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1.
Removal of tetrachloroethylene (perchloroethylene; C2Cl4) by microbial consortia from two sites with different C2Cl4 exposure histories was examined in a bench-scale anaerobic column bioreactor. It was hypothesized that optimal removal would
be observed in the reactor packed with sediments having an extensive exposure history. Microbial consortia were enriched from
hyporheic-zone (HZ) sediments from the Portneuf aquifer near Pocatello, Idaho, and from industrial-zone (IZ) sediments from
a highly contaminated aquifer in Portland, Oregon. Lactate and acetate were the electron donors during experiments conducted
over 9 and 7 months for HZ and IZ sediments, respectively. In the HZ bioreactor, the retention time ranged from 31 h to 81 h,
and inlet C2Cl4 concentrations ranged from 0.1 ppm to 1.0 ppm. Dechlorination of C2Cl4 averaged 60% and reached a maximum of 78%. An increase in C:N from 27:1 to 500:1 corresponded to an 18% increase in removal
efficiency. Trichloroethylene production corresponded to decreased effluent C2Cl4; further intermediates were not detected. In the IZ bioreactor, the retention time varied from 34 h to 115 h; the inlet C2Cl4 concentration was 1.0 ppm. C2Cl4 removal averaged 70% with a maximum of 98%. Trichloroethylene and cis-dichloroethylene were detected in the effluent. Increases in C:N from 50:1 to 250:1 enhanced dechlorination activity.
Received: 3 February 1997 / Received revision: 15 May 1997 / Accepted: 1 June 1997 相似文献
2.
Aerobic biodegradation of gasoline and its constituents, benzene, toluene and ethylbenzene were studied by an enrichment
from soil indigenous microbial population. The enrichment culture completely degraded 16.1–660 mg/l gasoline in 2.5–16 days
respectively, without accumulation of any by-products. The kinetics of gasoline as well as benzene, toluene and ethylbenzene
biodegradation was investigated with initial gasoline concentrations of 16.1–62.6 mg/l. The maximum specific rates of biodegradation
of benzene, toluene and ethylbenzene were 0.12, 0.38 and 0.19 mg mg biomass−1 day−1 respectively. When benzene and toluene were used as sole substrate, the maximum specific rates of their biodegradation were
62.9 and 16.4 times greater than the corresponding values for a mixture (gasoline). The microbial culture was able to mineralize
up to 200 mg/l pure toluene and benzene. Maximum mineralization efficiencies of benzene and toluene were 76.7 ± 5.1% and 76.8 ± 1.3%
respectively. Self-inhibition and competitive inhibition patterns were observed during the biodegradation of benzene and toluene
alone and in the mixture respectively. The observed kinetics was modeled according to Andrews' inhibition model.
Received: 6 August 1997 / Received revision: 18 November 1997 / Accepted: 29 November 1997 相似文献
3.
Bioreactor selection is important for maximising the productivity of recombinant organisms. In this paper a comparison is
made between growth and recombinant protein synthesis in three types of bioreactor containing a marine Vibrio capable of heterologous expression and secretion of the non-toxic B-subunit pentamer of Escherichia coli heat-labile enterotoxin, EtxB. The heterologous gene was located on the plasmid pMMB68. Resistance to carbenicillin was used
to select for plasmid-containing cells. In batch and continuous culture, volumetric productivities were highest when cells
were grown in the presence of carbenicillin. Without antibiotic selection, the highest volumetric productivity (9.4 mg EtxB−1 h−1) was observed in hollow-fibre bioreactors, and the production phase could be maintained for over 50 h. The highest specific
productivity under these conditions was found in batch culture, but the maximal production phase was only of 5 h duration.
In hollow-fibre reactors the type of fibre used significantly affected productivity, both with regards to the maintenance
of reactor integrity and by allowing passage of the recombinant toxoid through the selectively permeable membrane. Where contamination
of the product with carbenicillin is to be avoided, these bioreactors are superior to batch or continuous culture.
Received: 29 January 1997 / Received revision: 9 April 1997 / Accepted: 13 April 1997 相似文献
4.
