Lithotrophic microorganisms of the oxidative cycles of sulfur and iron

The review deals with sulfur bacteria (the first chemolithotrophs ever studied) and with the acidophilic bacteria of sulfur and iron cycles which were investigated as a result of Winogradsky’s discovery. The diversity of these organisms and the factors and mechanism of its origin are emphasized; their metabolic functions and nutritional regulation are discussed.     

Interaction of the sulfur and iron cycles in the Tinto River ecosystem

The identification, in the Tinto River (IberianPyritic Belt), of iron- and sulfur-oxidizingprokaryotes responsible for the extremeconditions of acidity (mean pH 2.3) and highconcentration of heavy metals found in itswaters (Fe, Cu, Zn, As, Cr), together withiron- and sulfur-reducing prokaryoticactivities, strongly suggest the coupledoperation of the iron and the sulfur cycles inthis ecosystem.     

冶金微生物的铁硫代谢多样性及其与矿物的相互作用

生物冶金是利用微生物铁硫元素代谢活性加速硫化矿物氧化溶解,并对其中有价金属加以提取回收的技术。冶金系统中微生物的代谢多样性及其耦合功能网络,尤其是以铁硫代谢途径为主的功能网络,在硫化矿物加速氧化溶解过程中承担了重要作用,是生物冶金技术理论研究的核心领域。本文归纳了冶金系统中多样化的微生物物种及其铁硫代谢途径,并从微生物代谢耦合角度探讨了微生物代谢多样性与矿物的相互作用。     

原核微生物的硫功能菌

总结迄今已经发现鉴定的原核微生物中磂菌48属150多种,绿硫菌6属20余种,紫硫菌33属近百种,硫菌23属56种,脱硫化功能菌50属210多种,脱硫和脱硫化物功能菌20多属50多种,硫歧化菌1属3种,共计170余属600余种。这些硫菌根据功能分类,大致上可以分成硫氧化、硫还原和硫歧化菌,对于自然界硫循环起着至关重要的作用。     

深海微生物高压适应与生物地球化学循环

深海是典型的高压环境,嗜压微生物是深海生态系统中的重要类群.随着深海采样技术的发展及高压微生物特殊培养设备的开发,已从深海环境中分离到一系列嗜压微生物,包括一些常压环境不能生长的严格嗜压菌.对这些嗜压菌的研究,不仅对微生物适应极端高压环境的机制有一定了解,而且发现了一些特殊的代谢产物.研究微生物高压嗜压机理,还有助于探索地球生命的温度压力极限及生命起源和演化等科学问题.从深海嗜压微生物多样性、深海微生物高压环境适应机理及深海微生物在生物地球化学循环中的作用等方面对嗜压微生物的研究进展进行综述.     

Influence of water management on the active root-associated microbiota involved in arsenic,iron, and sulfur cycles in rice paddies

Applied Microbiology and Biotechnology - In recent years, the role of microorganisms inhabiting rice rhizosphere in promoting arsenic contamination has emerged. However, little is known concerning...     

Microbial processes of the carbon and sulfur cycles in the Chukchi Sea

The research performed in August 2004 within the framework of the Russian-American Long-term Census of the Arctic (RUSALCA) resulted in the first data concerning the rates of the key microbial processes in the water column and bottom sediments of the Bering strait and the Chukchi Sea. The total bacterial counts in the water column varied from 30 x 10(3) cells ml(-1) in the northern and eastern parts to 245 x 10(3) cells ml(-1) in the southern part. The methane content in the water column of the Chukchi sea varied from 8 nmol CH4 l(-1) in the eastern part of the sea to 31 nmol CH4 l(-1) in the northern part of the Herald Canyon. Active microbial processes occurred in the upper 0-3 cm of the bottom sediments; the methane formation rate varied from 0.25 to 16 nmol CH4 dm(-3) day(-1). The rates of methane oxidation varied from 1.61 to 14.7 nmol CH4 dm(-3) day(-1). The rates of sulfate reduction varied from 1.35 to 16.2 micromol SO4(2-) dm(-3) day(-1). The rate of methane formation in the sediments increased with depth, while sulfate reduction rates decreased (less than 1 micromol SO4(2-) dm(-3) day(-1)). These high concentrations of biogenic elements and high rates of microbial processes in the upper sediment layers suggest a specific type of trophic chain in the Chukchi Sea. The approximate calculated balance of methane emission from the water column into the atmosphere is from 5.4 to 57.3 micromol CH4 m(-2) day(-1).     

