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1.
Anjali Madhavan Sriappareddy Tamalampudi Aradhana Srivastava Hideki Fukuda Virendra S. Bisaria Akihiko Kondo 《Applied microbiology and biotechnology》2009,82(6):1037-1047
Previously, a Saccharomyces cerevisiae strain was engineered for xylose assimilation by the constitutive overexpression of the Orpinomyces xylose isomerase, the S. cerevisiae xylulokinase, and the Pichia stipitis SUT1 sugar transporter genes. The recombinant strain exhibited growth on xylose, under aerobic conditions, with a specific growth
rate of 0.025 h−1, while ethanol production from xylose was achieved anaerobically. In the present study, the developed recombinant yeast was
adapted for enhanced growth on xylose by serial transfer in xylose-containing minimal medium under aerobic conditions. After
repeated batch cultivations, a strain was isolated which grew with a specific growth rate of 0.133 h−1. The adapted strain could ferment 20 g l−1 of xylose to ethanol with a yield of 0.37 g g−1 and production rate of 0.026 g l−1 h−1. Raising the fermentation temperature from 30°C to 35°C resulted in a substantial increase in the ethanol yield (0.43 g g−1) and production rate (0.07 g l−1 h−1) as well as a significant reduction in the xylitol yield. By the addition of a sugar complexing agent, such as sodium tetraborate,
significant improvement in ethanol production and reduction in xylitol accumulation was achieved. Furthermore, ethanol production
from xylose and a mixture of glucose and xylose was also demonstrated in complex medium containing yeast extract, peptone,
and borate with a considerably high yield of 0.48 g g−1. 相似文献
2.
Lactic acid production from xylose by the fungus Rhizopus oryzae 总被引:1,自引:1,他引:0
Lignocellulosic biomass is considered nowadays to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid. The filamentous fungus Rhizopus oryzae is able to grow in mineral medium with glucose as sole carbon source and to produce optically pure l(+)-lactic acid. Less is known about the conversion by R. oryzae of pentose sugars such as xylose, which is abundantly present in lignocellulosic hydrolysates. This paper describes the conversion of xylose in synthetic media into lactic acid by ten R. oryzae strains resulting in yields between 0.41 and 0.71 g g−1. By-products were fungal biomass, xylitol, glycerol, ethanol and carbon dioxide. The growth of R. oryzae CBS 112.07 in media with initial xylose concentrations above 40 g l−1 showed inhibition of substrate consumption and lactic acid production rates. In case of mixed substrates, diauxic growth was observed where consumption of glucose and xylose occurred subsequently. Sugar consumption rate and lactic acid production rate were significantly higher during glucose consumption phase compared to xylose consumption phase. Available xylose (10.3 g l−1) and glucose (19.2 g l−1) present in a mild-temperature alkaline treated wheat straw hydrolysate was converted subsequently by R. oryzae with rates of 2.2 g glucose l−1 h−1 and 0.5 g xylose l−1 h−1. This resulted mainly into the product lactic acid (6.8 g l−1) and ethanol (5.7 g l−1). 相似文献
3.
Laura Pinilla Rodrigo Torres Claudia Ortiz 《World journal of microbiology & biotechnology》2011,27(11):2521-2528
Two wild strains of Zymomonas mobilis were isolated (named as ML1 and ML2) from sugar cane molasses obtained from different farms of Santander, Colombia. Initially,
selection of the best ethanol-producer strains was carried out using ethanol production parameters obtained with a commercial
strain Z. mobilis DSM 3580. Three isolated strains were cultivated in a culture medium containing yeast extract, peptone, glucose and salts,
at pH 6 and 32°C with stirring rate of 65 rpm during 62 h. The best results of ethanol production were obtained with the native
strain ML1, reaching a maximum ethanol concentration of 79.78 g l−1. ML1 and ML2 strains were identified as Z.