Bioremediation of pentachlorophenol-contaminated soil by bioaugmentation using activated soil 总被引:11,自引:0,他引:11
C. Barbeau L. Deschênes D. Karamanev Y. Comeau R. Samson 《Applied microbiology and biotechnology》1997,48(6):745-752
The use of an indigenous microbial consortium, pollutant-acclimated and attached to soil particles (activated soil), was
studied as a bioaugmentation method for the aerobic biodegradation of pentachlorophenol (PCP) in a contaminated soil. A 125-l
completely mixed soil slurry (10% soil) bioreactor was used to produce the activated soil biomass. Results showed that the
bioreactor was very effective in producing a PCP-acclimated biomass. Within 30 days, PCP-degrading bacteria increased from
105 cfu/g to 108 cfu/g soil. Mineralization of the PCP added to the reactor was demonstrated by chloride accumulation in solution. The soil-attached
consortium produced in the reactor was inhibited by PCP concentrations exceeding 250 mg/l. This high level of tolerance was
attributed to the beneficial effect of the soil particles. Once produced, the activated soil biomass remained active for 5
weeks at 20 °C and for up to 3 months when kept at 4 °C. The activated attached soil biomass produced in the completely mixed
soil slurry bioreactor, as well as a PCP-acclimated flocculent biomass obtained from an air-lift immobilized-soil bioreactor,
were used to stimulate the bioremediation of a PCP-impacted sandy soil, which had no indigenous PCP-degrading microorganisms.
Bioaugmentation of this soil by the acclimated biomass resulted in a 99% reduction (from 400 mg/kg to 5 mg/kg in 130 days)
in PCP concentration. The PCP degradation rates obtained with the activated soil biomass, produced either as a biomass attached
to soil particles or as a flocculent biomass, were similar.
Received: 31 March 1997 / Received revision: 22 July 1997 / Accepted: 25 August 1997 相似文献
5.
The fate of thiocyanate (SCN−) and cyanate (OCN−) under methanogenic conditions was investigated at 35 °C. Thiocyanate and cyanate were added to mixed methanogenic cultures
along with an organic mixture. Thiocyanate was stable under these conditions, and had no adverse effect on methanogenesis
at a concentration as high as 2.5 mM. In contrast, cyanate at a concentration as low as 0.3 mM initially inhibited methanogenesis
but, after the complete removal of cyanate, methanogenesis gradually recovered. The inhibitory effect of cyanate on methanogenesis
became more profound with repeated additions of cyanate. The transformation of cyanate followed the hydrolytic route to ammonia
and bicarbonate under anaerobic conditions and its hydrolysis rate was enhanced by microbial activity. Cyanide was not detected
as a cyanate transformation product under the methanogenic conditions of this study.
Received: 13 June 1997 / Received revision: 29 August 1997 / Accepted: 15 September 1997 相似文献
6.
P. Rosenbrock R. Martens F. Buscot F. Zadrazil J. C. Munch 《Applied microbiology and biotechnology》1997,48(5):665-670
The potential for aerobic mineralization of [U-14C]dibenzo-p-dioxin (DD) was investigated in samples of three different agricultural soils already contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) by industrial activities. The influence of amendments, i.e. wheat straw and compost, and
of soil treatment by inoculation with lignolytic fungi, grown on wheat straw substrate, was tested. All the soils tested contained
an indigenous DD-mineralizing microflora. The soil characterized by the highest organic matter content and the highest content
of soil microbial biomass displayed the best DD mineralization of 36.6% within 70 days, compared with the two organic-matter-poor
soils with an endogenous DD mineralization of 19.5% and 23.3% respectively. Amendments with compost increased DD mineralization
up to 28% in both soils with low organic matter and microbial biomass content, but did not affect mineralization in the organic-matter-rich
soil. Addition of wheat straw had no constant influence on DD mineralization in the soils tested. The best DD mineralization
resulted from inoculation with lignolytic white-rot fungi (Phanerochaete chrysosporium, Pleurotus sp. Florida, Dichomitus squalens) and with an unidentified lignolytic fungus, which was isolated originally from a long-term PCDD/F-contaminated soil. A mineralization
of up to 50% within 70 days was reached by this treatment. The influence of inoculated fungi on mineralization differed between
the soils investigated.
Received: 14 April 1997 / Received revision: 24 June 1997 / Accepted: 29 June 1997 相似文献
7.
