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1.
Bacterial polyhydroxyalkanoates (PHAs) are perceived to be a suitable alternative to petrochemical plastics because they have
similar material properties, are environmentally degradable, and are produced from renewable resources. In this study, the
in situ degradation of medium-chain-length PHA (PHAMCL) films in tropical forest and mangrove soils was assessed. The PHAMCL was produced by Pseudomonas putida PGA1 using saponified palm kernel oil (SPKO) as the carbon source. After 112 d of burial, there was 16.7% reduction in gross
weight of the films buried in acidic forest soil (FS), 3.0% in the ones buried in alkaline forest soil by the side of a stream
(FSst) and 4.5% in those buried in mangrove soil (MS). There was a slight decrease in molecular weight for the films buried
in FS but not for the films buried in FSst and in MS. However, no changes were observed for the melting temperature, glass
transition temperature, monomer compositions, structure, and functional group analyses of the films from any of the burial
sites during the test period. This means that the integral properties of the films were maintained during that period and
degradation was by surface erosion. Scanning electron microscopy of the films from the three sites revealed holes on the film
surfaces which could be attributed to attack by microorganisms and bigger organisms such as detritivores. For comparison purposes,
films of polyhydroxybutyrate (PHB), a short-chain-length PHA, and polyethylene (PE) were buried together with the PHAMCL films in all three sites. The PHB films disintegrated completely in MS and lost 73.5% of their initial weight in FSst, but
only 4.6% in FS suggesting that water movement played a major role in breaking up the brittle PHB films. The PE films did
not register any weight loss in any of the test sites. 相似文献
2.
Diniz SC Taciro MK Gomez JG da Cruz Pradella JG 《Applied biochemistry and biotechnology》2004,119(1):51-70
We studied high-density cultures of Pseudomonas putida IPT 046 for the production of medium-chain-length polyhydroxyalkanoates (PHAMCL) using an equimolar mixture of glucose and fructose as carbon sources. Kinetics studies of P. putida growth resulted in a maximum specific growth rate of 0.65 h(-1). Limitation and inhibition owing to NH4+ ions were observed, respectively, at 400 and 3500 mg of NH4+/L. The minimum concentration of dissolved oxygen in the broth must be 15% of saturation. Fed-batch strategies for high-cell-density cultivation were proposed. Pulse feed followed by constant feed produced a cell concentration of 32 g/L in 18 h of fermentation and low PHAMCL content. Constant feed produced a cell concentration of 35 g/L, obtained in 27 h of fermentation, with up to 15% PHAMCL. Exponential feed produced a cell concentration of 30 g/L in 20 h of fermentation and low PHAMCL content. Using the last strategy, 21% PHAMCL was produced during a period of 34 h of fed-batch operation, with a final cell concentration of 40 g/L and NH4+ limitation. Using phosphate limitation, 50 g/L cell concentration, 63% PHAMCL and a productivity of 0.8 g/(L x h) were obtained in 42 h of fed-batch operation. The PHAMCL yield factors from consumed carbohydrate for N-limited and P-limited experiments were, respectively, 0.15 and 0.19 g/g. 相似文献
3.
The medium-chain-length polyhydroxyalkanoate (PHAMCL) produced by Pseudomonas putida PGA1 using saponified palm kernel oil as the carbon source could degrade readily in water taken from Kayu Ara River in Selangor,
Malaysia. A weight loss of 71.3% of the PHA film occurred in 86 d. The pH of the river water medium fell from 7.5 (at d 0)
to 4.7 (at d 86), and there was a net release of CO2. In sterilized river water, the PHA film also lost weight and the pH of the water fell, but to lesser extents. The C8 monomer
of the PHA was completely removed after 6 d of immersion in the river water, while the proportions of the other monomers (C10,
C12, and C14) were reversed from that of the undegraded PHA. By contrast, the monomer composition of the PHA immersed in sterilized
river water did not change significantly from that of the undegraded PHA. Scanning electron microscopy showed physical signs
of degradation on the PHA film immersed in the river water, but the film immersed in sterilized river water was relatively
unblemished. The results thus indicate that the PHAMCL was degraded in tropical river water by biologic as well as nonbiologic means. A significant finding is that shorter-chain
monomers were selectively removed throughout the entire PHA molecule, and this suggests enzymatic action. 相似文献
4.
