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1.
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
2.
Waldemar Rymowicz Alina R. Fatykhova Svetlana V. Kamzolova Anita Rywińska Igor G. Morgunov 《Applied microbiology and biotechnology》2010,87(3):971-979
Yarrowia lipolytica A-101-1.22 produces high citric acid (112 g l−1) with a yield of 0.6 g g−1 and a productivity of 0.71 g l−1 h−1 during batch cultivation in the medium with glycerol-containing waste of biodiesel industry. However, it was observed that
the specific citric acid production rate, which was maximal at the beginning of the biosynthesis, gradually decreases in the
late production phase and it makes continuation of the process over 100 h pointless. The cell recycle and the repeated batch
regimes were performed as ways for prolongation of citric acid synthesis by yeast. Using cell recycle, the active citric acid
biosynthesis (96–107 g l−1) with a yield of 0.64 g g−1 and a productivity of 1.42 g l−1 h−1 was prolongated up to 300 h. Repeated batch culture remained stable for over 1000 h; the RB variant of 30% feed every 3 days
showed the best results: 124.2 g l-1 citric acid with a yield of 0.77 g g-1 and a productivity of 0.85 g l-1 h-1. 相似文献
3.
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
4.
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
5.
Mendes FS González-Pajuelo M Cordier H François JM Vasconcelos I 《Applied microbiology and biotechnology》2011,92(3):519-527
In this work, the production of 1,3-propanediol from glucose and molasses was studied in a two-step process using two recombinant
microorganisms. The first step of the process is the conversion of glucose or other sugar into glycerol by the metabolic engineered
Saccharomyces cerevisiae strain HC42 adapted to high (>200 g l−1) glucose concentrations. The second step, carried out in the same bioreactor, was performed by the engineered strain Clostridium acetobutylicum DG1 (pSPD5) that converts glycerol to 1,3-propanediol. This two-step strategy led to a flexible process, resulting in a 1,3-propanediol
production and yield that depended on the initial sugar concentration. Below 56.2 g l−1 of sugar concentration, cultivation on molasses or glucose showed no significant differences. However, at higher molasses
concentrations, glycerol initially produced by yeast could not be totally converted into 1,3-propanediol by C. acetobutylicum and a lower 1,3-propanediol overall yield was observed. In our hand, the best results were obtained with an initial glucose
concentration of 103 g l−1, leading to a final 1,3-propanediol concentration of 25.5 g l−1, a productivity of 0.16 g l−1 h−1 and 1,3-propanediol yields of 0.56 g g−1 glycerol and 0.24 g g−1 sugar, which is the highest value reported for a two-step process. For an initial sugar concentration (from molasses) of
56.2 g l−1, 27.4 g l−1 of glycerol were produced, leading to 14.6 g l−1 of 1.3-propanediol and similar values of productivity, 0.15 g l−1 h−1, and overall yield, 0.26 g g−1 sugar. 相似文献
6.
Sachin Kumar Surendra P. Singh Indra M. Mishra Dilip K. Adhikari 《Journal of industrial microbiology & biotechnology》2009,36(12):1483-1489
A yeast strain Kluyveromyces sp. IIPE453 (MTCC 5314), isolated from soil samples collected from dumping sites of crushed sugarcane bagasse in Sugar Mill,
showed growth and fermentation efficiency at high temperatures ranging from 45°C to 50°C. The yeast strain was able to use
a wide range of substrates, such as glucose, xylose, mannose, galactose, arabinose, sucrose, and cellobiose, either for growth
or fermentation to ethanol. The strain also showed xylitol production from xylose. In batch fermentation, the strain showed
maximum ethanol concentration of 82 ± 0.5 g l−1 (10.4% v/v) on initial glucose concentration of 200 g l−1, and ethanol concentration of 1.75 ± 0.05 g l−1 as well as xylitol concentration of 11.5 ± 0.4 g l−1 on initial xylose concentration of 20 g l−1 at 50°C. The strain was capable of simultaneously using glucose and xylose in a mixture of glucose concentration of 75 g l−1 and xylose concentration of 25 g l−1, achieving maximum ethanol concentration of 38 ± 0.5 g l−1 and xylitol concentration of 14.5 ± 0.2 g l−1 in batch fermentation. High stability of the strain was observed in a continuous fermentation by feeding the mixture of glucose
concentration of 75 g l−1 and xylose concentration of 25 g l−1 by recycling the cells, achieving maximum ethanol concentration of 30.8 ± 6.2 g l−1 and xylitol concentration of 7.35 ± 3.3 g l−1 with ethanol productivity of 3.1 ± 0.6 g l−1 h−1 and xylitol productivity of 0.75 ± 0.35 g l−1 h−1, respectively. 相似文献
7.
