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1.
Succinoglycan was produced by cultivating Agrobacterium tumefaciens on various solid substrates, including agar medium, spent malt grains, ivory nut shavings, and grated carrots, impregnated
with a nutrient solution. Fermentations were performed on a laboratory scale, both under static conditions and with agitation,
using bottles and a prototype horizontal bioreactor. Several fermentation parameters were examined and optimized, including
carbon and nitrogen composition, water content and layer thickness of the substrate. The yields and rheological properties
of the polymers obtained under different fermentation conditions were compared. The highest succinoglycan yield was achieved
in static cultivation, reaching 42 g/l of impregnating solution, corresponding to 30 g/kg of wet substrate. The polymer production
in the horizontal bioreactor was faster, but the final yield was lower (29 g/l of impregnating solution).
Received: 26 January 1999 / Received revision: 20 April 1999 / Accepted: 23 April 1999 相似文献
2.
L. Escalante I. Ramos I. Imriskova E. Langley S. Sanchez 《Applied microbiology and biotechnology》1999,52(4):572-578
The effect of glucose on growth and anthracycline production by Streptomyces peucetius var. caesius was examined in a chemically defined medium. Glucose concentrations above 100 mM inhibited anthracycline synthesis in the
original strain without causing significant change in growth and final pH values. This effect was observed when the carbohydrate
was added initially or after 24 h fermentation, but not when added during the stationary growth phase. When the microorganism
was pregrown in 100 mM glucose and then transferred to a resting cell system with 444 mM glucose, no significant differences
in antibiotic production were observed compared to the control without glucose. The negative effect of glucose on antibiotic
synthesis was not observed in a mutant (2-dogR–21) resistant to growth inhibition by 2-deoxyglucose. Glucose consumption by this mutant was approximately 30% of that utilized
by the original strain. Compared to the original strain, the mutant 2-dogR–21 exhibited a reduction of 50% in glucose transport and an 85% decrease in glucose kinase activity. The experimental evidence
obtained suggests that glucose represses anthracycline formation in a transitory manner and that this effect is related to
glucose transport and phosphorylation.
Received: 15 January 1999 / Received revision: 7 April 1999 / Accepted: 1 May 1999 相似文献
3.
Industrial 20-m3-scale and laboratory-scale aerobic fed-batch processes with Escherichia coli were compared. In the large-scale process the observed overall biomass yield was reduced by 12% at a cell density of 33 g/l
and formate accumulated to 50 mg/l during the later constant-feeding stage of the process. Though the dissolved oxygen signal
did not show any oxygen limitation, it is proposed that the lowered yield and the formate accumulation are caused by mixed-acid
fermentation in local zones where a high glucose concentration induced oxygen limitation. The hypothesis was further investigated
in a scale-down reactor with a controlled oxygen-limitation compartment. In this scale-down reactor similar results were obtained:
i.e. an observed yield lowered by 12% and formate accumulation to 238 mg/l. The dynamics of glucose uptake and mixed-acid
product formation (acetate, formate, d-lactate, succinate and ethanol) were investigated within the 54 s of passage time through the oxygen-limited compartment.
Of these, all except succinate and ethanol were formed; however, the products were re-assimilated in the oxygen-sufficient
reactor compartment. Formate was less readily assimilated, which accounts for its accumulation. The total volume of the induced-oxygen-limited
zones was estimated to be 10% of the whole liquid volume in the large bioreactor. It is also suggested that repeated excretion
and re-assimilation of mixed-acid products contribute to the reduced yield during scale-up and that formate analysis is useful
for detecting local oxygen deficiency in large-scale E. coli processes.
Received: 7 November 1998 / Received revision: 4 February 1999 / Accepted: 5 February 1999 相似文献
4.