mobilis, according to the morphology, biochemical tests and molecular characterization by PCR of specific DNA sequences from Z. mobilis. Subsequently, the effect of different nitrogen sources on production of ethanol was evaluated. The best results were obtained
using urea at a 0.73 g/l. In this case, maximum concentration of ethanol was 83.81 g l−1, with kinetic parameters of yield of ethanol on biomass (YP/X) = 69.01(g g−1), maximum volumetric productivity of ethanol (Qpmax) = 2.28 (g l−1 h−1), specific productivity of ethanol (qP) = 3.54 (h−1) and specific growth rate (μ) = 0.12 h−1. Finally, we studied the effect of different culture conditions (pH, temperature, stirring, C/N ratio) with a Placket-Burman′s
experimental design. This optimization indicated that the most significant variables were temperature and stirring. In the
best culture conditions a significant increase in all variables of response was achieved, reaching a maximum ethanol concentration
of 93.55 g l−1. 相似文献
4.
Continuous ethanol fermentation of cheese whey powder solution was realized using pure culture of Kluyveromyces marxianus (DSMZ 7239) at hydraulic residence times (HRT) between 12.5 and 60 h. Sugar utilization, ethanol and biomass formation were
investigated as functions of HRT. Effluent sugar concentration decreased, but percent sugar utilization, ethanol and biomass
concentrations increased with HRT. Ethanol productivity was maximum (0.745 gE l−1h−1) at an HRT of 43.2 h where the biomass productivity was almost minimum (0.18 gX l−1 h−1). The ethanol yield coefficient was almost constant at 0.4 gE g−1S up to HRT of 43.2 h and the growth yield coefficient was minimum at HRT of 43.2 h. Kinetic models were developed and the
constants were determined by using the experimental data. 相似文献
5.
Kiviharju K Moilanen U Leisola M Eerikäinen T 《Applied microbiology and biotechnology》2007,73(6):1267-1274
The behavior of Streptomyces peucetius var. caesius N47 was studied in a glucose limited chemostat with a complex cultivation medium. The steady-state study yielded the characteristic
constants μ
max over 0.10 h−1, Y
XS 0.536 g g−1, and mS 0.54 mg g−1 h−1. The product of secondary metabolism, ɛ-rhodomycinone, was produced with characteristics Y
PX 12.99 mg g−1 and m
P 1.20 mg g−1 h−1. Significant correlations were found for phosphate and glucose consumption with biomass and ɛ-rhodomycinone production. Metabolic
flux analysis was conducted to estimate intracellular fluxes at different dilution rates. TCA, PPP, and shikimate pathway
fluxes exhibited bigger values with production than with growth. Environmental perturbation experiments with temperature,
airflow, and pH changes on a steady-state chemostat implied that an elevation of pH could be the most effective way to shift
the cells from growing to producing, as the pH change induced the biggest transient increase to the calculated ɛ-rhodomycinone
flux. 相似文献
6.
The biokinetics of glucose metabolism were evaluated in Aeromonas hydrophila during growth in an anaerobic biosystem. After approx 34 h growth, A. hydrophila metabolized 5,000 mg glucose l−1 into the end-products ethanol, acetate, succinate and formate. The maximum growth rate, μ
m, half saturation coefficients, K
s, microbial yield coefficient, Y, cell mass decay rate coefficient, k
d, and substrate inhibition coefficient, K
si were 0.25 ± 0.03 h−1, 118 ± 31 mg glucose l−1, 0.12 μg DNA mg glucose−1, 0.01 h−1, and 3,108 ± 1,152 mg glucose l−1, respectively. These data were used to predict the performance of a continuous growth system with an influent glucose concentration
of 5,000 mg l−1. Results of the analysis suggest that A. hydrophila will metabolize glucose at greater than 95% efficiency when hydraulic retention times (HRTs) exceed 7 h, whereas the culture
is at risk of washing out at an HRT of 6.7 h. 相似文献
7.
