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1.
Xiangzhao Mao Feng Wang Jianguo Zhang Shi Chen Zixin Deng Yaling Shen Dongzhi Wei 《Applied biochemistry and biotechnology》2009,159(3):673-686
CS103, the novel derivative of polyene macrolides antibiotic FR-008/candicidin with lower toxicity has been isolated from
the culture mycelia of the mutant of Streptomyces sp. FR-008, with targeted deletions of the fscP cytochrome P450 gene from its chromosome. To enhance biosynthesis of CS103, pH shift and precursor feeding strategy for fermentation
process by the mutant of Streptomyces sp. FR-008 in a stirred tank bioreactor was developed. According to the process parameters analysis, the effectiveness of
the strategy was examined and confirmed by experiments. A maximal CS103 concentration of 139.98 μg/mL was obtained, 2.05-fold
higher than that in the pH-uncontrolled fermentation. Compared to other three cases as pH-uncontrolled, pH-controlled, and
two-stage pH-controlled batch cultures, the proposed “pH shift and precursor feeding strategy” effectively avoided the scarcity
of the antibiotic precursor, increased the CS103 yield from biomass (Y
P/X) and substrate (Y
P/S) by 110.61% and 48.52%, respectively, and at the time the fermentation time was shortened from 120 to 96 h. The highest CS103
production rate (1.46 μg mL−1 h−1) of the pH shift and precursor feeding strategy was 284.21%, 97.30%, and 58.70% higher than that of pH-uncontrolled, pH-controlled,
and two-stage pH-controlled batch culture cases, respectively. 相似文献
2.
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
3.
The recovery of an inhibiting product from a bioreactor soon after its formation is an important issue in industrial bioprocess
development. In the present study, the potential of the anion exchanger-based in situ product recovery (ISPR) technique for
the biocatalytic production of propionic acid was discussed. The focus of the current work was the selection of a suitable
configuration of metabolically active cells for application in propionic acid production. Accumulation of propionic acid in
fermentation broth caused feedback inhibition of the growth and biotransformation activity of Propionibacterium freudenreichii CICC 10019. Relevant product inhibition kinetics was discussed, and the results showed that keeping the aqueous propionic
acid concentration below 10.02 g L−1 was an essential prerequisite for ISPR process. A batch study, in which three ISPR configuration mode designs were compared,
was conducted. The comparison indicated that employing an external direct mode had significant advantages over other modes
in terms of increased productivity and product yield, with a corresponding decrease in the number of downstream processing
steps, as well as in substrate consumption. The fed-batch culture using an external direct mode for the continuous accumulation
of propionic acid resulted in a cumulative propionic acid concentration of 62.5 g L−1, with a corresponding product yield of 0.78 g propionic acid/g glucose. 相似文献
4.
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
5.
Nie ZK Ji XJ Huang H Du J Li ZY Qu L Zhang Q Ouyang PK 《Applied biochemistry and biotechnology》2011,163(8):946-953
Substrate concentration in 2,3-butanediol (2,3-BD) fermentation could not be controlled well in traditional feeding strategies,
such as constant, impulse, and exponential feeding strategies. In the present study, fermentative 2,3-BD production by Klebsiella oxytoca was investigated under different batch and fed-batch strategies. The glucose-feedback fed-batch strategy was proved to be
not effective for economical 2,3-BD production for the inability of timely feeding, leading that the bacteria reused 2,3-BD
as carbon source for cell growth. Based on the phenomena that the byproducing acids caused the pH declining and the requirement
of maintaining the pH at a proper level for both cell growth and 2,3-BD accumulation, an improved strategy of pH-stat fed-batch
culture with glucose and sodium hydrate fed at the same time was established. Thus, the residual glucose concentration could
be controlled through the adjustment of pH automatically. At last, efficient 2,3-BD production was fulfilled under this fed-batch
strategy, and the highest 2,3-BD concentration, productivity, and yield were 127.9 g/l, 1.78 g/(l•h), and 0.48 g/g (2,3-BD/glucose),
respectively, compared to 98.5 g/l, 1.37 g/(l•h), and 0.43 g/g obtained in glucose-feedback fed-batch strategy. This feeding
strategy was simple and easy to operate and could be feasible for industrial 2,3-BD production in the future. 相似文献
6.
