Biotechnology and Bioengineering
0006-3592
1097-0290
Đức
Cơ quản chủ quản: WILEY , Wiley-VCH Verlag
Lĩnh vực:
BiotechnologyApplied Microbiology and BiotechnologyBioengineering
Các bài báo tiêu biểu
Microalgae for oil: Strain selection, induction of lipid synthesis and outdoor mass cultivation in a low‐cost photobioreactor Abstract Thirty microalgal strains were screened in the laboratory for their biomass productivity and lipid content. Four strains (two marine and two freshwater), selected because robust, highly productive and with a relatively high lipid content, were cultivated under nitrogen deprivation in 0.6‐L bubbled tubes. Only the two marine microalgae accumulated lipid under such conditions. One of them, the eustigmatophyte Nannochloropsis sp. F&M‐M24, which attained 60% lipid content after nitrogen starvation, was grown in a 20‐L Flat Alveolar Panel photobioreactor to study the influence of irradiance and nutrient (nitrogen or phosphorus) deprivation on fatty acid accumulation. Fatty acid content increased with high irradiances (up to 32.5% of dry biomass) and following both nitrogen and phosphorus deprivation (up to about 50%). To evaluate its lipid production potential under natural sunlight, the strain was grown outdoors in 110‐L Green Wall Panel photobioreactors under nutrient sufficient and deficient conditions. Lipid productivity increased from 117 mg/L/day in nutrient sufficient media (with an average biomass productivity of 0.36 g/L/day and 32% lipid content) to 204 mg/L/day (with an average biomass productivity of 0.30 g/L/day and more than 60% final lipid content) in nitrogen deprived media. In a two‐phase cultivation process (a nutrient sufficient phase to produce the inoculum followed by a nitrogen deprived phase to boost lipid synthesis) the oil production potential could be projected to be more than 90 kg per hectare per day. This is the first report of an increase of both lipid content and areal lipid productivity attained through nutrient deprivation in an outdoor algal culture. The experiments showed that this marine eustigmatophyte has the potential for an annual production of 20 tons of lipid per hectare in the Mediterranean climate and of more than 30 tons of lipid per hectare in sunny tropical areas. Biotechnol. Bioeng. 2009;102: 100–112. © 2008 Wiley Periodicals, Inc.
Tập 102 Số 1 - Trang 100-112 - 2009
Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems Abstract Information pertaining to enzymatic hydrolysis of cellulose by noncomplexed cellulase enzyme systems is reviewed with a particular emphasis on development of aggregated understanding incorporating substrate features in addition to concentration and multiple cellulase components. Topics considered include properties of cellulose, adsorption, cellulose hydrolysis, and quantitative models. A classification scheme is proposed for quantitative models for enzymatic hydrolysis of cellulose based on the number of solubilizing activities and substrate state variables included. We suggest that it is timely to revisit and reinvigorate functional modeling of cellulose hydrolysis, and that this would be highly beneficial if not necessary in order to bring to bear the large volume of information available on cellulase components on the primary applications that motivate interest in the subject. © 2004 Wiley Periodicals, Inc.