Microbial processes of the carbon and sulfur cycles in the White Sea

The present paper contains the results of our microbiological and biogeochemical investigations carried out during a series of expeditions to the White Sea in 2002–2006. The studies were conducted in the open part of the White Sea, as well as in the Onega, Dvina, and Kandalaksha bays. In August 2006, the photosynthetic productivity in the surface water layer was low (47–145 mg C m^?2 day^?1). Quantitative characteristics of microbial numbers and activity of the the key microbial processes occurring in the water column of the White Sea were explored. Over the 5-year period of observations, the total number of bacterial cells in the surface layer of the water column varied from 50 to 600 thousand cells ml^?1. In August 2006, bacterioplankton production (BP) was estimated to be 0.26–3.3 μg C l^?1 day^?1; the P/B coefficient varied from 0.22 to 0.93. The suspended organic matter had a lighter isotope composition (from ?28.0 to ?30.5‰) due to the predominance of terrigenous organic matter delivered by the Northern Dvina waters. The interseasonal and interannual variation coefficients for phytoplankton production and BP numbers are compared. The bacterioplankton community of the White Sea’s deep water was found to be more stable than that of the surface layer. In the surface layer of bottom sediments, methane concentration was 0.2–5.2 μl dm^?3; the rate of bacterial sulfate reduction was 18–260 μg S dm^?3 day^?1; and the rates of methane production and oxidation were 24–123 and 6–13 nl CH₄ dm^?3 day^?1, respectively. We demonstrated that the rates of microbial processes of the carbon and sulfur cycles occurring in the sediments of the White Sea basin were low.     

Microbial processes of the carbon and sulfur cycles in the Chukchi Sea

The research performed in August 2004 within the framework of the Russian-American Long-term Census of the Arctic (RUSALCA) resulted in the first data concerning the rates of the key microbial processes in the water column and bottom sediments of the Bering strait and the Chukchi Sea. The total bacterial counts in the water column varied from 30 × 10³ cells ml^?1 in the northern and eastern parts to 245 × 10³ cells ml^?1 in the southern part. The methane content in the water column of the Chukchi sea varied from 8 nmol CH₄l^?1 in the eastern part of the sea to 31 nmol CH₄l^?1 in the northern part of the Herald Canyon. Microbial activity occurred in the upper 0–3 cm of the bottom sediments; the methane formation rate varied from 0.25 to 16 nmol CH₄dm^?3 day^?1. The rates of methane oxidation varied from 1.61 to 14.7 nmol CH₄dm^?3 day^?1. The rates of sulfate reduction varied from 1.35 to 16.2 μmol SO ₄ ^2? dm^?1 day^?1. The rate of methane formation in the sediments increased with depth, while sulfate reduction rates decreased (less than 1 μmol SO ₄ ^2? dm^?3 day^?1). These high concentrations of biogenic elements and high rates of microbial processes in the upper sediment layers suggest a specific type of trophic chain in the Chukchi Sea. The approximate calculated balance of methane emission from the water column into the atmosphere is from 5.4 to 57.3 μmol CH₄m^?2 day^?1.     

微生物铁载体运输系统

铁是大多数生物生长所必需的元素,在生命活动中占有极其重要的地位.尽管自然界中铁元素含量丰富,但是大多敬好氧生物包括微生物都面临着铁缺乏的问题,铁载体运输系统是微生物获得铁元素的重要途径.本文就铁载体运输系统的组成、调控机制及当前微生物中的铁载体运输系统的进展作以综述.     

Lithotrophic growth and hydrogen metabolism by Clostridium magnum

Clostridium magnum, originally described as a non-autotrophic homoacetogenic bacterium, was found to be able to grow with H2/CO2, formate, or methanol with stoichiometric acetate formation, provided that the growth medium contained at least 0.025% (w/v) yeast extract. Hydrogen was also formed as a byproduct of glucose fermentation, and was consumed again after glucose consumption. Hydrogen formation from glucose was independent of growth conditions and reached similar maximal concentrations in mineral media with or without ammonia added as well as in non-growing cultures or in the presence of carbon monoxide.     

