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Extremophiles - Technological advances in the field of life sciences have led to discovery of organisms that live in harsh environmental conditions referred to as extremophiles. These organisms...  相似文献   

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To meet the demand of its fast growing economy, China has become already the second largest buyer of crude oil. China is facing critical problems of energy shortage and environment deterioration. Rational and efficient energy use and environment protection are both getting more attention in China. Biomass energy is renewable energy made from biological sources. China's biomass resources are abundant, which could provide energy for future social and economic development. However technologies for biomass resource conversion in China are still just beginning. In this paper, current biomass resource distribution and technologies of biomass energy, including power generation, biofuel production and biomass-based chemical production are reviewed.  相似文献   

5.
There are substantial variations in bulbing (bulb formation) efficiency among micropropagated tulip cultivars. The mechanisms involved are poorly understood, but presumably involve cytokinins (CKs) for several reasons. Therefore, we explored CK profiles and dynamics in ‘Blue Parrot’ and ‘Prominence’ cultivars (which have low and high bulbing efficiency, respectively) during the in vitro propagation stages: the last shoot multiplication subculture extended to 14 weeks (S1–S2), the shoot cooling at 5 °C for induction of bulb formation (S3–S4) and the bulb growth initiation after the end of cooling (S5–S6). The CK thidiazuron (TDZ) is routinely used in tulip micropropagation at the shoot multiplication stage, but replacing it with isopentenyladenine (iP) during the last multiplication subculture substantially changed CK dynamics in later stages, and significantly increased bulb formation rates in both cultivars. Generally, the most abundant CKs in both cultivars were the isoprenoid CK types, trans-zeatin (tZ), iP, cis-zeatin and dihydrozeatin. However, ‘Prominence’ shoots had much lower cis- to trans-Z-type CK ratios than ‘Blue Parrot’ shoots, and generally higher levels of physiologically active CKs (free bases tZ, iP and their ribosides) until the last phase of bulb formation, S6 (bulb growth initiation, i.e. swelling of shoot bases), 6 weeks after the end of cold treatment. In this phase total active CK and O-glucoside contents sharply declined in ‘Prominence’ shoots, but not in ‘Blue Parrot’ shoots pretreated with iP. In contrast, the low bulbing ability observed in ‘Prominence’ shoots pretreated with TDZ and ‘Blue Parrot’ shoots pretreated with either TDZ or iP was associated with a gradual rise in active CK and O-glucoside contents after the end of cooling. The results suggest that low bulbing efficiency may be related to down-regulation of tZ biosynthesis, and high bulbing efficiency to a transient increase in active CK forms (mainly tZs) in response to cold treatment during the bulb induction phase, S4 (at the end of cold treatment), followed by a rapid decrease during bulb formation, S6 (6 weeks after the end of cooling).  相似文献   

6.
Geopolitical concerns (unstable supply of gasoline, environmental pollution, and regular price hikes), economic, and employment concerns have been prompting researchers, entrepreneurs, and policy makers to focus on harnessing the potential of lignocellulosic feedstock for fuel ethanol production and its commercialization. The carbohydrate skeleton of plant cell walls needs to be depolymerised into simpler sugars for their application in fermentation reactions as a chief carbon source of suitable ethnologic strains for ethanol production. The role of cellulolytic enzymes in the degradation of structural carbodydrates of the plant cell wall into ready-to-fermentable sugar stream is inevitable. Cellulase synergistically acts upon plant cell wall polysaccharides to release glucose into the liquid media. Cellulase predominantly dominates all the plant cell wall degrading enzymes due to their vast and diverse range of applications. Apart from the major applications of cellulases such as in detergent formulations, textile desizing, and development of monogastric feed for ruminants, their role in biorefinery is truly remarkable. This is a major area where new research tools based upon fermentation based formulations, biochemistry, and system biology to expedite the structure–function relationships of cellulases including cellulosomes and new designer enzymatic cocktails are required. In the last two decades, a considerable amount of research work has been performed on cellulases and their application in biomass saccharification. However, there are still technical and economic impediments to the development of an inexpensive commercial cellulase production process. Advancements in biotechnology such as screening of microorganisms, manipulation of novel cellulase encoding traits, site-specific mutagenesis, and modifications to the fermentation process could enhance the production of cellulases. Commercially, cheaper sources of carbohydrates and modified fermentation conditions could lead to more cost-effective production of cellulases with the goal to reduce the cost of ethanol production from lignocellulosics. Implementation of integrated steps like cellulase production and cellulase mediated saccharification of biomass in conjunction with the fermentation of released sugars in ethanol in a single step so called consolidated bio-processing (CBP) is very important to reduce the cost of bioethanol. This paper aims to explore and review the important findings in cellulase biotechnology and the forward path for new cutting edge opportunities in the success of biorefineries.  相似文献   