High-cell-density production of recombinant growth hormone of Lateolabrax japonicus (rljGH) expressed intracellularly in Pichia pastoris was investigated. In the regular strategy of induction at a cell density of 160 g l−1, short duration of intracellular rljGH accumulation (17 h) resulted in a low final cell density of 226 g l−1. Thus, a novel strategy of induction at a cell density of 320 g l−1 was investigated. In this strategy, the preinduction glycerol-feeding scheme had a significant effect on the post-induction
production. Constant glycerol feeding led to a decrease of the specific rljGH production and specific production rate because
of low preinduction specific growth rate. This decrease was avoided by exponential glycerol feeding to maintain a preinduction
specific growth rate of 0.16 h−1. The results from exponential glycerol feeding indicated that the rljGH production depended on the preinduction specific
growth rate. Moreover, mixed feeding of methanol and glycerol during induction improved the specific production rate to 0.07 mg
g−1 h−1 from 0.043 mg g−1 h−1. Consequently, both high cell density (428 g l−1) and high rljGH production could be achieved by the novel strategy: growing the cells at the specific growth rate of 0.16 h−1 to the cell density of 320 g l−1 and inducing the expression by mixed feeding. 相似文献
8.
Compared with steady state, oscillation in continuous very-high-gravity ethanol fermentation with Saccharomyces cerevisiae improved process productivity, which was thus introduced for the fermentation system composed of a tank fermentor followed
by four-stage packed tubular bioreactors. When the very-high-gravity medium containing 280 g l−1 glucose was fed at the dilution rate of 0.04 h−1, the average ethanol of 15.8% (v/v) and residual glucose of 1.5 g l−1 were achieved under the oscillatory state, with an average ethanol productivity of 2.14 g h−1 l−1. By contrast, only 14.8% (v/v) ethanol was achieved under the steady state at the same dilution rate, and the residual glucose was as high as 17.1 g l−1, with an ethanol productivity of 2.00 g h−1 l−1, indicating a 7% improvement under the oscillatory state. When the fermentation system was operated under the steady state
at the dilution rate of 0.027 h−1 to extend the average fermentation time to 88 h from 59 h, the ethanol concentration increased slightly to 15.4% (v/v) and residual glucose decreased to 7.3 g l−1, correspondingly, but the ethanol productivity was decreased drastically to 1.43 g h−1 l−1, indicating a 48% improvement under the oscillatory state at the dilution rate of 0.04 h−1. 相似文献
9.
Pseudomonas putida KT2440 grew on glucose at a specific rate of 0.48 h−1 but accumulated almost no poly-3-hydroxyalkanoates (PHA). Subsequent nitrogen limitation on nonanoic acid resulted in the
accumulation of only 27% medium-chain-length PHA (MCL-PHA). In contrast, exponential nonanoic acid-limited growth (μ = 0.15 h−1) produced 70 g l−1 biomass containing 75% PHA. At a higher exponential feed rate (μ = 0.25 h−1), the overall productivity was increased but less biomass (56 g l−1) was produced due to higher oxygen demand, and the biomass contained less PHA (67%). It was concluded that carbon-limited
exponential feeding of nonanoic acid or related substrates to cultures of P. putida KT2440 is a simple and highly effective method of producing MCL-PHA. Nitrogen limitation is unnecessary. 相似文献
10.
Lakkana Laopaiboon Pornthap Thanonkeo Prasit Jaisil Pattana Laopaiboon 《World journal of microbiology & biotechnology》2007,23(10):1497-1501
Sweet sorghum juice supplemented with 0.5% ammonium sulphate was used as a substrate for ethanol production by Saccharomyces cerevisiae TISTR 5048. In batch fermentation, kinetic parameters for ethanol production depended on initial cell and sugar concentrations.
The optimum initial cell and sugar concentrations in the batch fermentation were 1 × 108 cells ml−1 and 24 °Bx respectively. At these conditions, ethanol concentration produced (P), yield (Y
ps) and productivity (Q
p
) were 100 g l−1, 0.42 g g−1 and 1.67 g l−1 h−1 respectively. In fed-batch fermentation, the optimum substrate feeding strategy for ethanol production at the initial sugar
concentration of 24 °Bx was one-time substrate feeding, where P, Y
ps and Q
p
were 120 g l−1, 0.48 g g−1 and 1.11 g l−1 h−1 respectively. These findings suggest that fed-batch fermentation improves the efficiency of ethanol production in terms of
ethanol concentration and product yield. 相似文献
11.
