Corrosion of metals in natural waters influenced by manganese oxidizing microorganisms

Case histories and proposed mechanisms formicrobiologically influenced corrosion of metals andalloys by metal depositing microorganisms arereviewed. Mechanisms with indirect participation ofthese microorganisms, usually iron- and manganeseoxidizing species, are distinguished from anothermechanism which accounts specifically for theelectrochemical properties of deposits containingoxides and hydroxides of Mn in higher oxidationstates. The possible influence of such deposits whichwere formed microbiologically is evaluated. Theevaluation is based on the principles ofelectrochemical corrosion of metals and on theelectrochemical properties of Mn^3+/4+- compounds.After briefly reviewing the microbiologicalMn-oxidation, experimental evidence for the predictedcorrosion by such deposits is provided and a model formicrobiologically influenced corrosion by manganeseoxidizing microorganisms is proposed for stainlesssteel. Possible consequences of the model andpractical aspects of such a corrosion are discussed.     

Modelling the effect of size on the aerial dispersal of microorganisms

Aim We investigate the long‐standing question of whether the small size of microbes allows most microbial species to colonize all suitable sites around the globe or whether their ranges are limited by opportunities for dispersal. In this study we use a modelling approach to investigate the effect of size on the probability of between‐continent dispersal using virtual microorganisms in a global model of the Earth’s atmosphere. Location Global. Methods We use a computer model of global atmospheric circulation to investigate the effect of microbe size (effective diameters of 9, 20, 40 and 60 μm) on the probability of aerial dispersal. Results We found that for smaller microbes, once airborne, dispersal is remarkably successful over a 1‐year period. The most striking results are the extensive within‐hemisphere distribution of virtual microbes of 9 and 20 μm diameter and the lack of dispersal between the Northern and Southern Hemispheres during the year‐long time‐scale of our simulations. Main conclusions Above a diameter of 20 μm wind dispersal of virtual microbes between continents becomes increasingly unlikely, and it does not occur at all (within our simulated 1‐year period) for those of 60 μm diameter. Within our simulation, the success of small microbes in long‐distance dispersal is due both to their greater abundance and to their longer time in the atmosphere – once airborne – compared with larger microbes.     

Purification and chemical characterization of staphyloferrin B,a hydrophilic siderophore from staphylococci

This paper describes the chemical characterization of staphyloferrin B, a new complexone type siderophore isolated from low iron cultures of Staphylococcus hyicus DSM 20459. Purification of the very hydrophilic metabolite was achieved by anion exchange high performance liquid chromatography HPLC. Mass spectrometry showed a molecular mass of 448 amu. Hydrolysis with 8 mHCl revealed the presence of l-2,3-diaminopropionic acid, citrate, ethylenediamine and succinic semialdehyde. The connections between the four building blocks were determined by two-dimensional nuclear magnetic resonance measurements. UV/Vis and circular dichroism spectra are consistent with the proposed structure, which could also be confirmed by precursor feeding. The siderophore activity of staphyloferrin B was demonstrated by iron transport measurements.     

兰州唐古特白刺根际微生物分离鉴定

【目的】从兰州唐古特白刺根际分离得到对植物有潜在促生效果的功能微生物，为研发相关菌种制剂的研究奠定基础。【方法】通过平板划线法从其根际分离纯化出6株细菌，并对菌株进行形态特征观察、革兰氏染色等一系列生理生化试验。用藜麦检测各菌株的促生功能，并对具有优良促生作用的1个菌株16S rRNA基因进行分子鉴定及基因草图绘制。【结果】根据生化鉴定结果，6株细菌分别属于不动杆菌属(Acinetobacter)、土壤杆菌属(Agrobacterium)、类芽孢杆菌属(Paenibacillus)、芽孢杆菌属(Bacillus)、鞘氨醇单胞菌属(Sphingomonas)和假单胞菌属(Pseudomonas)。其中，16S rRNA基因鉴定BC4属于肠杆菌属(Enterobacter)，具有较好的促生效果。【结论】BC4具有较好的促生效果，为兰州唐古特白刺菌种资源的开发和利用提供了一定的理论依据。     

Biological methods for speciation of heavy metals: different approaches

Heavy metals are found in their different forms in the environment. The distribution, mobility, and toxicity of metals are strongly related to these different forms. This necessitates the exploration of different methods for the remediation and speciation of heavy metals. Some direct and indirect physico-chemical methods such as filtration, chemical precipitation, ion-exchange, electro deposition, and membrane systems have been used for the last four decades. However, it is only in last few years that reliable biological methods have also been used. The biological methods include the use of microorganisms (fungi, algae, bacteria), plants (live or dead) and biopolymers. The use of these methods for the speciation of heavy metals is reviewed here.     

Variations of soil structure and microbial population in a compost amended soil

Changes in soil structure and in microbial population were recorded in a long term field experiment over the growing season of maize (June–November). Determinations were made on samples from plots which had received, for two years, the following treatments: mineral fertilizers, farmyard manure and three rates of compost. Seasonal variations were observed for the stability of soil aggregates, total porosity, pore size distribution, mycorrhizal infection and aerobic cellulolytic microorganisms. The stability of the soil aggregates changed in a similar way to that found for both mycorrhizal infection and the number of aerobic cellulolytic microorganisms. Physical characteristics were not affected in any instance by the organic dressings and microbiological populations were generally influenced only by the higher doses of compost.     

微生物嗜铁素介导的铁摄取

嗜铁素是好氧菌和兼性厌氧菌的一种产物,它是微生物在低铁条件下产生的小分子的、特异性的Fe^3＋螯合因子。大多数的好氧和兼性厌氧微生物至少合成一种嗜铁素,由嗜铁素介导的铁摄取可能是细菌最普遍的一种获取铁元素的方式。