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1.
Production and characterization of pullulan from beet molasses using a nonpigmented strain of Aureobasidium pullulans in batch culture 总被引:2,自引:0,他引:2
Lazaridou A Biliaderis CG Roukas T Izydorczyk M 《Applied biochemistry and biotechnology》2002,97(1):1-22
The production of pullulan from beet molasses by a pigment-free strain of Aureobasidium pullulans on shake-flask culture was investigated. Combined pretreatment of molasses with sulfuric acid and activated carbon to remove
potential fermentation inhibitors present in molasses resulted in a maximum pullulan concentration of 24 g/L, a biomass dry
wt of 14 g/L, a pullulan yield of 52.5%, and a sugar utilization of 92% with optimum fermentation conditions (initial sugar
concentration of 50 g/L and initial pH of 7.0). The addition of other nutrients as carbon and nitrogen supplements (olive
oil, ammonium sulfate, yeast extract) did not further improve the production of the exopolysaccharides. Structural characterization
of the isolated polysaccharides from the fermentation broths by 13C-nuclear magnetic resonance spectroscopy and pullulanase digestion combined with size-exclusion chromatography confirmed
the identity of pullulan and the homogeneity (>93% dry basis) of the elaborated polysaccharides by the microorganism. Using
multiangle laser light scattering and refractive index detectors in conjunction with high-performance size-exclusion chromatography
molecular size distributions and estimates of the molecular weight (M
w
=2.1−4.1×105), root mean square of the radius of gyration (R
g
=30−38 nm), and polydispersity index (M
w
/M
n
=1.4−2.4) were obtained. The fermentation products of molasses pretreated with sulfuric acid and/or activated carbon were
more homogeneous and free of contaminating proteins. In the concentration range of 2.8−10.0 (w/v), the solution’s rheologic
behavior of the isolated pullulans was almost Newtonian (within 1 and 1200 s−1 at 20°C); a slight shear thinning was observed at 10.0 (w/v) for the high molecular weight samples. Overall, beet molasses
pretreated with sulfuric acid and activated carbon appears as an attractive fermentation medium for the production of pullulan
by A. pullulans. 相似文献
2.
The study deals with the development of an immobilized biocatalyst for the production of fructooligosaccharides. Several commercial
anion-exchange resins and polymethacrylate carriers were tested for the immobilization either by the direct attachment of
fructosyltransferase or by the attachment accompanied by simultaneous glutaraldehyde crosslinking in the pH range from 5.7
to 7.1. On the basis of the efficiency of immobilization and the storage stability, Amberlite IRA 900 and Dowex Marathon MSA
were selected as the best carriers for fructosyltransferase immobilization by direct attachment at pH 5.7.
Regular paper
An erratum to this article is available at . 相似文献
3.
The production of pigment-free pullulan byAureobasidium pullulans, using olive oil and sucrose as carbon (C) sources, in shake flasks, was investigated. Optimum medium composition for pullulan
elaboration was 80 g/L sucrose, 25 mL/L olive oil, 5 mL/L Tween-80, 10 g/L glutamic acid, and an initial pH of 5.5. Maximum
pullulan concentration (51.5 g/L), productivity (8.6 g/L·d), and yield (80.3%) were achieved under these conditions after
120 h of fermentation. The principal advantage of using olive oil and sucrose simultaneously as C sources was the elimination
of the inhibitory effect of high sucrose concentrations (> 60 g/L) on pullulan production by the microorganism. Structural
characterization by13C-NMR, monosaccharide, and methylation analyses, and pullulanase digestion, combined with size-exclusion chromatography, confirmed
the identity of pullulan and the homogeneity of the released polysaccharide in the fermentation broths. There were no significant
differences in structure between pullulan samples isolated from either olive oil-supplemented media or olive oil-free media.
The molecular size of pullulan from the combined olive oil-sucrose fermentation was slightly lower (1.1 X 106) than that of conventional fermentation with sucrose as a single C source (1.4 X 106). Lowering the initial pH of the medium resulted in increased molecular size for the released polymer, but a lower pullulan
yield. 相似文献
4.