Jin-Nam Kim Jong-Sok Choo Young-Jung Wee Jong-Sun Yun Hwa-Won Ryu 《Applied biochemistry and biotechnology》2005,123(1-3):861-869
A new acetic acid-producing microorganism, Acetobacter sp. RKY4, was isolated from Korean traditional persimmon vinegar, and we optimized the culture medium for acetic acid production
from ethanol using the newly isolated Acetobacter sp. RKY4. The optimized culture medium for acetic acid production using this microorganism was found to be 40 g/L ethanol,
10 g/L glycerol, 10 g/L corn steep liquor, 0.5 g/L MgSO4·7H2O, and 1.0 g/L (NH4H2PO4. Acetobacter sp. RKY4 produced 47.1 g/L of acetic acid after 48 h of fermentation in a 250 mL Erlenmeyer flask containing 50 mL of the
optimized medium. 相似文献
5.
Butanol production using Clostridium beijerinckii BA101 hyper-butanol producing mutant strain and recovery by pervaporation 总被引:1,自引:0,他引:1
Clostridium beijerinckii BA101 (mutant strain) and C. beijerinckii 8052 (wild type) were compared for substrate and butanol inhibition. The wild-type strain is more strongly inhibited by added
butanol than is the mutant strain. Acetone and butanol were removed from a fed-batch reactor inoculated with C. beijcrinckii BA101 by pervaporation using a silicone membrane. In the batch reactor, C. beijerinckii BA101 produced 25.3 g/L of total solvents, whereas in the fermentation-recovery experiment it produced 165.1 g/L of total
solvents. Solvent productivity increased from 0.35 (batch reactor) to 0.98 g/L·h (fed-batch reactor). The fed-batch reactor
wasfed with 500 g/L of glucose-based P2 medium. Acetone selectivities ranged from 2 to 10 whereas butanol selectivities ranged
from 7 to 19. Total flux varied from 26 to 31 g/m2·h. 相似文献
6.
Carla Zanella Guidini Líbia Diniz Santos Marquez Helisângela de Almeida Silva Miriam Maria de Resende Vicelma Luiz Cardoso Eloízio Júlio Ribeiro 《Applied biochemistry and biotechnology》2014,172(3):1623-1638
Studies have been conducted on selecting yeast strains for use in fermentation for ethanol production to improve the performance of industrial plants and decrease production costs. In this paper, we study alcoholic fermentation in a fed-batch process using a Saccharomyces cerevisiae yeast strain with flocculant characteristics. Central composite design (CCD) was used to determine the optimal combination of the variables involved, with the sucrose concentration of 170 g/L, a cellular concentration in the inoculum of 40 % (v/v), and a filling time of 6 h, which resulted in a 92.20 % yield relative to the theoretical maximum yield, a productivity of 6.01 g/L h and a residual sucrose concentration of 44.33 g/L. With some changes in the process such as recirculation of medium during the fermentation process and increase in cellular concentration in the inoculum after use of the CCD was possible to reduce the residual sucrose concentration to 2.8 g/L in 9 h of fermentation and increase yield and productivity for 92.75 % and 9.26 g/L h, respectively. A model was developed to describe the inhibition of alcoholic fermentation kinetics by the substrate and the product. The maximum specific growth rate was 0.103 h?1, with K I and K s values of 109.86 and 30.24 g/L, respectively. The experimental results from the fed-batch reactor show a good fit with the proposed model, resulting in a maximum growth rate of 0.080 h?1. 相似文献
7.
Rodrigues Denise C. G. A. Da Silva Silvio S. Almeida E Silva J. B. Vitolo Michele 《Applied biochemistry and biotechnology》2002,98(1-9):875-883
Xylose reductase activity of Candida guilliermondii FTI 20037 was evaluated during xylitol production by fed-batch fermentation of sugarcane bagasse hydrolysate. A 24-1 fractional factorial design was used to select process variables. The xylose concentrations in the feeding solution (S
F
) and in the fermentor (S
0), the pH, and the aeration rate were selected for optimization of this process, which will be undertaken in the near future.
The best experimental result was achieved at S
F
=45 g/L, S
0=40 g/L, pH controlled at 6.0, and aeration rate of 1.2 vvm. Under these conditions, the xylose reductase activity was 0.81
U/mg of protein and xylitol production was 26.3 g/L, corresponding to a volumetric productivity of 0.55 g/(L·h) and a xylose
xylitol yield factor of 0.68 g/g. 相似文献
8.