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Within the biorefinery paradigm, many non-monomeric sugar compounds have been shown to be inhibitory to enzymes and microbial organisms that are used for hydrolysis and fermentation. Here, two novel separation technologies, polyelectrolyte polymer adsorption and resin-wafer electrodeionization (RW-EDI), have been evaluated to detoxify a dilute acid pretreated biomass slurry. Results showed that detoxification of a dilute acid pretreated ponderosa pine slurry by sequential polyelectrolyte and RW-EDI treatments was very promising, with significant removal of acetic acid, 5-hydroxymethyl furfural, and furfural (up to 77%, 60%, and 74% removed, respectively) along with >97% removal of sulfuric acid. Removal of these compounds increased the cellulose conversion to 94% and elevated the hydrolysis rate to 0.69 g glucose/L/h. When using Saccharomyces cerevisiae D5A for fermentation of detoxified slurry, the process achieved 99% of the maximum theoretical ethanol yield and an ethanol production rate nearly five-times faster than untreated slurry.  相似文献   

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Advanced control of glutathione fermentation process   总被引:18,自引:0,他引:18  
A study was performed to understand the fermentation process for production of glutathione fermentation (GSH) with an improved strain of baker's yeast. Simultaneous utilization of sugar and ethanol has been found to be a key factor in the industrial process to produce GSH using Saccharomyces cerevisiae KY6186. Based on this observation, the optimal sugar feed profile for the fed-batch operation has been determined. A feedforward/feedback control system was developed to regulate the sugar feed rate so as to maximize GSH production yields. Using the feedforward/feedback control system and the on-line data of oxygen and ethanol concentration in exhaust gas, the successful scaleup to the production level was accomplished. An average of 40% improvement of glutathione production compared to a conventionally programmed control of exponential fed-batch operation was found in the new process. (c) 1992 John Wiley & Sons, Inc.  相似文献   

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Geopolitical concerns (unstable supply of gasoline, environmental pollution, and regular price hikes), economic, and employment concerns have been prompting researchers, entrepreneurs, and policy makers to focus on harnessing the potential of lignocellulosic feedstock for fuel ethanol production and its commercialization. The carbohydrate skeleton of plant cell walls needs to be depolymerised into simpler sugars for their application in fermentation reactions as a chief carbon source of suitable ethnologic strains for ethanol production. The role of cellulolytic enzymes in the degradation of structural carbohydrates of the plant cell wall into ready-to-fermentable sugar stream is inevitable. Cellulase synergistically acts upon plant cell wall polysaccharides to release glucose into the liquid media. Cellulase predominantly dominates all the plant cell wall degrading enzymes due to their vast and diverse range of applications. Apart from the major applications of cellulases such as in detergent formulations, textile desizing, and development of monogastric feed for ruminants, their role in biorefinery is truly remarkable. This is a major area where new research tools based upon fermentation based formulations, biochemistry, and system biology to expedite the structure-function relationships of cellulases including cellulosomes and new designer enzymatic cocktails are required. In the last two decades, a considerable amount of research work has been performed on cellulases and their application in biomass saccharification. However, there are still technical and economic impediments to the development of an inexpensive commercial cellulase production process. Advancements in biotechnology such as screening of microorganisms, manipulation of novel cellulase encoding traits, site-specific mutagenesis, and modifications to the fermentation process could enhance the production of cellulases. Commercially, cheaper sources of carbohydrates and modified fermentation conditions could lead to more cost-effective production of cellulases with the goal to reduce the cost of ethanol production from lignocellulosics. Implementation of integrated steps like cellulase production and cellulase mediated saccharification of biomass in conjunction with the fermentation of released sugars in ethanol in a single step so called consolidated bio-processing (CBP) is very important to reduce the cost of bioethanol. This paper aims to explore and review the important findings in cellulase biotechnology and the forward path for new cutting edge opportunities in the success of biorefineries.  相似文献   

10.
赵建  曲音波 《生命科学》2014,(5):489-496
开发利用可再生性的木质纤维素资源来生产液体燃料和大宗化学品,对于解决人类发展面临的资源与环境危机具有重要的意义。然而,作为其代表性工艺的纤维素乙醇生产却因为经济上无法过关而迟迟不能真正实现产业化。采用生物精炼技术,充分利用木质纤维素材料中各种组分,生产包括部分高值产品的多种产品,是克服其转化技术产业化经济可行性问题的有效措施。综述了木质纤维素原料生物精炼技术的研究发展现状,着重阐述了玉米芯的生物精炼技术产业化进展,并对木质纤维素的生物精炼前景进行了展望。  相似文献   