Miho Sasaki Toru Jojima Masayuki Inui Hideaki Yukawa 《Applied microbiology and biotechnology》2010,86(4):1057-1066
Wild-type Corynebacterium glutamicum produced 0.6 g l−1 xylitol from xylose at a productivity of 0.01 g l−1 h−1 under oxygen deprivation. To increase this productivity, the pentose transporter gene (araE) from C. glutamicum ATCC31831 was integrated into the C. glutamicum R chromosome. Consequent disruption of its lactate dehydrogenase gene (ldhA), and expression of single-site mutant xylose reductase from Candida tenuis (CtXR (K274R)) resulted in recombinant C. glutamicum strain CtXR4 that produced 26.5 g l−1 xylitol at 3.1 g l−1 h−1. To eliminate possible formation of toxic intracellular xylitol phosphate, genes encoding xylulokinase (XylB) and phosphoenolpyruvate-dependent
fructose phosphotransferase (PTSfru) were disrupted to yield strain CtXR7. The productivity of strain CtXR7 increased 1.6-fold over that of strain CtXR4. A fed-batch
21-h CtXR7 culture in mineral salts medium under oxygen deprivation yielded 166 g l−1 xylitol at 7.9 g l−1 h−1, representing the highest bacterial xylitol productivity reported to date. 相似文献
8.
Butanol, a four-carbon primary alcohol (C4H10O), is an important industrial chemical and has a good potential to be used as a superior biofuel. Bio-based production of
butanol from renewable feedstock is a promising and sustainable alternative to substitute petroleum-based fuels. Here, we
report the development of a process for butanol production from glycerol, which is abundantly available as a byproduct of
biodiesel production. First, a hyper butanol producing strain of Clostridium pasteurianum was isolated by chemical mutagenesis. The best mutant strain, C. pasteurianum MBEL_GLY2, was able to produce 10.8 g l−1 butanol from 80 g l−1 glycerol as compared to 7.6 g l−1 butanol produced by the parent strain. Next, the process parameters were optimized to maximize butanol production from glycerol.
Under the optimized batch condition, the butanol concentration, yield, and productivity of 17.8 g l−1, 0.30 g g−1, and 0.43 g l−1 h−1 could be achieved. Finally, continuous fermentation of C. pasteurianum MBEL_GLY2 with cell recycling was carried out using glycerol as a major carbon source at several different dilution rates.
The continuous fermentation was run for 710 h without strain degeneration. The acetone–butanol–ethanol productivity and the
butanol productivity of 8.3 and 7.8 g l−1 h−1, respectively, could be achieved at the dilution rate of 0.9 h−1. This study reports continuous production of butanol with reduced byproducts formation from glycerol using C. pasteurianum, and thus could help design a bioprocess for the improved production of butanol. 相似文献
9.
Yuedong Zhang Yujiu Ma Fangxiao Yang Chunhui Zhang 《Journal of industrial microbiology & biotechnology》2009,36(8):1117-1121
Corn stalk was used as a support to immobilize Clostridia beijerinckii ATCC 55025 in the fermentation process of acetone, butanol, and ethanol production. The effect of the dilution rate on solvent
production was examined in a steady-state 20-day continuous flow operation. The maximum total solvent concentration of 8.99 g l−1 was obtained at a dilution rate of 0.2 h−1. Increasing the dilution rate between 0.2 and 1.0 h−1 resulted in an increased solvent productivity, and the highest solvent productivity was obtained at 5.06 g l−1 h−1 with a dilution rate of 1 h−1. The maximum solvent yield from glucose of 0.32 g g−1 was observed at 0.25 h−1. The cell adsorption and morphology change during the growth on corn stalk support were examined by the SEM. 相似文献
10.
