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141.
Paul Linhardt 《Biodegradation》1997,8(3):201-210
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 Mn3+/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. 相似文献
142.
《Critical reviews in biotechnology》2013,33(4):307-312
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. 相似文献
143.
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. 相似文献
144.
Michael Burton John D. Perry Stephen P. Stanforth Hayley J. Turner 《Bioorganic & medicinal chemistry》2018,26(17):4841-4849
The preparation and evaluation of chromogenic substrates for detecting bacterial glycosidase enzymes is reported. These substrates are monoglycoside derivatives of the metal chelators catechol, 2,3-dihydroxynaphthalene (DHN) and 6,7-dibromo-2,3-dihydroxynaphthalene (6,7-dibromo-DHN). When hydrolysed by appropriate bacterial enzymes these substrates produced coloured chelates in the presence of ammonium iron(III) citrate, thus enabling bacterial detection. A β-d-riboside of DHN and a β-d-glucuronide derivative of 6,7-dibromo-DHN were particularly effective for the detection of S. aureus and E. coli respectively. 相似文献
145.
目的研究摄入不同咖啡浓度对小鼠酶活性、肠道微生物、体重的影响,从分析肠道四种微生物变化和四种酶的活性变化来讨论摄入咖啡对健康的影响。方法 SPF级昆明小鼠随机分为4组,即低、中、高咖啡浓度组和正常对照组,所有实验组小鼠日常给予蒸馏水饮用,实验低、中、高浓度组每天2次分别灌胃给予0.0045g/mL、0.0090g/mL、0.0180g/mL的咖啡溶液0.4mL/(只·次),对照组给予蒸馏水灌胃,实验时间为1个月,测小鼠体重、肠道微生物和酶活性等指标并进行分析。结果与对照组相比,低浓度咖啡摄入组乳杆菌、双歧杆菌、大肠埃希菌数显著增加(P0.01或P0.05),需氧和厌氧细菌数显著降低(P0.01);中浓度咖啡摄入组乳杆菌、双歧杆菌数显著低于对照组和低浓度组(P0.01),大肠埃希菌显著高于对照组(P0.05);高浓度咖啡摄入组乳杆菌和大肠埃希菌总数显著低于对照组(P0.01或P0.05);低浓度摄入组的木聚糖酶、纤维素酶、淀粉酶、蛋白酶的活性均显著高于(Ps0.01)对照组和中浓度咖啡摄入组;各组小鼠体重差异无统计学意义(P0.05)。结论适当摄入咖啡小鼠肠道双歧杆菌和乳杆菌等益生菌数量增加显著,小鼠肠道中具有代表性的淀粉酶、纤维素酶、蛋白酶、木聚糖酶的活性均显著增加,但咖啡摄入对小鼠体重影响不显著。 相似文献
146.
AbstractMicrostructural post mortem changes to skeletal tissues by microorganisms are driven by several factors including the death history of an animal, its decomposition trajectory, and the depositing environment itself. The study we describe here brings together material from recent and fossil contexts that are depositionally distinct from a terrestrial-marine transitionary shoreline environment. We compare these changes with those of marine environments previously identified in the Mary Rose material, and those of continental waters (lakes) previously identified in the Cerro de la Garita (Concud) site, and we document this against bacterially related changes observed from terrestrial contexts. A new microstructural change identified in material from terrestrial sites is also described relating to rootlet damage. By considering microstructural change in skeletal tissues, it is maybe possible to ascribe environmental context, or, to better understand the complexity of material presented by transitionary environments. 相似文献
147.
Abraham Verghese Suresh Devi Thangam Senthil Kumar Radhakrishnan Nallur Kothandaraman Krishna Kumar Gopalakrishna Pommaiah Shetty 《Biocontrol Science and Technology》2018,28(10):961-969
ABSTRACTConservation biological control is an approach to enhance the efficacy of natural enemies by ensuring their availability in an agro-ecosystem on a long temporal scale. An increased survival often leads to better fecundity and improved behaviour of the natural enemies, which in turn ensures sustainable pest management. This paper, apart from being a concise review of conservation biological control, deals with selected India-specific case studies and field experiences on habitat manipulation and refugia. Results from a Bengaluru-based study during 2012–2015 on conservation biological control in an organic mango ecosystem are also presented. It also dwells briefly on conservation of insectivorous birds and touches upon conservation biocontrol with respect to entomopathogenic microorganisms and plant disease antagonists. 相似文献
148.
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150.
Feather‐degrading bacteria,uropygial gland size and feather quality in House Sparrows Passer domesticus
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Feathers are dead integumentary structures that are prone to damage and thus show gradual degradation over the course of a year. This loss of quality might have negative fitness consequences. Feather‐degrading bacteria are some of the most prevalent feather‐degrading organisms, yet the relationship between feather‐degrading bacteria load and flight feather quality has rarely been assessed. We studied this relationship in free‐living House Sparrows during breeding and non‐breeding annual lifecycle stages. We also considered the size of the uropygial gland, given the antimicrobial function of its secretions, and the effect of body condition. The number of feather holes was positively associated with feather‐degrading bacteria load and was negatively related to uropygial gland size and body condition during the breeding season in both sexes. In the non‐breeding season we found the same relationships, but only in females. The degree of feather wear was unrelated to any of the variables measured during the breeding season, whereas it was negatively associated with uropygial gland size and positively with feather‐degrading bacteria load in the non‐breeding season, but only in females. Our results suggest that feather‐degrading bacteria may induce the formation of feather holes, but play only a minor role in the abrasion of flight feathers. 相似文献