Sha Li Heng Cai Yujia Qing Ben Ren Hong Xu Hongyang Zhu Jun Yao 《Applied biochemistry and biotechnology》2011,163(1):52-63
The sucrose isomerase (SIase) gene from an efficient strain of Erwinia rhapontici NX-5 for isomaltulose hyperproduction was cloned and overexpressed in Escherichia coli. Protein sequence alignment revealed that SIase was a member of the glycoside hydrolase 13 family. The molecular mass of
the purified recombinant protein was estimated at 66 kDa by SDS-PAGE. The SIase had an optimal pH and temperature of 5.0 and
30 °C, respectively, with a K
m of 257 mmol/l and V
max of 48.09 μmol/l/s for sucrose. To the best of our knowledge, the recombinant SIase has the most acidic optimum pH for isomaltulose
synthesis. When the recombinant E. coli (pET22b- palI) cells were used for isomaltulose synthesis, almost complete conversion of sucrose (550 g/l solution) to isomaltulose was
achieved in 1.5 h with high isomaltulose yields (87%). The immobilized E. coli cells remained stable for more than 30 days in a “batch”-type enzyme reactor. This indicated that the recombinant SIase could
continuously and efficiently produce isomaltulose. 相似文献
7.
N. S. Shaligram S. K. Singh R. S. Singhal A. Pandey G. Szakacs 《Applied biochemistry and biotechnology》2009,159(2):505-520
In the present study, compactin production by Penicillium brevicompactum WA 2315 was optimized using solid-state fermentation. The initial one factor at a time approach resulted in improved compactin
production of 905 μg gds−1 compared to initial 450 μg gds−1. Subsequently, nutritional, physiological, and biological parameters were screened using fractional factorial and Box–Behnken
design. The fractional factorial design studied inoculum age, inoculum volume, pH, NaCl, NH4NO3, MgSO4, and KH2PO4. All parameters were found to be significant except pH and KH2PO4. The Box–Behnken design studied inoculum volume, inoculum age, glycerol, and NH4NO3 at three different levels. Inoculum volume (p = 0.0013) and glycerol (p = 0.0001) were significant factors with greater effect on response. The interaction effects were not significant. The validation
study using model-defined conditions resulted in an improved yield of 1,250 μg gds−1 compactin. Further improvement in yield was obtained using fed batch mode of carbon supplementation. The feeding of glycerol
(20% v/v) on day 3 resulted in further improved compactin yield of 1,406 μg gds−1. The present study demonstrates that agro-industrial residues can be successfully used for compactin production, and statistical
experiment designs provide an easy tool to improve the process conditions for secondary metabolite production. 相似文献
8.
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
9.
Karina B. Hueso Domínguez Ildikó V. Tóth M. Renata S. Souto Filipa Mendes Cándido García De María Isabel Vasconcelos António O. S. S. Rangel 《Applied biochemistry and biotechnology》2010,160(6):1664-1673
A sequential injection system to monitor glycerol in a Saccharomyces cerevisiae fermentation process was developed. The method relies on the rate of formation of nicotinamide adenine dinucleotide in its
reduced form (NADH, measured spectrophotometrically at 340 nm) from the reaction of glycerol with NAD+ cofactor, catalysed by the enzyme glycerol dehydrogenase present in solution. This procedure enables the determination of
glycerol between 0.046 and 0.46 g/l, (corresponding to yeast fermentation samples with concentrations up to 50 g/l) with good
repeatability (relative standard deviation for n = 10 lower than 2.2% for three different samples) at a sampling frequency of 25/h. The detection and quantification limits
using a miniaturised spectrophotometer were 0.13 and 0.44 mM, respectively. Reagent consumption was of 0.45 μmol NAD+ and 1.8 μg enzyme per assay, and the waste production was 2.8 ml per determination. Results obtained for samples were in
agreement with those obtained with a high-performance liquid chromatography method. 相似文献
10.