Production of (R)-3-pentyn-2-ol through stereoinversion of racemic 3-pentyn-2-ol by Nocardia fusca AKU 2123 总被引:1,自引:0,他引:1
Wet cells of Nocardia fusca AKU 2123 are good catalysts for the production of (R)-3-pentyn-2-ol (PYOH) from (RS)-PYOH through a stereoinversion reaction. Under optimal conditions (350 mM potassium phosphate buffer, pH 8.0, 30% (w/v)
wet cells, 0.12% NADPH, 10% glucose, and 30 U/ml glucose dehydrogenase) (R)-PYOH of high optical purity (98.7% e.e.) was produced from 2% (v/v) (RS)-PYOH with a yield of 70.4% by 140 h incubation.
Received: 22 January 1999 / Received revision: 23 April 1999 / Accepted: 1 May 1999 相似文献
5.
K. Hofvendahl C. Åkerberg G. Zacchi B. Hahn-Hägerdal 《Applied microbiology and biotechnology》1999,52(2):163-169
Simultaneous saccharification of starch from whole-wheat flour and fermentation to lactic acid (SSF) was investigated. For
saccharification the commercial enzyme mixture SAN Super 240 L, having α-amylase, amyloglucosidase and protease activity,
was used, and Lactococcus lactis ssp. lactis ATCC 19435 was used for the fermentation. SSF was studied at flour concentrations corresponding to starch concentrations
of 90 g/l and 180 g/l and SAN Super concentrations between 3 μl/g and 8 μl/g starch. Kinetic models, developed for the saccharification
and fermentation, respectively, were used for simulation and data from SSF experiments were used for model verification. The
model simulated SSF when sufficient amounts of nutrients were available during fermentation. This was achieved with high wheat
flour concentrations or with addition of yeast extract or amino acids. Nutrient release was dependent on the level of enzyme
activity.
Received: 26 January 1999 / Accepted: 20 February 1999 相似文献
6.
A comparative study was carried out in anaerobic batch cultures on 20 g/l of either glycerol or glucose using two propionibacteria
strains, Propionibacterium acidipropionici and Propionibacterium freudenreichii ssp. shermanii. In all cases, fermentation end-products were the same and consisted of propionic acid as the major product, acetic acid
as the main by-product and two minor metabolites, n-propanol and succinic acid. Evidence was provided that greater production of propionic acid by propionibacteria was obtained
with glycerol as carbon and energy sources. P. acidipropionici showed higher efficiency in glycerol conversion to propionic acid with a faster substrate consumption (0.64 g l−1 h−1) and a higher propionic acid production (0.42 g l−1 h−1 and 0.79 mol/mol). The almost exclusive production of propionic acid from glycerol by this bacterium suggested an homopropionic
tendency of this fermentation. Acetic acid final concentration was two times lower on glycerol (2 g/l) than on glucose (4 g/l)
for both micro-organisms. P. freudenreichii ssp. shermanii exhibited a glycerol fermentation pattern typical of non-associated glycerol-consumption-product formation. This could indicate
a particular metabolism for P. freudenreichii ssp. shermanii oriented towards the production of other specific components. These results tend to show that glycerol could be an excellent
alternative to conventional carbon sources such as carbohydrates for propionic acid production.
Received: 21 May 1999 / Accepted: 1 November 1999 相似文献
7.
K. Hofvendahl E. W. J. van Niel B. Hahn-Hägerdal 《Applied microbiology and biotechnology》1999,51(5):669-672
Lactococcus lactis ssp. lactis ATCC 19435 is known to produce mixed acids when grown on maltose. A change in fermentation conditions only, elevated temperatures
(up to 37 °C) and reduced pH values (down to 5.0) resulted in a shift towards homolactic product formation. This was accompanied
by decreased growth rate and cell yield. The results are discussed in terms of redox balance and maintenance, and the regulation
of lactate dehydrogenase and pyruvate formate-lyase.
Received: 14 December 1998 / Received revision: 12 January 1999 / Accepted: 22 January 1999 相似文献
8.
