共查询到20条相似文献,搜索用时 15 毫秒
1.
Christopher T. Straub Piyum A. Khatibi Jonathan K. Otten Michael W. W. Adams Robert M. Kelly 《Biotechnology and bioengineering》2019,116(8):1901-1908
The extreme thermophile Caldicellulosiruptor bescii solubilizes and metabolizes the carbohydrate content of lignocellulose, a process that ultimately ceases because of biomass recalcitrance, accumulation of fermentation products, inhibition by lignin moieties, and reduction of metabolic activity. Deconstruction of low loadings of lignocellulose (5 g/L), either natural or transgenic, whether unpretreated or subjected to hydrothermal processing, by C. bescii typically results in less than 40% carbohydrate solubilization. Mild alkali pretreatment (up to 0.09 g NaOH/g biomass) improved switchgrass carbohydrate solubilization by C. bescii to over 70% compared to less than 30% for no pretreatment, with two-thirds of the carbohydrate content in the treated switchgrass converted to acetate and lactate. C. bescii grown on high loadings of unpretreated switchgrass (50 g/L) retained in a pH-controlled bioreactor slowly purged (τ = 80 hr) with growth media without a carbon source improved carbohydrate solubilization to over 40% compared to batch culture at 29%. But more significant was the doubling of solubilized carbohydrate conversion to fermentation products, which increased from 40% in batch to over 80% in the purged system, an improvement attributed to maintaining the bioreactor culture in a metabolically active state. This strategy should be considered for optimizing solubilization and conversion of lignocellulose by C. bescii and other lignocellulolytic microorganisms. 相似文献
2.
Yu‐Sin Jang Alok Malaviya Joungmin Lee Jung Ae Im Sang Yup Lee Julia Lee Moon‐Ho Eom Jung‐Hee Cho Do Young Seung 《Biotechnology progress》2013,29(4):1083-1088
Butanol is considered as a superior biofuel, which is conventionally produced by clostridial acetone‐butanol‐ethanol (ABE) fermentation. Among ABE, only butanol and ethanol can be used as fuel alternatives. Coproduction of acetone thus causes lower yield of fuel alcohols. Thus, this study aimed at developing an improved Clostridium acetobutylicum strain possessing enhanced fuel alcohol production capability. For this, we previously developed a hyper ABE producing BKM19 strain was further engineered to convert acetone into isopropanol. The BKM19 strain was transformed with the plasmid pIPA100 containing the sadh (primary/secondary alcohol dehydrogenase) and hydG (putative electron transfer protein) genes from the Clostridium beijerinckii NRRL B593 cloned under the control of the thiolase promoter. The resulting BKM19 (pIPA100) strain produced 27.9 g/l isopropanol‐butanol‐ethanol (IBE) as a fuel alcohols with negligible amount of acetone (0.4 g/l) from 97.8 g/l glucose in lab‐scale (2 l) batch fermentation. Thus, this metabolically engineered strain was able to produce 99% of total solvent produced as fuel alcohols. The scalability and stability of BKM19 (pIPA100) were evaluated at 200 l pilot‐scale fermentation, which showed that the fuel alcohol yield could be improved to 0.37 g/g as compared to 0.29 g/g obtained at lab‐scale fermentation, while attaining a similar titer. To the best of our knowledge, this is the highest titer of IBE achieved and the first report on the large scale fermentation of C. acetobutylicum for IBE production. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1083–1088, 2013 相似文献
3.
