Colonisation of polyurethane reticulated foam biomass support particle by methanogen species

Summary The ability of methanogen species to colonise reticulated polyurethane foam biomass support particles (BSP) in a continuous culture system using formate as carbon source was investigated. Scanning electron micrograph evidence and biomass measurements indicate that two methanogen species effectively colonised within the the matrix of the support particle.The freely suspended colonised BSP are resistant to washout, and a comparison of methane output of the immobilised culture and a liquid culture of the methanogens indicates the potential for process intensification of methane production.     

Levels of coenzyme F420, coenzyme M, hydrogenase, and methylcoenzyme M methylreductase in acetate-grown Methanosarcina

Methanosarcina barkeri strain 227 maintained on an acetate medium for 2 years was found to possess hydrogenase, methylcoenzyme M methylreductase, coenzyme F420, and coenzyme M. The levels of these constituents in acetate-grown cells were similar to those found in cells of the same strain grown on methanol or hydrogen and carbon dioxide.     

Stimulation of the methyltetrahydromethanopterin: coenzyme M methyltransferase reaction in cell-free extracts of Methanobacterium thermoautotrophicum by the heterodisulfide of coenzyme M and 7-mercaptoheptanoylthreonine phosphate

The conversion of formaldehyde to methylcoenzyme M in cell-free extracts of Methanobacterium thermoautotrophicum was stimulated up to 10-fold by catalytic amounts of the heterodisulfide (CoM-S-S-HTP) of coenzyme M and 7-mercaptoheptanoylthreonine phosphate. The stimulation required the additional presence of ATP, also in catalytic concentrations. ATP and CoM-S-S-HTP were mutually stimulatory on the methylcoenzyme M formation and it was concluded that the compounds were both involved in the reductive activation of the methyltetrahydromethanopterin: coenzyme M methyltransferase. Micromolar concentrations of benzyl viologen or cyanocobalamin inhibited the formaldehyde conversion; these compounds, however, strongly stimulated the reduction of CoM-S-S-HTP. The results described here closely resemble observations made on the activation and reduction of CO₂ to formylmethanofuran indicating that this step and the reductive activation of the methyltransferase are controlled by some common mechanism.Abbreviations HS-CoM Coenzyme M, 2-mercaptoethanesulfonate - CH₃S-CoM methylcoenzyme M, 2-(methylthio)ethanesulfonate - H₄MPT 5,6,7,8-tetrahydromethanopterin - MFR methanofuran - HS-HTP 7-mercaptoheptanoylthreonine phosphate - CoM-S-S-HTP the heterodisulfide of HS-CoM and HS-HTP - BES 2-bromoethanesulfonate - TES N-tris(hydroxymethyl)methyl-2-aminoethanesulfonate - CN-Cbl cyanocobalamin - HO-Cbl hydroxycobalamin - HBI 5-hydroxybenzimidazole - DMBI 5,6-dimethylbenzimidazole     

Preparation of coenzyme M analogues and their activity in the methyl coenzyme M reductase system of Methanobacterium thermoautotrophicum.

A number of 2-(methylthio)ethanesulfonate (methyl-coenzyme M) analogues were synthesized and investigated as substrates for methyl-coenzyme M reductase, an enzyme system found in extracts of Methanobacterterium thermoautotrophicum. Replacement of the methyl moiety by an ethyl group yielded an analogue which served as a precursor for ethane formation. Propyl-coenzyme M, however, was not converted to propane. Analogues which contained additional methylene carbons such as 3-(methylthio)propanesulfonate or 4-(methylthio)butanesulfonate or analogues modified at the sulfide or sulfonate position, N-methyltaurine and 2-(methylthio)ethanol, were inactive. These analogues, in addition to a number of commercially available compounds, also were tested for their ability to inhibit the reduction of methyl-coenzyme M to methane. Bromoethanesulfonate and chloroethanesulfonate proved to be potent inhibitors of the reductase, resulting in 50% inhibition at 7.9 X 10(6) M and 7.5 X 10(5) M. Analogues to coenzyme M which contained modifications to other regions were evaluated also and found to be weak inhibitors of methane biosynthesis.     