Automated feeding strategies for high-cell-density fed-batch cultivation of Pseudomonas putida KT2440 总被引:1,自引:0,他引:1
Four automatic substrate feeding strategies were developed and investigated in this study to obtain rapid, repeatable, and reliable high cell densities of Pseudomonas putida KT2440 from glucose. Growth yield data of the key nutrients, Y
X/Glucose, Y
X/NH4, Y
X/PO4, Y
X/Mg, and Y
CO2/Glucose, were determined to be 0.41, 5.44, 13.70, 236, and 0.65 g g−1, respectively. Although standard exponential feeding strategy worked well when the predetermined μ was set at 0.25 h−1, an exponential glucose feeding strategy with online μ
max estimation resulted in a higher average biomass productivity (3.4 vs 2.8 g l−1 h−1). A CO2 production rate based pulse glucose feeding strategy also resulted in good overall productivity (3.0 g l−1 h−1) and can be used as an alternative to pH-stat or DO-stat feeding. A cumulative CO2 production based continuous feed with real-time cumulative glucose consumption estimation resulted in much higher biomass productivity (4.3 g l−1 h−1) and appears to be an excellent and reliable approach to fully automating high-cell-density fed-batch cultivation of P. putida. 相似文献
12.
The growth performance of malolactic fermenting bacteria Oenococcus oeni NCIMB 11648 and Lactobacillus brevis X2 was assessed in continuous culture. O. oeni grew at a dilution rate range of 0.007 to 0.052 h−1 in a mixture of 5:6 (g l−1) of glucose/fructose at an optimal pH of 4.5, and L. brevis X2 grew at 0.010 to 0.089 h−1 in 10 g l−1 glucose at an optimal pH of 5.5 in a simple and safe medium. The cell dry weight, substrate uptake and product formation
were monitored, as well as growth kinetics, yield parameters and fermentation balances were also evaluated under pH control
conditions. A comparison of growth characteristics of two strains was made, and this showed significantly different performance.
O. oeni has lower maximum specific growth rate (μmax=0.073 h−1), lower maximum cell productivity (Q
x
max=17.6 mg cell l−1 h−1), lower maximum biomass yield (Y
x/s
max=7.93 g cell mol−1 sugar) and higher maintenance coefficient (m
s=0.45 mmol−1 sugar g−1 cell h−1) as compared with L. brevis X2 (μmax=0.110 h−1; Q
x
max=93.2 g−1 cell mol−1 glucose; Y
x/s
max=22.3 g cell mol−1 glucose; m
s=0.21 mmol−1 glucose g−1 cell h−1). These data suggest a possible more productive strategy for their combined use in maturation of cider and wine. 相似文献
13.
Yoshida A Nishimura T Kawaguchi H Inui M Yukawa H 《Applied microbiology and biotechnology》2007,74(4):754-760
A three-step biohydrogen production process characterized by efficient anaerobic induction of the formate hydrogen lyase (FHL)
of aerobically grown Escherichia coli was established. Using E. coli strain SR13 (fhlA
++, ΔhycA) at a cell density of 8.2 g/l medium in this process, a specific hydrogen productivity (28.0 ± 5.0 mmol h−1 g−1 dry cell) of one order of magnitude lower than we previously reported was realized after 8 h of anaerobic incubation. The
reduced productivity was attributed partly to the inhibitory effects of accumulated metabolites on FHL induction. To avoid
this inhibition, strain SR14 (SR13 ΔldhA ΔfrdBC) was constructed and used to the effect that specific hydrogen productivity increased 1.3-fold to 37.4 ± 6.9 mmol h−1 g−1. Furthermore, a maximum hydrogen production rate of 144.2 mmol h−1 g−1 was realized when a metabolite excretion system that achieved a dilution rate of 2.0 h−1 was implemented. These results demonstrate that by avoiding anaerobic cultivation altogether, more economical harvesting
of hydrogen-producing cells for use in our biohydrogen process was made possible. 相似文献
14.