D. Naki C. Paech G. Ganshaw V. Schellenberger 《Applied microbiology and biotechnology》1998,49(3):290-294
Mutants that secrete increased amounts of enzyme into a selection medium can be efficiently enriched from large populations
of mutagenized microorganisms during growth in hollow fibers. Under these conditions, each colony grows in its own microenvironment
and cross-feeding between neighboring colonies is limited. We applied the technique to B. subtilis carrying a plasmid-encoded protease gene. The plasmid was subjected to random mutagenesis and clones secreting up to fivefold-increased
amounts of enzyme were selected using a medium containing bovine serum albumin as the sole nitrogen source.
Received: 22 May 1997 / Received revision: 21 October 1997 / Accepted: 7 November 1997 相似文献
8.
C. A. Dunster K. H. Cheeseman S. P. Maddix 《Applied microbiology and biotechnology》1997,48(2):198-203
The CHO320 cell line, engineered to produce human interferon γ was investigated with regard to its susceptibility to oxidative
stress. Batch cultures of the cells grown in a bench-top bioreactor exhibited no marked response to changes in oxygen concentration
between 6% and 14% whereas cell growth and recombinant protein production were inhibited by increasing the oxygen to 20%.
High concentrations of hydrogen peroxide (in excess of 200 μM) were required to inhibit growth of the CHO320 cells whereas
concentrations of 50 μm and 100 μM had no effect on recombinant protein production. Buthionine sulphoximine (50 μM and 100 μM)
completely depleted the cells of glutathione within 24 h; however, no quantitative effect on recombinant protein production
was seen. It is concluded that the CHO320 cells are, possibly as a consequence of the long selection process they have undergone,
very resistant to oxidative stress.
Received: 14 November 1996 / Received last revision: 14 April 1997 / Accepted: 19 April 1997 相似文献
9.
K. Nakamura M. A. Yudiarto N. Kaneko H. Kurosawa Y. Amano 《Applied microbiology and biotechnology》1997,48(6):753-757
A microbial method to determine sulphate concentration in water was developed on the basis of sulphate-dependent acid phosphatase
(APase) in whole cells of Thiobacillus thiooxidans. The activity of the APase was determined colorimetrically by using p-nitrophenylphosphate as substrate. The APase was activated by sulphate. A linear relationship was obtained between the activity
of the APase and the concentration of sulphate in the range 0–0.6 mM. Therefore, the sulphate concentration was estimated
from the APase activity, represented by the absorbance (A
400). The microbial method was applied to the determination sulphate in water. The lower limit of detection was 0.02 mM, the
relative standard deviation being 2% for 10 measurements on a standard sample. As for practical samples, which were taken
from rain, river and tap water, good agreement was obtained between the values measured by the microbial method and those
given by a conventional barium chloranilate method. The relative standard deviation was 2.1% for 12 measurements of tap water.
The activity of the APase was stable over a period of more than 100 days when the cells were stored in 0.1 M sodium acetate/acetic
acid buffer (pH 5.0) at 4 °C.
Received: 21 March 1997 / Received revision: 30 June 1997 / Accepted: 27 July 1997 相似文献
10.
Biological treatment of drinking water is a cost-effective alternative to conventional physico/chemical processes. A new
concept was tested to overcome the main disadvantage of biological denitrification, the intensive post-treatment process to
remove microorganisms and remnant carbon source. The biological reaction zone and carbon supply were separated from the raw
water stream by a nitrate-permeable membrane. Denitrification takes place in a biofilm, which is immobilized at the membrane.
In a series of bench-scale runs, different types of membranes and reactor configurations were investigated. The best denitrification
rates achieved were 1230 mg NO3
−-N m−2 day−1. In one run, raw water containing 100 mg NO3
− l−1 was completely freed from nitrate. The membrane and the attached biofilm also represent a barrier against the passage of
the C source and nutrients into the raw water. At concentrations of 20 mg l−1 ethanol and 15 mg l−1 phosphate in the bioreactor no diffusion through the membrane into the treated water was observed. Without any post-treatment,
the effluent met nearly all the relevant criteria for drinking water; only the colony count was slightly increased.
Received: 18 December 1996 / Received last revision: 14 April 1997 / Accepted: 19 April 1997 相似文献
11.
