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1.
An aquatic weed biomass, Eicchornia crassipes, present in abundance and leading to a threatening level of water pollution was used as substrate for cellulase and β-glucosidase
production using wild-type strain Aspergillus niger RK3 that was isolated from decomposing substrate. Alkali treatment of the biomass (10%) resulted in a 60–66% increase in
endoglucanase, exoglucanase, and β-glucosidase production by the A. niger RK3 strain in semi-solid-state fermentation. Similarly, the alkali-treated biomass led to a 45–54% increase in endo- and
exoglucanase and a higher (98%) increase in β-glucosidase production by Trichoderma reesei MTCC164 under similar conditions. However, the cocultivation of A. niger RK3 and T. reesei MTCC164 at a ratio of 3:1 showed a 20–24% increase in endo- and exoglucanase activities and about a 13% increase in the β-glucosidase
activity over the maximum enzymatic activities observed under single culture conditions. Multistep physical (ultraviolet)
and chemical (N-methyl-N′-nitrosoguanidine, sodium azide, colchicine) mutagenesis of the A. niger RK3 strain resulted in a highly cellulolytic mutant, UNSC-442, having an increase of 136, 138, and 96% in endoglucanase,
exoglucanase, and β-glucosidase, activity, respectively. The cocultivation of mutant UNSC-442 along with T. reesei MTCC164 (at a ratio of 3:1) showed a further 10–11% increase in endo- and exoglucanase activities and a 29% increase in β-glucosidase
activity in semi-solid-state fermentation. 相似文献
2.
Pleurotus ostreatus mushroom mycelium was cultivated in submerged culture in shake-flask experiments with acid extract from peat and yeast extract
as nutrient sources. Different concentrations of water-diluted peat extract were tested in an attempt to overcome the effect
of growth inhibitors apparently present in nondiluted peat extracts. The best results were obtained with a ratio of one part
of peat extract diluted with one part of water. Several operating variables were studied to optimize the growth of mycelial
biomass ofP. ostreatus. The best results produced approximately 5 g/L dry biomass with a yield of 60% and an efficiency of 33%. These results were
obtained in 8 d at 5% (v/v) inoculum ratio, 28°C, pH of 5.0, and 150 rpm. 相似文献
3.
The structure and the biosorption properties of fungal biomass of Aspergillus niger originated from citric acid fermentation industry was investigated. This waste biomass, produced in high quantity in carefully
controlled industrial processes, has certain favourable characteristics that may be improved for its usefulness. In environmental
chemistry, it is known for the removal of heavy metals cations. In this work, different alkaline treatments (1M NaOH/20°C/24
h and 10M NaOH/107°C/6 h) were used to evaluate the dependence of sorption properties of biomass on the cell wall composition.
The biosorption was studied by the batch method, with the biomass concentration of 1 g/l, at pH 6. The adsorption of lead
was more effective than that of cadmium. The biosorption capacity was evaluated using the biosorption isotherm derived from
the equilibrium data. At pH 6, the maximmum lead biosorption capacity estimated with the Langmuir model was 93 mg/g dry biomass. 相似文献
4.
Rodrigues C Vandenberghe LP Teodoro J Pandey A Soccol CR 《Applied biochemistry and biotechnology》2009,158(1):72-87
Citric acid (CA) production has been conducted through a careful strain selection, physical–chemical optimization and mutation.
The aim of this work was to optimize the physical–chemical conditions of CA production by solid-state fermentation (SSF) using
the Aspergillus niger LPB BC strain, which was isolated in our laboratory. The parental and mutant strain showed a good production of CA using
citric pulp (CP) as a substrate. The physical–chemical parameters were optimized and the best production was reached at 65%
moisture, 30 °C and pH 5.5. The influence of the addition of commercial and alternative sugars, nitrogen sources, salts, and
alcohols was also studied. The best results (445.4 g of CA/kg of CP) were obtained with sugarcane molasses and 4% methanol
(v/w). The mutagenesis induction of LPB BC was performed with UV irradiation. Eleven mutant strains were tested in SSF where two
mutants showed a higher CA production when compared to the parental strain. A. niger LPB B3 produced 537.6 g of CA/kg of CP on the sixth day of fermentation, while A. niger LPB B6 produced 616.5 g of CA/kg of CP on the fourth day of fermentation, representing a 19.5% and 37% gain, respectively. 相似文献
5.
