤微生物多样性的变化。栽培时间对三叶赤楠根际微生物特征有很大影响：随着栽培时间增加,土壤微生物多样性增加,在第4年多样性指数达到最高值2.741,第8年时多样性指数降为1.378。不同栽培时间三叶赤楠根际微生物类群组成有所变化。根际微生物特征可以作为盆景换盆的一个指导因素,三叶赤楠盆景的换盆在其生长4~6年时进行可能最为合适,此时三叶赤楠根际微生物的多样性最为丰富,进行换盆会加快其根际微生态系统的建成。     

Exocellular electron transfer in anaerobic microbial communities

Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory syntrophic consortia of proton-reducing acetogenic bacteria and hydrogen-consuming methanogenic archaea. Anaerobic microorganisms that use insoluble electron acceptors for growth, such as iron- and manganese-oxide as well as inert graphite electrodes in microbial fuel cells, also transfer electrons exocellularly. Soluble compounds, like humic substances, quinones, phenazines and riboflavin, can function as exocellular electron mediators enhancing this type of anaerobic respiration. However, direct electron transfer by cell-cell contact is important as well. This review addresses the mechanisms of exocellular electron transfer in anaerobic microbial communities. There are fundamental differences but also similarities between electron transfer to another microorganism or to an insoluble electron acceptor. The physical separation of the electron donor and electron acceptor metabolism allows energy conservation in compounds as methane and hydrogen or as electricity. Furthermore, this separation is essential in the donation or acceptance of electrons in some environmental technological processes, e.g. soil remediation, wastewater purification and corrosion.     

非流体介质中多环芳烃污染的微生物固定化修复技术

非流体介质中多环芳烃(PAHs)污染的修复是目前环境工作者所面临的艰巨而紧迫的任务.由于非流体介质环境的特殊性,常规修复方法难以高效地发挥作用,传统微生物修复技术采用的游离微生物也存在许多弊端.而微生物固定化能大幅度地提高参加反应的微生物浓度,避免优势菌受土著菌的恶性竞争,增强微生物的耐环境冲击性.微生物固定化技术在一定程度上克服了传统工艺的不足,因而广泛应用于流体介质(废水等)和半流体介质(泥浆等)环境污染的修复.在概述固定化微生物技术的特点和分析国内外研究进展的基础上,指出将该技术应用于非流体介质中PAHs污染的原位修复领域的可行性,并论述了需要解决的关键科学问题,提出了利用微生物固定化技术修复非流体介质中PAHs污染的未来研究课题.     

Non‐homogeneous biofilm modeling applied to bioleaching processes

A two‐dimensional non‐homogeneous biofilm model is proposed for the first time to study chemical and biochemical reactions at the microorganism scale applied to biological metal leaching from mineral ores. The spatial and temporal relation between these reactions, microorganism growth and the morphological changes of the biofilm caused by solid inorganic precipitate formation were studied using this model. The model considers diffusion limitations due to accumulation of inorganic particles over the mineral substratum, and allows the study of the effect of discrete phases on chemical and microbiological mineral solubilization. The particle‐based modeling strategy allowed representation of contact reactions between the microorganisms and the insoluble precipitates, such as those required for sulfur attack and solubilization. Time‐dependent simulations of chemical chalcopyrite leaching showed that chalcopyrite passivation occurs only when an impervious solid layer is formed on the mineral surface. This mineral layer hinders the diffusion of one kinetically determinant mineral‐attacking chemical species through a nearly irreversible chemical mechanism. Simulations with iron and sulfur oxidizing microorganisms revealed that chemolithoautotrophic biofilms are able to delay passivation onset by formation of corrosion pits and increase of the solid layer porosity through sulfur dissolution. The model results also show that the observed flat morphology of bioleaching biofilms is favored preferentially at low iron concentrations due to preferential growth at the biofilm edge on the surface of sulfur‐forming minerals. Flat biofilms can also be advantageous for chalcopyrite bioleaching because they tend to favor sulfur dissolution over iron oxidation. The adopted modeling strategy is of great interest for the numerical representation of heterogeneous biofilm systems including abiotic solid particles. Biotechnol. Bioeng. 2010;106: 660–676. © 2010 Wiley Periodicals, Inc.     