Shen Xuesong Wang Tao Jin Meihua Zhao Chunxia Qin Xuelian Liu Hanfu Qiu Zhuangping Liu Yi 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1307-1313
A thermal dynamic model of nanoformulations entrapped in artesunate liposomes was established and biological thermodynamics
was applied for investigation of the drug formulations. Effects of artesunate liposomes on the growth metabolism of Escherichia coli were studied by microcalorimetry. The results showed that (1) Comparison of artesunate and artesunate liposomes, the thermogenesis
curves of E. coli were significant different in the metabolic process: lag phase (AB), log phase (BC), stationary phase (CD), and decline phase
(DE); (2) Linear fit of the data of total metabolic heat of E. coli effected by different concentration artesunate (1–300 μg), the equation can be obtained as follows: Y = 364720.61−1075.25x, R = 0.9985; Linear fit of the data of total metabolic heat of E. coli effected by different concentration artesunate liposomes (30–120 μg), the linear equation can be obtained as follows: Y = 54251.5765−35.71122x, R = 0.98345; (3) The half inhibitory concentration I
C50 was 50.05 μg/mL, the relative sensitivity was obviously different; (4) Artesunate liposomes having better sustained release
properties as compare to artesunate. 相似文献
11.
Žaneta Dohnalová Petra Šulcová Miroslav Trojan 《Journal of Thermal Analysis and Calorimetry》2010,101(3):973-978
The main aim of this work was to synthesize the magnesium orthostannate doped by terbium cations and tested whether these
materials can be used for colouring of the different materials, e.g. organic binder and ceramic glazes. Initial composition
of pigments was counted according the general formula 2MgO(1 − x)SnO2–xTbO2, where values of x varied from 0.1 to 0.5 in 0.1 steps. The simultaneous TG/DTA measurements of mixture containing tin oxide, magnesium carbonate
hydroxide and terbium oxide showed that the formation of a new compound started at temperature 1,029 °C, but single-phase
system was not prepared. Granulometric compositions of samples that were prepared by calcining at temperatures 1,300–1,400 °C
are characterized by values of median (d
50) in range 4–8 μm. The calcining temperature 1,500 °C caused the increase of the particle sizes at around 12 μm. The composition
of sample 2MgO–1.5SnO2–0.5TbO2 and heating temperature 1,500 °C are the most suitable conditions for preparation of colourfully interesting pigment that
can be recommended also for colouring of ceramic glazes. Especially, for colouring of decorative lead containing glaze G 07091
containing 5 wt% of PbO and 8 wt% of Al2O3. 相似文献
12.
Soojin Lee Borim Kim Kyungmoon Park Youngsoon Um Jinwon Lee 《Applied biochemistry and biotechnology》2012,166(7):1801-1813
meso-2,3-Butanediol (meso-2,3-BDO) is essential for the synthesis of various economically valuable biosynthetic products; however, the production of
meso-2,3-BDO from expensive carbon sources is an obstacle for industrial applications. In this study, genes involved in the synthesis
of 2,3-BDO in Klebsiella pneumoniae were identified and used to genetically modify Escherichia coli for meso-2,3-BDO production. Two 2,3-BDO biosynthesis genes—budA, encoding acetolactate, and meso-budC, encoding meso-SADH—from K. pneumoniae were cloned into the pUC18 plasmid and introduced into E. coli. In 2 l batch culture, the SGSB03 E. coli strain yielded meso-2,3-BDO at 0.31 g/gglucose (with a maximum of 15.7 g/lculture after 48 h) and 0.21 g/gcrude glycerol (with a maximum of 6.9 g/lculture after 48 h). Batch cultures were grown under optimized conditions (aerobic, 6% carbon source, 37 °C, and initial pH 7). To
find the optimal culture conditions for meso-2,3-BDO production, we evaluated the enzyme activity of meso-SADH and the whole cell conversion yield (meso-2,3-BDO/acetoin) of the E. coli SGSB02, which contains pSB02. meso-SADH showed high enzyme activity at 30–37 °C and pH 7 (30.5–41.5 U/mg of protein), and the conversion yield of SGSB02 E. coli was highest at 37–42 °C and a pH of 7 (0.25–0.28 g
meso-2,3-BDO/gacetoin). 相似文献
13.