The economics of large-scale production of fuel ethanol from biomass and wastes requires the efficient utilization of all
the sugars derived from the hydrolysis of the heteropolymeric hemicellulose component of lignocellulosic feedstocks. Glucuronic
and 4-0-methyl-glucuronic acids are major side chains in xylans of the grasses and hardwoods that have been targeted as potential
feedstocks for the production of cellulosic ethanol. The amount of these acids is similar to that of arabinose, which is now
being viewed as another potential substrate in the production of biomass-derived ethanol.
This study compared the end-product distribution associated with the fermentation of D-glucose (Glc) and D-glucuronic acid
(GlcUA) (as sole carbon and energy sources) byEscherichia coli B (ATCC 11303) and two different ethanologenic recombinants—a strain in whichpet expression was via a multicopy plasmid (pLOI297) and a chromosomally integrated construct, strain KO11. pH-stat batch fermentations
were conducted using a modified LB medium with 2% (w/v) Glc or GlcUA with the set-point for pH control at either 6.3 or 7.0.
The nontransformed host culture produced only lactic acid from glucose, but fermentation of GlcUA yielded a mixture of ethanol,
acetic, and lactic acids, with acetic acid being the predominant end-product. The ethanol yield associated with GlcUA fermentation
by both recombinants was similar, but acetic acid was a significant by-product. Increasing the pH from 6.3 to 7.0 increased
the rate of glucuronate fermentation, but it also decreased the ethanol mass yield from 0.22 to 0.19 g/g primarily because
of an increase in acetic acid production. In all fermentations there was good closure of the carbon mass balance, the exception
being the recombinant bearing plasmid pLOI297 that produced an unidentified product from GlcUA. The metabolism of GlcUA by
this metabolically engineered construct remains unresolved. The results offered insights into metabolic fluxes and the regulation
of pyruvate catabolism in the wild-type and engineered strains. End-product distribution for metabolism of glucuronic acid
by the nontransformed, wild-typeE. coli B and recombinant strain KO11 suggests that the enzyme pyruvate-formate lyase is not solely responsible for the production
of acetylCoA from pyruvate and that derepressed pyruvate dehydrogenase may play a significant role in the metabolism of GlcUA. 相似文献
6.
Production of chitinolytic enzymes with Trichoderma longibrachiatum IMI 92027 in solid substrate fermentation 总被引:1,自引:0,他引:1
Kovacs K Szakacs G Pusztahelyi T Pandey A 《Applied biochemistry and biotechnology》2004,118(1-3):189-204
Thirty Trichoderma strains representing 15 species within the genus were screened for extracellular production of chitinolytic enzymes in solid
substrate fermentation. Trichoderma longibrachiatum IMI 92027 (ATCC 36838) gave the highest yield (5.0 IU/g of dry matter of substrate) after 3 d of fermentation on wheat bran-crude
chitin (9:1 mixture) medium. The optimal moisture content (66.7%), chitin content (20%), initial pH of the medium (2.0–5.0),
and time course (5 d) of solid substrate fermentation were determined for strain IMI 92027. Cellulase, xylanase, α-amylase,
and β-xylosidase activities were also detected. The pH and temperature optima of the chitinase complex of T. longibrachiatum IMI 92027 were 4.5 and 55°C, respectively. The enzyme totally lost its activity at 70°C in 5 min in the absence of the substrate
but retained about 15% of its initial activity even at 70°C after a 60-min incubation in the presence of solid substrate fermentation
solids. Purification of protein extract from the solid substrate fermentation material revealed high chitinolytic activities
between pI 5.9 and 4.8, where N-acetyl-β-d-hexosaminidase and chitinase peaks have been found in the same pI range. Two chitinases of 43.5 and 30 kDa were purified at acidic pI. 相似文献
7.