In these studies, butanol (acetone butanol ethanol or ABE) was produced from wheat straw hydrolysate (WSH) in batch cultures
using Clostridium beijerinckii P260. In control fermentation 48.9 g L−1 glucose (initial sugar 62.0 g L−1) was used to produce 20.1 g L−1 ABE with a productivity and yield of 0.28 g L−1 h−1 and 0.41, respectively. In a similar experiment where WSH (60.2 g L−1 total sugars obtained from hydrolysis of 86 g L−1 wheat straw) was used, the culture produced 25.0 g L−1 ABE with a productivity and yield of 0.60 g L−1 h−1 and 0.42, respectively. These results are superior to the control experiment and productivity was improved by 214%. When
WSH was supplemented with 35 g L−1 glucose, a reactor productivity was improved to 0.63 g L−1 h−1 with a yield of 0.42. In this case, ABE concentration in the broth was 28.2 g L−1. When WSH was supplemented with 60 g L−1 glucose, the resultant medium containing 128.3 g L−1 sugars was successfully fermented (due to product removal) to produce 47.6 g L−1 ABE, and the culture utilized all the sugars (glucose, xylose, arabinose, galactose, and mannose). These results demonstrate
that C. beijerinckii P260 has excellent capacity to convert biomass derived sugars to solvents and can produce over 28 g L−1 (in one case 41.7 g L−1 from glucose) ABE from WSH. Medium containing 250 g L−1 glucose resulted in no growth and no ABE production. Mixtures containing WSH + 140 g L−1 glucose (total sugar approximately 200 g L−1) showed poor growth and poor ABE production.
Mention of trade names or commercial products in this article is solely for the purpose of providing scientific information
and does not imply recommendation or endorsement by the United States Department of Agriculture. 相似文献
15.
In order to improve the production rate of l-lysine, a mutant of Corynebacterium glutamicum ATCC 21513 was cultivated in complex medium with gluconate and glucose as mixed carbon sources. In a batch culture, this
strain was found to consume gluconate and glucose simultaneously. In continuous culture at dilution rates ranging from 0.2
h−1 to 0.25 h−1, the specific l-lysine production rate increased to 0.12 g g−1 h−1 from 0.1 g g−1 h−1, the rate obtained with glucose as the sole carbon source [Lee et al. (1995) Appl Microbiol Biotechnol 43:1019–1027]. It
is notable that l-lysine production was observed at higher dilution rates than 0.4 h−1, which was not observed when glucose was the sole carbon source. The positive effect of gluconate was confirmed in the shift
of the carbon source from glucose to gluconate. The metabolic transition, which has been characterized by decreased l-lysine production at the higher glucose uptake rates, was not observed when gluconate was added. These results demonstrate
that the utilization of gluconate as a secondary carbon source improves the maximum l-lysine production rate in the threonine-limited continuous culture, probably by relieving the limiting factors in the lysine
synthesis rate such as NADPH supply and/or phosphoenolpyruvate availability.
Received: 16 May 1997 / Received revision: 28 August 1997 / Accepted: 29 August 1997 相似文献
16.