Optimization of immobilization conditions was carried out for covalent binding of Aureobasidium pullulans fructosyltransferase to a copolymer of butyl acrylate and ethylene glycol dimethacrylate using a glutaraldehyde method. It
was found that the highest activity of the preparation could be obtained for the immobilization pH 6.0 and initial protein
amount 8.5 g per dm3 of the carrier. Effects of the reaction pH, temperature, and initial sucrose concentration on the activity and stability
of the preparation were analyzed. Further investigations involved storage stability and operational stability in a mechanically
stirred-tank reactor. 相似文献
5.
Noah Karl S. Fox Sandra L. Bruhn Debby F. Thompson David N. Bala Gregory A. 《Applied biochemistry and biotechnology》2002,98(1-9):803-813
The biosurfactant surfactin has the potential to aid in the recovery of subsurface organic contaminants (environmental remediation)
or crude oils (oil recovery). However, high medium and purification costs limit its use in these high-volume applications.
In previous work, we showed that surfactin can be produced from an inexpensive low-solids (LS) potato process effluent with
minimal amendments or pretreatments. Previous research has also shown that 95% or more of the surfactin in Bacillus subtilis cultures can be recovered by foam fractionation. In this work, we present the results of research to integrate surfactin
production with foam fractionation. Experiments were performed in an airlift reactor, with continuous collection of the foam
through a tube at the top of the column. Preliminary results using both purified potato starch and unamended low-solids potato
process effluent as substrates for surfactin production indicate that the process is oxygen limited and that recalcitrant
indigenous bacteria in the potato process effluent may hamper continuous surfactin production. 相似文献
6.
Culture conditions for pullulan production by Aureobasidium pullulans were optimized using response surface methodology at shake flask level without pH control. In the present investigation,
a five-level with five-factor central composite rotatable design of experiments was employed to optimize the levels of five
factors significantly affecting the pullulan production, biomass production, and sugar utilization in submerged cultivation.
The selected factors included concentration of sucrose, ammonium sulphate, yeast extract, dipotassium hydrogen phosphate,
and sodium chloride. Using this methodology, the optimal values for concentration of sucrose, ammonium sulphate, yeast extract,
dipotassium hydrogen phosphate, and sodium chloride were 5.31%, 0.11%, 0.07%, 0.05%, and 0.15% (w/v), respectively. This optimized medium has projected a theoretically production of pullulan of 4.44%, biomass yield of 1.03%,
and sugar utilization of 97.12%. The multiple correlation coefficient ‘R’ was 0.9976, 0.9761 and 0.9919 for pullulan production, biomass production, and sugar utilization, respectively. The value
of R being very close to one justifies an excellent correlation between the predicted and the experimental data. 相似文献
7.
Al-Qodah Z 《Applied biochemistry and biotechnology》2000,87(1):37-55
In this study, a series of experiments was conducted to demonstrate the feasibility of continuous production of penicillin
antibiotic using a three-phase magneto airlift fermentor with immobilized Penicillium chrysogenum. The fermentation processes were carried out in a 2.4-L external loop airlift utilizing a transverse magnetic field. It was
found that the application of the magnetic field to a bed of ferromagnetic beads affects both the hydrodynamics of the reactor
and the rate of the bioconversion process occurring inside it. One hundred hours after startup, the maximum penicillin concentration
increased 48% as the magnetic field intensity increased from 0 to 35 mT, owing to the increased residence time of the substrate
in the riser and the positive effect of the magnetic field on the effective fluid-solid interfacial area. In addition, the
detached biomass concentration in the liquid phase was found to be only 5% of the immobilized biomass, owing to low shear
levels and the absence of friction among the solid-phase particles. 相似文献
8.
Production of acetone-butanol-ethanol from corn mash and molasses in batch fermentation 总被引:2,自引:0,他引:2
The production of solvents from corn mash and molasses in batch fermentation usingClostridium acetobutylicum P 262 was examined. The content of saccharose of beet molasses used in experiments is determined by using the gravimetric
method (52.45% saccharose). The quantities of molasses that are used in the nutrient medium are calculated after doing the
above determination. The samples of fermentation liquid are taken within a certain time, the determination of saccharose is
done by using the same method, and all the saccharose is converted by the microorganism to organic end products. The quantitative
and qualitative determination of acetone-butanol has been made by using gas chromatography. On the other hand, using the three
isolation way, three different cultures are obtained, and with microscopic observations, the cultures obtained are of the
C.acetobutylicum genus. According to the literature values, the concentration of maximum mixed solvent formed during fermentation is about
2%. This is seen in this experiment. There is only a slight difference from this value. This difference is caused by another
organic product that is formed during fermentation. 相似文献
9.
