Molecular-sieve chromatography of humic substances extracted with chelating resin from chernozemic Ah horizons

Summary Humic substances extracted with chelating resin from a Dark Brown Chernozem (Typic Haploboroll) Ah, a Black Chernozem (Udic Haploboroll) Ah, and a Dark Gray Luvisol (Typic Cryoboralf) Ahe were fractionated by Bio-Gel P. The eluted material was combined to form three or four fractions for further characterization.Most of the extracted polydisperse humic substances of the three soils were eluted near V₀ and distributed around a single mean value. The ash content of this material varied from 1.36 to 1.78 per cent. Carboxyl acidity may thus be obtained without interference from any cations.The humic substances from the Dark Brown and Black Chernozem Ah gave similar elution profiles, whereas those from the Dark Gray Luvisol Ahe were less aliphatic and more aromatic in nature. The materials of low molecular weight had the highest content of ash, C, and carboxyl groups. They represented only 3.6 to 14.1 per cent of the C extracted and were considered, on the basis of increased C content, decreased optical density, and infrared spectral configurations, to consist of polynuclear, fused-ring, aromatic structures.     

Proximate analyses and predicting HHV of chars obtained from cocracking of petroleum vacuum residue with coal, plastics and biomass

Higher heating value (HHV) and analysis of chars obtained from cocracking of petroleum vacuum residue (XVR) with coal (SC), biomass (BG, CL) and plastics (PP, PS, BL) are important which define the energy content and determine the clean and efficient use of these chars. The main aim of the present study is to analyze the char obtained from cocracking in terms of their proximate analysis data and determination of the HHV of the chars. The char obtained from XVR+PP cocracking showed a HHV of 32.84 MJ/kg, whereas that from CL cracking showed a HHV of 18.52 MJ/kg. The experimentally determined heating values of the char samples obtained from cocracking have been correlated with the theoretical equation based on proximate analysis data. There exists a variety of correlations for predicting HHV from proximate analysis of fuels. Based upon proximate analysis data, the models were tested. The best results show coefficient of determination (R2) of 0.965 and average absolute and bias error of 3.07% and 0.41%, respectively. The heating values obtained from the model were in good agreement with that obtained by experiment. Proximate analysis of the chars obtained from the cocracking of XVR with coal, biomass and plastics showed that there exists a definite interaction of the reactive species, when they were cocracked together.     

On-line recovery of large molecules from mixtures using reciprocating size exclusion chromatography

Blue Dextran, a standard large molecule, was successfully recovered on-line from the aqueous mixture solution with nickel nitrate using a novel reciprocating size exclusion chromatography. After 7 cycles of repeating operations of frontal mode, 70% of Blue Dextran in the feed was isolated as a pure solution. On-line recovery of large molecules from the mixture is an unusual trial, comparing to the routine practice of filtration where small molecule is isolated from the mixture.     

Combining bio- and chemo-catalysis: from enzymes to cells, from petroleum to biomass

In the future, biomass will continue to emerge as a viable source of chemicals. The development of new industries that utilize bio-renewables provides opportunities for innovation. For example, bio- and chemo-catalysts can be combined in 'one pot' to prepare chemicals of commercial value. This has been demonstrated using isolated enzymes and whole cells for a variety of chemical transformations. The one-pot approach has been successfully adopted to convert chemicals derived from biomass, and, in our opinion, it has an important role to play in the design of a more sustainable chemical industry. To implement new one-pot bio- and chemo-catalytic processes, issues of incompatibility must be overcome; the strategies for which are discussed in this opinion article.     