Batch and continuous cultivation of Anaerobiospirillum succiniciproducens for the production of succinic acid from whey 总被引:3,自引:0,他引:3
Batch and continuous cultivation of Anaerobiospirillum succiniciproducens were systematically studied for the production of succinic acid from whey. Addition of 2.5 g l−1 yeast extract and 2.5 g l−1 polypeptone per 10 g l−1 whey was most effective for succinic acid production from both treated and nontreated whey. When 20 g l−1 nontreated whey and 7 g l−1 glucose were used as cosubstrates, the yield and productivity of succinic acid reached at the end of fermentation were 95%
and 0.46 g (l h)−1, respectively. These values were higher than those obtained using nontreated whey alone [93% and 0.24 g (l h)−1 for 20 g l−1 whey]. Continuous fermentation of A. succiniciproducens at an optimal dilution rate resulted in the production of succinic acid with high productivity [1.35 g (l h)−1], high conversion yield (93%), and higher ratio of succinic acid to acetic acid (5.1:1) from nontreated whey.
Received: 23 July 1999 / Received revision: 17 November 1999 / Accepted: 24 December 1999 相似文献
9.
Fibrobacter succinogenes S85 cultures that were cellobiose-limited converted cellobiose to succinate and acetate, produced little glucose or cellotriose,
maintained an intracellular ATP concentration of 4.1 mM and a membrane potential of 140 mV for 24 h, did not lyse at a rapid
rate once they had reached stationary phase, and had a most probable number of viable cells that was greater than 106/ml. When the cellobiose concentration was increased 6-fold (5 mM to 30 mM), ammonia was depleted and the cultures left 10 mM
cellobiose. Cultures provided with excess cellobiose produced succinate and acetate while they were growing, but there was
little increase in fermentation acids after the ammonia was depleted and growth ceased. The stationary-phase, cellobiose-excess
cultures had a lysis rate that was 7-fold faster than that of the cellobiose-limited cultures, and the most probable number
was only 3.3 × 103 cells/ml. The stationary-phase, cellobiose-excess cultures had 2.5 times as much cellular polysaccharide as the cellobiose-limited
cultures, but the intracellular ATP and membrane potential were very low (0.1 mM and 40 mV respectively). Methylglyoxal, a
potentially toxic end-product of carbohydrate fermentation, could not be detected, and fresh inocula grew rapidly in spent
medium that was supplemented with additional ammonia. Stationary-phase, cellobiose-excess cultures converted cellobiose to
glucose and cellotriose, but the apparent K
m of cellotriose formation was 15-fold lower than the K
m of glucose production (0.7 mM compared to 10 mM).
Received: 26 June 1997 / Received revision: 12 August 1997 / Accepted: 29 August 1997 相似文献
10.
C. Suresh A. K. Dubey S. Srikanta S. Umesh Kumar N. G. Karanth 《Applied microbiology and biotechnology》1999,51(5):673-675
A UV-induced mutant strain of Aspergillus niger (CFTRI-1105-U9) overproduced a starch-hydrolysing enzyme with properties characteristically different from the known amylases
of the fungus. The purified enzyme of 4.0 pI had an apparent molecular mass of 125 kDa and it dextrinised starch and then
saccharified the dextrins. Patterns of the enzyme activity on starch, resulting in glucose at 60 °C and glucose, maltose and
maltodextrins at 70 °C as primary products, suggested significant applications for the enzyme in starch-processing industries.
Received: 29 October 1998 / Received revision: 11 January 1999 / Accepted: 19 January 1999 相似文献
11.
Factors affecting Lactobacillus fermentation of shrimp waste for chitin and protein liquor production were determined. The objective of the fermentation
is medium conditioning by Lactobacillus through production of proteases and lowering of the pH. The efficiency was tested by conducting fermentation of biowaste
in 1-l beakers with or without pH adjustment using different acids. Addition of 5% glucose to the biowaste supported the growth
of lactic acid bacteria and led to better fermentation. Among four acids tested to control pH at the start and during fermentation,
acetic acid and citric acid proved to be the most effective. In biowaste fermented with 6.7% L. plantarum inoculum, 5% glucose, and pH 6.0 adjusted with acetic acid, 75% deproteination and 86% demineralization was achieved. Replacement
of acetic acid by citric acid gave 88% deproteination and 90% demineralization. The fermentation carried out in the presence
of acetic acid resulted in a protein fraction that smelled good and a clean chitin fraction.