Anh Do Quynh Nguyen Seon-Won Kim Sung Bae Kim Yang-Gon Seo In-Young Chung Dae Hwan Kim Chang-Joon Kim 《Biotechnology and Bioprocess Engineering》2012,17(6):1196-1204
Natural β-carotene has received much attention as consumers have become more health conscious. Its production by various microorganisms including metabolically engineered Escherichia coli or Saccharomyces cerevisiae has been attempted. We successfully created a recombinant E. coli with an engineered whole mevalonate pathway in addition to β-carotene biosynthetic genes and evaluated the engineered cells from the aspects of metabolic balance between central metabolism and β-carotene production by comparison with conventional β-carotene producing recombinant E. coli (control) utilizing a native methylerythritol phosphate (MEP) pathway using bioreactor cultures generated at different temperatures or pHs. Better production of β-carotene was obtained in E. coli cultured at 37°C than at 25°C. A two-fold higher titer and 2.9-fold higher volumetric productivity were obtained in engineered cells compared with control cells. Notably, a marginal amount of acetate was produced in actively growing engineered cells, whereas more than 8 g/L of acetate was produced in control cells with reduced cell growth at 37°C. The data indicated that the artificial operon of the whole mevalonate pathway operated efficiently in redirecting acetyl-CoA into isopentenyl pyrophosphate (IPP), thereby improving production of β-carotene, whereas the native MEP pathway did not convert a sufficient amount of pyruvate into IPP due to endogenous feedback regulation. Engineered cells also produced lycopene with a reduced amount of β-carotene in weak alkaline cultures, consistent with the inhibition of lycopene cyclase. 相似文献
4.
A. Boonsombuti K. Tangmanasakul J. Nantapipat K. Komolpis S. Wongkasemjit 《Preparative biochemistry & biotechnology》2016,46(2):141-149
Corncob is a potential feedstock in Thailand that can be used for fermentable sugar production through dilute sulfuric acid pretreatment and enzymatic hydrolysis. To recover high amounts of monomeric sugars from corncob, the sulfuric pretreatment conditions were optimized by using response surface methodology with three independent variables: sulfuric acid concentration, temperature, and time. The highest response of total sugars, 48.84 g/L, was found at 122.78°C, 4.65 min, and 2.82% (v/v) H2SO4. With these conditions, total sugars from the confirmation experiment were 46.29 g/L, with 5.51% error from the predicted value. The hydrolysate was used as a substrate for acetone–butanol–ethanol fermentation to evaluate its potential for microbial growth. The simultaneous saccharification and fermentation (SSF) showed that C. beijerinckii TISTR 1461 can generate acetone–butanol–ethanol products at 11.64 g/L (5.29 g/L acetone, 6.26 g/L butanol, and 0.09 g/L ethanol) instantly using sugars from the hydrolysed corncob with Novozymes 50013 cellulase enzyme without an overliming process. 相似文献
5.
Pan W Perrotta JA Stipanovic AJ Nomura CT Nakas JP 《Journal of industrial microbiology & biotechnology》2012,39(3):459-469
Sugar maple hemicellulosic hydrolysate containing 71.9 g/l of xylose was used as an inexpensive feedstock to produce polyhydroxyalkanoates
(PHAs) by Burkholderia cepacia ATCC 17759. Several inhibitory compounds present in wood hydrolysate were analyzed for effects on cell growth and PHA production
with strong inhibition observed at concentrations of 1 g/l furfural, 2 g/l vanillin, 7 g/l levulinic acid, and 1 M acetic
acid. Gradual catabolism of lower concentrations of these inhibitors was observed in this study. To increase the fermentability
of wood hydrolysate, several detoxification methods were tested. Overliming combined with low-temperature sterilization resulted
in the highest removal of total inhibitory phenolics (65%). A fed-batch fermentation exhibited maximum PHA production after
96 h (8.72 g PHA/L broth and 51.4% of dry cell weight). Compositional analysis by NMR and physical–chemical characterization
showed that PHA produced from wood hydrolysate was composed of polyhydroxybutyrate (PHB) with a molecular mass (M
N) of 450.8 kDa, a melting temperature (T
m) of 174.4°C, a glass transition temperature (T
g) of 7.31°C, and a decomposition temperature (T
decomp) of 268.6°C. 相似文献
6.