Estimation of the biomass of plankton

Summary A mathematical function is demonstrated in the numbers of individuals of the various species in a planktonic biocoenosis. The logarithms of the numbers form a Gauss or normal probability curve. A similar probability relation is found in the volumes of the individuals of the various species as well as in the biomass of the various populations.This relationship in the numbers is caused by the effect of the numerous ecological factors influencing the rate of proliferation of the various plankton species. The cause of this relationship concerning the volumes of the various species is not understood. The relationship between the various biomasses is the mathematical product of number and mean volume.An approximate hyperbolic function can be derived from the population volumes and with the aid of a simple equation the plankton biomass is calculated. A modus operandi is given to abbreviate the work necessary to determine the plankton biomass with Lohmann's method. Only ten or twenty of the most dominant populations out of all species present in a plankton sample, have to be counted and measured.The biomasses of the populations in various plankton samples may easily be compared using the hyperbolic or the probability relationship.The biomasses of plankton in various habitats may easily be compared in a graphic way. The logarithms of the biomasses found during the year follow a probability curve and may be plotted and compared on a cumulative logarithmic probability graph.The number of organisms of each species to be counted depends on the degree of accuracy and has to be about a hundred. A chance determined spread is always found in plankton counts.The spatial distribution of most plankters shows a very broad spread. Therefore, sampling at ten places and working with the mean of the ten samples is compulsory.Some gregariously living zooplankters form bunches in the water. A reliable mean may be calculated using the hyperbolic function which seems to describe their densities at the various places.From the existing methods of collection of plankton the rotary, electric pump is chosen. A translucent hose with a special and moving mouth is let down into the water. First the water passes through the plankton-net and after that through the pump and the water-meter. A series of 7 samples of increasing decimal volumes is drawn in this way. From these samples the plankton is concentrated and fractionated by means of two sedimentation chambers, four small plankton sieves and three plankton nets. The sieves and nets have various standardized meshes.Square counting chambers of 10 cm² area are used. These chambers have a thin glass bottom and a broad rim. The sedimentation chambers and the small plankton sieves fit on and into the chambers thus minimizing the loss of organisms.The plankton organisms are enumerated by means of an inverted microscope projecting the image on a ground glass which makes counting easier. Only those organisms seen within a measured square on the ground glass are counted.By standardization of the sample volumes, the magnifications of the microscope and the dimensions of the squares the conversion factors are so simple that only zeros or a decimal point have to be placed in the number counted to obtain the result.International standardization of the method of estimation of the biomass of plankton and the expression of the results is proposed.     

Levels of coenzyme F420, coenzyme M, hydrogenase, and methylcoenzyme M methylreductase in acetate-grown Methanosarcina.

Methanosarcina barkeri strain 227 maintained on an acetate medium for 2 years was found to possess hydrogenase, methylcoenzyme M methylreductase, coenzyme F420, and coenzyme M. The levels of these constituents in acetate-grown cells were similar to those found in cells of the same strain grown on methanol or hydrogen and carbon dioxide.     

Methanogenesis by methanogen species immobilised on reticulated foam biomass support particles. Inhibition of methane production at high substrate concentrations

Summary The rate of methanogenesis by a substrate depleted methanogenic culture immobilised on reticulated polyurethane foam particles became increasingly inhibited at –S>300 mM. (–S=Reactor substrate concentration). Inhibition was duplicated by the sequential addition of metabolically inert sorbitol to cultures 40–60 mins after initiating methane production with formate (–S<300 mM).     

