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1.
Xylanase-induced reduction of chlorine dioxide consumption during elemental chlorine-free bleaching of different pulp types 总被引:4,自引:0,他引:4
Andreas M. Madlala Sadhvir Bissoon Suren Singh Lew Christov 《Biotechnology letters》2001,23(5):345-351
The potential of crude xylanase from Thermomyces lanuginosus and Xylanase P (a commercial xylanase) was evaluated in bleaching of various paper pulp types. Xylanases released chromophores and reducing sugars and decreased kappa number of pulps. Chlorine-bleached, alkali-extracted bagasse and post-oxygen kraft pulps, pretreated with enzymes, gained over 5 brightness points over controls. Biobleaching of soda-aq pulp with Xylanase P produced chlorine dioxide savings of up to 30% or 4.5 kg chlorine dioxide t–1 pulp. 相似文献
2.
【目的】筛选并鉴定西藏林芝八一镇土壤中产生抗肿瘤活性物质的放线菌。【方法】用平板稀释法分离放线菌, 用MTT法和纸碟法对放线菌发酵产物进行体外抗肿瘤与抑菌活性检测, 并用多相分类技术对抗肿瘤活性菌株进行鉴定。【结果】共分离出29株放线菌, 得到6个抑制体外肿瘤细胞增殖的活性菌株(20.7%), 同时它们也具有抑菌活性, 其中4株菌的检测样品对Hela细胞的抑制率达80%以上。多相分类研究表明, 6个活性菌株分别隶属于链霉菌属(Streptomyces)的3个已知物种的变种。【结论】林芝八一镇土壤放线菌中蕴藏抗肿瘤活性链霉菌, 是一个潜在的抗肿瘤药用微生物资源。 相似文献
3.
An alkalophilic laccase from Rheinheimera species isolate: Production and biobleaching of kraft pulp
Medium optimization was carried out to enhance laccase production from a novel Rheinheimera species, isolated from industrial effluent. Out of the 15 variables tested by Placket–Burman design (PBD)—yeast extract, soyabean meal, and peptone were the positively significant ones, enhancing laccase production. Both simple and complex sugars showed a negative effect on laccase production. Central composite design (CCD) of experiments, using the three positively significant variables in combinations, showed that laccase production was not affected by molar carbon, molar nitrogen levels or molar C/N ratio. Maximum laccase yield of 2.5 × 105 nkat L?1, 31 fold enhancement over the unoptimized medium, was achieved when soyabean meal (0.6%) was used alone as medium showing that laccase production was substrate dependent. Laccase was used, in the presence of 2 mM ABTS, for the biobleaching of eucalyptus kraft pulp resulting in kappa number reduction by 20% and brightness increase by 2.9%. Biobleaching improved further by sequential application of an alkalophilic xylanase (X) and laccase‐ABTS system (LAS) that decreased kappa number by 10, 15, and 35%, increased brightness by 2.7, 3.2, and 5.9% as compared to X treated, LAS treated and untreated control, respectively. XLAS treatment resulted in 15, 13, 10.9% increase in burst factor, tear factor, and viscosity with a 20% reduced consumption of elemental chlorine and hypochlorite. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012 相似文献
4.
Some properties of eucalyptus kraft pulp treated with xylanase from Aspergillus niger 总被引:2,自引:0,他引:2
Máximo C. Costa-Ferreira M. Duarte J. 《World journal of microbiology & biotechnology》1998,14(3):365-367
An Aspergillus niger isolate produced about 2500nkat xylanase/ml when cultivated in a medium containing 3% xylose. Application of the crude xylanolytic preparation to unbleached eucalyptus kraft pulp resulted in a decreased kappa number and increased brightness. Handsheets made from the xylanase-treated pulp after ECF bleaching retained good structural and mechanical characteristics. 相似文献
5.
