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1.
Effect of the addition of microbial surfactants on hydrocarbon degradation in a soil population in a stirred reactor 总被引:19,自引:0,他引:19
Summary The hydrocarbon degradation rate could be doubled by the addition of sophorose lipids as biosurfactants in a model system containing 10% soil and a 1.35% hydrocarbon mixture of tetradecane, pentadecane, hexadecene, 1,2,4-trimethylcyclohexane, pristane (2,6,10,14-tetramethylpentadecane) phenyldecane and naphthalene suspended in mineral salts medium. The adaptation phases for two degradation phases were shortened, and the extent of degradation and final biomass were increased. The added biosurfactants were degraded after they had facilitated degradation of all hydrocarbon components. 相似文献
2.
Summary The purpose of this investigation was to show whether or no employing a starter culture of the bacterium Rhodococcus erythropolis that produces 6,6-trehalosedicorynomycolates could replace the addition of purified biosurfactant known to accelerate hydrocarbon degradation by an original soil population in a stirred reactor. The rate of degradation, degree of elimination of hydrocarbons, mineralization and degree of oxidation were determined in order to assess the extent of degradation. In comparison with degradation by soil microorganisms only an acceleration of utilization of the hydrocarbons was observed in cultivations of growing cells of R. erythropolis, although the effect of purified trehalosedicorynomycolates is not reached. Except for a higher degree of oxidation a sufficient amount of trehalosedicorynomycolates bound to autoclaved biomass of R. erythropolis does not have any effect. 相似文献
3.
Zhang ZP Show KY Tay JH Liang DT Lee DJ Jiang WJ 《Biotechnology and bioengineering》2007,96(6):1040-1050
A novel approach to rapidly initiate granulation of hydrogen-producing sludge was developed in an anaerobic continuous stirred tank reactor at 37 degrees C. To induce microbial granulation, the acclimated culture was subject to an acid incubation for 24 h by shifting the culture pH from 5.5 to 2.0. The culture was resumed to pH 5.5 after the incubation and the reactor was operated at hydraulic retention times (HRTs) of 12, 6, 2, 1, and 0.5 h in sequence. Microbial aggregation took place immediately with the initiation of acid incubation and granules were developed at 114 h. No granule was observed in the absence of acid incubation in the control test. Changing the culture pH resulted in improvement in surface physicochemical properties of the culture favoring microbial granulation. The zeta potential increased from -11.6 to -3.5 mV, hydrophobicity in terms of contact angle improved from 31 degrees to 43 degrees and extracellular proteins/polysaccharides ratio increased from 0.2 to 0.5-0.8. Formation of granular sludge facilitated biomass retention of up to 32.2 g-VSS/L and enhanced hydrogen production. The hydrogen production rate and hydrogen yield increased with the reduction in HRT at an influent glucose concentration of 10 g/L once steady granular sludge layer was formed, achieving the respective peaks of 3.20 L/L x h and 1.81 mol-H(2)/mol-glucose at 0.5 h HRT. The experimental results suggested that acid incubation was able to initiate the rapid formation of hydrogen-producing granules by regulating the surface characteristics of microbial aggregates in a well-mixed reactor, which enhanced the hydrogen production. 相似文献
4.
Studies of microbial purification of a model waste water containing 4-nitrophenol were carried out in a continuously working
aerobic solid-bed reactor. The main emphasis was on the dynamic behaviour of the system after a sudden change in cultivation
conditions and on the steady-state performance of the reactor as a function of the pollution load. A change from ammonium-free
to ammonium-containing medium hardly influenced the nitrophenol degradation. The reactor responded differently to an increase
in pollutant load, which was brought about by increasing either the 4-nitrophenol content or the flow of the waste water.
Up to a load of 270 mg l−1 h−1 the pollutant was stably and almost completely degraded. At a higher load, only a partial 4-nitrophenol degradation took
place. A mathematical model was derived to describe the processes that occurred in the reactor. By segregation into two compartments
– the aqueous phase and the biofilm – account was taken of the fact that the pollutant is carried into the biofilm by diffusion
and is degraded there. The observed relations between the pollutant load, the pollutant concentration in the outlet of the
reactor and the reactor performance agreed with the simulated process behaviour. As the model simulation showed, the incomplete
pollutant degradation at a higher reactor load was caused by oxygen limitation.
Received: 5 August 1998 / Received revision: 22 October 1998 / Accepted: 24 October 1998 相似文献
5.