Reduction of humic substances by halorespiring, sulphate-reducing and methanogenic microorganisms

Physiologically distinct anaerobic microorganisms were explored for their ability to oxidize different substrates with humic acids or the humic analogue, anthraquinone-2,6-disulphonate (AQDS), as a terminal electron acceptor. Most of the microorganisms evaluated including, for example, the halorespiring bacterium, Desulfitobacterium PCE1, the sulphate-reducing bacterium, Desulfovibrio G11 and the methanogenic archaeon, Methanospirillum hungatei JF1, could oxidize hydrogen linked to the reduction of humic acids or AQDS. Desulfitobacterium dehalogenans and Desulfitobacterium PCE1 could also convert lactate to acetate linked to the reduction of humic substances. Humus served as a terminal electron acceptor supporting growth of Desulfitobacterium species, which may explain the recovery of these microorganisms from organic rich environments in which the presence of chlorinated pollutants or sulphite is not expected. The results suggest that the ubiquity of humus reduction found in many different environments may be as a result of the increasing number of anaerobic microorganisms, which are known to be able to reduce humic substances.     

On-line recovery of large molecules and concentration of small molecules using reciprocating size exclusion chromatography with temperature swing

The reciprocating size exclusion chromatography (RSEC) was operated with swing between two temperatures in a synchronous way with flow direction to recover a large solute on-line from the mixture, in addition to the small solute concentration. The concentration of small solutes in RSEC with a temperature swing was made possible by taking advantage of the temperature-dependent swelling properties of the porous gel. After 7 cycles of frontal mode operation, 76% of Blue Dextran in the feed was recovered and nickel nitrate in the feed reservoir was concentrated by 13%.     

Size-exclusion high performance liquid chromatography of native trypsinogen, the denatured protein, and partially refolded molecules. Further evidence that non-native disulfide bonds are dominant in refolding the completely reduced protein

Size-exclusion high performance liquid chromatography was used to compare the Stokes radius of the mixed disulfide of trypsinogen refolded for 10 min with the Stokes radius of denatured trypsinogen in high concentrations of urea. After folding for 10 min, rechromatography of a collection of sequential fractions of an initial separation showed that the fractions display microheterogeneity as seen in the value of the Stokes radius of each fraction. These intermediate species differed in their Stokes radius, and each had a globular structure cross-linked by disulfide bonds. In contrast, when trypsinogen with the native disulfides intact was equilibrated at different concentrations of urea (0-8 M), a progressive increase in Stokes radius was observed with extent of unfolding. Rechromatography of a series of fractions collected at a specific urea concentration showed that each had the same Stokes radius as the fraction in the initial separation. Urea-denatured trypsinogen and partially refolded trypsinogen must therefore differ in the disulfide pairing that links regions of the polypeptide chain. These observations support the suggestion that non-native disulfide bonds are responsible for the many stable conformations that form early in the folding of the mixed disulfide of trypsinogen (Light, A., and Higaki, J.N. (1987) Biochemistry 26, 5556-5564). These intermediates initially are loose structures (large Stokes radius) that become more compact with time (decreasing Stokes radius). The intermediates must therefore undergo a continuing disulfide interchange until native disulfides form late in the process when the stable conformation of the native molecule is reached.     

Effects of humic substances derived from organic waste enhancement on the growth and mineral nutrition of maize

A physico-chemical process has been developed to transform and enhance lignocellulosic waste in liquid humic extracts: humic-like substances (HLS). The aim of this study was to determine the effects of HLS on plant physiology in order to consider their agricultural use as organic fertilizers. The effects of HLS were evaluated on maize seed germination, and their impact on growth, development and mineral nutrition was studied on maize plants cultivated under hydroponic conditions. The experimental results showed that HLS do not increase the percentage and rate of germination but enhance the root elongation of seeds thus treated. Positive effects were also observed on the whole plant growth as well as on root, shoot and leaf biomass. These effects can be related to the high water and mineral consumption of plants undergoing this treatment. The high water efficiency indicated that such plants produce more biomass than non-treated plants for the same consumption of the nutrient solution. Furthermore, the use of HLS induced a flowering precocity and modified root development suggesting a possible interaction of HLS with developmental processes. Considering the beneficial effect of HLS on different stages of plant growth, their use may present various scientific and economic advantages. The physico-chemical transformation of sawdust is an interesting way of enhancing organic waste materials.     