AIMS: To determine the effect of environmental conditions on the production of extracellular lignocellulose-degrading enzymes by Streptomyces sp. F2621 and to assess the potential use of these enzymes in the hydrolysis of lignocellulose material. METHODS AND RESULTS: The production of extracellular lignocellulose-degrading enzymes, endoxylanase, endoglucanase and peroxidase during the growth of Streptomyces sp. F2621 in basal salts-yeast extract medium containing different carbon sources and the effect of a number of environmental parameters (e.g. carbon sources and concentrations, pH and temperature) were investigated. The highest endoxylanase (22.41 U ml(-1)) and peroxidase (0.58 U ml(-1)) activities were obtained after 2-4 days of incubation at 30 degrees C in a basal salts medium containing 0.4% (w/v) oat spelt xylan and 0.6% (w/v) yeast extract, corresponding to C : N ratio of 6 : 1. Cell-free extracellular enzyme preparations from the strain were capable of releasing both sugar and aromatic compounds during incubation with eucalyptus paper pulp, straw and xylan. Overall, 9.3% hydrolysis of xylan occurred after 24-h incubation. However the rates of hydrolysis of paper pulp and straw were approximately twofold less than xylan hydrolysis, although the total percentage hydrolysis of available substrate (24.5% and 16.3%, respectively) was greater than xylan hydrolysis. CONCLUSIONS: The high levels of enzyme production achieved under batch cultivation conditions, coupled with no significant production of endoglucanase during the growth phase of organism and the release of both sugar and aromatic compounds from paper pulp and straw signify the suitability for these enzymes for industrial applications such as pulp and paper production. SIGNIFICANCE AND IMPACT OF THE STUDY: The results highlight the environmental conditions for the production of extracellular lignocellulose-degrading enzymes by Streptomyces sp. F2621 and suggest the use of streptomycetes and/or their enzymes in industrial processes. 相似文献
6.
Banu Avcioglu Banu Eyupoglu Ufuk Bakir 《World journal of microbiology & biotechnology》2005,21(1):65-68
Xylanase production was performed by growing a Bacillus isolate on agricultural by-products, wheat straw, wheat bran, corn cobs and cotton bagasse. A maximum xylanase activity of 180 U/ml was obtained together with a cellulase activity of 0.03 U/ml on 4 (w/v) corn cobs. Electrophoretic analysis showed the presence of three endo--1, 4-xylanases having molecular weights of about 22, 23 and 40 kDa. Xylanolytic activity was stable up to 50 °C in the pH range of 4.5–10 and the highest activity was observed at 70 °C and pH 6.5. 相似文献
7.
Effects of a pulp and paper mill on the ecology of the La Trobe River,Victoria, Australia 总被引:1,自引:1,他引:0
Four riverine animal communities were measured to assess the impact of extensively treated wastewater from a pulp and paper mill on the lower La Trobe River in Victoria, Australia. Benthic macroinvertebrates in channel and bankside habitats were sampled using a new air-lift corer. Population density was expressed in relation to substrate volume. Other communities measured at five sites upstream and downstream of the mill's wastewater outfall were the zooplankton, and the animals associated with submerged littoral vegetation. Ten environmental variables were also measured during the two sampling periods.A total of 50 benthic macro-invertebrate taxa were dominated by Oligochaeta, Chironomidae and Bivalvia. Benthic communities upstream and downstream of the outfall were very similar. Benthic samples showed large unexplained variation between stations and seasons, despite the similarity of stations and the stratified sampling design, but within-sample variation was small. There was some evidence that benthic faunal patchiness was associated with patterns of stream-bed scouring and deposition in periods of high flow. Littoral samples collected 28 taxa, dominated by Decapoda and Hemiptera. The benthic and littoral communities were quite distinct, with only three species common to both.Only two of the biological and environmental variables responded to wastewater from the mill: total dissolved solids rose by 20–25% over upstream levels; and zooplankton density increased by 2–3 orders of magnitude. It was concluded that wastewater treatment had successfully avoided the major environmental problems often associated with pulp and paper mills. 相似文献
8.
Xylanase and Mannanase enzymes from Streptomyces galbus NR and their use in biobleaching of softwood kraft pulp 总被引:2,自引:0,他引:2
Enzymatic pretreatment of softwood kraft pulp was investigated using xylanase and mannanase, singly or in combination, either sequentially or simultaneously. Enzymes were obtained from Streptomyces galbus NR that had been cultivated in a medium, containing either xylan of sugar cane bagasse or galactomannan of palm-seeds, when they were used as sole carbon sources from local wastes in fermentation media. No cellulase activity was detected. Incubation period, temperature, initial pH values and nature of nutritive constituents were investigated. Optimum production of both enzymes was achieved after 5 days incubation on a rotary shaker (200 rpm) at 35 degrees C and initial pH 7.0. Partial purification of xylanase and mannanase in the cultures supernatant were achieved by salting out at 40-60 and 60-80% ammonium sulphate saturation with a purification of 9.63- and 8.71-fold and 68.80 and 62.79% recovery, respectively. The xylanase and mannanase from S. galbus NR have optimal activity at 50 and 40 degrees C, respectively. Both enzymes were stable at a temperature up to 50 degrees C. Xylanase and mannanase showed highest activity at pH 6.5 and were stable from 5.0 to 8.0 and from 5.5 to 7.5, respectively. The partial purified enzymes preparations of xylanase and mannanase enzymes showed high bleaching activity, which is an important consideration for industry. Xylanase was found to be more effective for paper-bleaching than mannanase. When xylanase and mannanase were dosed together (simultaneously), both enzymes were able to enhance the liberation of reducing sugars and improve pulp bleachability, possibly as a result of nearly additive interactions. The simultaneous addition of both enzymes was more effective in pulp treatment than their sequential addition. 相似文献
9.