Estimation of the microbial biomass in tidal flat sediment by fumigation-extraction

A transect of ten profiles was laid out in 20 m intervals on a tidal sand flat approximately 100 m from the east shore of Sylt until the next tideway was reached. Sediment samples were taken from 0–2 cm depth (oxic layer) and 2–4 cm depth (anoxic layer). The average content of organic carbon (C) was 2.41 mg g⁻¹ in the oxic layer and 1.86 mg g⁻¹ in the anoxic layer. The organic C content correlated positively with non-biomass C, 0.5M K₂SO₄ extractable C, total nitrogen (N), cation exchange capacity (CEC), and the textural classes <200 μm, and negatively correlated with the coarse sand fraction. The average total C:N ratio was 7.0 in the oxic layer and 6.7 in the anoxic layer, indicating that the C input comes entirely from the microflora. CHCl₃-labile C was measured by the fumigation-extraction method and was converted to microbial biomass C (values in brackets). The average content of CHCl₃-labile C was 407 μg g⁻¹ (903 μg g⁻¹) in the oxic layer and 214 μg g⁻¹ (476 μg g⁻¹) in the anoxic layer. CHCl₃-labile C did not correlate with CEC and the textural classes <200 μm, indicating that conditions other than the physical environment determine this fraction (C input, grazing).     

荒漠草原牧草生物量的遥感估算及空间分布

应用2005年5-10月份EOS/MODIS资料,采用光能利用率算法,估算了中国西北荒漠绿洲区域NPP,并结合地上生物量观测资料,建立了基于NPP的地上生物量估算模型,同时分析了生物量和NPP时空分布特征。结果表明,2005年牧草生长期内NPP的变化基本是6、7月份最大,其它月份较小,5-6月份是牧草叶面积变化比较大的时期,也是NPP变化比较显著的时期;生物量模型估算得到的44个样本的生物量误差基本都小于20%,说明模型能够反映牧草的实际生长状况;不同荒漠牧草对光的利用能力和对CO2同化能力有很大差异,骆驼刺、红砂、黑果枸杞是荒漠牧草生物量较大的牧草类型;牧草类型、牧草盖度以及平均高度是造成不同牧草产量相差较大的重要原因。     

几种荒漠植物地上生物量估算的初步研究

在调查植物样方的基础上,利用植株冠幅特征如冠幅长与宽、株高、基径、新生枝条数、总枝条数等作为变量建立了估算典型荒漠植物地上生物量的模型,利用植株冠幅长与宽所建拟合方程对估算琵琶柴灌丛生物量的精确度较高,经验证,预测值与实测值的相关系数为O．9989,相对误差在4．79％～10．12％之间利用植株株高、基径所建拟合方程对估算梭梭、多枝柽柳生物量计算值与实测值的相关系数在0.9418以上,显著性检验表明相关系数均为极显著经验证,预测值与实测值的相关系数分别为0．9902和0．9875．相对误差分别为6．87％～19．22％和7．49％～18．47％。研究表明,在大面积荒漠植物生物量研究中,利用植株冠幅特征作为变量来估算琵琶柴灌丛地上生物量方法简便可行,用来估算梭梭、多枝柽柳等灌木地上生物量时存在一定误差     

Estimation of Methanogen Biomass by Quantitation of Coenzyme M

Determination of the role of methanogenic bacteria in an anaerobic ecosystem often requires quantitation of the organisms. Because of the extreme oxygen sensitivity of these organisms and the inherent limitations of cultural techniques, an accurate biomass value is very difficult to obtain. We standardized a simple method for estimating methanogen biomass in a variety of environmental matrices. In this procedure we used the thiol biomarker coenzyme M (CoM) (2-mercaptoethanesulfonic acid), which is known to be present in all methanogenic bacteria. A high-performance liquid chromatography-based method for detecting thiols in pore water (A. Vairavamurthy and M. Mopper, Anal. Chim. Acta 78:363–370, 1990) was modified in order to quantify CoM in pure cultures, sediments, and sewage water samples. The identity of the CoM derivative was verified by using liquid chromatography-mass spectroscopy. The assay was linear for CoM amounts ranging from 2 to 2,000 pmol, and the detection limit was 2 pmol of CoM/ml of sample. CoM was not adsorbed to sediments. The methanogens tested contained an average of 19.5 nmol of CoM/mg of protein and 0.39 ± 0.07 fmol of CoM/cell. Environmental samples contained an average of 0.41 ± 0.17 fmol/cell based on most-probable-number estimates. CoM was extracted by using 1% tri-(N)-butylphosphine in isopropanol. More than 90% of the CoM was recovered from pure cultures and environmental samples. We observed no interference from sediments in the CoM recovery process, and the method could be completed aerobically within 3 h. Freezing sediment samples resulted in 46 to 83% decreases in the amounts of detectable CoM, whereas freezing had no effect on the amounts of CoM determined in pure cultures. The method described here provides a quick and relatively simple way to estimate methanogenic biomass.     