Production of hydrogen from marine macro-algae biomass using anaerobic sewage sludge microflora 总被引:1,自引:0,他引:1
Jae-Il Park Jinwon Lee Sang Jun Sim Jae-Hwa Lee 《Biotechnology and Bioprocess Engineering》2009,14(3):307-315
Hydrogen was produced from various marine macro-algae (seaweeds) through anaerobic fermentation using an undefined bacterial
consortium. In this study, anaerobic fermentation from various marine macro-algae for Ulva lactuca, Porphyra tenera, Undaria pinnatifida, and Laminaria japonica was studied. From this analysis Laminaria japorica was determined to be the optimum substrate for hydrogen production. When L. japornica was used as the carbon source for enhanced hydrogen production, the optimum fermentation temperature, substrate concentration,
initial pH, and pretreatment condition were determined to be 35°C, 5%, 7.5, and BT120 (Ball mill and thermal treatments at
120°C for 30 min), respectively. In addition, hydrogen production was improved when the sludge was heat-treated at 65°C for
20 min. Under these conditions, about 4,164 mL of hydrogen was produced from 50 g/L of dry algae (L. japonica) for 50 h, with a hydrogen concentration around 34.4%. And the maximum hydrogen production rate and yield were found to be
70 mL/L·h and 28 mL/g dry algae, respectively. 相似文献
7.
Development of a butanologenic strain with high selectivity for butanol production is often proposed as a possible route for
improving the economics of biobutanol production by solventogenic Clostridium species. The acetoacetate decarboxylase (aadc) gene encoding acetoacetate decarboxylase (AADC), which catalyzes the decarboxylation of acetoacetate into acetone and CO2, was successfully disrupted by homologous recombination in solventogenic Clostridium beijerinckii NCIMB 8052 to generate an aadc
−
mutant. Our fermentation studies revealed that this mutant produces a maximum acetone concentration of 3 g/L (in P2 medium),
a value comparable to that produced by wild-type C. beijerinckii 8052. Therefore, we postulated that AADC-catalyzed decarboxylation of acetoacetate is not the sole means for acetone generation.
Our subsequent finding that non-enzymatic decarboxylation of acetoacetate in vitro, under conditions similar to in vivo acetone–butanol–ethanol
(ABE) fermentation, produces 1.3 to 5.2 g/L acetone between pH 6.5 and 4 helps rationalize why various knock-out and knock-down
strategies designed to disrupt aadc in solventogenic Clostridium species did not eliminate acetone production during ABE fermentation. Based on these results, we discuss alternatives to
enhance selectivity for butanol production. 相似文献
8.
9.
10.
Jin Young Lee Yu-Sin Jang Joungmin Lee Eleftherios Terry Papoutsakis Sang Yup Lee Professor 《Biotechnology journal》2009,4(10):1432-1440
To improve butanol selectivity, Clostridium acetobutylicum M5(pIMP1E1AB) was constructed by adhE1-ctfAB complementation of C. acetobutylicum M5, a derivative strain of C. acetobutylicum ATCC 824, which does not produce solvents due to the lack of megaplasmid pSOL1. The gene products of adhE1-ctfAB catalyze the formation of acetoacetate and ethanol/butanol with acid re-assimilation in solventogenesis. Effects of the adhE1-ctfAB complementation of M5 were studied by batch fermentations under various pH and glucose concentrations, and by flux balance analysis using a genome-scale metabolic model for this organism. The metabolically engineered M5(pIMP1E1AB) strain was able to produce 154 mM butanol with 9.9 mM acetone at pH 5.5, resulting in a butanol selectivity (a molar ratio of butanol to total solvents) of 0.84, which is much higher than that (0.57 at pH 5.0 or 0.61 at pH 5.5) of the wild-type strain ATCC 824. Unlike for C. acetobutylicum ATCC 824, a higher level of acetate accumulation was observed during fermentation of the M5 strain complemented with adhE1 and/or ctfAB. A plausible reason for this phenomenon is that the cellular metabolism was shifted towards acetate production to compensate reduced ATP production during the largely growth-associated butanol formation by the M5(pIMP1E1AB) strain. 相似文献
11.