The present work presents an alternative approach to ethanol production from sweet sorghum: without detoxification, acid-impregnated
fresh sweet sorghum stem which contains soluble (glucose and sucrose) and insoluble carbohydrates (cellulose and hemicellulose)
was steam pretreated under mild temperature of 100 °C. Simultaneous saccharification and fermentation experiments were performed
on the pretreated slurries using Saccharomyces cerevisiae. Experimentally, ground fresh sweet sorghum stem was combined with H2SO3 at dosages of 0.25, 0.50, and 0.75 g/g dry matter (DM) and steam pretreated by varying the residence time (60, 120, or 240 min).
According to enzymatic hydrolysis results and ethanol yields, H2SO3 was a powerful and mild acid for improving enzymatic digestibility of sorghum stem. At a solid loading of 10% (w/v) and acid dosage of 0.25 g/g DM H2SO3 at 100 °C for 120 min, 44.5 g/L ethanol was obtained after 48 ± 4 h of simultaneous saccharification and fermentation. This
corresponded to an overall ethanol yield of 110% of the theoretical one, based on the soluble carbohydrates in the fresh sweet
sorghum stem. The concentrations of hydroxymethylfurfural and furfural of the sulfurous acid pretreated samples were below
0.4 g/L. Ethanol would not inhibit the cellulase activity, at least under the concentration of 34 g/L. 相似文献
14.
Mohamad Faizal Ibrahim Suraini Abd-Aziz Mohamad Nafis Abdul Razak Lai Yee Phang Mohd Ali Hassan 《Applied biochemistry and biotechnology》2012,166(7):1615-1625
Acetone–butanol–ethanol (ABE) production from renewable resources has been widely reported. In this study, Clostridium butyricum EB6 was employed for ABE fermentation using fermentable sugar derived from treated oil palm empty fruit bunch (OPEFB). A
higher amount of ABE (2.61 g/l) was produced in a fermentation using treated OPEFB as the substrate when compared to a glucose
based medium that produced 0.24 g/l at pH 5.5. ABE production was increased to 3.47 g/l with a yield of 0.24 g/g at pH 6.0.
The fermentation using limited nitrogen concentration of 3 g/l improved the ABE yield by 64%. The study showed that OPEFB
has the potential to be applied for renewable ABE production by C. butyricum EB6. 相似文献
15.
Xiao-Jun Ji He Huang Jian-Guo Zhu Nan Hu Shuang Li 《Applied biochemistry and biotechnology》2009,159(3):605-613
The fermentative production of 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae under different fed-batch strategies was investigated. pH-stat fed-batch strategies proved to be not effective for economical
1,3-PD production for the existence of relatively high concentration of byproducts and residual glycerol at the end of the
fermentation. However, in the pH-stat fed-batch strategy, an important phenomenon was observed that the yields of two main
byproducts, 2,3-butanediol and lactic acid, were closely related to pH value. The dominant byproduct was 2,3-butanediol at
a pH value of 5.0 to 6.5 but changed to be lactic acid at a pH value of 7.1 to 8.0. Based on the analysis of the phenomenon,
a self-protection mechanism in K. pneumoniae, namely that the growing K. pneumoniae cells switch the metabolic pathways responding to environmental pH changes, was proposed. Thus a kind of feeding strategy
was further applied during which the pH value was fluctuated between 6.3 and 7.3 periodically by feeding glycerol–ammonia
mixture and sulphuric acid to make the metabolic pathways of 2,3-butanediol and lactic acid sub-active under the periodical
low or high pH stress. At last, efficient 1,3-PD production was fulfilled under this fed-batch strategy, and the best results
were achieved leading to 70 g/l 1,3-PD with a yield of 0.70 mol/mol glycerol and productivity of 0.97 g/l/h, while the two
main byproducts and residual glycerol were under low concentrations. 相似文献
16.