Pryor SW Gibson DM Hay AG Gossett JM Walker LP 《Applied biochemistry and biotechnology》2007,143(1):63-79
Bacillus subtilis strain TrigoCor 1448 was grown on wheat middlings in 0.5-l solid-state fermentation (SSF) bioreactors for the production
of an antifungal biological control agent. Total antifungal activity was quantified using a 96-well microplate bioassay against
the plant pathogen Fusarium oxysporum f. sp. melonis. The experimental design for process optimization consisted of a 26−1 fractional factorial design followed by a central composite face-centered design. Initial SSF parameters included in the
optimization were aeration, fermentation length, pH buffering, peptone addition, nitrate addition, and incubator temperature.
Central composite face-centered design parameters included incubator temperature, aeration rate, and initial moisture content
(MC). Optimized fermentation conditions were determined with response surface models fitted for both spore concentration and
activity of biological control product extracts. Models showed that activity measurements and spore production were most sensitive
to substrate MC with highest levels of each response variable occurring at maximum moisture levels. Whereas maximum antifungal
activity was seen in a limited area of the design space, spore production was fairly robust with near maximum levels occurring
over a wider range of fermentation conditions. Optimization resulted in a 55% increase in inhibition and a 40% increase in
spore production over nonoptimized conditions. 相似文献
8.
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
9.
Effects of pH and Temperature on Recombinant Manganese Peroxidase Production and Stability 总被引:1,自引:0,他引:1
Jiang F Kongsaeree P Schilke K Lajoie C Kelly C 《Applied biochemistry and biotechnology》2008,146(1-3):15-27
The enzyme manganese peroxidase (MnP) is produced by numerous white-rot fungi to overcome biomass recalcitrance caused by
lignin. MnP acts directly on lignin and increases access of the woody structure to synergistic wood-degrading enzymes such
as cellulases and xylanases. Recombinant MnP (rMnP) can be produced in the yeast Pichia pastoris αMnP1-1 in fed-batch fermentations. The effects of pH and temperature on recombinant manganese peroxidase (rMnP) production
by P. pastoris αMnP1-1 were investigated in shake flask and fed-batch fermentations. The optimum pH and temperature for a standardized fed-batch
fermentation process for rMnP production in P. pastoris αMnP1-1 were determined to be pH 6 and 30 °C, respectively. P. pastoris αMnP1-1 constitutively expresses the manganese peroxidase (mnp1) complementary DNA from Phanerochaete chrysosporium, and the rMnP has similar kinetic characteristics and pH activity and stability ranges as the wild-type MnP (wtMnP). Cultivation
of P. chrysosporium mycelia in stationary flasks for production of heme peroxidases is commonly conducted at low pH (pH 4.2). However, shake
flask and fed-batch fermentation experiments with P. pastoris αMnP1-1 demonstrated that rMnP production is highest at pH 6, with rMnP concentrations in the medium declining rapidly at
pH less than 5.5, although cell growth rates were similar from pH 4–7. Investigations of the cause of low rMnP production
at low pH were consistent with the hypothesis that intracellular proteases are released from dead and lysed yeast cells during
the fermentation that are active against rMnP at pH less than 5.5. 相似文献
10.
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
11.
Oil Palm Frond (OPF) is one of lignocellulosic biomass, which can be utilized as raw material for bioethanol production. Bioethanol is produced as alternative energy to substitute gasoline. There are four steps in bioethanol production from OPF, i.e pretreatement, saccharification, fermentation and purification process. In this study, optimization of saccharification and fermentation process for OPF was investigated. Two methods and the variations of enzyme concentration were carried out in the saccharification and fermentation process. Separate hydrolysis and fermentation process (SHF) and simultaneous saccharification and fermentation process (SSF) were conducted to produce ethanol optimally. Variations of enzyme concentration used in this process were 10, 20, 30 and 40 FPU/g substrate. The result shows that the highest ethanol concentration can be obtained in SSF process with 30 FPU/g substrate of enzyme concentration. The process produced 59.20 g/L ethanol (95.95% yield ethanol) at 96 h of SSF process. 相似文献
12.
Bogar B Szakacs G Tengerdy RP Linden JC Pandey A 《Applied biochemistry and biotechnology》2002,102(1-6):453-461
Ten Aspergillus oryzae strains were screened in solid substrate fermentation for α-amylase production on spent brewing grain (SBG) and on corn fiber.