Pei-Wen Mao Liu-Dingji Li Yu-liang Wang 《Preparative biochemistry & biotechnology》2020,50(4):357-364
AbstractIn order to obtain a better fermentation parameter for the production of recombinant Ganoderma lucidum immunomodulatory protein (rFIP-glu), an engineered Pichia pastoris GS115 was investigated on the fermentation time, temperature, methanol concentration and initial pH of media, while immunomodulatory activities of the rFIP-glu was confirmed. L9(33) orthogonal experiment were firstly employed to optimize various fermentation parameters in the shake-flask level. The optimized fermentation parameters were subsequently verified in a 5?L fermenter. Biological activities including cell viability and tumor necrosis factor-alpha (TNF-α) mRNA of the rFIP-glu were evaluated on murine macrophage RAW264.7 cells. The results showed that the yield of rFIP-glu was up to 368.71?μg/ml in the shake-flask, and 613.47?μg/ml in the 5?L fermenter, when the Pichia pastoris was incubated in basic media with the methanol concentration 1.0% and initial pH 6.5, and with constant shaking at 280?rpm for 4?days at 26?°C. In vitro assays of biological activity indicated that rFIP-glu had significant toxicity against RAW264.7 cells, and possessed the ability to induce TNF-α mRNA expression in macrophage RAW264.7 cells. In conclusion, engineered P. pastoris showed a good fermentation property under the optimum fermentation parameters. It could be a candidate industrial strain for further study. 相似文献
12.
Rena Matsuura Mayumi Kishida Rie Konishi Yuuki Hirata Noriko Adachi Shota Segawa Kenta Imao Tsutomu Tanaka Akihiko Kondo 《Biotechnology and bioengineering》2019,116(10):2640-2651
Microbial production of 1,5-diaminopentane (DAP) from renewable feedstock is a promising and sustainable approach for the production of polyamides. In this study, we constructed a β-glucosidase (BGL)-secreting Corynebacterium glutamicum and successfully used this strain to produce DAP from cellobiose and glucose. First, C. glutamicum was metabolically engineered to produce l -lysine (a direct precursor of DAP), followed by the coexpression of l -lysine decarboxylase and BGL derived from Escherichia coli and Thermobifida fusca YX (Tfu0937), respectively. This new engineered C. glutamicum strain produced 27 g/L of DAP from cellobiose in CGXII minimal medium using fed-batch cultivation. The yield of DAP was 0.43 g/g glucose (1 g of cellobiose corresponds to 1.1 g of glucose), which is the highest yield reported to date. These results demonstrate the feasibility of DAP production from cellobiose or cellooligosaccharides using an engineered C. glutamicum strain. 相似文献
13.
B. Zeli T. Gerharz M. Bott . Vasi‐Ra
ki C. Wandrey R. Takors 《Engineering in Life Science》2003,3(7):299-305
Fed‐batch fermentation was applied to the production of pyruvate by using a recombinant Escherichia coli YYC202 strain. This strain is completely blocked in its ability to convert pyruvate into acetyl‐CoA or acetate, resulting in acetate auxotrophy during growth in glucose minimal medium. By controlling acetate and glucose feed rate, a series of lab‐scale fed‐batch experiments were performed at pH 7 and 37 °C. CO2 production rate (CTR) was used for on‐line regulation of the acetate feed rate. The correlation between CTR and acetate consumption rate (ACR) was determined experimentally. At optimal process conditions a final pyruvate concentration higher than 62 g/L, a space‐time yield of up to 42 g/L/d and pyruvate/glucose molar yield of 1.11 mol/mol were achieved. Experimental evidence was gathered that pyruvate export is active. 相似文献
14.
Naturally mevalonate-resistant acetogen Clostridium sp. MT1243 produced only 425 mM acetate during syngas fermentation. Using Clostridium sp. MT1243 we engineered biocatalyst selectively producing mevalonate from synthesis gas or CO2/H2 blend. Acetate production and spore formation were eliminated from Clostridium sp. MT1243 using Cre-lox66/lox71-system. Cell energy released via elimination of phosphotransacetylase, acetate kinase and early stage sporulation genes powered mevalonate accumulation in fermentation broth due to expression of synthetic thiolase, HMG-synthase, and HMG-reductase, three copies of each, integrated using Tn7-approach. Recombinants produced 145 mM mevalonate in five independent single-step fermentation runs 25 days each in five repeats using syngas blend 60 % CO and 40 % H2 (v/v) (p < 0.005). Mevalonate production was 97 mM if only CO2/H2 blend was fed instead of syngas (p < 0.005). Mevalonate from CO2/H2 blend might serve as a commercial route to mitigate global warming in proportion to CO2 fermentation scale worldwide. 相似文献
15.