The role of dissolved organic matter, particularly free amino acids and humic substances, in freshwater ecosystems

1. Although the mass of dissolved organic matter (DOM) often exceeds that of living organisms in freshwaters, little is known about the roles of its constituent molecules as sources of energy and information for aquatic organisms. In the present review attention is focused on free amino acids (FAA) and humic substances (HS) as examples of labile and refractory components within DOM. 2. The following questions are addressed. (i) What are spatiotemporal patterns in the distribution of DOM, HS and FAA? (ii) What are the origins of the components of DOM and how are their concentrations regulated? (iii) What is the significance of the spatial and temporal distributional patterns of DOM, HS and FAA to detritivorous invertebrates and other organisms associated with them? (iv) What is the relevance of DOM to the food web concept and to the biochemical ecology of freshwater ecosystems? 3. Concentrations of DOM, FAA and HS within lentic ecosystems are ranked as follows: Sediment pore water > Air–water interface > Midwater column. Comparisons between water bodies show that the concentrations of labile constituents of DOM, such as FAA, are usually positively correlated with base cations, nutrients and biological activity. In contrast, HS concentrations are negatively correlated with base cations or nutrients but positively correlated with the rate of biological degradation (the maximum values occurring in the autumn). The FAA : HS ratios might serve therefore as an indicator of the potential productivity of a water body. 4. External sources of DOM in general, and FAA and HS in particular, include rainwater, windborne material, surface flow and groundwater. The relative importance of these allochthonous sources of DOM decreases along the length of lotic ecosystems and also with increase in size of lentic ecosystems. Internal sources of FAA and HS include synthesis or polymerization from existing organic matter, degradation of organic matter and release from both living and dead organisms. The net accumulation of DOM released by living bacteria, phytoplankton, epilithon, macrophytes and invertebrates is much reduced due to heterotrophic uptake. Hence, most of the allochthonous DOM in freshwater originates from dead organic matter deposited on the sediment. Phytoplankton-dominated ecosystems may, however, differ, as most of their DOM may be recycled within the water column. 5. The factors that determine the external concentrations of DOM, FAA and HS are discussed. Evidence is cited in support of the following testable hypotheses. (i) The rates of production of DOM components will be favoured by increasing base cation and nutrient concentrations. (ii) Colloidal clay, base cations, biopolymers and living organisms, particularly bacteria, facilitate the removal of HS. Consequently, base-rich eutrophic waters tend to have lower HS concentrations than oligotrophic, base-deficient waters. (iii) As a result of higher productivity and selective removal of FAA, eutrophic waters tend to have higher FAA concentrations than those that are oligotrophic. 6. Labile DOM components, such as FAA, act as sources of information for aquatic organisms. More research is needed in this field. There is a consensus that DOM acts as an important source of energy for aquatic bacteria, thus forming the microbial loop. However, higher eukaryotic organisms also utilize DOM, including components released by bacteria and plants as metabolic end-products and photoassimilates, respectively. As a result, these DOM components may be more important as food for macrodecomposers than the microdecomposers themselves. HS may also benefit aquatic organisms by promoting their growth and protecting them from inimical forces. Conversely, the removal of photons and the release of toxins by HS may be detrimental to aquatic organisms. 7. It is concluded that the central dogma of the foodweb, and its implicit assumption that the energy flow in aquatic ecosystems can be quantified solely by measuring rates of photosynthesis, ingestion of solid food and its digestion by higher organisms, is invalid. To extend our understanding of the role of DOM as a source of nutrition and information to aquatic organisms it is suggested that the subject should be studied within the context of ‘modules’ which have the following properties: (i) the components have co-evolved; (ii) the more vulnerable components will have protective mechanisms; (iii) the components will derive mutual benefits from co-existence; (iv) sedentary components will release kairomonal attractants or developmental primers; (v) living components will exchange energy and information; (vi) the module will collapse following the removal of strongly interactive keystone species. An example of a three-component, three-subset module, is provided by tubificid worms, epilithic bacteria and algae. A more complex module consisting of pulmonate snails, associated macrophytes, their epiphytic bacteria and algae has four components and six subsets. The elucidation of the interactive mechanisms within such modules demands an interdisciplinary approach, involving microbiology, biochemistry and behavioural biology.     