The taxonomic position of an actinomycete isolated from an ultramafic soil in New Caledonia was examined using a polyphasic
approach. The organism, which was designated SFOCin 76, was found to have chemical and morphological properties typical of
streptomycetes and formed a distinct phyletic line in the Streptomyces violaceusniger clade of the 16S rDNA tree. It also showed a unique pattern of phenotypic properties that distinguished it from representatives
of all of the validly described species classified in this clade. It is, therefore, proposed that strain SFOCin 76 be classified
in the genus Streptomyces as Streptomyces yatensis sp. nov.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
A metagenomic xylanase gene (Mxyl) was successfully cloned into shuttle vector pWH1520 and expressed in Bacillus subtilis extracellularly. On induction with xylose, recombinant xylanase secretion commenced after 6 h. Identifying critical variables for recombinant xylanase production by one‐variable‐at‐time approach followed by optimization of the selected variables (xylose, inoculum density, incubation density) by response surface methodology (RSM) led to three‐fold enhancement in extracellular xylanase production (119 U mL?1). When the pulp was treated with recombinant xylanase at 80°C and pH 9.0, kappa number of the pulp was reduced with concomitant increase in brightness and 24% reduction in chlorine consumption. This is the first report on the expression of metagenomic xylanase gene in Bacillus subtilis extracellularly and its utility in developing an environment‐friendly pulp bleaching process. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1441–1447, 2013 相似文献
11.
Galina Matafonova Galina Shirapova Christian Zimmer Friedrich Giffhorn Valeriy Batoev Gert-Wieland Kohring 《International biodeterioration & biodegradation》2006,58(3-4):209
A pure culture of 2,4-dichlorophenol (2,4-DCP)-degrading bacteria was isolated from a natural enrichment that had been adapted to chlorophenols in the aeration pond of the Baikalsk pulp and paper mill (Russia). The bacteria were identified by 16S rDNA intergenic region analysis, using PCR with universal primers. Comparative analysis of the 16S rDNA sequence (1545 bp) in the GenBank database revealed that these bacteria are related to Bacillus cereus GN1. Degradation of 2,4-DCP was studied using this culture in liquid medium under aerobic conditions, at initial concentrations of 20–560 μM 2,4-DCP. The 2,4-DCP degradation rates by B. cereus GN1 could be determined at concentrations up to 400 μM. However, higher concentrations of 2,4-DCP (560 μM) were inhibitory to cell growth. 相似文献
12.
纸浆废液中有机物资源的利用 总被引:2,自引:1,他引:2
将硫酸盐纸浆废液浓缩后,100%用作生产木材胶粘剂的原料.对废液中木素进行活化处理,用酚醛树脂、PAPI增强废液胶的效果.结果表明,在废液中加入甲醛后,可提高废液中木素的反应活性;用30%甲阶酚醛树脂或20%PAPI作增强剂,可使废液混合胶代替纯酚醛树脂生产Ⅰ类胶合板;原料成本比纯酚醛树脂分别降低了55.5%和49.0%.该法充分利用了废液中的有机物资源,减少了环境污染,具有较好的经济、社会和生态效益.文中还运用红外光谱分析了废液制胶粘剂方法的可行性. 相似文献
13.
