共查询到20条相似文献,搜索用时 484 毫秒
1.
The effects of different aeration conditions on xylitol production from corncob hemicellulose hydrolysate by Candida sp. ZU04 were investigated. Batch fermentations were carried out in a 3.7-L fermentor at 30°C, pH5.5, and agitation of 300
rpm. It was found that the two-phase aeration process was more effective than the one-phase aeration process in xylitol production.
In the first 24h of the aerobic phase, a high aeration rate was applied, glucose was soon consumed, and biomass increased
quickly. In the second fermentation phase, aeration rate was reduced and an improved xylitol yield was obtained. The maximum
xylitol yield (0.76 g/g) was obtained with an aeration rate of 1.5 vvm (KLa of 37 h−1) for the first 24 h and 0.3 vvm (KLa of 6 h−1) from 24 to 96 h. 相似文献
2.
Concentrated dilute acid hydrolysate was obtained from hot water extracts of Acer saccharum (sugar maple) and was fermented to ethanol by Pichia stipitis in a 1.3-L-benchtop bioreactor. The conditions under which the highest ethanol yield was achieved were when the air flow rate was set to 100?cm3 and the agitation rate was set to 150?rpm resulting in an overall mass transfer coefficient (K L a) of 0.108?min?1. A maximum ethanol concentration of 29.7?g/L was achieved after 120?h of fermentation; however, after 90?h of fermentation, the ethanol concentration was only slightly lower at 29.1?g/L with a yield of 0.39?g ethanol per gram of sugar consumed. Using the same air flow rate and adjusting the agitation rate resulted in lower ethanol yields of 0.25?g/g at 50?rpm and 0.30?g/g at 300?rpm. The time it takes to reach the maximum ethanol concentration was also affected by the agitation rate. The ethanol concentration continued to increase even after 130?h of fermentation when the agitation rate was set at 50?rpm, whereas the maximum ethanol concentration was reached after only 68.5?h at 300?rpm. 相似文献
3.
Inês C. Roberto Ismael M. de Mancilha Sunao Sato 《Applied biochemistry and biotechnology》1999,77(1-3):205-210
The fermentation kinetics for the conversion of rice straw hemicellulosic hydrolysate to xylitol by the yeast Candida guilliermondii was evaluated under batch conditions. The fermentation was accomplished in a 1 L working volume stirred-tank reactor with
aeration of 1.3 vvm and agitation of 300 rpm (kLa=15/h). The maximum specific rate of xylitol formation (0.12 g/g) was achieved when the specific growth rate was lowered
to 1/5 of its highest value. From analysis of the fermentation kinetics, a linear correlation between specific growth rate
(μx) and specific rate of xylitol formation (qp) was evident. Based on the Gaden model, this bioprocess was classified as growth-associated production and the relationship
between μx and qp can be described by the equation qp=6.31μx. 相似文献
4.
George G. G. Oliveira Daniel P. Silva Ines Conceição Roberto Michele Vitolo Adalberto Pessoa Jr. 《Applied biochemistry and biotechnology》2003,108(1-3):787-797
This study dealt with the partition behavior and partial purification of hexokinase (HK) from baker’s yeast by liquid-liquid
extraction using aqueous two-phase polyethylene glycol (PEG)/citrate systems. First, we investigated the effect of agitation
type (vortex and 8 rpm rotation) on the stability of the system, and then the effects of sodium citrate concentration, PEG
concentration, and molar mass of PEG on the partition coefficient of this enzyme by using a 25 factorial experimental design. The results of this factorial experiment showed the possibility of a partial purification
of HK by using two extraction steps, since the enzyme preferentially migrated to the top phase and the total proteins (mainly
contaminants) remained in the bottom phase. The purification factor (Pur
TOP) of the enzyme in the top phase was 1.87, and the partition coefficient of the total proteins (K
Prot
) was 0.47. 相似文献
5.