The hyperthermophilic bacterium, Thermotoga neapolitana, has potential for use in biological hydrogen (H2) production. The objectives of this study were to (1) determine the fermentation stoichiometry of Thermotoga neapolitana and examine H2 production at various growth temperatures, (2) investigate the effect of oxygen (O2) on H2 production, and (3) determine the cause of glucose consumption inhibition. Batch fermentation experiments were conducted at temperatures of 60, 65, 70, 77, and 85°C to determine product yield coefficients and volumetric productivity rates. Yield coefficients did not show significant changes with respect to growth temperature and the rate of H2 production reached maximum levels in both the 77°C and 85°C experiments. The fermentation stoichiometry for T. neapolitana at 85°C was 3.8 mol H2, 2 mol CO2, 1.8 mol acetate, and 0.1 mol lactate produced per mol of glucose consumed. Under microaerobic conditions H2 production did not increase when compared to anaerobic conditions, which supports other evidence in the literature that T. neapolitana does not produce H2 through microaerobic metabolism. Glucose consumption was inhibited by a decrease in pH. When pH was adjusted with buffer addition cultures completely consumed available glucose. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
16.
Hacı Ali Güleç Sevim Gürdaş Nedim Albayrak Mehmet Mutlu 《Biotechnology and Bioprocess Engineering》2010,15(6):1006-1015
The aim of this study was to produce galactooligosaccharides (GOS) from lactose using β-galactosidase from Aspergillus oryzae immobilized on a low-pressure plasma-modified cellulose acetate (CA) membrane. Specifically, a novel method was developed
for multilayer enzyme immobilization involving polyethyleneimine (PEI)-enzyme aggregate formation and growth on a CA membrane.
A large amount of enzyme (997 μg/cm2 membrane) was immobilized with 66% efficiency. The K
m
value for the immobilized enzyme was estimated to be 48 mM, which indicates decreased affinity for the substrate, whereas
the Vmax value was smaller. The immobilized enzyme showed good storage and operational stability. The half-life of the immobilized
enzyme on the membrane was about 1 month at 30°C and ∼ 60 h at 60°C. Maximum GOS production of 27% (w/w) was achieved with
70% lactose conversion from 320 g/L of lactose at pH 4.5 and 60°C. Trisaccharides were the major types of GOS formed and accounted
for about 75% of the total GOS produced. Based on these results, immobilized enzyme technology could be applied to GOS production
from lactose. 相似文献
17.
Brevibacterium flavum ATCC14067 was engineered for l-valine production by overexpression of different ilv genes; the ilvEBNrC genes from B. flavum NV128 provided the best candidate for l-valine production. In traditional fermentation, l-valine production reached 30.08 ± 0.92 g/L at 31°C in 72 h with a low conversion efficiency of 0.129 g/g. To further improve
the l-valine production and conversion efficiency based on the optimum temperatures of l-valine biosynthesis enzymes (above 35°C) and the thermotolerance of B. flavum, the fermentation temperature was increased to 34, 37, and 40°C. As a result, higher metabolic rate and l-valine biosynthesis enzymes activity were obtained at high temperature, and the maximum l-valine production, conversion efficiency, and specific l-valine production rate reached 38.08 ± 1.32 g/L, 0.241 g/g, and 0.133 g g−1 h−1, respectively, at 37°C in 48 h fermentation. The strategy for enhancing l-valine production by overexpression of key enzymes in thermotolerant strains may provide an alternative approach to enhance
branched-chain amino acids production with other strains. 相似文献
18.