Tập 88 Số 7 - Trang 797-824 - 2004
Rules for optimization of biocatalysis in organic solvents Abstract General rules for the optimization of different biocatalytic systems in various types of media containing organic solvents are derived by combining data from the literature, and the logarithm of the partition coefficient, log P , as a quantitative measure of solvent polarity. (1) Biocatalysis in organic solvents is low in polar solvents having a log P < 2, is moderate in solvents having a log P between 2 and 4, and is high in a polar solvents having a log P > 4. It was found that this correlation between polarity and activity parallels the ability of organic solvents to distort the essential water layer that stabilizes the biocatalysts. (2) Further optimization of biocatalysis in organic solvents is achieved when the polarity of the microenvironment of the biocatalyst (log P i P cph ) is tuned to the polarities of both the substrate (log P s P p P i P s P cph − log P p P cph − log P s P i P p P i P s
Tập 30 Số 1 - Trang 81-87 - 1987
Group‐specific primer and probe sets to detect methanogenic communities using quantitative real‐time polymerase chain reaction Abstract Real‐time polymerase chain reaction (PCR) is a highly sensitive method that can be used for the detection and quantification of microbial populations without cultivating them in anaerobic processes and environmental samples. This work was conducted to design primer and probe sets for the detection of methanogens using a real‐time PCR with the TaqMan system. Six group‐specific methanogenic primer and probe sets were designed. These sets separately detect four orders (Methanococcales , Methanobacteriales , Methanomicrobiales , and Methanosarcinales ) along with two families (Methanosarcinaceae and Methanosaetaceae ) of the order Methanosarcinales . We also designed the universal primer and probe sets that specifically detect the 16S rDNA of prokaryotes and of the domain Bacteria and Archaea , and which are fully compatible with the TaqMan real‐time PCR system. Target‐group specificity of each primer and probe set was empirically verified by testing DNA isolated from 28 archaeal cultures and by analyzing potential false results. In general, each primer and probe set was very specific to the target group. The primer and probe sets designed in this study can be used to detect and quantify the order‐level (family‐level in the case of Methanosarcinales ) methanogenic groups in anaerobic biological processes and various environments. © 2005 Wiley Periodicals, Inc.
Tập 89 Số 6 - Trang 670-679 - 2005
Use of the upflow sludge blanket (USB) reactor concept for biological wastewater treatment, especially for anaerobic treatment Abstract In recent years considerable effort has been made in the Netherlands toward the development of a more sophisticated anaerobic treatment process, suitable for treating low a strength wastes and for applications at liquid detention times of 3–4 hr. The efforts have resulted in new type of upflow anaerobic sludge blanket (UASB) process, which in recent 6 m3 pilot‐plant experiments has shown to be capable of handling organic space loads of 15–40 kg chemical oxygen demand (COD)·m−3 /day at 3–8 hr liquid detention times. In the first 200 m3 full‐scale plant of the UASB concept, organic space loadings of up to 16 kg COD·m−3 /day could be treated satisfactorily at a detention times of 4 hr, using sugar beet waste as feed. The main results obtained with the process in the laboratory as well as in 6 m3 pilot plant and 200 m3 full‐scale experiments are presented and evaluated in this paper. Special attention is given to the main operating characteristics of the UASB reactor concept. Moreover, some preliminary results are presented of laboratory experiments concerning the use of the USB reactor concept for denitrification as well as for the acid formation step in anaerobic treatment. For both purposes the process looks feasible because very satisfactory results with respect to denitrification and acid formation can be achieved at very high hydraulic loads (12 day−1 ) and high organic loading rates, i.e., 20 kg COD·m−3 /day in the denitrification and 60–80 kg COD·m−3 /day in the acid formation experiments.
Tập 22 Số 4 - Trang 699-734 - 1980
A mathematical model for the continuous culture of microorganisms utilizing inhibitory substrates Abstract A mathematical model is presented for both batch and continuous cultures of microorganisms utilizing inhibitory substrates. The key feature of the model is the use of a inhibition function to relate substrate concentration and specific growth rate. Simulation studies show that the primary result of inhibition by substrate in a batch culture is an increase in the lag time whereas in continuous culture inhibition by substrate may result in process instability. The model should be of value in investigations of the stability of biological processes used for the treatment of certain industrial wastes such as those containing phenols, thiocyanates, nitrates, ammonia, volatile acids, etc., which are known to be inhibitory to many of the organisms metabolizing them.