Lienhardt Jason Schripsema Justin Qureshi Nasib Blaschek Hans P. 《Applied biochemistry and biotechnology》2002,98(1-9):591-598
Acetone butanol ethanol was produced in a continuous immobilized cell (biofilm) plug-flow reactor inoculated with Clostridium beijerinckii BA101. To achieve high reactor productivity, C. beijerinckii BA101 cells were immobilized by adsorption onto clay brick. The continuous plug-flow reactor offers high productivities owing
to reduced butanol inhibition and increased cell concentration. Although high productivity was achieved, it was at the expense
of low sugar utilization (30.3%). To increase sugar utilization, the reactor effluent was recycled. However, this approach
is complicated by butanol toxicity. The effluent was recycled after removal of butanol by pervaporation to reduce butanol
toxicity in the reactor. Recycling of butanolfree effluent resulted in a sugar utilization of 100.7% in addition to high productivity
of 10.2g/(L·h) at a dilution rate of 1.5 h−1. A dilution rate of 2.0h−1 resulted in a reactor productivity of 16.2g/(L·h) and sugar utilization of 101.4%. It is anticipated that this reactor-recovery
system would be economical for butanol production when using C. beijerinckii BA101. 相似文献
10.
l-Glutamine amidohydrolase (l-glutaminase, EC 3.5.1.2) is a therapeutically and industrially important enzyme. Because it is a potent antileukemic agent
and a flavor-enhancing agent used in the food industry, many researchers have focused their attention on l-glutaminase. In this article, we report the continuous production of extracellular l-glutaminase by the marine fungus Beauveria bassiana BTMF S-10 in a packed-bed reactor. Parameters influencing bead production and performance under batch mode were optimized
in the order-support (Na-alginate) concentration, concentration of CaCl2 for bead preparation, curing time of beads, spore inoculum concentration, activation time, initial pH of enzyme production
medium, temperature of incubation, and retention time. Parameters optimized under batch mode for l-glutaminase production were incorporated into the continuous production studies. Beads with 12×108 spores/g of beads were activated in a solution of 1% glutamine in seawater for 15 h, and the activated beads were packed
into a packed-bed reactor. Enzyme production medium (pH 9.0) was pumped through the bed, and the effluent was collected from
the top of the column. The effect of flow rate of the medium, substrate concentration, aeration, and bed height on continuous
production of l-glutaminase was studied. Production was monitored for 5 h in each case, and the volumetric productivity was calculated. Under
the optimized conditions for continuous production, the reactor gave a volumetric productivity of 4.048 U/(mL·h), which indicates
that continuous production of the enzyme by Ca-alginate-immobilized spores is well suited for B. bassiana and results in a higher yield of enzyme within a shorter time. The results indicate the scope of utilizing immobilized B. bassiana for continuous commercial production of l-glutaminase. 相似文献
11.
Martínez Ernesto Acosta Silva Silvio S. Felipe Maria G. A. 《Applied biochemistry and biotechnology》2000,84(1-9):633-641
The effect of the oxygen transfer coefficient on the production of xylitol by biocon version of xylose present in sugarcane
bagasse hemicellulosic hydrolysate using the yeast Candiada guilliermondii was investigated. Continuous cultivation was carried out in a 1.25-L fermentor at 30°C, pH 5.5, 300 rpm, and a dilution rate
of 0.03/h, using oxygen transfer coefficients of 10,20, and 30/h. The results showed that the microbial xylitol production
(11 g/L) increased by 108% with the decrease in the oxygen volumetric transfer coefficient from 30 to 20/h. The maximum values
of xylitol productivity (0.7g/[L…h]) and yield (0.58 g/g) were obtained at k
L
a 20/h. 相似文献
12.