沈阳城市森林绿量测算

借助ARC/GIS地理信息系统,以“平面量推算平面量”的方法,测算了沈阳市城市森林的绿量.结果表明:沈阳市城市森林不同类型单位面积绿量以风景游憩林最高,为3·86m2·m-2;生态公益林最低,为2·27m2·m-2;城市森林分布区单位面积绿量为2·99m2·m-2;城区单位面积绿量为0·25m2·m-2.沈阳城市森林总体绿量约为1·13×108m2·其中,附属林为4·15×107m2,占36·64%;生态公益林2·72×107m2,占23·99%;风景游憩林2·20×107m2,占19·38%;道路林1·84×107m2,占16·20%;生产经营林0·43×107m2,占3·79%.经检验,平面量推算平面量方法测算精度达到91·81%(α=0·05).     

Estimation of fish biomass using environmental DNA

Environmental DNA (eDNA) from aquatic vertebrates has recently been used to estimate the presence of a species. We hypothesized that fish release DNA into the water at a rate commensurate with their biomass. Thus, the concentration of eDNA of a target species may be used to estimate the species biomass. We developed an eDNA method to estimate the biomass of common carp (Cyprinus carpio L.) using laboratory and field experiments. In the aquarium, the concentration of eDNA changed initially, but reached an equilibrium after 6 days. Temperature had no effect on eDNA concentrations in aquaria. The concentration of eDNA was positively correlated with carp biomass in both aquaria and experimental ponds. We used this method to estimate the biomass and distribution of carp in a natural freshwater lagoon. We demonstrated that the distribution of carp eDNA concentration was explained by water temperature. Our results suggest that biomass data estimated from eDNA concentration reflects the potential distribution of common carp in the natural environment. Measuring eDNA concentration offers a non-invasive, simple, and rapid method for estimating biomass. This method could inform management plans for the conservation of ecosystems.     

Estimation of Trichoderma QM 9414 biomass and growth rate by indirect means

Trichoderma QM 9414 was aerobically grown on glucose as the sole carbon and energy sources in a chemostat culture. The specific rates of glucose consumption (Q_G), oxygen consumption (Q), and carbon dioxide production (Q) at the steady state were measured to estimate the growth and maintenance requirements. From the results it was estimated that 2 mol adenosine triphosphate (ATP) were produced when1 mol NADH was oxidized through the respiratory chain of this microorganism. The true growth yield for ATP (Y_ATP) and specific ATP consumption rate for maintenance (Q) calculated with this value were 0.0106 g dry cell/mmol ATP and 5.2 mmol ATP/g dry cell/hr, respectively. Using the relationships between specific growth rate (μ) and (Q) and between μ and Q_G obtained from chemostat-culture data, cell and glucose concentration histories were estimated from the carbon dioxide production rate during the batch culture. The estimated cell concentrations agreed with the experimentally measured values. Glucose concentration were slightly overestimated.     

Estimation of fungal biomass in a solid substrate by three independent methods

Summary Dry matter increase of Agaricus bisporus mycelium in liquid culture, was found to be directly proportional to quantities of fungal derived chitin and extracellular laccase for up to 28 days following inoculation. Fungal ergosterol showed a similar relationship to mycelial growth which was sustained for 56 days of culture. In cultures grown on autoclaved rye grain a correlation was found between the three biochemical indices and linear extension of the mycelium. Each method gave a similar biomass estimate for cultures grown on cereal grains.     