Received: 4 April 2000 / Received revision: 9 June 2000 / Accepted: 9 June 2000 相似文献
12.
Jean-Luc Tholozan Jean-Philippe Grivet Christelle Vallet 《Archives of microbiology》1994,162(6):401-408
Pectinatus frisingensis, a recently described species of anaerobic mesophilic beer-spoilage bacteria, grows by fermenting various organic compounds,
and produces mainly propionate, acetate, and succinate. Although acrylate and succinate were both dismutated by dense resting-cell
suspensions, propionate production proceeded through the succinate pathway: [3-13C]pyruvate consumption led to equal 13C-labeling of propionate on methyl and methylene groups. Growth on glucose or glycerol led to a similar propionate to acetate
ratio, suggesting dihydroxyacetone phosphate as being a common metabolic intermediate. Diacetyl, 1,3-propanediol, and 2,3-butanediol
were not growth substrates or fermentation products, but they were all dismutated by dense resting-cell suspensions to acetate
and propionate. Acetoin was a minor fermentation product. The consumption of [2-13C] or [3-13C]pyruvate by dense resting-cell suspensions demonstrated the involvement of two equivalent pyruvate molecules during acetoin
production. Key enzymes involved in this metabolism were measured in anoxic cell-free extracts. A tentative metabolic pathway
to the main fermentation products was proposed from the above results.
Received: 17 February 1994 / Accepted: 30 August 1994 相似文献
13.
Microbial production of 1,3-propanediol 总被引:79,自引:2,他引:77
H. Biebl K. Menzel A.-P. Zeng W.-D. Deckwer 《Applied microbiology and biotechnology》1999,52(3):289-297
1,3-Propanediol (1,3-PD) production by fermentation of glycerol was described in 1881 but little attention was paid to this
microbial route for over a century. Glycerol conversion to 1,3-PD can be carried out by Clostridia as well as Enterobacteriaceae.
The main intermediate of the oxidative pathway is pyruvate, the further utilization of which produces CO2, H2, acetate, butyrate, ethanol, butanol and 2,3-butanediol. In addition, lactate and succinate are generated. The yield of 1,3-PD
per glycerol is determined by the availability of NADH2, which is mainly affected by the product distribution (of the oxidative pathway) and depends first of all on the microorganism
used but also on the process conditions (type of fermentation, substrate excess, various inhibitions). In the past decade,
research to produce 1,3-PD microbially was considerably expanded as the diol can be used for various polycondensates. In particular,
polyesters with useful properties can be manufactured. A prerequisite for making a “green” polyester is a more cost-effective
production of 1,3-PD, which, in practical terms, can only be achieved by using an alternative substrate, such as glucose instead
of glycerol. Therefore, great efforts are now being made to combine the pathway from glucose to glycerol successfully with
the bacterial route from glycerol to 1,3-PD. Thus, 1,3-PD may become the first bulk chemical produced by a genetically engineered
microorganism.
Received: 12 January 1999 / Received revision: 9 March 1999 / Accepted: 14 March 1999 相似文献
14.
Simultaneous bioconversion of glucose and xylose to ethanol by Saccharomyces cerevisiae in the presence of xylose isomerase 总被引:3,自引:0,他引:3
Simultaneous isomerisation and fermentation (SIF) of xylose and simultaneous isomerisation and cofermentation (SICF) of a
glucose/xylose mixture was carried out by Saccharomyces cerevisiae in the presence of xylose isomerase. The SIF of 50 g l−1 xylose gave an ethanol concentration and metabolic yield of 7.5 g l−1 and 0.36 g (g xylose consumed)−1. These parameters improved to 13.4 g l−1 and 0.40 respectively, when borate was added to the medium. The SICF of a mixture of 50 g l−1 glucose and 50 g l−1 xylose gave an ethanol concentration and metabolic yield of 29.8 g l−1 and 0.42 respectively, in the presence of borate. Temperature modulation from 30 °C to 35 °C during fermentation further
enhanced the above parameters to 39 g l−1 and 0.45 respectively. The approach was extended to the bioconversion of sugars present in a real lignocellulose hydrolysate
(peanut-shell hydrolysate) to ethanol, with a fairly good yield.