Gimenes Maria Antonieta P. Carlos Luiz Cláudio S. Faria Luís F. F. Pereira Nei 《Applied biochemistry and biotechnology》2002,98(1-9):1049-1059
The global oxygen uptake rate (OUR) and specific oxygen uptake rates (SOUR) were determined for different values of the volumetric
oxygen mass transfer coefficient (15, 43, and 108 h−1), and for varying initial xylose concentrations (50, 100, 150, and 200 g/L) in shaking flasks. The initial cell concentration
was 4.0 g/L, and there was only significant growth in the fermentation with the highest oxygen availability. In this condition,
OUR increased proportionally to cell growth, reaching maximum values from 2.1 to 2.5 g of O2/(L·h) in the stationary phase when the initial substrate concentration was raised from 50 to 200 g/L, respectively. SOUR
showed different behavior, growing to a maximum value coinciding with the beginning of the exponential growth phase, after
which point it decreased. The maximum SOUR values varied from 265 to 370 mg of O2/(g of cell·h), indicating the interdependence of this parameter and the substrate concentration. Although the volumetric
productivity dropped slightly from 1.55 to 1.18 g of xylitol/(L·h), the strain producing capacity (γ
P/X
) rose from 9 to 20.6 g/g when the initial substrate concentration was increased from 50 to 200 g/L. As for the xylitol yield
over xylose consumed (γ
P/S
), there was no significant variation, resulting in a mean value of 0.76 g/g. The results are of interest in establishing
a strategy for controlling the dynamic oxygen supply to maximize volumetric productivity. 相似文献
9.
Chen N Huang J Feng ZB Yu L Xu QY Wen TY 《Applied biochemistry and biotechnology》2009,158(3):595-604
In this study, the fed-batch fermentation technique was applied to improve the yield of l-threonine produced by Escherichia coli TRFC. Various fermentation substrates and conditions were investigated to identify the optimal carbon source, its concentration
and C/N ratio in the production of l-threonine. Sucrose was found to be the optimal initial carbon source and its optimal concentration was determined to be 70 g/L
based on the results of fermentations conducted in a 5-L jar fermentor using a series of fed-batch cultures of E. coli TRFC. The effects of glucose concentration and three different feeding methods on the production of l-threonine were also investigated in this work. Our results showed that the production of l-threonine by E. coli was enhanced when glucose concentration varied between 5 and 20 g/L with DO-control pulse fed-batch method. Furthermore,
the C/N ratio was a more predominant factor than nitrogen concentration for l-threonine overproduction and the optimal ratio of ammonium sulfate to sucrose (g/g) was 30. Under the optimal conditions, a final l-threonine concentration of 118 g/L was achieved after 38 h with the productivity of 3.1 g/L/h (46% conversion ratio from
glucose to threonine). 相似文献
10.
Balasubramanian Niru Seok Kim Jun Lee Y. Y. 《Applied biochemistry and biotechnology》2001,91(1-9):367-376
For optimum fermentation, fermenting xylose into acetic acid by Clostridium thermoaceticum (ATCC 49707) requires adaptation of the strain to xylose medium. Exposed to a mixture of glucose and xylose, it preferentially
consumesxylose over glucose. The initial concentration of xylose in the medium affects the final concentration and the yield
of acetic acid. Batch fermentation of 20 g/L of xylose with 5g/L of yeast extract as the nitrogen source results in a maximum
acetate concentration of 15.2 g/L and yield of 0.76 g of acid/g of xylose. Corn steep liquor (CLS) is a good substitute for
yeast extract and results in similar fermentation profiles. The organism consumes fructose, xylose, and glucose from a mixture
of sugars in batch fermentation. Arabinose, mannose, and galactose are consumed only slightly. This organism loses viability
on fed-batch operation, even with supplementation of all the required nutrients. In fed-batch fermentation with CSL supplementation,
d-xylulose (an intermediate in the xylose metabolic pathway) accumulates in large quantities. 相似文献
11.
The conversion of glucose and fructose into gluconic acid (GA) and sorbitol (SOR) was conducted in a batch reactor with free
(CTAB-treated or not) or immobilized cells of Zymomonas mobilis. High yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/L (glucose
plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 U/L. The concentration of the
products varied hyperbolically with time according to the equations (GA)=t(GA)max/(WGA +t), (SOR)=t (SOR)max/(WSor+t), vGA=[WGA (GA)max]/(WGA+t)2 and VSOR=[WSOR (SOR)max]/(WSOR+t)2. Taking the test carried out with free CTAB-treated cells as an example, the constant parameters were (GA)max= 541 g/L, (SOR)max=552 g/L, WGA=4.8h, WSOR=4.9h, υGA=112.7 g/L· and υSOR=112.7 g/L·. 相似文献
12.
