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1.
Countercurrent fermentation of rice straw and chicken manure to carboxylic acids was performed using a mixed culture of marine
mesophilic microorganisms. To increase the digestibility of the biomass, rice straw, and chicken manure were pretreated with
0.1 g Ca(OH)2/g biomass. Fermentation was performed for 80% rice straw and 20% chicken manure at various volatile solid loading rates (VSLR)
and liquid residence times (LRT). The highest acid productivity of 1.69 g/(L·d) occurred at a total acid concentration of
32.4 g/L. The highest conversion (0.69 g VS digested/g VS fed) and yield (0.29 g total acids/g VS fed) were at a total acid
concentration of 25 g/L. A Continuum Particle Distribution Model of the process predicted the experimental total acid concentration
and conversion results with an average error of 6.41% and 6.15%, respectively. Results show how total acid concentrations,
conversions, and yields vary with VSLR and LRT in the MixAlco process. 相似文献
2.
Sugarcane bagasse and chicken manure were anaerobically fermented to carboxylic acids using a mixed culture of marine microorganisms
at 55 °C. Using the MixAlco process— an example of consolidated bioprocessing— the resulting carboxylate salts can be converted
to mixed alcohol fuels or gasoline. To enhance digestibility, sugarcane bagasse was lime pretreated with 0.1 g Ca(OH)2/g dry biomass at 100 °C for 2 h. Four-stage countercurrent fermentation of 80% sugarcane bagasse/20% chicken manure was performed
at various volatile solids (VS) loading rates and liquid residence times. Calcium carbonate was used as a buffer during fermentation.
The highest acid productivity of 0.79 g/(L day) occurred at a total acid concentration of 21.5 g/L. The highest conversion
(0.59 g VS digested/g VS fed) and yield (0.18 g total acids/g VS fed) occurred at a total acid concentration of 15.5 g/L.
The continuum particle distribution model (CPDM) predicted the experimental total acid concentrations and conversions at an
average error of 10.14% and 12.68%, respectively. CPDM optimizations show that high conversion (>80%) and total acid concentration
of 21.3 g/L are possible with 300 g substrate/(L liquid), 30 days liquid residence time, and 3 g/(L day) solid loading rate.
Thermophilic fermentation has a higher acetate content (∼63 wt%) than mesophilic fermentation (∼39 wt%). 相似文献
3.
The purpose of this research is to generate carboxylic acids from the biodegradable fraction of municipal solid wastes (MSW)
and municipal sewage sludge (MSS) by using a thermophilic (55°C), anaerobic, high-solid fermentation. With terrestrial inocula,
the highest total carboxylic acid concentration achieved was 20.5 g/L, the highest conversion obtained was 69%, and the highest
acetic acid selectivity was 86.4%. Marine inocula were also used to compare against terrestrial sources. Continuum particle
distribution modeling (CPDM) was used to predict the final acid product concentrations and substrate conversions at a wide
range of liquid residence times (LRT) and volatile solid loading rates (VSLR). “Maps” showing the product concentration and
conversion for various LRT and VSLR were generated from CPDM. The predictions were compared to the experimental results. On
average, the difference between the predicted and experimental values were 13% for acid concentration and 10% for conversion.
CPDM “maps” show that marine inocula produce higher concentrations than terrestrial inocula. 相似文献
4.
Débora Danielle Virgínio da Silva Maria das Graças de Almeida Felipe Ismael Maciel de Mancilha Sílvio Silvério da Silva 《Applied biochemistry and biotechnology》2005,121(1-3):427-437
The effect of glucose on xylose-xylitol metabolism in fermentation medium consisting of sugarcane bagasse hydrolysate was
evaluated by employing an inoculum of Candida guilliermondii grown in synthetic media containing, as carbon sources, glucose (30 g/L), xylose (30 g/L), or a mixture of glucose (2 g/L)
and xylose (30 g/L). The inoculum medium containing glucose promoted a 2.5-fold increase in xylose reductase activity (0.582
IU/mgprot) and a 2-fold increase in xylitol dehydrogenase activity (0.203 IU/mgprot) when compared with an inoculum-grown medium containing only xylose. The improvement in enzyme activities resulted in higher
values of xylitol yield (0.56 g/g) and productivity (0.46 g/[L·h]) after 48 h of fermentation. 相似文献
5.