Poly(3-hydroxybutyrate) (PHB) biosynthesis from soybean oil by Cupriavidus necator was studied using a bench scale bioreactor. The highest cell concentration (83 g l−1) was achieved using soybean oil at 40 g l−1 and a pulse of the same concentration. The PHB content was 81% (w/w), PHB productivity was 2.5 g l−1 h−1, and the calculated Yp/s value was 0.85 g g−1. Growth limitation and the onset of PHB biosynthesis took place due to exhaustion of P, and probably also Cu, Ca, and Fe. 相似文献
11.
Anita Rywińska Waldemar Rymowicz 《Journal of industrial microbiology & biotechnology》2010,37(5):431-435
An acetate negative mutant of Yarrowia lipolytica Wratislavia AWG7 was found to be suitable for the production of high amounts of citric acid in long-term repeated-batch cultures.
When 40% of fresh replaced medium was fed, this strain produced 154 g l−1, on average, which corresponded to a 0.78 g g−1 yield and a productivity of 1.05 g l−1 h−1. The activity of the culture remained stable for more than 1,650 h, i.e., 16 cycles of the repeated-batch bioreactors. 相似文献
12.
Francisco B. Pereira Pedro M. R. Guimarães José A. Teixeira Lucília Domingues 《Biotechnology letters》2010,32(11):1655-1661
An optimized very high gravity (VHG) glucose medium supplemented with low cost nutrient sources was used to evaluate bio-ethanol
production by 11 Saccharomyces cerevisiae strains. The industrial strains PE-2 and CA1185 exhibited the best overall fermentation performance, producing an ethanol
titre of 19.2% (v/v) corresponding to a batch productivity of 2.5 g l−1 h−1, while the best laboratory strain (CEN.PK 113-7D) produced 17.5% (v/v) ethanol with a productivity of 1.7 g l−1 h−1. The results presented here emphasize the biodiversity found within S. cerevisiae species and that naturally adapted strains, such as PE-2 and CA1185, are likely to play a key role in facilitating the transition
from laboratory technological breakthroughs to industrial-scale bio-ethanol fermentations. 相似文献
13.
A new bacterial strain producing succinic acid was enriched from bovine rumen content. It is facultatively anaerobic, belongs
to the family Pasteurellaceae and has similarity to the genus Mannheimia. In batch cultivations with D-glucose or sucrose the strain produced up to 5.8 g succinic acid l−1 with a productivity and a yield of up to 1.5 g l−1 h−1 and 0.6 g g−1, respectively. With crude glycerol up to 8.4 g l−1, 0.9 g l−1 h−1 and 1.2 g g−1 were obtained.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Xin Zhao Cuimin Hu Siguo Wu Hongwei Shen Zongbao K. Zhao 《Journal of industrial microbiology & biotechnology》2011,38(5):627-632
Microbial lipid is a potential alternative feedstock for the biodiesel industry. New culture strategies remain to be developed
to improve the economics of microbial lipid technology. This work describes lipid production by the oleaginous yeast Rhodosporidium toruloides Y4 using a 15-l bioreactor with different substrate feeding strategies. Among these strategies, the intermittent feeding
mode gave a lipid productivity of 0.36 g l−1 h−1, whereas the constant glucose concentration II (CC-II) mode gave the highest lipid productivity of 0.57 g l−1 h−1. The repeated fed-batch mode according to the CC-II mode was performed with a duration time of 358 h, and the overall lipid
productivity was 0.55 g l−1 h−1. Our results suggested that substrate feeding modes had a great impact on lipid productivity and that the repeated fed-batch
process was the most appealing method by which to enhance microbial lipid production. 相似文献
15.
Using the recombinant flocculating Angel yeast F6, long-term repeated batch fermentation for ethanol production was performed
and a high volumetric productivity resulted from half cells not washed and the optimum opportunity of residual glucose 20
g l−1 of last medium. The obtained highest productivity was 2.07 g l−1 h−1, which was improved by 75.4% compared with that of 1.18 g l−1 h−1 in the first batch fermentation. The ethanol concentration reached 8.4% corresponding to the yield of 0.46 g g−1. These results will contribute greatly to the industrial production of fuel ethanol using the commercial method with the
flocculating yeast. 相似文献
16.