A. G. Colodey P. G. Wells 《Journal of Aquatic Ecosystem Stress and Recovery (Formerly Journal of Aquatic Ecosystem Health)》1992,1(3):201-226
This review examines the impact of pulp and paper mill effluents by comparing effects from Canada's east and west coasts at a time when revisions to the federal Fisheries Act (Pulp and Paper Effluent Regulations) are being finalized. Pulp and paper mill effluents from Canadian coastal mills were usually acutely toxic at source, and in many cases had marked deleterious effects on receiving waters due to toxicity, high biochemical oxygen demand (BOD), and total suspended solids (TSS) loadings. Extreme reductions in ambient dissolved oxygen, impacts on benthic and intertidal organisms, changes in water colour and primary productivity, have been demonstrated over the years and continue to cause environmental damage. Contamination of biota by a wide range of chlorinated organic compounds has been more recently the focus of investigations.While sublethal effects of lowered dissolved oxygen levels and suspended solids on the water column and bottom communities are well known, the potential effects of major organochlorine contamination of water (measured as Adsorbable Organic Halogens=AOX), sediments, and biota are not fully understood, especially under natural and perturbated conditions. The findings of recent North American and Scandinavian studies which describe liver enzyme activation, histological damage, reproductive and population level changes in fish, are a major concern as they are a sign of ecosystem stress and pathology.The environmental effects described herein are long-term impacts which will not respond quickly to changes in pollutant loading. Integrated site-specific assessments need to be undertaken to document ecosystem response to process and treatment improvements at mill sites. Current biomonitoring techniques including measures of population structure and ecosystem function are needed in addition to sensitive biochemical indicators of contaminant exposure. 相似文献
14.
Two basidiomycetous fungi (Merulius aureus syn. Phlebia sp. and an unidentified genus) and a deuteromycetous fungus (Fusarium sambucinum Fuckel MTCC 3788) were isolated from soils affected with effluents of a pulp and paper mill over several years. These isolates were immobilized on nylon mesh and the consortium was used for bioremediation of pulp and paper mill effluent in a continuously aerated bench-top bioreactor. The treatment resulted in the reduction of color, lignin and COD of the effluent in the order of 78.6%, 79.0% and 89.4% in 4 days. A major part of reductions in these parameters occurred within first 24h of the treatment, which was also characterized by a steep decline in the pH of the effluent. During this period, total dissolved solids, electrical conductivity and salinity of the effluent also registered marked decline. It is pertinent to note that this is the first report of bioremediation of pulp and paper mill effluent by an immobilized fungal consortium. 相似文献
15.
Peter B. Skals Anders Krabek Per H. Nielsen Henrik Wenzel 《The International Journal of Life Cycle Assessment》2008,13(2):124-132
Background Aims and Scope The pulp and paper (P&P) industry is traditionally known to be a large contributor to environmental pollution due its large
consumptions of energy and chemicals. Enzymatic processing, however, offers potential opportunities for changing the industry
towards more environmentally friendly and efficient operations compared to the conventional methods. The aims of the present
study has been to investigate whether the enzyme technology is a more environmentally sound alternative than the conventional
ways of producing paper. The study addresses five enzyme applications by quantitative means and discusses the environmental
potential of a range of other enzyme applications by qualitative means.
Methods LCA is used as analytical tool and modelling is facilitated in SimaPro software. Foreground LCA data are production/company
specific and collected from P&P technology service providers, specific P&P companies and P&P researchers. The background data
on energy systems, auxiliary chemicals, etc. are primarily taken from the ecoinvent database.
Results The study shows that fossil energy consumption and potential environmental impacts (global warming, acidification, nutrient
enrichment, photochemical smog formation) induced by enzyme production are low compared with the impacts that they save when
applied in bleach boosting, refining, pitch control, deinking, and stickies control.
Discussion The general explanation is that small amounts of enzyme provide the same function as large amounts of chemicals and that enzymatic
processes generally require less fossil energy inputs than conventional processes. Data quality assessments and sensitivity
analyses indicate that this observation is robust for all processes except deinking, although the results are subject to uncertainty
and much variation.
Conclusions and Recommendations The environmental improvements that can be achieved by application of enzymatic solutions in the P&P industry are promising.
To get a greater penetration of enzymatic solutions in the market and to harvest the environmental advantages of biotechnological
inventions, it is recommended that enzymatic solutions should be given more attention in, for instance, ‘Best Available Technology’
notes within the framework of the European Directive on Integrated Pollution Prevention and Control (IPPC).
ESS-Submission Editor: Roland Hischier (roland.hischier@empa.ch) 相似文献
16.
17.