Anaerobic treatment of animal byproducts from slaughterhouses at laboratory and pilot scale 总被引:1,自引:0,他引:1
Different mixtures of animal byproducts, other slaughterhouse waste (i.e., rumen, stomach and intestinal content), food waste,
and liquid manure were codigested at mesophilic conditions (37°C) at laboratory and pilot scale. Animal byproducts, including
blood, represent 70–80% of the total biogas potential from waste generated during slaughter of animals. The total biogas potential
from waste generated during slaughter is about 1300 MJ/cattle and about 140 MI/pig. Fed-batch digestion of pasteurized (70°C,
1h) animal byproducts resulted in a fourfold increase in biogas yield (1.14L/g of volatile solids [VS]) compared with nonpasteurized
animal bypproducts (0.31L/g of VS). Mixtures with animal byproducts representing 19–38% of the total dry matter were digested
in continuous-flow stirred tank reactors at laboratory and pilot scale. Stable processes at organic loading rates (OLRs) exceeding
2.5g of VS/(L·d) and hydraulic retention times (HRTs) less than 40 d could be obtained with total ammonia nitrogen concentrations
(NH4−N+NH3−N) in the range of 4.0–5.0 g/L. After operating one process for more than 1.5 yr at total ammonia nitrogen concentrations
>4 g/L, an increase in OLR to 5 g of VS/(L·d) and a decrease in HRT to 22 d was possible without accumulation of volatile
fatty acids. 相似文献
6.
Equipment and procedures were developed to study the conversion of lignocellulosic biomass to carboxylic acids using high-solids countercurrent fermentations. Countercurrent fermentations of cattle manure yielded a rapid fermentation (maximum 2.98 g of total acid/[L x d]) with high acid concentrations (maximum of 32.5 g of total acid/L), but the acid yield tended to be low (maximum of 0.24 g of total acid/g of volatile solids). Countercurrent fermentations of a mixture of 80% municipal solid waste/20% sewage sludge fermented more slowly (maximum of 1.98 g of total acid/[L x d]) with a lower acid concentration (maximum of 26.5 g of total acids/L), but higher acid yields were achieved (maximum of 0.34 g of total acid/g of volatile solids). 相似文献
7.
Thaddeus C. Ezeji Marisa Groberg Nasib Qureshi Hans P. Blaschek 《Applied biochemistry and biotechnology》2003,106(1-3):375-382
Acetone, butanol, ethanol (ABE, or solvents) were produced from starch-based packing peanuts in batch and continuous reactors.
In a batch reactor, 18.9 g/L of total ABE was produced from 80 g/L packing peanuts in 110 h of fermentation. The initial and
final starch concentrations were 69.6 and 11.1 g/L, respectively. In this fermentation, ABE yield and productivity of 0.32
and 0.17 g/(L·h) were obtained, respectively. Compared to the batch fermentation, continuous fermentation of 40 g/L of starch-based
packing peanuts in P2 medium resulted in a maximum solvent production of 8.4 g/L at a dilution rate of 0.033 h−1. This resulted in a productivity of 0.27 g/(L·h). However, the reactor was not stable and fermentation deteriorated with
time. Continuous fermentation of 35 g/L of starch solution resulted in a similar performance. These studies were performed
in a vertical column reactor using Clostridium beijerinckii BA101 and P2 medium. It is anticipated that prolonged exposure of culture to acrylamide, which is formed during boiling/autoclaving
of starch, affects the fermentation negatively. 相似文献
8.
Saccharification and fermentation of cassava (Manihot esculenta) bagasse was carried out in a single step for the production of L-(+)-lactic acid by Lactobacillus casei and Lactobacillus delbrueckii. Using 15.5% w/v of cassava bagasse as the raw material, a maximum starch to lactic acid conversion of 96% was obtained with
L. casei with a productivity rate of 1.40mg/mL·h and maximum yield of 83.8 mg/mL. It was 94% with L. delbrueckii with a productivity rate of 1.36 mg/mL·h. and maximum yeild of 81.9 mg/mL. Supplementation of bagasse with 0.01% w/v MnCl2 showed positive influence on the lactic acid production by L. casei. 相似文献
9.
10.
Heizir F. de Castro Samuel C. Oliveira Sandra A. Furlan 《Applied biochemistry and biotechnology》2003,107(1-3):547-555
A new approach for the utilization of hemicellulosic hydrolysate from sugarcane bagasse is described. This approach consists
of using the hydrolysate to dilute the conventional feedstock (sugarcane juice) to the usual sugar concentration (150 g/L)
employed for the industrial production of ethanol. The resulting sugar mixture was used as the substrate to evaluate the performance
of a continuous reactor incorporating a cell recycle module, operated at several dilution rates. An induced flocculent pentose-fermenting
yeast strain was used for this bioconversion. Under the conditions used, the reactor performance was satisfactory at substrate
feed rates of 30 g/(L·h) or less, corresponding to an ethanol productivity of about 11.0 g/(L·h) and an overall sugar conversion
>95%. These results show real advantages over the existing alternatives for a better exploitation of surplus bagasse to increase
industrial alcohol production. 相似文献
11.