The effect of ammonium nitrate concentration in the citric acid biosynthesis by Aspergillus niger NC-12 in single-stage continuous cultures with biomass retention was investigated. Experiments were carried out in a BIOMER
laboratory fermenter with 5 dm3 working volume. At the initial stage of each cultivation, the substrate in the bioreactor contained 1.5 g NH4NO3 dm−3. After 120 h onwards, the bioreactor was fed continuously at a constant dilution rate of 0.009 h−1. NH4NO3 concentration in the feed was varied from one culture to another, ranging between 0.5 g dm−3 and 2.5 g dm−3. Promising results were obtained when NH4NO3 concentration of 1.5 g dm−3 was used. The observed concentration of citric acid (c
P) and yield of citric acid with respect to the introduced sucrose (Y
P/S) were 117.88 g dm−3 and 78.59 %, respectively. The efficiency coefficient of citric acid biosynthesis (K
ef) was very high, amounting to 83.38.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
13.
Actinobacillus succinogenes 130 Z was used to produce succinic acid from cheese whey in this study. At the presence of external CO2 supply, the effects of initial cheese whey concentration, pH, and inoculum size on the succinic acid production were studied.
The by-product formation during the fermentation process was also analyzed. The highest succinic acid yield of 0.57 was obtained
at initial cheese whey concentration of 50 g/L, while the highest succinic acid productivity of 0.58 g h−1 L−1 was obtained at initial cheese whey concentration of 100 g/L. Increase in pH and inoculum size caused higher succinic acid
yield and productivity. At the preferred fermentation condition of pH 6.8, inoculum size of 5% and initial cheese whey concentration
of 50 g/L, succinic acid yield of 0.57, and productivity of 0.44 g h−1 L−1 were obtained. Acetic acid and formic acid were the main by-products throughout the fermentation run of 48 h. It is feasible
to produce succinic acid using lactose from cheese whey as carbon resource by A. succinogenes 130 Z. 相似文献
14.
Scheffersomyces stipitis was cultivated in an optimized, controlled fed-batch fermentation for production of ethanol from glucose–xylose mixture. Effect of feed medium composition was investigated on sugar utilization and ethanol production. Studying influence of specific cell growth rate on ethanol fermentation performance showed the carbon flow towards ethanol synthesis decreased with increasing cell growth rate. The optimum specific growth rate to achieve efficient ethanol production performance from a glucose-xylose mixture existed at 0.1 h?1. With these optimized feed medium and cell growth rate, a kinetic model has been utilized to avoid overflow metabolism as well as to ensure a balanced feeding of nutrient substrate in fed-batch system. Fed-batch culture with feeding profile designed based on the model resulted in high titer, yield, and productivity of ethanol compared with batch cultures. The maximal ethanol concentration was 40.7 g/L. The yield and productivity of ethanol production in the optimized fed-batch culture was 1.3 and 2 times higher than those in batch culture. Thus, higher efficiency ethanol production was achieved in this study through fed-batch process optimization. This strategy may contribute to an improvement of ethanol fermentation from lignocellulosic biomass by S. stipitis on the industrial scale. 相似文献
15.
Chattopadhyay S Srivastava AK Bisaria VS 《Applied biochemistry and biotechnology》2002,102(1-6):381-393
The root explants of the germinated seedlings of Podophyllum hexandrum were grown in MS medium supplemented with indole acetic acid (IAA) (2 mg/L) and activated charcoal (0.5%), and healthy callus
culture was obtained after incubation for 3 wk at 20°C. The cultivation of plant cells in shake flask was associated with
problems such as clumping of cells and browning of media, which were solved by the addition of pectinase and polyvinylpyrrolidone.
The effect of major media components and carbon source was studied on the growth and podophyllotoxin production in suspension
culture. It was found that glucose was a better carbon source than sucrose and that NH4
+:NO3
− ratio (total nitrogen concentration of 60 mM) and PO4
3− did not have much effect on the growth and product formation. The relative effect of culture parameters (inoculum level,
pH, IAA, glucose, NH4
+:NO3
− ratio, and PO4
3−) on the overall growth and product response of the plant cell suspension culture was further investigated by Plackett-Burman
design. This indicated that inoculum level, glucose, IAA, and pH had significant effects on growth and production of podophyllotoxin.
To identify the exact optimum concentrations of these parameters on culture growth and podophyllotoxin production, central
composite design experiments were formulated. The overall response equations with respect to growth and podophyllotoxin production
as a function of these culture parameters were developed and used to determine the optimum concentrations of these parameters,
which were pH 6.0, 1.25 mg/L of IAA, 72 g/L of glucose, and inoculum level of 8 g/L. 相似文献
16.