Received: 14 May 1999 / Received revision: 27 September 1999 / Accepted: 2 October 1999 相似文献
15.
Pilot-scale production of butanol by Clostridium beijerinckii BA101 using a low-cost fermentation medium based on corn steep water 总被引:3,自引:0,他引:3
To improve the economic competitiveness of the acetone/butanol/ethanol fermentation process, glucose/corn steep water (CSW)
medium was used on a pilot scale for the production of solvents. The production of butanol by the Clostridium beijerinckii NCIMB 8052 parent strain and the solvent-hyperproducing BA101 mutant was compared. In a 20-l fermentation using 5% glucose/CSW
medium, C. beijerinckii 8052 produced 8.5 g butanol/l and 5 g acetone/l, while C. beijerinckii BA101 produced 16 g butanol/l and 7.5 g acetone/l. Further studies were carried out on a larger scale using an optimized
6% glucose/CSW medium. In a 200-l pilot-scale fermentor, C. beijerinckii 8052 produced 12.7 g butanol/l and 6 g acetone/l following 96 h of fermentation. C. beijerinckii BA101 produced 17.8 g/l and 5.5 g/l butanol and acetone respectively, following 130 h of fermentation. These results represent
a 40% increase in final butanol concentration by the C. beijerinckii BA101 mutant strain when compared to the 8052 parent strain. The total solvents (acetone, butanol, and ethanol) produced
by C. beijerinckii NCIMB 8052 and BA101 in a 200-l fermentation were 19.2 g/l and 23.6 g/l respectively. This is the first report of pilot-scale
butanol production by the solvent-hyperproducing C. beijerinckii BA101 mutant employing an inexpensive glucose/CSW medium.
Received: 26 May 1998 / Received revision: 21 September 1998 / Accepted: 11 October 1998 相似文献
16.
Enterobacter cloacae NRRL B-23289 was isolated from local decaying wood/corn soil samples while screening for microorganisms for conversion of
l-arabinose to fuel ethanol. The major product of fermentation by the bacterium was meso-2,3-butanediol (2,3-BD). In a typical
fermentation, a BD yield of 0.4 g/g arabinose was obtained with a corresponding productivity of 0.63 g/l per hour at an initial
arabinose concentration of 50 g/l. The effects of initial arabinose concentration, temperature, pH, agitation, various monosaccharides,
and multiple sugar mixtures on 2,3-BD production were investigated. BD productivity, yield, and byproduct formation were influenced
significantly within these parameters. The bacterium utilized sugars from acid plus enzyme saccharified corn fiber and produced
BD (0.35 g/g available sugars). It also produced BD from dilute acid pretreated corn fiber by simultaneous saccharification
and fermentation (0.34 g/g theoretical sugars).
Received: 17 December 1998 / Revision received: 9 March 1999 / Accepted: 20 March 1999 相似文献
17.
J. Oddou C. Stentelaire L. Lesage-Meessen M. Asther B. Colonna Ceccaldi 《Applied microbiology and biotechnology》1999,53(1):1-6
High-density cultures of Pycnoporus cinnabarinus were tested with a view to optimisation of ferulic acid bioconversion into vanillin. The dry weight was increased fourfold
by using glucose, fructose or a mixture of glucose and phospholipids as carbon source instead of maltose, the carbon source
previously used. 5 mmol l−1 vanillin, i.e. 760 mg l−1, was produced over 15 days with glucose-phospholipid medium. In contrast, formation of vanillin was lower using glucose or
fructose compared to the maltose control. A bioreactor (2 l) with a glucose-phospholipid medium gave a molar yield of vanillin
of 61% (4 mmol l−1). An alternative strategy was to grow the fungus on a glucose or fructose medium for 3 days, then switch to maltose during
the bioconversion phase: this method allowed 3.3 mmol l−1 vanillin to be obtained in 10 days. Many by-products such as methoxyhydroquinone and vanillyl alcohol were also produced.