Wee Young-Jung Yun Jong-Sun Kang Kui-Hyun Ryu Hwa-Won 《Applied biochemistry and biotechnology》2002,98(1-9):1093-1104
Enterococcus faecalis RKY1, a fumarate-reducing bacterium, was immobilized in an asymmetric hollow-fiber bioreactor (HFBR) for the continuous production
of succinic acid. The cells were inoculated into the shell side of the HFBR, which was operated in transverse mode. Since
the pH values in the HFBR declined during continuous operation to about 5.7, it was necessary to change the feed pH from 7.0
to 8.0 after 24 h of operation in order to enhance production of succinic acid. During continuous operation with a medium
containing fumarate and glycerol, the productivity of succinate was 3.0–10.9 g/(L·h) with an initial concentration of 30 g/L
of fumarate, 4.9–14.9 g/(L·h) with 50 g/L of fumarate, and 7.2–17.1 g/(L·h) with 80 g/L of fumarate for dilution rates between
0.1 and 0.4 h−1. The maximum productivity of succinate obtained by the HFBR (17.1 g of succinate /[L·h]) was 1.7 times higher than that of
the batch bioconversions (9.9 g of succinate /[L·h]) with 80 g/L of fumarate. Furthermore, the long-term stability of the
HFBR was demonstrated with a continuously efficient production of succinate for more than 15 d (360 h). 相似文献
12.
Tsao George T. Gong Cheng S. Cao Ning J. 《Applied biochemistry and biotechnology》2000,84(1-9):505-524
Solid-phase fermentation has been found to have a much higher productivity than the popular liquid submerged fermentation
in producing cellulase enzymes. The highest reported productivity in the literature for cellulases by Trichoderma cultures in submerged fermentation is 158 filter paper units (FPU)/(h·L) of fermenting liquid. From preliminary experiments
of solid-phase fermentation in 1000-m L flasks, a productivity of 234 FPU of cellulases/(h·L) of solid-bed volume was obtained.
When two novel techniques—pressure pulsation and repeated extraction—were applied, a productivity of 806 FPU/(h·L) was achieved.
The same techniques also greatly enhanced the productivity of other enzymes by fungal cultures in solid-phase fermentation. 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.
Novel, laboratory-scale, high-solids reactors operated under mesophilic conditions were used to study the anaerobic fermentation
of processed municipal solid waste (MSW) to methane. Product gas rate data were determined for organic loading rates ranging
from 2.99–18.46 g of volatile solids (VS) per liter (L) per day (d). The data represent the anaerobic fermentation at high-solids
levels within the reactor of 21–32%, while feeding a refuse-derived fuel (RDF)/MSW feedstock supplemented with a vitamin/mineral/nutrient
solution. The average biogas yield was 0.59 L biogas/g VS added to the reactor system/d. The average methane composition of
the biogas produced was 57.2%. The data indicate a linear relationship of increasing total biogas production with increasing
organic loading rate to the process. The maximum organic loading rate obtainable with high-solids anaerobic digestion is in
the range of 18–20 g VS/L·d to obtain 80% or greater bioconversion for the RDF/MSW feedstock. This loading rate is approximately
four to six times greater than that which can be obtained with comparable low-solids anaerobic bioreactor technology. 相似文献
15.
Cateryna Aiello-Mazzarri Guillermo Coward-Kelly Frank K. Agbogbo Mark T. Holtzapple 《Applied biochemistry and biotechnology》2005,127(2):79-93
Municipal solid waste (MSW) and sewage sludge (SS) were combined and anaerobically converted into carboxylate salts by using
a mixed culture of acid-forming microorganisms. MSW is an energy source and SS is a source of nutrients. In this study, MSW
and SS were combined, so they complemented each other. Four fermentors were arranged in series for a countercurrent fermentation
process. In this process, the solids and liquid were transferred in opposite directions, with the addition of fresh biomass
to fermentor 1 and fresh liquid media to fermentor 4. An intermediate lime treatment of solids exiting fermentor 3 before
entering fermentor 4 was applied to improve the product acid concentration from the untreated MSW/SS fermentations. All fermentations
were performed under anaerobic conditions at 40°C. Calcium carbonate was added to neutralize the carboxylic acids and to control
the pH. Iodoform was used as a methanogen inhibitor. Carboxylic acid concentration and gas composition were determined by
gas chromatography. Substrate conversion was measured by volatile solids loss, and carboxylic acid productivity was calculated
as the function of the total carboxylic acids produced, the amount of liquid in all fermentors, and time. The addition of
intermediate lime treatment increased product concentration and conversion by approx 30 and 15%, respectively. The highest
carboxylic acid concentrations for untreated MSW/SS fermentations with and without intermediate lime treatment were 22.2 and
17.7 g of carboxylic acid/L of liquid, respectively. These results confirm that adding a treatment step between fermentor
3 and fermentor 4 will increase the digestibility and acid productivity of the fermentation. 相似文献
16.