SBG proved to be a better substrate for enzyme production than corn fiber. A Plackett-Burman experimental design was used
to optimize the medium composition for the best strain. Solid substrate fermentation on optimized medium with A. oryzae NRRL 1808 (=ATCC 12892) strain in stationary 500-mL Erlenmeyer flask culture yielded 4519 U of α-amylase/g of dry matter
substrate in 3 d. The whole solid substrate fermentation material (crude enzyme, in situ enzyme) may be considered a cheap biocatalytic material for animal feed rations and for bioalcohol production from starchy
materials. 相似文献
13.
A feeding technology that was suitable for improving the nisin production by Lactococcus lactis subsp. lactis W28 was established. The effects of initial sucrose concentration (ISC) in the fermentation broth, feeding time, and feeding
rate on the fermentation were studied. It was observed that a fed-batch culture (ISC = 10 g l−1) with 100 ml sucrose solution (190 g l−1) being evenly fed (9–10 ml h−1) into the fermenter after 3-h fermentation gave the best performance in terms of biomass and nisin yield. Under these conditions,
the total biomass and the total nisin yield were approximately 23% and 51% higher than those in batch fermentation, respectively.
When the sucrose concentration was controlled at 5–10 g l−1 in variable volume intermittent fed-batch fermentation (VVIF) with ISC = 10 g l−1, the total biomass and the total nisin yield were 29% and 60% above those in batch fermentation, respectively. The VVIF proved
to be effective to eliminate the substrate inhibition by maintaining sucrose at appropriate levels. It is also easy to be
scaled up, since various parameters involved in industrial production were taken into account. 相似文献
14.
Madhavan Nampoothiri K Roopesh K Chacko S Pandey A 《Applied biochemistry and biotechnology》2005,120(2):97-108
Escherichia coli NCIM 2569 was evaluated for its potential for amidase production under submerged fermentation. Among the various amide compounds
screened, maximum substrate specificity and enzyme yield (8.1 U/mL) were obtained by using 1% acetamide. Fermentation was
carried out at 30°C in shake-flask culture under optimized process conditions. A maximum of 0.52 U/mL of intracellular amidase
activity was also obtained from cells incubated for 24 h. Studies were also performed to elucidate the optimal conditions
(gel concentration, initial biomass, curing period of beads, and calcium ion concentration in the production medium) for immobilization
of whole cells. By using E. coli cells entrapped in alginate, a maximum of 6.2 U/mL of enzyme activity was obtained after 12 h of incubation under optimized
conditions. Using the immobilized cells, three repeated batches were carried out successfully, and 85% of the initial enzyme
activity was retained in the second and third batches. The study indicated that the immobilized E. coli cells offered certain advantages such as less time for maximum enzyme production, more stability in the enzyme production
rate, and repeated use of the biocatalyst. 相似文献
15.
Steam-exploded corn stover biomass was used as the substrate for fed-batch separate enzymatic hydrolysis and fermentation
(SHF) to investigate the solid concentration ranging from 10% to 30% (w/w) on the lignocellulose enzymatic hydrolysis and fermentation. The treatment of washing the steam-exploded material was also
evaluated by experiments. The results showed that cellulose conversion changed little with increasing solid concentration,
and fermentation by Saccharomyces cerevisiae revealed a nearly same ethanol yield with the water-washed steam-exploded corn stover. For the washed material at 30% substrate
concentration, i.e., 30% water insoluble solids (WIS), enzymatic hydrolysis yielded 103.3 g/l glucose solution and a cellulose
conversion of 72.5%, thus a high ethanol level up to 49.5 g/l. With the unwashed steam-exploded corn stover, though a cellulose
conversion of 70.9% was obtained in hydrolysis at 30% solid concentration (27.9% WIS), its hydrolysate did not ferment at
all, and the hydrolysate of 20% solid loading containing 3.3 g/l acetic acid and 145 mg/l furfural already exerted a strong
inhibition on the fermentation and ethanol production. 相似文献
16.