The role of zinc in the methylation of the coenzyme M thiol group in methanol:coenzyme M methyltransferase from Methanosarcina barkeri.

Methanol:coenzyme M methyltransferase from methanogenic archaea is a cobalamin-dependent enzyme composed of three different subunits: MtaA, MtaB and MtaC. MtaA is a zinc protein that catalyzes the methylation of coenzyme M (HS-CoM) with methylcob(III)alamin. We report zinc XAFS (X-ray absorption fine structure) results indicating that, in the absence of coenzyme M, zinc is probably coordinated by a single sulfur ligand and three oxygen or nitrogen ligands. In the presence of coenzyme M, one (N/O)-ligand was replaced by sulfur, most likely due to ligation of the thiol group of coenzyme M. Mutations in His237 or Cys239, which are proposed to be involved in ligating zinc, resulted in an over 90% loss in enzyme activity and in distinct changes in the zinc ligands. In the His237-->Ala and Cys239-->Ala mutants, coenzyme M also seemed to bind efficiently by ligation to zinc indicating that some aspects of the zinc ligand environment are surprisingly uncritical for coenzyme M binding.     

Investigation of methanogen population structure in biogas reactor by molecular characterization of methyl-coenzyme M reductase A (mcrA) genes

The methanogen community in biogas reactor running on cattle dung was investigated in two different seasons; summer (April, 36 °C) and winter (December, 24 °C), in the year 2004 by a culture-independent approach. Community structure was determined by phylogenetic analyses of 343 and 278 mcrA clones belonging to summer and winter month libraries, respectively. In summer month’s library, 41.7% clones were affiliated to Methanomicrobiales, 30% to Methanosarcinales, 19% to Methanobacteriales, 5% to Methanococcales and a total of 4.3% clones belonged to unclassified euryarchaeotal lineages. In winter month’s library, Methanomicrobiales encompassed 98.6% clones, and Methanobacteriales included 1.4% of total clone diversity. Biogas plant performance data collected during the winter month indicated significant reduction in daily biogas produced as compared to summer month because of lowering in ambient temperature and associated shift in microbial community. Results from this molecular study showed the existence of highly diverse and complex methanogens communities present in biogas plant.     

The MtsA subunit of the methylthiol:coenzyme M methyltransferase of Methanosarcina barkeri catalyses both half-reactions of corrinoid-dependent dimethylsulfide: coenzyme M methyl transfer

Methanogenesis from dimethylsulfide requires the intermediate methylation of coenzyme M. This reaction is catalyzed by a methylthiol:coenzyme M methyltransferase composed of two polypeptides, MtsA (a methylcobalamin:coenzyme M methyltransferase) and MtsB (homologous to a class of corrinoid proteins involved in methanogenesis). Recombinant MtsA was purified and found to be a homodimer that bound one zinc atom per polypeptide, but no corrinoid cofactor. MtsA is an active methylcobalamin:coenzyme M methyltransferase, but also methylates cob(I)alamin with dimethylsulfide, yielding equimolar methylcobalamin and methanethiol in an endergonic reaction with a K(eq) of 5 x 10(-)(4). MtsA and cob(I)alamin mediate dimethylsulfide:coenzyme M methyl transfer in the complete absence of MtsB. Dimethylsulfide inhibited methylcobalamin:coenzyme methyl transfer by MtsA. Inhibition by dimethylsulfide was mixed with respect to methylcobalamin, but competitive with coenzyme M. MtbA, a MtsA homolog participating in coenzyme M methylation with methylamines, was not inhibited by dimethylsulfide and did not catalyze detectable dimethylsulfide:cob(I)alamin methyl transfer. These results are most consistent with a model for the native methylthiol:coenzyme M methyltransferase in which MtsA mediates the methylation of corrinoid bound to MtsB with dimethylsulfide and subsequently demethylates MtsB-bound corrinoid with coenzyme M, possibly employing elements of the same methyltransferase active site for both reactions.