Rodrigues Denise C. G. A. Suva Silvio S. Prata Arnaldo Marcio R. Felipe Maria das Gracas A. 《Applied biochemistry and biotechnology》1998,(1):869-875
Batch, fed-batch, and semicontinuous fermentation processes were used for the production of xylitol from sugarcane bagasse
hemicellulosic hydrolysate. The best results were achieved by the semicontinuous fermentation process: a xylitol yield of
0.79 g/g with an efficiency of 86% and a volumetric productivity of 0.66 g/L/h. 相似文献
17.
Lactic acid production from cellulosic material by synergetic hydrolysis and fermentation 总被引:2,自引:0,他引:2
The hydrolysis process on corncob residue was catalyzed synergetically by the cellulase from Trichoderma reesei and the immobilized cellobiase. The feedback inhibition to cellulase reaction caused by the accumulation of cellobiose was
eliminated efficiently. The hydrolysis yield of corncob residue was 82.5%, and the percentage of glucose in the reducing sugar
reached 88.2%. The glucose in the cellulosic hydrolysate could be converted into lactic acid effectively by the immobilized
cells of Lactobacillus delbrueckii. When the enzymatic hydrolysis of cellulose and the fermentation of lactic acid were coupled together, no glucose was accumulated
in the reaction system, and the feedback inhibition caused by glucose was also eliminated. Under the batch process of synergetic
hydrolysis and lactic acid fermentation with 100 g/L of cellulosic substrate, the conversion efficiency of lactic acid from
cellulose and the productivity of lactic acid reached 92.4% and 0.938 g/(L·h), respectively. By using a fed-batch technique,
the total concentration of cellulosic substrate and lactic acid in the synergetic process increased to 200 and 107.5 g/L,
respectively, whereas the dosage of cellulase reduced from 20 to 15 IU/g of substrate in the batch process. The results of
the bioconversion of renewable cellulosic resources were significant. 相似文献
18.
In pH-controlled batch fermentations with pure sugar synthetic hardwood hemicellulose (1% [w/v] glucose and 4% xylose) and
corn stover hydrolysate (8% glucose and 3.5% xylose) lacking acetic acid, the xyloseutilizing, tetracycline (Tc)-sensitive,
genomically integrated variant of Zymomonas mobilis ATCC 39676 (designated strain C25) exhibited growth and fermentation performance that was inferior to National Renewable
Energy Laboratory's first-generation, Tc-resistant, plasmid-bearing Zymomonas recombinants. With C25, xylose fermentation following glucose exhaustion wasmarkellyslower, and the ethanol yield (based
on sugars consumed) was lower, owing primarily to an increase in lactic acid formation. There was an apparent increased sensitivity
to acetic acid inhibition with C25 compared with recombinants 39676:pZB4L, CP4:pZB5, and ZM4:pZB5. However, strain C25 performed
well in continous ferm entation with nutrient-rich synthetic corn stover medium over the dilution range 0.03–0.06/h, with
a maximum provess ethanol yield at D=0.03/h of 0.46 g/g and a maximum ethanol productivity of 3 g/(L·h). With 0.35% (w/v) acetic acid in the medium, the process
yield at D=0.04/h dropped to 0.32 g/g, and the maximum productivity decreased by 50% to 1.5 g/(L·h). Under the same operating conditions,
rec Zm Zm 4:pZB5 performed better; however, the medium contained 20 mg/L of Tc to constantly maintain selective pressure.
The absence of any need for antibiotics and antiboitic resistance genes makes the chromosomal integrant C25 more com patible
with current regulatory specifications for biocatalysts in large-scale commercial operations. 相似文献
19.
Eliana V. Canettieri João B. Almeida E. Silva Maria G. A. Felipe 《Applied biochemistry and biotechnology》2001,94(2):159-168
This study deals with the bioconversion of xylose into xylitol by Candida guilliermondii FTI 20037 using eucalyptus hemicellulosic hydrolysate obtained by acid hydrolysis. The influence of various parameters (ammonium
sulfate, rice bran, pH, and xylose concentration) on the production of xylitol was evaluated. The experiments were based on
multivariate statistical concepts, with the application of factorial design techniques to identify the most important variables
in the process. The levels of these variables were quantified by the response surface methodology, which permitted the establishment
of a significant mathematical model with a coefficient determination of R
2=0.92. The best results (xylitol=10.0 g/L, yield factor=0.2 g/g, and productivity=0.1 g/[L·h]) were attained with hydrolysate
containing ammonium sulfate (1.1 g/L), rice bran (5.0 g/L), and xylose (initial concentration of 60.0 g/L), after 72 h of
fermentation. The pH of fermentation was adjusted to 8.0 and the inoculum level utilized was 3 g/L. 相似文献
20.
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