Chen Chee-Shan Chan E. Wang S. L. Gong C. S. Chen L. F. 《Applied biochemistry and biotechnology》1994,(1):531-544
A self-aggregating strain ofSaccharomyces uvarum (U4) was used as a biocatalyst to carry out continuous ethanol fermentation in a tower fermentor equipped with a cell separator.
Cell aggregates (2–3 mm) formed a stable packed bed in the fermentor, and the cell separator retained yeast cells effectively.
Corn steep liquor was used as a nitrogen source for the fermentation of corn syrup and black strap molasses. An ethanol productivity
of 54 g/L/h was reached using corn syrup at a dilution rate of 0.7/h, and sugar concentration in the feed was 15% (w/v). For
molasses fermentation, an ethanol productivity of 22 g/L/h was obtained at a dilution rate of 0.7/h, and sugar concentration
in the feed was 12.5% (w/v). Ethanol yields obtained from tower fermentation are higher than those obtained from flask fermentation
(96% for corn syrup fermentation and 92% for molasses fermentation). No significant loss in fermentation activity was observed
after 3 mo of operation. 相似文献
17.
Nasib Qureshi Patrick Karcher Michael Cotta Hans P. Blaschek 《Applied biochemistry and biotechnology》2004,114(1-3):713-721
Corn steep liquor (CSL), a byproduct of the corn wet-milling process, was used in an immobilized cell continuous biofilm reactor
to replace the expensive P2 medium ingredients. The use of CSL resulted in the production of 6.29 g/L of total acetone-butanol-ethanol
(ABE) as compared with 6.86 g/L in a control experiment. These studies were performed at a dilution rate of 0.32 h−1. The productivities in the control and CSL experiment were 2.19 and 2.01 g/(L·h), respectively. Although the use of CSL resulted
in a 10% decrease in productivity, it is viewed that its application would be economical compared to P2 medium. Hence, CSL
may be used to replace the P2 medium. It was also demonstrated that inclusion of butyrate into the feed was beneficial to
the butanol fermentation. A control experiment produced 4.77 g/L of total ABE, and the experiment with supplemented sodium
butyrate produced 5.70 g/L of total ABE. The butanol concentration increased from 3.14 to 4.04 g/L. Inclusion of acetate in
the feed medium of the immobilized cell biofilm reactor was not found to be beneficial for the ABE fermentation, as reported
for the batch ABE fermentation.
Names are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard
of the product, and the use of the names by USDA implies no approval of the product to the exclusion of others that may also
be suitable. 相似文献
18.
Summary An extracellular lipase was produced by Bacillus coagulans by solid-state fermentation. Solid waste from melon was used as the basic nutrient source and was supplemented with olive
oil. The highest lipase production (78,069 U/g) was achieved after 24h of cultivation with 1% olive oil enrichment. Enzyme
had an optimal activity at 37°C and pH 7.0, and sodium dodecyl sulfate increased lipase activity. NH 4NO3 increased enzyme production, whereas organic nitrogen had no effect. The effect of the type of carbon sources on lipolytic
enzyme production was also studied. The best results were obtained with starch and maltose (148,932 and 141,629 U/g, respectively),
whereas a rather low enzyme activity was found in cultures grown on glucose and galactose (approx 118,769 and 123,622 U/g,
respectively). Enzyme was inhibited with Mn+2 and Ni+2 by 68 and 74%, respectively. By contrast, Ca+2 enhanced enzyme production by 5%. 相似文献
19.
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
20.
Soo-Yeon Kim Jin-Nam Kim Young-Jung Wee Don-Hee Park Hwa-Won Ryu 《Applied biochemistry and biotechnology》1996,131(1-3):705-715
The optimum fermentation medium for the production of bacterial cellulose (BC) by a newly isolated Gluconacetobacter sp. RKY5 was investigated. The optimized medium composition for cellulose production was determined to be 15 g/L glycerol,
8 g/L yeast extract, 3 g/L K2HPO4, and 3 g/L acetic acid. Under these optimized culture medium, Gluconacetobacter sp. RKY5 produced 5.63 g/L of BC after 144 h of shaken culture, although 4.59 g/L of BC was produced after 144 h of static
culture. The amount of BC produced by Gluconacetobacter sp. RKY5 was more than 2 times in the optimized medium found in this study than in a standard Hestrin and Shramm medium,
which was generally used for the cultivation of BC-producing organisms. 相似文献