Tobias Pereira de Morais Paula Mirella Gomes Barbosa Nayara Fernanda Lisboa Garcia Nathália Gonsales da Rosa-Garzon Gustavo Graciano Fonseca Marcelo Fossa da Paz 《Preparative biochemistry & biotechnology》2013,43(9):777-786
AbstractThe objective of the present study was to optimize parameters for the cultivation of Lichtheimia corymbifera (mesophilic) and Byssochlamys spectabilis (thermophilic) for the production of β-glucosidases and to compare the catalytic and thermodynamic properties of the partially purified enzymes. The maximum amount of β-glucosidase produced by L. corymbifera was 39?U/g dry substrate (or 3.9?U/mL), and that by B. spectabilis was 77?U/g (or 7.7?U/mL). The optimum pH and temperature were 4.5 and 55?°C and 4.0 and 50?°C for the enzyme from L. corymbifera and B. spectabilis, respectively. β-Glucosidase produced by L. corymbifera was stable at pH 4.0–7.5, whereas the enzyme from B. spectabilis was stable at pH 4.0–6.0. Regarding the thermostability, β-glucosidase produced by B. spectabilis remained stable for 1?h at 50?°C, and that from L. corymbifera was active for 1?h at 45?°C. Determination of thermodynamic parameters confirmed the greater thermostability of the enzyme produced by the thermophilic fungus B. spectabilis, which showed higher values of ΔH, activation energy for denaturation (Ea), and half-life t(1/2). The enzymes were stable in the presence of ethanol and were competitively inhibited by glucose. These characteristics contribute to their use in the simultaneous saccharification and fermentation of vegetable biomass. 相似文献
19.
Diacetyl, a highly valuable product that is extensively used as an ingredient of food, tobacco, and daily chemicals such as perfumes, can be produced from the nonenzymatic oxidative decarboxylation of α-acetolactate during bacterial fermentation and converted to acetoin and 2,3-butanediol by 2,3-butanediol dehydrogenase. In the present study, Bacillus sp. DL01, which gives high acetoin production, was metabolically engineered to improve diacetyl production. After the deletion of α-acetolactate decarboxylase (ALDC)-encoding gene (alsD) by homologous recombination, the engineered strain, named Bacillus sp. DL01-ΔalsD, lost ALDC activity and produced 1.53 g/L diacetyl without acetoin and 2,3-butanediol accumulation. The channeling of carbon flux into diacetyl biosynthetic pathway was amplified by an overexpressed α-acetolactate synthase (ALS)-encoding gene (alsS) in Bacillus sp. DL01-ΔalsD-alsS, which produced 4.02 g/L α-acetolactate and 1.94 g/L diacetyl, and the conversion from α-acetolactate to diacetyl was increased by 1-fold after 20 mM Fe3+ was added to the fermentation medium. A titer of 8.69 g/L diacetyl, the highest reported diacetyl production, was achieved by fed-batch fermentation in optimal conditions using the metabolically engineered strain of Bacillus sp. DL01-ΔalsD-alsS. These results are of great importance as a new method for the efficient production of diacetyl by food-safe bacteria. 相似文献
20.
Effect of fermentation temperature on hydrogen production from cow waste slurry by using anaerobic microflora within the slurry 总被引:9,自引:0,他引:9
Yokoyama H Waki M Moriya N Yasuda T Tanaka Y Haga K 《Applied microbiology and biotechnology》2007,74(2):474-483
We examined hydrogen production from a dairy cow waste slurry (13.4 g of volatile solids per liter) by batch cultures in a
temperature range from 37 to 85°C, using microflora naturally present within the slurry. Without the addition of seed bacteria,
hydrogen was produced by simply incubating the slurry, using the microflora within the slurry. Interestingly, two peaks of
fermentation temperatures for hydrogen production from the slurry were observed at 60 and 75°C (392 and 248 ml H2 per liter of slurry, respectively). After the termination of the hydrogen evolution, the microflora cultured at 60°C displayed
hydrogen-consuming activity, but hydrogen-consuming activity of the microflora cultured at 75°C was not detected, at least
for 24 days. At both 60 and 75°C, the main by-product was acetate, and the optimum pH of the slurry for hydrogen production
was around neutral. Bacteria related to hydrogen-producing moderate and extreme thermophiles, Clostridium thermocellum and Caldanaerobacter subterraneus, were detected in the slurries cultured at 60 and 75°C, respectively, by denaturing gradient gel electrophoresis analyses,
using the V3 region of 16S rDNA. 相似文献