Understanding microbial inhibition of corrosion. A comprehensive overview

Microorganisms are able to drastically change the electrochemical conditions at the metal/solution interface by biofilm formation. These changes can range from the induction or acceleration of corrosion to corrosion inhibition. Any inhibitory action developed by bacteria may be accomplished within the varied and complex biofilm/corrosion products interactions occurring on a biofouled metal surface.Biocorrosion and its counter process, microbial inhibition of corrosion, are rarely linked to a single mechanism or to a single species of microorganisms. Microorganisms can induce corrosion inhibition according to two general mechanisms or their combination: i) neutralizing the action of corrosive substances present in the environment; ii) forming protective films or stabilizing pre-existing protective films on a metal. Different practical cases illustrating these mechanisms are presented in this overview.It must be stressed that some times the inhibitory action of bacteria can be reversed to a corrosive action in bacterial consortia located within biofilm thickness.     

The ultrastructure of microorganisms in the tissues of Casinaria infesta (Hymenoptera:Ichneumonidae)

Two types of microorganisms were observed in the tissues of Casinaria infesta. Type I was a typical rickettsialike microorganism which occurred in digestive, reproductive, nerous, respiratory, and connective tissue. This microoganism appeared to undergo changes within the cells of the calyx resulting in a uniformly dense coccoid organism. The Type II microorganisms were observed in the cytoplasm, nucleus, and lumen of the calyx, and within the lumen of the oviduct. This microorganism was small, rod-shaped, and had a bled or protrusion at one or both ends. Type II microorganisms appear to form de novo in the nucleus of the calyx cells and to replicate by fission or budding. The nature of the Type II microorganism is unresolved.     

微生物改善土体性能研究进展

土体中除含固体颗粒、液体与气体以外,还存在细菌、真菌等微生物,其存在势必会对土体性能产生一定作用。现有研究表明:微生物改善土体性能的机理是通过改变微观结构作用土体性能,主要有微生物吸附、诱导无机物沉淀、生物表面活性剂附着与气体填充等四种方式。微生物作用土体的宏观表现主要有降低渗透性与提高强度两方面。除理论分析与试验研究取得了一定成果外,微生物在土体封堵防渗与胶结加固工程上也得到了很好应用。     

Continuing fascination of exploration in natural substances from microorganisms†

In the search for novel organic compounds, I think it is of paramount importance not to overlook the pursuit of microorganism diversity and the abilities those microorganisms hold as a resource. In commemoration of Professor Satoshi ōmura’s Nobel Prize in Physiology or Medicine, I will briefly describe the microorganism that produces avermectin and then discuss how innovating isolation methods and pioneering isolation sources have opened the door to numerous new microorganism resources. Furthermore, as exploratory research of substances views the world from many different angles—from biological activity to a compound’s physiochemical properties—it is possible to discover a novel compound from a well-known microorganism. Based on this, I will discuss the future prospects of exploratory research.     

高温菌生物学特性的应用

高温菌是一个热点研究领域。这一领域不断发现新的苗种及特性。高温菌广泛地存在于自然界中,它与常温菌相比有着许多不同的特性。例如,其酶在高温下的稳定性,为化工应用提供了便利。简要介绍了高温微生物已有的应用领域,为进一步的研究工作提供参考。     

固定化微生物处理氨氮废水的研究进展

生物方法因其高效、持久及无二次污染已经成为治理水污染的重要方法,固定化微生物不仅加强微生物治理效果,更能保证微生物生存稳定,是现阶段生物方法治理水污染的主要组分。近年来学者们也做了很多固定化微生物处理各类废水的研究,并取得了大量优异成果。文章对固定化微生物技术进行剖析,分析各类固定化载体材料及各种固定化方法优缺点;解析利用固定化微生物处理氨氮废水效果研究及固定化微生物处理效果影响因素;综述近年来固定化微生物处理氨氮废水应用情况;最后进行总结,并提出自己的展望。     