Composition,size, and biomass of zooplankton in large productive Florida lakes

Crustacean zooplankton data were compiled from long-term observational studies at seven large shallow Florida lakes, to determine whether there are general characteristics in regard to species composition, body size, and biomass. In particular, we examined whether patterns in body size and species richness fit empirical models developed by Stanley Dodson. The lakes included range in size from 125 to 1730 km² and encompass mesotrophic to hyper-eutrophic conditions. We found that zooplankton biomass was strongly dominated by one species of calanoid copepod—Arctodiaptomus dorsalis. Large daphnids were absent, and Cladocera assemblages were dominated by small taxa such as Ceriodaphnia, Chydorus, and Eubosmina. The total number of species of pelagic cladocerans (8–12) was consistent with Dodson’s predictions based on lake area. The average size of crustacean zooplankton in Florida lakes is small in comparison with temperate communities. A. dorsalis is the smallest calanoid copepod in North America, and the mean length of Cladocera (0.6 mm) is consistent with Dodson’s results that size decreases from temperate to tropical zones. Total biomass of crustacean zooplankton was very low, ratios of zooplankton to phytoplankton biomass (0.01–0.1) are among the lowest reported in the literature, and the zooplankton displayed short-lasting early spring peaks in biomass. Cladocera were almost entirely absent in spring and summer. Factors known to occur in Florida lakes, which appear to explain these characteristics of biomass, include intense fish predation and high summer water temperature.     

The effect of UV-B radiation and humic substances on growth and motility of the flagellate, Euglena gracilis

The effects of ultraviolet-B radiation (UV-B, 250–315nm) were determined on Euglena gracilis with respect to speed,phototactic orientation, specific growth rate, and in the presenceof humic substances. Humic substances had a protective effectwhen studying the speed and specific growth rate. However, thedegree of phototactic orientation decreased in UV-B radiationboth with and without humic substances. The inhibition of O₂evolution and speed was most pronounced when using cutoff filtersWG280 and WG295. The photosynthetic inhibitor DCMU (10^–6M) did not have any effect on the speed, but the 0₂ evolutiondecreased to zero. The effect of different wavelengths in theUV-B region on the speed of E.gracilis showed the maximum sensitivityat 280 and 290 nm.     

Bactenecins, defense polypeptides of bovine neutrophils, are generated from precursor molecules stored in the large granules

Bactenecins are highly cationic polypeptides of bovine neutrophil granules and exert in vitro a potent antimicrobial activity. We have previously purified two bactenecins, designated in an abbreviated form Bac7 and Bac5 from their approximate molecular masses of 7 and 5 kD (Gennaro, R., B. Skerlavaj, and D. Romeo. 1989. Infect. Immun. 57:3142-3146). Here we have studied the biosynthesis, processing, and localization of precursors of Bac7 and Bac5 in bovine bone marrow cells of the myeloid lineage. In vitro translation directed by mRNA isolated from these cells has shown that the primary translation products are preprobactenecins of 23.5 and 21 kD, and are processed to polypeptides of 20 and 15.8 kD, respectively. The 20-kD polypeptide is the granule storage form of Bac7, or proBac7, as also demonstrated by Western blot analysis of lysates of peripheral neutrophils. Between 15 and 50 min from the beginning of its biosynthesis the 15.8-kD polypeptide is converted into the 15-kD granule storage form of Bac5, or proBac5. As shown by immunogold EM, proBac7 and proBac5 are sorted and targeted to the matrix of the so called large granules, which are the predominant organelles in the cytoplasm of bovine neutrophils and are the exclusive store of the nonoxidative antimicrobial system of these cells. Solubilization of granules with Triton X-100 with concomitant unmasking of proteases leads to cleavage of the proforms to Bac7 and Bac5. Experiments performed with protease inhibitors suggest that the proteolytic cleavage is catalyzed in detergent-solubilized neutrophils by neutral serine protease(s), very likely derived from the azurophil granules.     