Hyang-Ok Kim Young-Jung Wee Jin-Nam Kim Jong-Sun Yun Hwa-Won Ryu 《Applied biochemistry and biotechnology》1996,131(1-3):694-704
The fermentative production of lactic acid from cheese whey and corn steep liquor (CSL) as cheap raw materials was investigated
by using Lactobacillus sp. RKY2 in order to develop a cost-effective fermentation medium. Lactic acid yields based on consumed lactose were obtained
at more than 0.98 g/g from the medium containing whey lactose. Lactic acid productivities and yields obtained from whey lactose
medium were slightly higher than those obtained from pure lactose medium. The lactic acid productivity gradually decreased
with increase in substrate concentration owing to substrate and product inhibitions. The fermentation efficiencies were improved
by the addition of more CSL to the medium. Moreover, through the cell-recycle repeated batch fermentation, lactic acid productivity
was maximized to 6.34 g/L/h, which was 6.2 times higher than that of the batch fermentation. 相似文献
17.
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
18.
Mahesh S. Krishnan Nancy W. Y. Ho George T. Tsao 《Applied biochemistry and biotechnology》1999,78(1-3):373-388
Fermentation kinetics of ethanol production from glucose, xylose, and their mixtures using a recombinant Saccharomyces 1400 (pLNH33) are reported. Single-substrate kinetics indicate that the specific growth rate of the yeast and the specific
ethanol productivity on glucose as the substrate was greater than on xylose as a substrate. Ethanol yields from glucose and
xylose fermentation were typically 95 and 80% of the theoretical yield, respectively. The effect of ethanol inhibition is
more pronounced for xylose fermentation than for glucose fermentation. Studies on glucose-xylose mixtures indicate that the
recombinant yeast co-ferments glucose and xylose. Fermentation of a 52.8 g/L glucose and 56.3 g/L xylose mixture gave an ethanol
concentration of 47.9 g/L after 36 h. Based on a theoretical yield of 0.51 g ethanol/g sugars, the ethanol yield from this
experiment (for data up to 24 h) was calculated to be 0.46 g ethanol/g sugar or 90% of the theoretical yield. The specific
growth rate of the yeast on glucose-xylose mixtures was found to lie between the specific growth rate on glucose and the specific
growth rate on xylose. Kinetic studies were used to develop a fermentation model incorporating the effects of substrate inhibition,
product inhibition, and inoculum size. Good agreements were obtained between model predictions and experimental data from
batch fermentation of glucose, xylose, and their mixtures. 相似文献
19.
Ethanol production was studied in simultaneous saccharification and fermentation (SSF) of steam-pretreated spruce at 42°C,
using a thermotolerant yeast. Three yeast strains of Kluyveromyces marxianus were compared in test fermentations. SSF experiments were performed with the best of these on 5% (w/w) of substrate at a
cellulase loading of 37 filter paper units/g of cellulose, and a β-glucosidase loading of 38 IU/gof cellulose. The detoxification
of the substrate and the lack of pH control in the experiments increased the final ethanol concentration. The final ethanol
yield was 15% lower compared to SSF with Saccharomyces cerevisiae at 37°C, owing to the cessation of ethanol fermentation after the first 10 h. 相似文献
20.
Laccase production by solid-state fermentation (SSF) using an indigenously isolated white rot basidiomycete Ganoderma sp. was studied. Among the various agricultural wastes tested, wheat bran was found to be the best substrate for laccase
production. Solid-state fermentation parameters such as optimum substrate, initial moisture content, and inoculum size were
optimized using the one-factor-at-a-time method. A maximum laccase yield of 2,400 U/g dry substrate (U/gds) was obtained using
wheat bran as substrate with 70% initial moisture content at 25°C and the seven agar plugs as the inoculum. Further enhancement
in laccase production was achieved by supplementing the solid-state medium with additional carbon and nitrogen source such
as starch and yeast extract. This medium was optimized by response surface methodology, and a fourfold increase in laccase
activity (10,050 U/g dry substrate) was achieved. Thus, the indigenous isolate seems to be a potential laccase producer using
SSF. The process also promises economic utilization and value addition of agro-residues. 相似文献