微生物抑制金属腐蚀机理的研究进展

传统金属防腐方法成本较高或者容易产生次生环境问题。微生物防腐蚀是一项新的绿色防腐技术,随着越来越多抗腐蚀微生物的发现,以及有益菌膜研究的开展,研究者们发现了微生物抑制金属腐蚀的众多机理,本文对此进行了归纳总结。微生物可以通过生物驱除、分泌腐蚀抑制剂、生成胞外多聚物、降低溶解氧、形成生物膜屏障、分泌生物表面活性剂、噬菌体控制、非生物膜屏障等过程控制和减缓金属腐蚀。金属的微生物腐蚀抑制作用通常不是由单一机制引起的,而是多种机制共同作用的结果。深入理解微生物抑制金属腐蚀的机理,有利于为减缓金属腐蚀行为提供借鉴。     

Allozyme genotypes of Drosophila buzzatii: feeding and oviposition preferences for microbial species, and habitat selection

Mature, mated female D. buzzatii were given a choice of nine microbial communities actively growing on cactus homogenate in laboratory population cages, and tests were made to determine if flies of different genotypes (for seven allozyme loci) chose different microorganism species for either feeding or oviposition. Variation in feeding preferences was determined from assays of electrophoretic genotypes and the ingested microorganism species of individual flies. Oviposition preference variation was analyzed indirectly by assaying the genotypes of individuals raised from eggs laid on different microorganisms. No significant evidence was found for differences in feeding preferences among adults of different genotypes. For oviposition preferences, there were significant microorganism-genotype associations for each of seven polymorphic loci. Analyses of the total electrophoretic genotype, rather than of individual loci, showed that the genotypes of eggs laid on the same microorganism species were more similar than those laid on different species. That is, females of different genotypes show habitat selection for oviposition sites, which would facilitate the maintenance of genetic polymorphisms.     

微生物的交流信号

多年来微生物一直被认为是相对孤立的个体,在环境中独立地生存,但近些年的研究使人们认识到微生物也使用复杂多样的方式进行种内、种间,甚至与其他生物间的跨界信息交流。这些交流由特定的信号分子来完成,称之为微生物语言。借助这些交流语言使微生物在特定的生态位中与其相邻个体或种群建立了多样的互动关系,包括合作、竞争与资源共享等,通过协调群体行为,共同应对多变的环境。随着现代分子科学对自然微生物群落的不断深入研究,人们对微生物交流也逐渐有了更为清晰的认知。本综述总结了原核和真核微生物所使用的主要信号物质(如群体感应、群体猝灭、抗生素等)和交流方式,讨论了这些通讯语言在种内(同种微生物)、种间(异种微生物),以及跨界(微生物与宿主)交流上的表现。旨在更为深入地解读这一有趣的多学科交叉研究领域,更好地理解微生物交流语言的形式、机制和目的,为微生物行为的解读和生态事件的解析获取基于化学生态学的新思路。     

The dual role of microbes in corrosion

Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced products are under increasing pressure of stringent environmental regulations. Furthermore, they are rather inefficient. Therefore, there is an urgent need for environmentally friendly and sustainable corrosion control strategies. The mechanisms of microbially influenced corrosion and microbially influenced corrosion inhibition are not completely understood, because they cannot be linked to a single biochemical reaction or specific microbial species or groups. Corrosion is influenced by the complex processes of different microorganisms performing different electrochemical reactions and secreting proteins and metabolites that can have secondary effects. Information on the identity and role of microbial communities that are related to corrosion and corrosion inhibition in different materials and in different environments is scarce. As some microorganisms are able to both cause and inhibit corrosion, we pay particular interest to their potential role as corrosion-controlling agents. We show interesting interfaces in which scientists from different disciplines such as microbiology, engineering and art conservation can collaborate to find solutions to the problems caused by corrosion.