José Luis Martínez-Hernández Marco Arnulfo Mata-Gómez Cristóbal Noé Aguilar-González Anna Ilyina 《Applied biochemistry and biotechnology》2010,160(7):2045-2053
The production of extracellular and mycelia-associated penicillin G acylase (maPGA) with Mucor griseocyanus H/55.1.1 by surface-adhesion fermentation using Opuntia imbricata, a cactus, as a natural immobilization support was studied. Enzyme activity to form 6-aminopencillanic acid (6-APA) from
penicillin G was assayed spectrophotometrically. The penicillin G hydrolysis to 6-APA was evaluated at six different times
using PGA samples recovered from the skim milk medium at five different incubation times. Additionally, the effect of varying
the penicillin G substrate concentration level on the PGA enzyme activity was also studied. The maximum reaction rate, V
max, and the Michaelis constant, K
M, were determined using the Michaelis–Menten model. The maximum levels for maPGA and extracellular activity were found to
be 2,126.50 international unit per liter (IU/l; equal to 997.83 IU/g of support) at 48 h and 755.33 IU/l at 60 h, respectively.
Kinetics of biomass production for total biomass showed a maximum growth at 60 h of 3.36 and 2.55 g/l (equal to 0.012 g of
biomass per gram of support) for the immobilized M. griseocyanus biomass. The maPGA was employed for the hydrolysis of penicillin G to obtain 6-APA in a batch reactor. The highest quantity
of 6-APA obtained was 226.16 mg/l after 40-min reaction. The effect of substrate concentration on maPGA activity was evaluated
at different concentrations of penicillin G (0–10 mM). K
M and V
max were determined to be 3.0 × 10−3 M and 4.4 × 10−3 mM/min, respectively. 相似文献
17.
In the present study, hexavalent chromium (Cr(VI)) reduction potential of chromium reductase associated with the cell-free
extracts (CFE) of Arthrobacter rhombi-RE species was evaluated. Arthrobacter rhombi-RE, an efficient Cr(VI) reducing bacterium, was enriched and isolated from a chromium-contaminated site. Chromium reductase
activity of Arthrobacter rhombi-RE strain was associated with the cell-free extract and the contribution of extracellular enzymes to Cr(VI) reduction was negligible.
NADH enhanced the chromium reductase activity. The enzyme activity was optimal at a pH of 5.5 and a temperature of 30 °C.
Among the ten electron donors screened, sodium pyruvate was the most effective one followed by NADH and propionic acid. Michaelis–Menten
constant, K
m, and maximum reaction rate, V
max, obtained from the Lineweaver–Burk plot were 48 μM and 4.09 nM/mg protein/min, respectively, in presence of NADH as electron
donor and 170.5 μM and 4.29 nM/mg protein/min, respectively, in presence of sodium pyruvate as electron donor. Ca2+ enhanced the enzyme activity while Hg2+, Cd2+, Ba2+, and Zn2+ inhibited the enzyme activity. Among the various immobilization matrices screened, calcium alginate beads seemed to be the
most effective one. Though immobilized enzyme system was able to reduce Cr(VI), the performance was not very encouraging in
continuous mode of operation. 相似文献
18.