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The paper discusses the dynamics of the accumulation of microscopic fungi, depending on the sludge load (Bx), in activated sludge used for landfill leachate pretreatment. The propagule washout from the sludge into pretreated leachates is determined, including genera and species that may threaten environmental health. An increased accumulation of microscopic fungi in sludge flocs occurred at Bx=0.23−0.45 mg chemical oxygen demand (COD) mg−1 d−1. Microscopic fungi were eluted at the maximal Bx value tested of 1.64 mg COD mg−1 d−1. Both the activated sludge and the leachate runoff from the sequencing batch reactor (SBR) pose health risks to the environment due to the occurrence of fungi such as Aspergillus fumigatus, Purpureocillium lilacinum, Cyberlindnera jadinii (C. utilis), Geotrichum candidum and G. fragrans. Their count is sufficient to cause multi-organ infections in homeothermal animals and in humans.  相似文献   

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Cellulosic biofuel systems have the potential to significantly reduce the environmental impact of the world's transportation energy requirements. However, realizing this potential will require systems level thinking and scale integration. Until now, we have lacked modeling tools for studying the behavior of integrated cellulosic biofuel systems. In this paper, we describe a new research tool, the Biorefinery and Farm Integration Tool (BFIT) in which the production of fuel ethanol from cellulosic biomass is integrated with crop and animal (agricultural) production models. Uniting these three subsystems in a single combined model has allowed, for the first time, basic environmental and economic analysis of biomass production, possible secondary products, fertilizer production, and bioenergy production across various regions of the United States. Using BFIT, we simulate cellulosic ethanol production embedded in realistic agricultural landscapes in nine locations under a collection of farm management scenarios. This combined modeling approach permits analysis of economic profitability and highlights key areas for environmental improvement. These results show the advantages of introducing integrated biorefinery systems within agricultural landscapes. This is particularly true in the Midwest, which our results suggest is a good setting for the cellulosic ethanol industry. Specifically, results show that inclusion of cellulosic biofuel systems into existing agriculture enhances farm economics and reduces total landscape emissions. Model results also indicate a limited ethanol price effect from increased biomass transportation distance. Sensitivity analysis using BFIT revealed those variables having the strongest effects on the overall system performance, namely: biorefinery size, switchgrass yield, and biomass farm gate price.  相似文献   

13.
Abstract Although they are the largest taxonomic group of animals, relatively few insects have been examined for symbiotic relationships with micro-organisms. However, this is rapidly changing because of the potential for examination of the natural insect–microbe–lignocellulose interactions to provide insights for biofuel technology. Micro-organisms associated with lignocellulose-consuming insects often facilitate the digestion of the recalcitrant plant diet; therefore these microbial communities may be mined for novel lignocellulose-degrading microbes, or for robust and inexpensive biocatalysts necessary for economically feasible biofuel production from lignocellulose. These insect–microbe interactions are influenced by the ecosystem and specific lignocellulose diet, and appreciating the whole ecosystem–insect–microbiota–lignocellulose as a natural biorefinery provides a rich and diverse framework from which to design novel industrial processes. One such natural biorefinery, the Tipula abdominalis larvae in riparian ecosystems, is reviewed herein with applications for biochemical processes and overcoming challenges involved in conversion of lignocellulosic biomass to fuel ethanol. From the dense and diverse T. abdominalis larval hindgut microbial community, a cellulolytic bacterial isolate, 27C64, demonstrated enzymatic activity toward many model plant polymers and also produced a bacterial antibiotic. 27C64 was co-cultured with yeast in fermentation of pine to ethanol, which allowed for a 20% reduction of commercial enzyme. In this study, a micro-organism from a lignocellulose-consuming insect was successfully applied for improvement of biomass-to-biofuel technology.  相似文献   

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Objectives: To evaluate the pattern of maxillary complete denture movement during chewing for free‐end removable partial dentures (RPD) wearers, compared to maxillary and mandibular complete denture wearers. Materials and methods: Eighteen edentulous participants (group I) and 10 volunteers with bilateral posterior edentulous mandibles (group II) comprised the sample. Measures of mean denture movement and its variability were obtained by a kinesiographic instrument K6‐I Diagnostic System, during the mastication of bread and a polysulphide block. Data were analysed using two‐way anova (α = 0.05). Results: Upper movement during chewing was significantly lower for group II, regardless of the test food. The test food did not influence the vertical or lateral position of the denture bases, but more anterior dislocation was found when polysulphide blocks were chewed. Group II presented lower intra‐individual variability for the vertical axis. Vertical displacement was also more precise with bread as a test food. Conclusion: It can be concluded that mandibular free‐end RPD wearers show smaller and more precise movements than mandibular complete denture wearers.  相似文献   