Efficient utilization of pentose sugars (xylose and arabinose) is an essential requirement for economically viable ethanol
production from cellulosic biomass. The desirable pentose-fermenting ethanologenic biocatalysts are the native microorganisms
or the engineered derivatives without recruited exogenous gene(s). We have used a metabolic evolution (adaptive selection)
approach to improve a non-transgenic homoethanol Escherichia coli SZ420 (ldhA pflB ackA frdBC pdhR::pflBp6-aceEF-lpd) for xylose fermentation. An improved mutant, E. coli KC01, was evolved through a 3 month metabolic evolution process. This evolved mutant increased pyruvate dehydrogenase activity
by 100%, cell growth rate (h−1) by 23%, volumetric ethanol productivity by 65% and ethanol tolerance by 200%. These improvements enabled KC01 to complete
50 g xylose l−1 fermentations with an ethanol titer of 23 g l−1 and a yield of 90%. The improved cell growth and ethanol production of KC01 are likely attributed to its three fold increased
ethanol tolerance. 相似文献
17.
Fermentation of high concentrations of lactose to ethanol by engineered flocculent Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
The development of microorganims that efficiently ferment lactose has a high biotechnological interest, particularly for cheese
whey bioremediation processes with simultaneous bio-ethanol production. The lactose fermentation performance of a recombinant
Saccharomyces cerevisiae flocculent strain was evaluated. The yeast consumed rapidly and completely lactose concentrations up to 150 g l−1 in either well- or micro-aerated batch fermentations. The maximum ethanol titre was 8% (v/v) and the highest ethanol productivity
was 1.5–2 g l−1 h−1, in micro-aerated fermentations. The results presented here emphasise that this strain is an interesting alternative for
the production of ethanol from lactose-based feedstocks. 相似文献
18.
Fernández-López CL Torrestiana-Sánchez B Salgado-Cervantes MA García PG Aguilar-Uscanga MG 《Bioprocess and biosystems engineering》2012,35(4):605-614
Molasses “B” is a rich co-product of the sugarcane process. It is obtained from the second step of crystallization and is
richer in fermentable sugars (50–65%) than the final molasses, with a lower non-sugar solid content (18–33%); this co-product
also contains good vitamin and mineral levels. The use of molasses “B” for ethanol production could be a good option for the
sugarcane industry when cane sugar prices diminish in the market. In a complex medium like molasses, osmotolerance is a desirable
characteristic for ethanol producing strains. The aim of this work was to evaluate the use of molasses “B” for ethanol production
using Saccharomyces cerevisiae ITV-01 (a wild-type yeast isolated from sugarcane molasses) using different initial sugar concentrations (70–291 g L−1), two inoculum sizes and the addition of nutrients such as yeast extract, urea, and ammonium sulphate to the culture medium.
The results obtained showed that the strain was able to grow at 291 g L−1 total sugars in molasses “B” medium; the addition of nutrients to the culture medium did not produce a statistically significant
difference. This yeast exhibits high osmotolerance in this medium, producing high ethanol yields (0.41 g g−1). The best conditions for ethanol production were 220 g L−1 initial total sugars in molasses “B” medium, pH 5.5, using an inoculum size of 6 × 106 cell mL−1; ethanol production was 85 g L−1, productivity 3.8 g L−1 h−1 with 90% preserved cell viability. 相似文献
19.
Guo T Tang Y Zhang QY Du TF Liang DF Jiang M Ouyang PK 《Journal of industrial microbiology & biotechnology》2012,39(3):401-407
Clostridium beijerinckii mutant strain IB4, which has a high level of inhibitor tolerance, was screened by low-energy ion implantation and used for
butanol fermentation from a non-detoxified hemicellulosic hydrolysate of corn fiber treated with dilute sulfuric acid (SAHHC).
Evaluation of toxicity showed C. beijerinckii IB4 had a higher level of tolerance than parent strain C. beijerinckii NCIMB 8052 for five out of six phenolic compounds tested (the exception was vanillin). Using glucose as carbon source, C. beijerinckii IB4 produced 9.1 g l−1 of butanol with an acetone/butanol/ethanol (ABE) yield of 0.41 g g−1. When non-detoxified SAHHC was used as carbon source, C. beijerinckii NCIMB 8052 grew well but ABE production was inhibited. By contrast, C. beijerinckii IB4 produced 9.5 g l−1 of ABE with a yield of 0.34 g g−1, including 2.2 g l−1 acetone, 6.8 g l−1 butanol, and 0.5 g l−1 ethanol. The remarkable fermentation and inhibitor tolerance of C. beijerinckii IB4 appears promising for ABE production from lignocellulosic materials. 相似文献
20.
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