Assamoi Allah Antoine Destain Jacqueline Philippe Thonart 《Applied biochemistry and biotechnology》2010,160(1):50-62
There is an increasing interest for the organic residues from various sectors of agriculture and industries over the past
few decades. Their application in the field of fermentation technology has resulted in the production of bulk chemicals and
value-added products such as amino acid, enzymes, mushroom, organic acids, single-cell protein, biologically active secondary
metabolites, etc. (Ramachandran et al., Bioresource Technology 98:2000–2009, 2007). In this work, the production of extracellular xylanase by the fungus Penicillium canescens was investigated in solid-state fermentation using five agro-industrial substrates (soya oil cake, soya meal, wheat bran,
whole wheat bran, and pulp beet). The best substrate was the soya oil cake. In order to optimize the production, the most
effective cultivation conditions were investigated in Erlenmeyer flasks and in plastic bags with 5 and 100 g of soya oil cake,
respectively. The initial moisture content, initial pH, and temperature of the culture affected the xylanase synthesis. The
optimal fermentation medium was composed by soya oil cake crushed to 5 mm supplemented with 3% and 4% (w/w) of casein peptone and Na2HPO4.2H2O. After 7 days of incubation at 30 °C and under 80% of initial moisture, a xylanase production level of 18,895 ± 778 U/g
(Erlenmeyer flasks) and 9,300 ± 589 U/g (plastic bags) was reached. The partially purified enzyme recovered by ammonium sulfate
fractionation was completely stable at freezing and refrigeration temperatures up to 6 months and reasonably stable at room
temperature for more than 3 months. 相似文献
19.
Jiang L Wang J Liang S Wang X Cen P Xu Z 《Applied biochemistry and biotechnology》2010,160(2):350-359
Butyric acid has many applications in chemical, food, and pharmaceutical industries. In the present study, Clostridium tyrobutyricum ATCC 25755 was immobilized in a fibrous-bed bioreactor to evaluate the performance of butyrate production from glucose and
xylose. The results showed that the final concentration and yield of butyric acid were 13.70 and 0.46 g g−1, respectively, in batch fermentation when 30 g L−1 glucose was introduced into the bioreactor. Furthermore, high concentration 10.10 g L−1 and yield 0.40 g g−1 of butyric acid were obtained with 25 g L−1 xylose as the carbon source. The immobilized cells of C. tyrobutyricum ensured similar productivity and yield from repeated batch fermentation. In the fed-batch fermentation, the final concentration
of butyric acid was further improved to 24.88 g L−1 with one suitable glucose feeding in the fibrous-bed bioreactor. C. tyrobutyricum immobilized in the fibrous-bed bioreactor would provide an economically viable fermentation process to convert the reducing
sugars derived from plant biomass into the final bulk chemical (butyric acid). 相似文献
20.
Application of a pH Feedback-Controlled Substrate Feeding Method in Lactic Acid Production 总被引:1,自引:0,他引:1
Substrate concentration in lactic acid fermentation broth could not be controlled well by traditional feeding methods, including
constant, intermittent, and exponential feeding methods, in fed-batch experiments. A simple feedback feeding method based
on pH was proposed to control pH and substrate concentration synchronously to enhance lactic acid production in fed-batch
culture. As the linear relationship between the consumption amounts of alkali and that of substrate was concluded during lactic
acid fermentation, the alkali and substrate in the feeding broth were mixed together proportionally. Thus, the concentration
of substrate could be controlled through the adjustment of pH automatically. In the fed-batch lactic acid fermentation with
Lactobacillus lactis-11 by this method, the residual glucose concentration in fermentation broth was controlled between 4.1 and 4.9 g L−1, and the highest concentration of lactic acid, maximum cell dry weight, volumetric productivity of lactic acid, and yield
were 96.3 g L−1, 4.7 g L−1, 1.9 g L−1 h−1, and 0.99 g lactic acid per gram of glucose, respectively, compared to 82.7 g L−1, 3.31 g L−1, 1.7 g L−1 h−1, and 0.92 g lactic acid per gram of glucose in batch culture. This feeding method was simple and easily operated and could
be feasible for industrial lactic acid production in the future. 相似文献