Pressurized extraction of unsaturated fatty acids and carotenoids from wet Chlorella vulgaris and Phaeodactylum tricornutum biomass using subcritical liquids

The objective of this study was to investigate the extraction of lipids, for example, mono‐ and polyunsaturated fatty acids (PUFA) as well as carotenoids, from wet microalgae biomass using pressurized subcritical extraction solvents, which meet the requirements of food and feed applications. To demonstrate the effect of the solvent and temperature on the lipid yield, we chose two microalgae species, viz. Chlorella vulgaris and Phaeodactylum tricornutum, differing in their biochemical composition fundamentally. In case of P. tricornutum, ethanol showed the highest fatty acid yield of 85.9% w/w. In addition to eicosapentaenoic acid (EPA), the ethanolic extracts contained exceptional amounts of fucoxanthin (up to 26.1 mg/g d. w.), which can be beneficial to protect unsaturated fatty acids from oxidation processes and in terms of human nutrition. For C. vulgaris, a fatty acid yield of 76.5% w/w was achieved from wet biomass using ethyl acetate at 150°C. In general, an increase in the extraction temperature up to 150°C was found to be important in terms of fatty acid yield when extracting wet microalgae biomass. The results suggest that it is possible to efficiently extract both fatty acids and carotenoids from wet microalgae by selecting suitable solvents and thus circumvent energy‐intensive drying of the biomass.     

黄土高原区不同植物凋落物搭配对土壤微生物量碳、氮的影响

黄土高原丘陵沟壑区进行的以退耕还林还草为主的生态建设,使得进入土壤生态系统有机物的种类和数量发生变化,不同种类凋落物混合对土壤微生物量碳、氮的影响是值得关注的问题。本文采用室内培养试验方法研究了采自黄土高原地区6种不同植物凋落物及等比例混合后对土壤微生物量碳、氮及矿质态氮含量的影响。结果表明,加入不同植物凋落物均显著提高了培养期间土壤微生物量碳、氮含量。总体平均,添加三种等量混合后植物凋落物的土壤微生物量碳、氮含量高于两种凋落物等量混合处理,而两种凋落物混合高于单种凋落物处理;土壤矿质态氮含量的变化则相反,即单种＞两种混合＞三种混合。单种和两种混合后土壤微生物量碳、氮含量与其碳氮显著相关,而三种凋落物混合后土壤微生物量碳、氮含量与其碳氮比无相关性,说明多种凋落物混合后土壤微生物量碳、氮含量受多种因素共同影响。因此,在黄土高原植被恢复重建中,有必要采用不同种类植物搭配,利用生物多样性促进生态系统健康持续发展。     

Quantitative estimation of peat,brown coal and lignite humic acids using chemical parameters, 1H-NMR and DTA analyses

Humic acids extracted from peats (P), brown coals (BC) and lignites (L), were characterized using different (chemical, 1H-nuclear magnetic resonance spectroscopy and differential thermal analysis) techniques. Fourteen variables were obtained from these analyses and only five were selected because uncorrelated in multiple partial correlation. The chosen variables were C concentration, aliphatic and aromatic components and the heat of reaction of the second exothermic peak. The multivariate discriminant analysis was performed on these variables and a discriminant function was obtained which was able to efficiently separate the P, BC and L. This function enables simple predictions on samples of unknown origin. The straightforward method proposed and the results obtained are discussed.     

Influence of mineral and organic fertilization on soil fungi,enzyme activities and humic substances in a long-term field experiment

Changes in microfungal communities, fungal activities and humic substances (HS) in agricultural soils kept under different fertilization regimes were observed and their causal relationships were investigated in a long-term field experiment. Fertilization did not change the abundance of HS-utilizing microfungi and, except for organic amendment alone, total culturable microfungi were also unaffected by this factor. Organic fertilization increased activities of manganese peroxidase (MnP) and proteinase, but decreased endo-1,4-beta-glucanase activity compared to the corresponding control without organic fertilization. In soils treated with mineral fertilizers, the activities of MnP, endo-1,4-beta-glucanase and proteinase were higher than in control without any mineral treatment. Both the aromaticity of fulvic acid and the molar mass of humic acid was lower in soil with organic fertilization, which may be a result of oxidative degradation mediated by higher MnP activity observed in treatments with organic fertilization.