Aerobic nonylphenol degradation and nitro-nonylphenol formation by microbial cultures from sediments 总被引:2,自引:0,他引:2
Jasperien De Weert Marc Viñas Tim Grotenhuis Huub Rijnaarts Alette Langenhoff 《Applied microbiology and biotechnology》2010,86(2):761-771
Nonylphenol (NP) is an estrogenic pollutant which is widely present in the aquatic environment. Biodegradation of NP can reduce
the toxicological risk. In this study, aerobic biodegradation of NP in river sediment was investigated. The sediment used
for the microcosm experiments was aged polluted with NP. The biodegradation of NP in the sediment occurred within 8 days with
a lag phase of 2 days at 30°C. During the biodegradation, nitro-nonylphenol metabolites were formed, which were further degraded
to unknown compounds. The attached nitro-group originated from the ammonium in the medium. Five subsequent transfers were
performed from original sediment and yielded a final stable population. In this NP-degrading culture, the microorganisms possibly
involved in the biotransformation of NP to nitro-nonylphenol were related to ammonium-oxidizing bacteria. Besides the degradation
of NP via nitro-nonylphenol, bacteria related to phenol-degrading species, which degrade phenol via ring cleavage, are abundantly
present. 相似文献
6.
7.
《Journal of Fermentation and Bioengineering》1992,73(6):471-476
Spinach thylakoid was immobilized by two different methods for the purpose of retention within a continuous-flow stirred tank reactor (CSTR). The glutaraldehyde crosslinked albumin polymer method completely inactivated the cyclic ATP photophosphorylation of thylakoid. In contrast, agarose-entrapped thylakoid retained about 17% of the activity of the cyclic photophosphorylation of non-immobilized thylakoid. This activity declined continuously during ATP production in the CSTR. Fifty percent of the initial activity was lost within about 5.5 h. Ascorbate was found to increase the stability of ATP photophosphorylation; about twice as much ATP was produced at the optimal ascorbate concentration of 5 mM. Under the optimal dilution rate of 2.36 h−1, about 60 μmol of ATP per mg chlorophyll were produced in 20 h by agarose-entrapped thylakoid in the CSTR. These results showed that, compared to non-immobilized thylakoid in batch operation, agarose-entrapped thylakoid produced only a low amount of ATP under continuous operation. 相似文献
8.
A microbial consortium capable of aerobic degradation of a mixture of azo dyes consisting of two isolated strains (RRL,TVM) and one known strain of Pseudomonas putida (MTCC 1194) was immobilized on laterite stones. The amount of bacterial biomass attached to the laterite stones was 8.64 g per 100 g of the stone on a dry weight basis. The packed bed reactor was filled with these stones and had a total capacity of 850 mL and a void volume of 210 mL. The feed consisted of an equal mixture of seven azo dyes both in water as well as in a simulated textile effluent, at a pH of 9.0 and a salinity of 900 mg/L. The dye concentrations of influent were 25, 50, and 100 microg/mL.The residence time was varied between 0.78 and 6.23 h. It was found that at the lowest residence time 23.55, 45.73, and 79.95 microg of dye was degraded per hour at an initial dye concentration of 25, 50, and 100 microg, respectively. The pH was reduced from 9.0 to 7.0. Simulated textile effluent containing 50 microg/mL dye was degraded by 61.7%. Analysis of degradation products by TLC and HPLC showed that the dye mixture was degraded to nontoxic smaller molecules. The bacteria-coated pebbles were stable, there was no washout even after 2 months, and the reactor was found to be suitable for the aerobic degradation of azo dyes. 相似文献
9.
10.
L. Deschênes P. Lafrance J.-P. Villeneuve R. Samson 《Applied microbiology and biotechnology》1996,46(5-6):638-646
The effect of two anionic surfactants was assessed during biodegradation of 13 of the 16 USEPA priority polycyclic aromatic
hydrocarbons (PAH) in a wood-preserving soil contaminated with creosote and pentacholorophenol for a period of at least 20
years. Sodium dodecyl sulfate (SDS) and biosurfactants from Pseudomonas aeruginosa UG2 were utilized at concentrations of 10, 100 and 500 μg/g soil. Because both surfactants are readily biodegradable, the
microcosms received a fresh spike of surfactant every 2 weeks. Biodegradation of aged PAH residues was monitored by GC/MS
for a period of 45 weeks. Results indicated that the biodegradation of the three-ring PAH was rapid and almost complete but
was slowed by the addition of 100 μg/g and 500 μg/g chemical surfactant. Similarly, at the same concentrations, the two surfactants
significantly decreased the biodegradation rate of the four-ring PAH. In this case, the inhibition was more pronounced with
SDS. High-molecular-mass PAH (more than four rings) were not biodegraded under the test conditions. It was suggested that
the preferential utilization of surfactants by PAH degraders was responsible for the inhibition observed in the biodegradation
of the hydrocarbons. The high biodegradability and the inhibitory effect of these two surfactants would have a significant
impact on the development of both above-ground and in situ site reclamation processes.