Silva Daniel Pereira Pessoa Adalberto Roberto Inês-Conceição Vitolo Michele 《Applied biochemistry and biotechnology》2001,91(1-9):605-613
A batch culture of Saccharomyces cerevisiae for the production of hexokinase was carried out in a 5-L fermentor containing 3 L of culture medium, which was in oculated
with cell suspension (about 0.7 g/L), and left ferm entingat 35°C and pH 4.0. The aeration and agitation were adjusted to
attain k
La values of 15, 60, 135, and 230 h−1. The highest hexokinase productivity (754.6 U/[L h]) and substrate-cell conversion yield (0.21 g/g) occurred for a k
La of 60 h−1. Moreover, the formation of hexokinase and cell growth are coupled events, which is in accordance with the constitutive character
of this enzyme. Hexokinase formation for k
La>60 h−1 was not enhanced probably owing to saturation of the respiratory pathway by oxygen. 相似文献
6.
Sene Luciane Felipe Maria G. A. Silva Silvio S. Vitolo Michele 《Applied biochemistry and biotechnology》2001,91(1-9):671-680
Candida guilliermondii FTI 20037 was cultured in sugarcane bagasse hydrolysate supplemented with 2.0 g/L of (NH4)2SO4, 0.1 g/L of CaCl2·2H2O, and 20.0 g/L of rice bran at 35°C; pH 4.0; agitation of 300 rpm; and aeration of 0.4, 0.6, or 0.8 vvm. The high xylitol
production (20.0 g/L) and xylose reductase (XR) activity (658.8 U/mg of protein) occurred at an aeration of 0.4 vvm. Under
this condition, the xylitol dehydrogenase (XD) activity was low. The apparent K
M for XR and XD against substrates and cofactors were as follows: for XR, 6.4×10−2
M (xylose) and 9.5×10−3 mM (NADPH); for XD, 1.6×10−1
M (xylitol) and 9.9×10−2 mM (NAD+). Because XR requires about 10-fold less xylose and cofactor than XD for the condition in which the reaction rate is
half of the V
max, some interference on the overall xylitol production by the yeast could be expected. 相似文献
7.
Majid Afshari Fakhri Shahidi Seyed Ali Mortazavi Farideh Tabatabai Zarin Es'haghi 《Natural product research》2015,29(14):1300-1306
In this study, the combined effect of pH, temperature and agitation speed on yellow pigment production and mycelial growth of Penicillium aculeatum ATCC 10409 was investigated in whey media. Different pH levels (5, 6.5 and 8), temperatures (25, 30 and 35°C) and agitation speed levels (100 and 150 rpm) were tested to determine the best conditions to produce a fungal yellow pigment under submerged fermentation. The best production of yellow pigment (1.38 g/L) was obtained with a pH value of 6.5, a temperature of 30°C and an agitation speed of 150 rpm. In contrast, the maximal biomass concentration (11.12 g/L) was obtained at pH value of 8, a temperature of 30°C and an agitation speed of 100 rpm. These results demonstrated that biomass and yellow pigment production were not directly associated. The identification of the structure of unknown P. aculeatum yellow pigment was detected using UV absorption spectrum and FT-IR spectroscopy. 相似文献
8.
Valduga E Valério A Treichel H Furigo Júnior A Di Luccio M 《Applied biochemistry and biotechnology》2009,157(1):61-69
With the objective of determining the kinetic behavior (growth, substrate, pH, and carotenoid production) and obtain the stoichiometric
parameters of the fermentative process by Sporidiobolus salmonicolor in synthetic and agroindustrial media, fermentations were carried out in shaken flasks at 25°C, 180 rpm, and initial pH of
4.0 for 120 h in the dark, sampling every 6 h. The maximum concentrations of total carotenoids in synthetic (913 μg/L) and
agroindustrial (502 μg/L) media were attained approximately 100 h after the start of the fermentative process. Carotenoid
bioproduction is associated with cell growth and the ratio between carotenoid production and cell growth (Y
P/X) is 176 and 163 μg/g in the synthetic and agroindustrial media, respectively. The pH of the agroindustrial fermentation medium
varied from 4.2 to 8.5 during the fermentation. The specific growth rate (μ
X) for S. salmonicolor in synthetic and agroindustrial media was 0.07 and 0.04 h−1, respectively. The synthetic medium allowed for greater productivity, obtaining maximum cell productivity (P
x) of 0.08 g L−1 h−1 and maximum total carotenoid productivity (P
car) of 14.2 μg L−1 h−1. Knowledge of the kinetics of a fermentative process is of extreme importance when transposing a laboratory experiment to
an industrial scale, as well as making a quantitative comparison between different culture conditions. 相似文献
9.