Laccase for biobleaching of eucalypt kraft pulp by means of a modified industrial bleaching sequence
Biobleaching of kraft pulp is a possible application of laccase, but it has not been described in detail for complete industrial bleaching sequences yet. Therefore, in this work, the biobleaching of Eucalyptus globulus kraft pulp was performed using a modified industrial totally chlorine‐free sequence. The modification consisted in the substitution of an enzymatic delignification stage, based on the application of laccase from Trametes villosa, for the first alkaline extraction one. The enzymatic stage was performed with several synthetic and natural mediators, namely 1‐hydroxybenzotriazole (HBT), violuric acid (VA), methyl syringate, and syringaldehyde. Several pulp properties were analyzed after each stage of the bleaching process—kappa number, ISO brightness, viscosity, and optical properties of CIEL*a*b* system. The new biobleaching sequence improved the pulp properties, in comparison to the conventional bleaching sequence, if HBT or VA was used as mediators. VA was selected as the best mediator of those tested and the effect of its concentration in the enzymatic stage was subsequently studied. Reducing the initial concentration by 30%, the same pulp quality was obtained, but if the reduction attained 60%, an important decrease in pulp integrity was detected. The modified bleaching sequence could improve the bleached pulp properties (kappa number 10%, ISO brightness 1%, and viscosity 5%) in comparison to the mill sequence. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012 相似文献
18.
Damiano V.B. Bocchini D.A. Gomes E. Da Silva R. 《World journal of microbiology & biotechnology》2003,19(2):139-144
Alkalophilic Bacillus licheniformis 77-2 produced an extracellular alkali-tolerant xylanase with negligible cellulase activity in medium containing corn straw. The effectiveness of crude xylanase on treatment of eucalyptus Kraft pulp was evaluated. A biobleaching experiment was carried out to compare the chlorine saving with pulp treated and untreated by the enzyme. Two-stage bleaching was employed, using a ClO2 chlorination and NaOH extraction (DE sequence). With the enzymatic treatment, in order to obtain the same value of Kappa number and brightness, respectively 28.5 and 30% less ClO2 was required in comparison to the enzymatically untreated samples. 相似文献
19.
Large numbers of filamentous actinomycetes which formed distinctive red coloured colonies were isolated from three out of four composite soil samples using a medium designed to be selective for members of the Streptomyces violaceoruber clade, a taxon which includes the model organisms "Streptomyces coelicolor" A3(2) and "Streptomyces lividans" 66. The isolation medium, dextran-histidine-sodium chloride-mineral salts agar supplemented with antibacterial and antifungal antibiotics, also supported the growth of representatives of the S. violaceoruber clade. One hundred and ninety one representatives of the isolates that produced red colour colonies on the isolation medium were distributed into four colour groups based on their ability to form distinctive pigments and morphological properties typical of members of the S. violaceoruber clade, an assignment that was confirmed by corresponding 16S rRNA gene sequencing studies. The selective isolation and characterisation procedures used in the present investigation provide a practical means of determining the taxonomic diversity, geographical distribution and roles of representatives of the S. violaceoruber clade in natural habitats. 相似文献
20.
Nyéssia Fernanda De Sousa Silva MáRcia Regina Simões Adriana Knob Sandra Schmidt De Moraes Caroline Henn Jose Luis Da ConceiçãO Silva 《Biocatalysis and Biotransformation》2016,34(3):119-127
Xylanase produced from the newly isolated Penicillium crustosum FP 11 and its potential in the prebleaching of kraft pulp were evaluated using a statistical approach. A Plackett–Burman design (PBD) was carried out to select the significant variables of the medium, these being NaNO3, KH2PO4, MgSO4, KCl, Fe2(SO4)3, yeast extract, corn stover, and initial pH, in a liquid culture under static conditions for 6 d at 28?°C. Statistical analysis with a central composite design and response surface methodology showed that 0.15% (w/v) KH2PO4, 2% (w/v) corn stover, and an initial pH of 6.0 provided the best conditions for xylanase production. Furthermore, xylanase from P. crustosum FP 11 was effective in the bleaching of Eucalyptus kraft pulp, with a significant kappa efficiency of 35.04%. Therefore, the newly isolated P. crustosum FP 11 from the Atlantic Forest biome in Brazil showed two advantages: xylanase production with agricultural residue (corn stover) as a carbon source and an improvement in the bleaching of kraft pulp. Environmental pollution could thus be minimized because of a reduction in the use of chlorine as a bleaching agent. 相似文献