Kaarel Adamberg Petri-Jaan Lahtvee Kaspar Valgepea Kristo Abner Raivo Vilu 《Antonie van Leeuwenhoek》2009,95(3):219-226
Quasi steady state growth of Lactococcus
lactis IL 1403 was studied in glucose-limited A-stat cultivation experiments with acceleration rates (a) from 0.003 to 0.06 h−2 after initial stabilization of the cultures in chemostat at D = 0.2–0.3 h−1. It was shown that the high limit of quasi steady state growth rate depended on the acceleration rate used—at an acceleration
rate 0.003 h−2 the quasi steady state growth was observed until μ
crit = 0.59 h−1, which is also the μ
max value for the culture. Lower values of μ
crit were observed at higher acceleration rates. The steady state growth of bacteria stabilized at dilution rate 0.2 h−1 was immediately disrupted after initiating acceleration at the highest acceleration rate studied—0.06 h−2. Observation was made that differences [Δ(μ − D)] of the specific growth rates from pre-programmed dilution rates were the lowest using an acceleration rate of 0.003 h−2 (< 4% of preset changing growth rate). The adaptability of cells to follow preprogrammed growth rate was found to decrease
with increasing dilution rate—it was shown that lower acceleration rates should be applied at higher growth rates to maintain
the culture in the quasi steady state. The critical specific growth rate and the biomass yields based on glucose consumption
were higher if the medium contained S
0 = 5 g L−1 glucose instead of S
0 = 10 g L−1. It was assumed that this was due to the inhibitory effect of lactate accumulating at higher concentrations in the latter
cultures. Parallel A-stat experiments at the same acceleration and dilution rates showed good reproducibility—Δ(μ − D) was less than 5%, standard deviations of biomass yields per ATP produced (Y
ATP), and biomass yields per glucose consumed (Y
XS) were less than 15%. 相似文献
17.
The fermentation characteristics of the novel, thermotolerant, isolate Kluyveromyces marxianus var marxianus were determined to evaluate its aptitude for use in an ethanol production process. Sustainable growth was not observed under
anaerobic conditions, even in the presence of unsaturated fatty acid and sterol. A maximum ethanol concentration of 40 g L−1 was produced at 45°C, with an initial specific ethanol production rate of 1.7 g g−1 h−1. This was observed at ethanol concentrations below 8 g L−1 and under oxygen-limited conditions. The low ethanol tolerance and low growth under oxygen-limited conditions required for
ethanol production implied that a simple continuous process was not feasible with this yeast strain. Improved productivity
was achieved through recycling biomass into the fermenter, indicating that utilising an effective cell retention method such
as cell recycle or immobilisation, could lead to the development of a viable industrial process using this novel yeast strain.
Received 14 February 1998/ Accepted in revised form 19 May 1998 相似文献
18.
Gabriel Vigueras Sonia Arriaga Keiko Shirai Marcia Morales Sergio Revah 《Biotechnology letters》2009,31(8):1203-1209
Rhinocladiella similis biodegraded volatile organic compounds (VOCs) of different polarity in gas-phase biofilters. Elimination capacities, (EC)
of 74 ghexane m−3 h−1, 230 gethanol m−3 h−1, 85 gtoluene m−3 h−1 and 30 gphenol m−3 h−1 were obtained. EC values correlated with the solubility of the VOCs. R. similis grown with n-hexane or ethanol in biofilters packed with Perlite showed that the surface hydrophobicity was higher with n-hexane
than ethanol. The hydrophobin-like proteins extracted from the mycelium produced with n-hexane (15 kDa) were different from
those in the ethanol biofilter (8.5 kDa and 7 kDa). 相似文献
19.
Batch cultivation of Ralstonia eutropha NRRL B14690 attained 21 g biomass l−1 and 9.4 g poly(β-hydroxybutyrate) l−1 (0.45 g PHB g−1 dry wt−1) in 60 h. Repeated batch operation (empty-and-fill protocol) to remove 20% (v/v) of the culture broth and to supplement an
equal volume of fresh media resulted in 49 g biomass l−1 and 25 g PHB l−1 (0.51 g PHB g−1 dry wt−1) with an overall productivity of 0.42 g PHB l−1 h−1 in 67 h. In the two cycles of repeated batch fermentation there was a 3-fold increase in productivity as compared to batch. 相似文献
20.
Sugarcane bagasse hemicellulose hydrolysates, pretreated by either over-liming or electrodialysis and, supplemented with nutrient
materials, were fermented to ethanol using Pachysolen tannophilus DW06. Compared with detoxification by over-liming, detoxification by electrodialysis decreased the loss of sugar and increased
the acetic acid removal, leading to better fermentability. A batch culture with electrodialytically pretreated hydrolysate
as substrate was developed giving 21 g ethanol l−1 with a yield of 0.35 g g−1 sugar and productivity of 0.59 g l−1 h−1. 相似文献