Hung-Yuan Fang Shin-Chin Chen Szu-Lin Chen 《Applied biochemistry and biotechnology》2003,111(2):81-91
EDTA, the target compound of this study from the effluent of secondary biotreatment units, can be biodegraded by special microorganisms.
So far, there are three species of microorganisms—Agrobacterium, Gram-negative BNCI, and DSM9103—that can degrade EDTA and are published in the literature. We have successfully isolated a bacterial strain that can degrade
EDTA. It was identified as Burkhol cepacia, an aerobic species, elliptically shaped with a length of 5–15 μm. The growth medium contains 1000 mg/L of ferric-EDTA as
carbon source, 750 mg/L of (NH4)2SO4+(NH2)2CO as nitrogen source, and 1000 mg/L of KH2PO4 as phosphorus source, and mineral factors such as Fe and Mg. Incubated at pH, 7.0, 30°C, and 150 rpm on a shaker for 15 d,
the average specific growth rate of this microbe is 0.135 d−1, which shows that the respective degradation efficiency of Fe-EDTA and Cu-EDTA is 90 and 75% individually. 相似文献
10.
D. A. Viana M. N. Carneiro-Cunha J. M. Araújo B. Barros-Neto J. L. Lima-Filho A. Converti A. Pessoa-Júnior A. L. F. Porto 《Applied biochemistry and biotechnology》2010,160(6):1797-1807
Clavulanic acid (CA) is a β-lactam antibiotic, which has a potent β-lactamase inhibiting activity. The influence of five variables,
namely pH (6.0, 6.4, and 6.8), temperature (28°C, 30°C, and 32°C), agitation intensity (150, 200, and 250 rpm), glycerol concentration
(5.0, 7.5, and 10 g/L) and soybean flour concentration (5.0, 12.5, and 20 g/L), on CA production by a new isolate of Streptomyces (DAUFPE 3060) was investigated in 250-mL Erlenmeyer flasks using a fractional factorial design. Temperature and soybean flour
concentration were shown to be the two variables that exerted the most important effects on the production of CA at 95% confidence
level. The highest CA concentration (494 mg/L) was obtained after 48 h at 150 rpm, 32°C, pH 6.0, 5.0 g/L glycerol, and 20 g/L
soybean flour concentrations. Under these conditions, the yields of biomass and product on consumed substrate were 0.26 gX/gS and 64.3 mgP/gS, respectively. Fermentations performed in 3.0-L bench-scale fermenter allowed increasing the CA production by about 60%. 相似文献
11.
Liakopoulou-Kyriakides M Psomas SK Kyriakidis DA 《Applied biochemistry and biotechnology》1999,82(3):175-183
Xanthomonas campestris w.t. was used for production of xanthan gum in fermentations with chestnut flour for the first time. Fermentations were carried
out with either chestnut flour or its soluble sugars (33.5%) and starch (53.6%), respectively, at 28°C and 200 rpm at initial
pH 7.0 in flasks. The effect of agitation rate (at 200, 400, and 600 rpm) on xanthan gum production was also studied in a
2-L batch reactor. It was found that xanthan production reaches a maximum value of 3.3 g/100 mL at 600 rpm and 28°C at 45
h. 相似文献
12.
Isci A Himmelsbach JN Strohl J Pometto AL Raman DR Anex RP 《Applied biochemistry and biotechnology》2009,157(3):453-462
Aqueous-ammonia-steeped switchgrass was subject to simultaneous saccharification and fermentation (SSF) in two pilot-scale
bioreactors (50- and 350-L working volume). Switchgrass was pretreated by soaking in ammonium hydroxide (30%) with solid to
liquid ratio of 5 L ammonium hydroxide per kilogram dry switchgrass for 5 days in 75-L steeping vessels without agitation
at ambient temperatures (15 to 33 °C). SSF of the pretreated biomass was carried out using Saccharomyces cerevisiae (D5A) at approximately 2% glucan and 77 filter paper units per gram cellulose enzyme loading (Spezyme CP). The 50-L fermentation
was carried out aseptically, whereas the 350-L fermentation was semiaseptic. The percentage of maximum theoretical ethanol
yields achieved was 73% in the 50-L reactor and 52–74% in the 350-L reactor due to the difference in asepsis. The 350-L fermentation
was contaminated by acid-producing bacteria (lactic and acetic acid concentrations approaching 10 g/L), and this resulted
in lower ethanol production. Despite this problem, the pilot-scale SSF of aqueous-ammonia-pretreated switchgrass has shown
promising results similar to laboratory-scale experiments. This work demonstrates challenges in pilot-scale fermentations
with material handling, aseptic conditions, and bacterial contamination for cellulosic fermentations to biofuels. 相似文献
13.