Tập 10 Số 6 - Trang 707-723 - 1968
Nanocomposite hydrogels for biomedical applications ABSTRACT Hydrogels mimic native tissue microenvironment due to their porous and hydrated molecular structure. An emerging approach to reinforce polymeric hydrogels and to include multiple functionalities focuses on incorporating nanoparticles within the hydrogel network. A wide range of nanoparticles, such as carbon‐based, polymeric, ceramic, and metallic nanomaterials can be integrated within the hydrogel networks to obtain nanocomposites with superior properties and tailored functionality. Nanocomposite hydrogels can be engineered to possess superior physical, chemical, electrical, and biological properties. This review focuses on the most recent developments in the field of nanocomposite hydrogels with emphasis on biomedical and pharmaceutical applications. In particular, we discuss synthesis and fabrication of nanocomposite hydrogels, examine their current limitations and conclude with future directions in designing more advanced nanocomposite hydrogels for biomedical and biotechnological applications. Biotechnol. Bioeng. 2014;111: 441–453. © 2013 Wiley Periodicals, Inc.
Tập 111 Số 3 - Trang 441-453 - 2014
Alginate làm vật liệu cố định: I. Mối liên hệ giữa tính chất hoá học và vật lý của các hạt gel alginate Tóm tắt Các hạt gel alginate calci đã được chuẩn bị từ một loạt các alginate đã được đặc trưng tốt. Tính chất vật lý của các hạt phụ thuộc mạnh vào thành phần, cấu trúc tuần tự, và kích thước phân tử của các polymer. Các hạt với độ bền cơ học cao nhất, độ co ngót thấp nhất, độ ổn định tốt nhất đối với các cation đơn hóa trị, và độ xốp cao nhất được tạo ra từ alginate có hàm lượng axit L ‐guluronic cao hơn 70% và chiều dài trung bình của các khối G cao hơn 15. Đối với những alginate “g cao” này, độ nhớt nội tại tại điểm trùng lặp quan trọng đã được xác định, và đối với trọng lượng phân tử cao hơn 2,4 × 105 , độ bền của gel không phụ thuộc vào trọng lượng phân tử.
Tập 33 Số 1 - Trang 79-89 - 1989
#alginate #calcium alginate #gel beads #mechanical strength #porosity #monovalent cations #<jats:sc>L</jats:sc>‐guluronic acid #molecular weight #intrinsic viscosities #polymer
The challenge of enzyme cost in the production of lignocellulosic biofuels Abstract With the aim of understanding the contribution of enzymes to the cost of lignocellulosic biofuels, we constructed a techno‐economic model for the production of fungal cellulases. We found that the cost of producing enzymes was much higher than that commonly assumed in the literature. For example, the cost contribution of enzymes to ethanol produced by the conversion of corn stover was found to be $0.68/gal if the sugars in the biomass could be converted at maximum theoretical yields, and $1.47/gal if the yields were based on saccharification and fermentation yields that have been previously reported in the scientific literature. We performed a sensitivity analysis to study the effect of feedstock prices and fermentation times on the cost contribution of enzymes to ethanol price. We conclude that a significant effort is still required to lower the contribution of enzymes to biofuel production costs. Biotechnol. Bioeng. 2012; 109:1083–1087. © 2011 Wiley Periodicals, Inc.
Tập 109 Số 4 - Trang 1083-1087 - 2012
Model of the anaerobic metabolism of the biological phosphorus removal process: Stoichiometry and pH influence Abstract In the anaerobic phase of a biological phosphorus removal process, acetate is taken up and converted to PHB utilizing both energy generated in the degradation of polyphosphate to phosphate, which is released, and energy generated in the conversion of glycogen to poly‐β‐hydroxy butyrate (PHB). The phosphate/acetate ratio cannot be considered a metabolic constant, because the energy requirement for the uptake of acetate is strongly influenced by the pH value. The observed phosphate/acetate ratio shows a variation of 0.25 to 0.75 P‐mol/C‐mol in a pH range of 5.5 to 8.5. It is shown that stored glycogen takes part in the metabolism to provide reduction equivalents and energy for the conversion of acetate to PHB. A structured metabolic model, based on glycogen as the source of the reduction equivalents in the anaerobic phase and the effect of the pH on the energy requirement of the uptake of acetate, is developed. The model explains the experimental results satisfactorily. © 1994 John Wiley & Sons, Inc.
Tập 43 Số 6 - Trang 461-470 - 1994