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Although chewing has been suggested to be a basal gnathostome trait retained in most major vertebrate lineages, it has not been studied broadly and comparatively across vertebrates. To redress this imbalance, we recorded EMG from muscles powering anteroposterior movement of the hyoid, and dorsoventral movement of the mandibular jaw during chewing. We compared muscle activity patterns (MAP) during chewing in jawed vertebrate taxa belonging to unrelated groups of basal bony fishes and artiodactyl mammals. Our aim was to outline the evolution of coordination in MAP. Comparisons of activity in muscles of the jaw and hyoid that power chewing in closely related artiodactyls using cross-correlation analyses identified reorganizations of jaw and hyoid MAP between herbivores and omnivores. EMG data from basal bony fishes revealed a tighter coordination of jaw and hyoid MAP during chewing than seen in artiodactyls. Across this broad phylogenetic range, there have been major structural reorganizations, including a reduction of the bony hyoid suspension, which is robust in fishes, to the acquisition in a mammalian ancestor of a muscle sling suspending the hyoid. These changes appear to be reflected in a shift in chewing MAP that occurred in an unidentified anamniote stem-lineage. This shift matches observations that, when compared with fishes, the pattern of hyoid motion in tetrapods is reversed and also time-shifted relative to the pattern of jaw movement.  相似文献   

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Background

There is currently considerable interest in developing renewable sources of energy. One strategy is the biological conversion of plant biomass to liquid transportation fuel. Several technical hurdles impinge upon the economic feasibility of this strategy, including the development of energy crops amenable to facile deconstruction. Reliable assays to characterize feedstock quality are needed to measure the effects of pre-treatment and processing and of the plant and microbial genetic diversity that influence bioconversion efficiency.

Results

We used the anaerobic bacterium Clostridium phytofermentans to develop a robust assay for biomass digestibility and conversion to biofuels. The assay utilizes the ability of the microbe to convert biomass directly into ethanol with little or no pre-treatment. Plant samples were added to an anaerobic minimal medium and inoculated with C. phytofermentans, incubated for 3 days, after which the culture supernatant was analyzed for ethanol concentration. The assay detected significant differences in the supernatant ethanol from wild-type sorghum compared with brown midrib sorghum mutants previously shown to be highly digestible. Compositional analysis of the biomass before and after inoculation suggested that differences in xylan metabolism were partly responsible for the differences in ethanol yields. Additionally, we characterized the natural genetic variation for conversion efficiency in Brachypodium distachyon and shrub willow (Salix spp.).

Conclusion

Our results agree with those from previous studies of lignin mutants using enzymatic saccharification-based approaches. However, the use of C. phytofermentans takes into consideration specific organismal interactions, which will be crucial for simultaneous saccharification fermentation or consolidated bioprocessing. The ability to detect such phenotypic variation facilitates the genetic analysis of mechanisms underlying plant feedstock quality.  相似文献   

18.
The spent liquor (SL) of a neutral sulfite semichemical (NSSC) pulping process contains a considerable amount of lignocelluloses and is treated in wastewater systems. The lignocelluloses, however, can be used for producing value‐added products if they are isolated from the SL. In this article, solvent treatment (mixing acetone, ethanol, or isopropyl with SL) was used as a method for isolating lignosulfonate from SL. The maximum lignosulfonate removal was obtained via mixing isopropyl alcohol with SL at the weight ratio of 20/80, room temperature, and 5.7 pH. The results also showed that the molecular weight and anionic charge density of the precipitates were in the range of 5,000–70,000 g/mol and 0.2–1.8 meq/g, respectively. Based on these results, a process was proposed for isolating lignosulfonate from SL and converting the NSSC process to an NSSC‐based biorefinery. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1508–1514, 2015  相似文献   

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Green olives of the Tunisian variety "Meski" were treated according to a Spanish-style green olive preservation process by using an alkaline treatment (1.5, 2 and 2.5% (w/v) NaOH) to eliminate bitterness, combined with different brine concentrations (6, 9 and 12% (w/v) NaCl). A spontaneous fermentation by the environmental microflora took place. Results showed that 2% NaOH solution and 9% sodium chloride brine was an optimal combination inducing the best growth of Lactobacillus species (10(8) CFU/ml) and acidity of 0.726 g lactic acid/100 ml brine. In all trials and independently of the treatment, Lb. plantarum was the most dominant strain of Lactobacillus. Moreover, pretreatment with lye and lactic fermentation of olives contributed to coliform elimination.  相似文献   

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