Received: 19 February 1999 / Received revision: 4 June 1999 / Accepted: 4 June 1999 相似文献
18.
Ashkenazy R Yannai S Rahman R Rabinovitz E Gottlieb L 《Applied microbiology and biotechnology》1999,52(4):608-611
Spent Saccharomyces cerevisiae cells from a beer fermentation process were evaluated for lead cation sorption. The crude biomass was washed with water and
acetone prior to any other treatment. Although the washed biomass showed substantial lead ion sorption it was susceptible
to microbial spoilage. Different aldehydes were tested as chemical fixation agents; however, most of them caused drastic lowering
of the metal uptake capacity. However, benzaldehyde was not only an excellent fixation agent, but the biomass treated with
it also retained its original lead sorption capacity. A mechanism for the fixation process is suggested.
Received: 11 January 1999 / Received revision: 26 April 1999 / Accepted: 1 May 1999 相似文献
19.
The role of the alternative respiratory pathway in the stimulation of cephalosporin C formation by soybean oil in Acremonium chrysogenum 总被引:1,自引:0,他引:1
L. Karaffa E. Sándor J. Kozma C. P. Kubicek A. Szentirmai 《Applied microbiology and biotechnology》1999,51(5):633-638
Addition of soybean oil to Acremonium chrysogenum cultures growing on sugars doubled the specific production of cephalosporin C during the idiophase of growth. While the addition
of soybean oil had no effect on the total rate of respiration, the respiration that proceeded via the alternative, cyanide-insensitive
pathway exhibited a more than twofold increase. Addition of soybean oil also stimulated the formation of isocitrate lyase
activities. Inhibition of oxidative metabolism of one of the products of isocitrate lyase (succinate) by thenoyltrifluoroacetone
completely inhibited the alternative respiratory pathway. The role of soybean-oil-stimulated alternative respiration in the
stimulation of cephalosporin C production and the role of isocitrate lyase are discussed.
Received: 13 October 1998 / Revised revision: 14 January 1999 / Accepted: 22 January 1999 相似文献
20.
Respiratory and fermentative pathways co-exist to support growth and product formation in Pichia stipitis. This yeast grows rapidly without ethanol production under fully aerobic conditions, and it ferments glucose or xylose under
oxygen-limited conditions, but it stops growing within one generation under anaerobic conditions. Expression of Saccharomyces cerevisiaeURA1 (ScURA1) in P. stipitis enabled rapid anaerobic growth in minimal defined medium containing glucose when essential lipids were present. ScURA1 encodes a dihydroorotate dehydrogenase that uses fumarate as an alternative electron acceptor to confer anaerobic growth.
Initial P. stipitis transformants grew and produced 32 g/l ethanol from 78 g/l glucose. Cells produced even more ethanol faster following two
anaerobic serial subcultures. Control strains without ScURA1 were incapable of growing anaerobically and showed only limited fermentation. P. stipitis cells bearing ScURA1 were viable in anaerobic xylose medium for long periods, and supplemental glucose allowed cell growth, but xylose alone could
not support anaerobic growth even after serial anaerobic subculture on glucose. These data imply that P. stipitis can grow anaerobically using metabolic energy generated through fermentation but that it exhibits fundamental differences
in cofactor selection and electron transport with glucose and xylose metabolism. This is the first report of genetic engineering
to enable anaerobic growth of a eukaryote.
Received: 6 January 1998 / Received revision: 9 April 1998 / Accepted: 19 April 1998 相似文献