Production of an extracellular lipase from Serratia marcescens ECU1010, which is an industrially important biocatalyst for the stereospecific synthesis of Diltiazem precusor, was carefully
optimized in both shake flasks and a fermenter, using Tween-80 as the enzyme inducer. Dextrin and beef extract combined with
ammonium sulfate were indicated to be the best carbon and nitrogen sources, respectively. With the increase of Tween-80 from
0 to 10 g l−1, the lipase production was greatly enhanced from merely 250 U l−1 to a maximum of 3,340 U l−1, giving the highest lipase yield of ca 640 U g−1 dry cell mass (DCW), although the maximum biomass (6.0 g DCW l−1) was achieved at 15 g l−1 of Tween-80. When the medium loading in shake flasks was reduced from 20 to 10% (v / v), the lipase production was significantly enhanced. The increase in shaking speed also resulted in an improvement of the
lipase production, although the cell growth was slightly repressed, suggesting that the increase of dissolved oxygen (DO)
concentration contributed to the enhancements of lipase yield. When the lipase fermentation was carried out in a 5-l fermenter,
the lipase production reached a new maximum of 11,060 U l−1 by simply raising the aeration rate from 0.5 to 1.0 vvm, while keeping the dissolved oxygen above 20% saturation via intermittent
adjustment of the agitation speed (≥400 rpm), in the presence of a relatively low concentration (2 g l−1) of Tween-80 to prevent a potential foaming problem, which is easy to occur in the intensively aerated fermenter. 相似文献
14.
Ahmed SU Singh SK Pandey A Kanjilal S Prasad RB 《Applied biochemistry and biotechnology》2009,152(1):108-116
To study the effect of agitation speed (rpm) and dissolved oxygen concentration (DO) on the production of gamma linolenic
acid by Mucor sp. RRL001, a central composite design experiment was performed in a 5-L stirred tank bioreactor. The design consisted of
a total of 10 runs consisting of runs at five levels for each factor and was divided in two blocks. The ANOVA analysis and
Pareto chart of effects suggested agitation speed (p = 0.0142) linear effect and DO concentration (p = 0.0342) quadratic effects were significant factors with significant contribution to the response. The validation run based
on the optimum production zone in response surface plot resulted in the maximum 350.3 mg l−1 GLA yield as compared with model predicted value of 340.7 mg l−1. The study suggests that agitation rate is having more pronounced effect on GLA yield than dissolved oxygen concentration
by ensuring enhanced mass transfer and by preventing wall growth at elevated agitation speed. Also, it shows that higher GLA
yields can be obtained in a simple medium at moderate oxygen saturation and that the Mucor sp. RRL001 is resistant to high agitation linked shear stress and suitable for GLA production at higher scale. 相似文献
15.
Agbaje Lateef Julius K. Oloke Evariste B. Gueguim Kana Solomon O. Oyeniyi Olukemi R. Onifade Ayokunmi O. Oyeleye Olabiyi C. Oladosu 《Chemical Papers》2008,62(6):635-638
Increasing awareness of the importance of fructooligosaccharides (FOS) as ingredients of functional foods has led to intensive
search of new sources of fructosyltransferases (FTase), enzymes responsible for the conversion of sucrose to fructooligosaccharides.
A local strain of Rhizopus stolonifer isolated from spoilt orange fruit with high fructosyltransferase activity (U
t) of 12.31–45.70 U mL−1 during a fermentation period of 24–120 h is herein reported. It showed low hydrolytic activity (U
h) in the range of 0.86–1.78 U mL−1 during the same period. FOS yield of 34 % (1-kestose, GF2, nystose, GF3) was produced by FTase obtained from a 72 h-old culture using 60 g of sucrose per 100 mL of the substrate. When the isolate
was grown in a defined submerged medium, its pH dropped sharply from the intial value of 5.5 to 1.0 within 24 h, and this
value was maintained throughout the fermentation. The biomass content ranged from 8.8 g L−1 at 24 h of fermentation to reach the maximum of 10 g L−1 at 72 h. It was reduced to 5.6 g L−1 at the end of 120 h of fermentation. This report represents the first reference to a strain of Rhizopus as a source of FTase for the production of FOS. The high U
t/U
h ratio shown by this isolate indicates that it may be a good strain for the industrial and commercial production of FOS. However,
there is a need of further optimization of the bioprocess to increase the conversion efficiency of sucrose to FOS by the enzyme. 相似文献
16.