Submerged culture fermentation studies were carried out in batch mode for optimizing the environmental parameters and carbon
source requirement by Pseudomonas elodea for the production of gellan gum. The maximum production of gellan gum was obtained with 16-h-old culture and 8% inoculum
at 30°C and pH 7.0 after 52 h of incubation (6.0 g/L). Of the various carbon sources tested, 2% sucrose, glucose, and soluble
starch yielded considerably high amounts of gellan. Studies on the concentration of various carbohydrates on gellan gum production
indicated that the optimum concentration of glucose and starch was 3%, whereas for sucrose it was 4%. The addition of glucose
in the medium above 3% had a detrimental effect on gellan yield. The investigation of intermediate two-step addition of glucose
under identical conditions of fermentation showed an enhanced production of gellan (8.12 g/L) as compared with the control
(6.0 g/L). To optimize the recovery of gellan from fermented broth, different solvents were tested for precipitation of gellan
gum. Among the various solvents tested, tetrahydrofuran gave better recovery of gellan (82%) as compared with the conventional
solvent isopropanol (49%). 相似文献
13.
This study was undertaken to identify factors exerting the strongest influence on the adsorption of dye. The maximum adsorption
capacity (at the adopted operating conditions) was the main parameter used to evaluate the process. In addition, the feasible
adsorption capacity of chitosan was evaluated. Breakthrough experiments were carried out in a circulating air-lift reactor
at a constant concentration of reactive dye Black 8 (100 mg/dm3). The tests studied different chitosan concentrations in the reactor and a range of flow intensities. The results of the
breakthrough tests were compared by means of apparent mass transfer coefficients, determined by slopes at C/C
0=1/2. The adsorption capacity of chitosan was affected to the greatest extent by the flow rate of the medium to the reactor.
In turn, the utilization of the maximum adsorption capacity of chitosan, at the assumed efficiency of dye removal, was determined
by chitosan concentration in the reactor. 相似文献
14.
Silva Silvio S. Ribeiro JoÃo D. Felipe Maria G. A. Vitolo Michelle 《Applied biochemistry and biotechnology》1997,(1):557-564
Batch fermentations of sugar cane bagasse hemicellulosic hydrolysate treated for removing the inhibitors of the fermentation
were performed byCandida guilliermondii FTI20037 for xylitol production. The fermentative parameters agitation and aeration rate were studied aiming the maximization
of xylitol production from this agroindustrial residue. The maximal xylitol volumetric productivity (0.87 g/L h) and yield
(0.67 g/g) were attained at 400/min and 0.45 v.v.m. (KLa 27/h). According to the results, a suitable control of the oxygen input permitting the xylitol formation from sugar cane
bagasse hydrolysate is required for the development of an efficient fermentation process for large-scale applications. 相似文献
15.
Operating costs for the production of Baker’s yeast from hydrolyzed permeate from the ultrafiltration of cottage cheese whey
were calculated as a function of the level of lactose conversion in the immobilized lactase reactor. These costs were calculated
for the case of 90% conversion of lactose in the reactor and compared to those that result when running the reactor at lower
conversions with recycle of unreacted lactose. Total operating costs were estimated by combining individual operating costs
for the immobilized enzyme reactor, costs associated with processing a lactose recycle stream, and energy costs associated
with cooling the reactor feed stream and sterilizing the hydrolysate stream. It was determined that operating costs are minimized
at about 9.9 ¢/lb. of lactose when the reactor is run at approx. 72% conversion. This represents a savings of 2.4 ¢/lb. of
lactose over the case of a once-through 90% conversion of lactose in the reactor. 相似文献
16.
Phosphodiesterase production in an aqueous two-phase system by Nicotiana tabacum 1507 总被引:1,自引:0,他引:1
Studies were conducted on the production of phosphodiesterases by Nicotiana tabacum 1507 cell suspension in an aqueous two-phase system formed by adding 4% polyethylene glycol (mol wt 20,000) and 7.5% dextran
(mol wt 70,000) to the medium. The time course of growth, biosynthesis, secretion, and partitioning of phosphodiesterases
was followed in comparison with N. tabacum 1507 cultivation as a free suspension. Partitioning of phosphodiesterases took place mainly in the bottom dextran phase,
and a possibility was revealed for obtaining an enzyme preparation with high phosphodiesterase activity. 相似文献
17.
Citric acid is finding new areas of use each year and the demand for the acid is constantly increasing. Being a bulk chemical,
the continuous production of citric acid would be advantageous. The paper presents the results from ammonia limited batch
and continuous fermentations using the yeast strainSaccharomycopsis (Candida) lipolytica (NRRL Y-7576). Mathematical models were developed for growth and glucose utilization in batch and continuous culture. Cell
and acid yields appeared to be almost the same in batch and continuous culture. The specific production rates were found to
be constant, equal to 0.053 g/g h, in the batch fermentations but varied in the continuous experiments from 0 to 0.11 g/g
h depending on the fermentation conditions. Continuous production in a single stage CSTR was studied for over 1,000 hours
without shutdown. 相似文献
18.