Evolution of iron and oxygen biogeochemical cycles during the Precambrian

Iron (Fe) is an essential element for life, and its geochemical cycle is intimately linked to the coupled history of life and Earth's environment. The accumulated geologic records indicate that ferruginous waters existed in the Precambrian oceans not only before the first major rise of atmospheric O₂ levels (Great Oxidation Event; GOE) during the Paleoproterozoic, but also during the rest of the Proterozoic. However, the interactive evolution of the biogeochemical cycles of O₂ and Fe during the Archean–Proterozoic remains ambiguous. Here, we develop a biogeochemical model to investigate the coupled biogeochemical evolution of Fe–O₂–P–C cycles across the GOE. Our model demonstrates that the marine Fe cycle was less sensitive to changes in the production rate of O₂ before the GOE (atmospheric pO₂ < 10⁻⁶ PAL; present atmospheric level). When the P supply rate to the ocean exceeds a certain threshold, the GOE occurs and atmospheric pO₂ rises to ~10⁻³–10⁻¹ PAL. After the GOE, the marine Fe(II) concentration is highly sensitive to atmospheric pO₂, suggesting that the marine redox landscape during the Proterozoic may have fluctuated between ferruginous conditions and anoxic non-ferruginous conditions with sulfidic water masses around continental margins. At a certain threshold value of atmospheric pO₂ of ~0.3% PAL, the primary oxidation pathway of Fe(II) shifts from the activity of Fe(II)-utilizing anoxygenic photoautotrophs in sunlit surface waters to abiotic process in the deep ocean. This is accompanied by a shift in the primary deposition site of Fe(III) hydroxides from the surface ocean to the deep sea, providing a plausible mechanistic explanation for the observed cessation of iron formations during the Proterozoic.     

Seasonal cycles of mitochondrial ADP sensitivity and oxidative capacities in trout oxidative muscle

Mitochondria from red myotomal muscle of rainbow trout, Oncorhynchus mykiss, showed seasonal cycles of their maximal rates of substrate oxidation (nmol · min⁻¹ mg⁻¹ mitochondrial protein) and their apparent ADP affinity (Km_app), as well as in the thermal sensitivity of these properties. Increases in the maximal capacity of pyruvate oxidation were sufficient to compensate for seasonal changes in temperature, except during the winter months when rates at habitat temperature were depressed relative to other periods. The ADP affinity of isolated mitochondria was highest during cold months. Thus, the Km_app for ADP at habitat temperature showed less seasonal variation than the ADP Km_app at a given temperature. A loss in ADP affinity with decreasing temperature occurred through much of the year, and only was definitively suppressed in December and July. Both the ADP affinity and the maximal oxidative capacities of muscle mitochondria seem to be regulated parameters. Accepted: 10 June 1999     

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。     

Microbial processes of carbon and sulfur cycles in lake Mogil'noe]

In the beginning of summer 1999, complex microbiological and biogeochemical investigations of meromictic Lake Mogil'noe (Kil'din Island, Barents Sea) were carried out. The analysis of the results shows clearly pronounced vertical zonality of the microbial processes occurring in the water column of the lake. To a depth of 8 m, the total number and activity of microorganisms was limited by the relatively low content of organic matter (OM). In the upper part of the hydrogen-sulfide zone of the lake (beginning at a depth of 8.25 m), the content of particulate OM and the microbial number sharply increased. In this zone, the daily production of OM during anaerobic photosynthesis at the expense of massive development of colored sulfur bacteria reached 620 mg C/m2, which was twofold greater than the daily production of phytoplankton photosynthesis and led to a considerable change in the isotopic composition (delta 13 C) of the particulate OM. In the same intermediate layer, the highest rates of sulfate reduction were recorded, and fractionation of stable sulfur isotopes occurred. Below 10 m was the third hydrochemical zone, characterized by maximum concentrations of H2S and CH4 and by a relatively high rate of autotrophic methanogenesis. The comparison of the results obtained with the results of investigations of previous years, performed in the end of summer, shows a decrease in the intensity of all microbial processes inspected. An exception was anoxygenic photosynthesis, which can utilize not only the de novo formed H2S but also the H2S accumulated in the lake during the winter period.