A fed-batch culture system with constant feeding (glucose 80 g L−1, 0.25 ml min−1) was used to study the influence of glucose on cell dry weight and exopolysaccharides production from submerged Tremella fuciformis spores in a 5-L stirred-tank bioreactor. The results showed that high levels of cell mass (9.80 g L−1) and exopolysaccharides production (3.12 g L−1) in fed-batch fermentation were obtained after 1 h of feeding, where the specific growth rate (μ) and exopolysaccharides yield on substrate consumed (YP/S) were 0.267 d−1 and 0.14 g g−1. Unlike batch fermentation, maximal cell mass and exopolysaccharides production merely reached 7.11 and 2.08 g L−1; the specific growth rate (μ) and exopolysaccharides yield on substrate consumed (YP/S) were 0.194 d−1 and 0.093 g g−1, respectively. It is concluded that the synthesis of exopolysaccharides can be promoted effectively when feeding glucose
at a late exponential phase. 相似文献
17.
Elżbieta Gasiorek 《Chemical Papers》2008,62(2):141-146
The effect of aeration, agitation, and bed loading on biomass and product concentration during citric acid biosynthesis by
solid-state fermentation was investigated. For this purpose, Aspergillus niger S was cultivated on sugar beet pulp in a 4.5 dm3 horizontal rotating drum bioreactor. The results suggest that the parameters examined have a remarkable effect on the quantity
of biomass being formed and on the product concentration. The maximum citric acid production (about 150 g per kg of the substrate
dry matter) was obtained under the following conditions: aeration rate 0.2 dm3 kg−1 min−1, mixing (periodical) 1 min once an hour, and bed loading 30 % of the bioreactor working volume. However, these values did
not favour biomass formation. Moreover, it was found that accumulation of the product reached its maximum when the amount
of biomass was minimal (approximately 252-29 g per kg of the substrate dry matter) under the conditions involved.
Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May
2007. 相似文献
18.
Bakri Yasser Jacques Philippe Shi Lin Kui Thonart Philippe 《Applied biochemistry and biotechnology》2002,98(1-9):1037-1048
The effects of a new axial impeller (HTPG4) on oxygen volumetric transfer coefficient, K
L
a, and xylanase production by Penicillium canescens 10-10c were studied and compared for dual-impeller systems, one with one DT4 impeller below and one HTPG4 above (DT4-HTPG4)
and one with two DT4 (DT4-DT4) impellers, in a 5-L bioreactor. The volumetric coefficient of oxygen transfer was measured
in culture medium using a gassing-out method at different gassing rates and agitation speeds. We observed that the DT4-HTPG4
combination provided better K
L
a performance than the DT4-DT4 combination. The two combinations were also tested for their influence on xylanase production
by a filamentous microorganism; P. canescens 10-10c. These experiments demonstrated that the DT4-HTPG4 combination impeller enhanced enzyme production up to 23% compared
with the DT4-DT4 combination at an aeration rate of 1 vvm and an agitation speed of 600 rpm. The main cause for this difference
is thought to be a higher shear stress generated by the DT4-DT4 combination, which damages the mycelium of P. canescens and decreases xylanase production. 相似文献
19.
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
20.
Yoshiharu Yamane Yozo Nakamura Hiroyuki Okamoto Hiroshi Ooshima Jyoji Kato 《Applied biochemistry and biotechnology》1995,50(3):317-322
Effects of pH and dissolved oxygen concentration on batchwise riboflavin production by a 5-fluorouracil (5-FU)-resistant mutant
ofArthrobacter sp. were investigated. The reaction was carried out in a jar fermentor. The optimal pH of culture medium was around 7.3.
Dissolved oxygen concentration was almost constant during fermentation at 600 rpm of agitation rate. Production of riboflavin
reached a maximum of 160 mg/L after 70 h fermentation under the agitation rate of 600 rpm, aeration rate of 1.0 L/min, and
pH 7.0. 相似文献