Effect of pH and phosphate on trapping capacity of various heavy metal ions with ferritin reactor in flowing seawater 总被引:1,自引:0,他引:1
We describe a protein reactor consisting of native liver ferritin of Dasyatis akajei (DALF) and a dialysis bag. Our goal was to study a ferritin reactor for its capacity to trap various heavy metal ions (M2+) in flowing seawater. The reactor is sensitive and inexpensive and can be operated by nonprofessional technicians. A positive
relationship between the number of trapped M2+ with the DALF reactor and its concentration in the flowing seawater was observed. Both the pH in the medium and the phosphate
content within the ferritin cavity strongly affected trapping capacity. It was found that the ferritin released its phosphate
compound directly with a shift in pH without the need for releasing reagent, which differs from the phosphate release characteristics
of horse spleen ferritin, as previously described. This behavior evidently makes the trapping capacity with the ferritin reactor
weaken, indicating that this trapping capacity is tightly connected to its phosphate compound. Our study shows that a self-regulation
ability of the ferritin shell rather than its phosphate compound plays an important role in controlling the rate and capacity
of trapping M2+. The ferritin reactor was constructed to monitor the contamination level of M2+ in flowing seawater. Our preliminary data along with fieldwork indicate that the DALF reactor is an analytical means for
effectively monitoring the contamination level of M2+ in flowing seawater. 相似文献
19.
碳源对SBR单级好氧工艺中微生物摄磷能力的影响及其机理研究 总被引:5,自引:0,他引:5
以两种典型基质:葡萄糖(R1)和乙酸钠(R2)作为单一碳源,考察了SBR单级好氧工艺在R1和R2中的除磷效果,并通过比较各自微生物体内储能物质的变化,探讨了SBR单级好氧工艺以不同基质作为碳源时影响其微生物摄磷能力的根本原因.结果表明:R1和R2中均观察到明显的超量摄磷现象,但在运行条件完全相同的情况下,两系统中微生物摄磷能力以及体内储能物质有很大的差别.稳定运行后,R1和R2中单位混合液挥发性悬浮固体(MLVSS)的总磷(TP)去除量分别为6.7~7.4、2.7~3.2mg·g^-1.R1中微生物体内储能物质多β羟基烷酸盐(PHA)含量没有明显的变化,另一储能物质糖原质在好氧段外碳源(葡萄糖)存在时有明显的积累现象(糖原质的最大积累量为3.21mmol-C·g^-1),在好氧段外碳源消耗完后呈下降趋势,并在好氧结束时下降到好氧前水平;R2中PHA与糖原质在好氧段外碳源(乙酸钠)存在时均有明显的积累现象(外碳源消耗完时PHA与糖原质积累量分别为2.1,0.55mmol—C·g^-1),PHA在好氧段外碳源消耗完后呈下降趋势,并在好氧结束时也几平下降到好氧前水平,而糖原质却在外碳源消耗完后继续积累,并在好氧2h左右时达到最大值(糖原质最大积累量为0.88mmol—C·g^-1),此后下降明显,在好氧结束时也几乎恢复到原始水平.在整个好氧过程中,R1中内碳源(PHA与糖原质)的积累/转化量大于R2系统.在闲置期内,R1与R2中PHA与糖原质均没有明显变化,但却观察到明显的释磷现象,且R1释磷量多于R2系统.此研究显示,由于R1与R2中进水碳源不同,在其反应系统内碳源的好氧代谢途径有所差别,使各自微生物在好氧段体内储能物质的类型与积累/转化量也有所不同,各自微生物在好氧摄磷时得到的可利用的能量也不同,因而各自微生物的摄磷能力亦有所差别. 相似文献
20.
Submerged fermentation experiments were carried out to study the stimulating effects of the surfactant Span 20 on the growth
of Aspergillus niger XP mutant and oxalic acid production from the post-refining fatty acids. Span 20 concentration of 0.75 g dm−3 was found to be the most suitable for oxalic acid production from fatty acids. Using this dose and a fermentation medium
containing 30 g dm−3 of post-refining fatty acids, the oxalic acid production, oxalate yield, and overall oxalate productivity were the highest.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献