Received: 22 February 1996 / Received revision: 31 May 1996 / Accepted: 16 June 1996 相似文献
11.
O Yagi A Hashimoto K Iwasaki M Nakajima 《Applied and environmental microbiology》1999,65(10):4693-4696
Two strains of 1,1,1-trichloroethane (TCA)-degrading bacteria, TA5 and TA27, were isolated from soil and identified as Mycobacterium spp. Strains TA5 and TA27 could degrade 25 and 75 mg. liter of TCA(-1) cometabolically in the presence of ethane as a carbon source, respectively. The compound 2,2,2-trichloroethanol was produced as a metabolite of the degradation process. 相似文献
12.
A mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainage samples collected from several chalcopyrite mines in China. Such mixed culture can be used to effectively extract copper from chalcopyrite. Furthermore, after being adapted to gradually increased concentration of chalcopyrite concentrate, the tolerance of the mixed culture to chalcopyrite concentrate was brought up to 80 g/L. The effects of several leaching parameters on copper recovery in stirred tank reactor also had been investigated. The results of the investigation show that it was possible to achieve a copper extraction rate of 75% in 44 days at a pulp density of 8%. The leaching rate of chalcopyrite concentrate tended to increase with dissolved total iron concentration. At low pH ranges, more microscopic counts of microorganisms were found in the solution. Furthermore, the analysis of leached residues indicates that the passivation of chalcopyrite concentrate was mainly due to a mass of jarosite and PbSO(4) on the mineral surface, other than the elemental sulphur layer. The bacterial community composition was analyzed by using Amplified Ribosomal DNA Restriction Analysis. Two moderately thermophilic bacteria species were identified as Leptospirillum ferriphilum and Acidithiobacillus caldus with abundance of 67% and 33% in the bio-pulp, respectively. 相似文献
13.
Candida guilliermondii FTI 20037 cells were entrapped in Ca-alginate beads and used for xylose-to-xylitol bioconversions during five successive batches in a stirred tank reactor. Supplemented sugarcane bagasse hemicellulosic hydrolysate was used as the fermentation medium. The average volume of the Ca-alginate beads was reduced by about 30% after the 600 h taken to perform the five bioconversion cycles, thus demonstrating physical instability under the conditions prevailing in the reactor vessel. In spite of this, almost steady bioconversion rates and yields were observed along the repeated batches. In average values, a production of 51.6 g l(-1), a productivity of 0.43 g l(-1 )h(-1) and a yield of 0.71 g g(-1) were attained in each batch, variation coefficients being smaller than 10%. 相似文献
14.
Staphylococcus xylosus MAK2, Gram-positive coccus, a nonpathogenic member of the coagulase-negative Staphylococcus family was isolated from soil and used to produce naringinase in a stirred tank reactor. An initial medium at pH 5.5 and
a cultivation temperature of 30°C was found to be optimal for enzyme production. The addition of Ca+2 caused stimulation of enzyme activity. The effect of various physico-chemical parameters, such as pH, temperature, agitation,
and inducer concentration was studied. The enzyme production was enhanced by the addition of citrus peel powder (CPP) in the
optimized medium. A twofold increase in naringinase production was achieved using different technological combinations. The
process optimization using technological combinations allowed rapid optimization of large number of variables, which significantly
improved enzyme production in a 5-l reactor in 34 h. An increase in sugar concentration (15 g l−1) in the fermentation medium further increased naringinase production (8.9 IU ml−1) in the bioreactor. Thus, availability of naringinase renders it attractive for potential biotechnological applications in
citrus processing industry. 相似文献
15.
16.
A Gallego VL Gemini AA Rossen SL Rossi V Trípodi D Corach E Planes SE Korol 《World journal of microbiology & biotechnology》2012,28(3):1245-1252
An indigenous strain of Pseudomonas putida capable of degrading 3-chlorobenzoic acid as the sole carbon source was isolated from the Riachuelo, a polluted river in
Buenos Aires. Aerobic biodegradation assays were performed using a 2-l microfermentor. Biodegradation was evaluated by spectrophotometry,
chloride release, gas chromatography and microbial growth. Detoxification was evaluated by using Vibrio fischeri, Pseudokirchneriella
subcapitata and Lactuca sativa as test organisms. The indigenous bacterial strain degrades 100 mg l−1 3-chlorobenzoic acid in 14 h with a removal efficiency of 92.0 and 86.1% expressed as compound and chemical oxygen demand
removal, respectively. The strain was capable of degrading up to 1,000 mg of the compound l−1. Toxicity was not detected at the end of the biodegradation process. Besides initial concentration, the effect of different
factors, such as initial pH, initial inoculum, adaptation to the compound and presence of other substrates and toxic related
compounds, was studied. 相似文献
17.
《Journal of Fermentation Technology》1986,64(1):25-28
A stirred catalytic basket reactor with immobilized yeast cells was used for the batchwise production of ethanol. Fractional conversions up to 0.99 in 10 h were attained, depending on the agitation rates, initial glucose, and cell densities. The volumetric productivity of the reactor was considerably better than that of conventional stirred tank reactors. Productivities were strongly dependent on the stirred speed. 相似文献
18.
Dr. A. Gebauer Dr. T. Scheper Prof. Dr. K. Schügerl 《Bioprocess and biosystems engineering》1987,2(1):13-23
E. coli ATCC 11105 was cultivated in a 10-1 stirred tank reactor and in a 60-1 tower loop reactor in batch and continuous operation. By on-line measurements of O2 and CO2 concentrations in the outlet gas, pH, temperature, cell mass concentration X as well as dissolved O2 concentration along the tower in the broth, gas holdup, broth recirculation rate through the loop and by offline measurements of substrate concentration DOC and cell mass concentration along the tower, the maximum specific growth rate
m
, yield coefficients Y
X/S. Y
X/DOC and
were evaluated in stirred tank and tower loop in batch and continuous cultures with and without motionless mixers in the tower and at different broth circulation rates through the loop. To control the accuracy of the measurements the C balance was calculated and 95% of the C content was covered.The biological parameters determined depend on the mode of operation as well as on the reactor used. Furthermore, they depend on the recirculation rate of the broth and built-ins in the tower. The unstructured cell and reactor models are unable to explain these differences. Obviously, structured cell and reactor models are needed. The cell mass concentration can be determined on line by NADH fluorescence in balanced growth, if the model parameters are determined under the same operational conditions in the same reactor.List of Symbols
a, b
empirical parameters in Eq. (1)
- CPR kg/(m3 h)
CO2 production rate
-
C kg/m3
concentration
-
D l/h
dilution rate
- DOC kg/m3
dissolved organic carbon
-
I
net. fluorescence intensity
-
K
S
kg/m3
Monod constant
-
k
L
a l/h
volumetric mass transfer coefficient
- OTR kg/(m3 h)
oxygen transfer rate
- OUR kg/(m3 h)
oxygen utilization rate
- RQ = CPR/OUR
respiratory quotient
-
S kg/m3
substrate concentration
-
t h,min, s
time
-
t
u
min
recirculation time
-
t
M
min
mixing time
-
v m3/h
volumetric flow rate through the loop
-
X kg/m3
(dry) cell mass concentration
-
Y
X/S
yield coefficient of cell mass with regard to the consumed substrate
-
Y
X/DOC
yield coefficient of the cell mass with regard to the consumed DOC
-
Y
X/O
yield coefficient of the cell mass with regard to the consumed oxygen
-
Z
relative distance in the tower from the aerator with regard to the height of the aerated broth
-
l/h
specific growth rate
-
m
l/h
maximum specific growth rate
Indices
f
feed
-
e
outlet 相似文献
19.
Production of biosurfactants by a mixed bacteria population grown in continuous culture on crude oil
Summary Large amounts (3 g.l–1) of tensio-active substances can be produced continuously and recuperated using a tangential-flow filtration device. These compounds can emulsify crude oil and the emulsions, obtained with a crude oil over biosurfactants ratio of 500, remain stable for hours. 相似文献
20.
The catalytic activity of amyloglucosidase covalently attached to DEAE-cellulose was studied in a packed bed reactor and a continuous feed stirred tank reactor (CSTR) for the reaction maltose → glucose. At low flow rates mass-transfer limitations in the bed reactor lead to lower conversions for this reactor compared to the CSTR. Simple theoretical expressions for these reactors were compared with the experimental results. There are significant differences between the kinetic parameters and pH profile of the immobilized and free enzyme. The immobilized enzyme also showed greater stability at 50°C than did free amyloglucosidase. The temperature dependence of the reaction rate was the same for immobilized and free enzyme. 相似文献