J. J. Crawford G. K. Sims R. L. Mulvaney M. Radosevich 《Applied microbiology and biotechnology》1998,49(5):618-623
Anaerobic biodegradation of atrazine by the bacterial isolate M91-3 was characterized with respect to mineralization, metabolite
formation, and denitrification. The ability of the isolate to enhance atrazine biodegradation in anaerobic sediment slurries
was also investigated. The organism utilized atrazine as its sole source of carbon and nitrogen under anoxic conditions in
fixed-film (glass beads) batch column systems. Results of HPLC and TLC radiochromatography suggested that anaerobic biotransformation
of atrazine by microbial isolate M91-3 involved hydroxyatrazine formation. Ring cleavage was demonstrated by 14CO2 evolution. Denitrification was confirmed by detection of 15N2 in headspace samples of K15NO3-amended anaerobic liquid cultures. In aquatic sediments, mineralization of uniformly ring-labeled [14C]atrazine occurred in both M91-3-inoculated and uninoculated sediment. Inoculation of sediments with M91-3 did not significantly
enhance anaerobic mineralization of atrazine as compared to uninoculated sediment, which suggests the presence of indigenous
organisms capable of anaerobic atrazine biodegradation. Results of this study suggest that the use of M91-3 in a fixed-film
bioreactor may have applications in the anaerobic removal of atrazine and nitrate from aqueous media.
Received: 3 September 1997 / Received revision: 4 December 1997 / Accepted: 2 January 1998 相似文献
12.
R. Céspedes A. Maturana U. Bumann M. Bronfman B. González 《Applied microbiology and biotechnology》1996,46(5-6):631-637
The removal of chlorophenolic compounds from kraft mill effluents bleached with chlorine (cBKME) or chlorine plus hemicellulases
(bBKME) was studied in reactors of aerobic treatment lagoons. In these laboratory models, a stable microbial population removed
biochemical oxygen demand at similar rates of the mill lagoon. Complete removal of nine chlorophenols and chloroguaiacols
during microbial treatment of these effluents was detected by gas chromatography. Abiotic removal was only observed with 2,4-dichlorophenol
and 2,4,5-trichlorophenol. There were no significant differences in degradative ability between microorganisms acclimated
to grow in reactors fed with cBKME or bBKME. The latter had a lower content of adsorbable organic halogen and chlorophenols
than cBKME. Microorganisms acclimated to cBKME or bBKME were only able to grow on phenol or guaiacol as sole carbon source.
However, these microorganisms removed (0.1–0.5 mM) 4-chlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxyacetate with
BKME as primary carbon source. Under these conditions, 2,4,6- and 2,4,5-trichlorophenol, 4,5-dichloroguaiacol, 4,5,6-trichloroguaiacol
and tetrachloroguaiacol were not removed. These results suggest that the microbial removal of bleaching chlorophenols and
chloroguaiacols during aerobic treatment, probably takes place only because of their very low concentration (1–200 ppb) in
BKME.
Received: 12 February 1996 / Received revision: 10 June 1996 / Accepted: 22 June 1996 相似文献
13.
Biological phosphate removal processes 总被引:9,自引:0,他引:9
M. C. M. van Loosdrecht C. M. Hooijmans D. Brdjanovic J. J. Heijnen 《Applied microbiology and biotechnology》1997,48(3):289-296
Biological phosphate removal has become a reliable and well-understood process for wastewater treatment. This review describes
the historical development of the process and the most important microbiological and process-engineering aspects. From a microbiological
point of view, the role of␣poly(hydroxyalkanoates) as storage material in a dynamic process and the use of polyphosphate as
an energy reserve are the most important findings. From a process-engineering point of view, the study of biological phosphate
removal has shown that highly complex biological processes can be designed and controlled, provided that the importance of
the prevailing microbiological ecological processes is recognised.
Received: 3 April 1997 / Received revision: 9 June 1997 / Accepted: 14 June 1997 相似文献
14.
Toluene vapour removal in a laboratory-scale biofilter 总被引:4,自引:0,他引:4
A bench-scale biofilter with a 0.5-m high filter bed, inoculated with a toluene-degrading strain of Acinetobacter sp. NCIMB 9689, was used to study toluene removal from a synthetic waste air stream. Different sets of continuous tests were
conducted at influent toluene concentrations ranging over 0.1–4.0 g m−3 and at superficial gas velocities ranging over 17.8–255 m h−1. The maximum volumetric toluene removal rate for the biofilter (242 g m−3 h−1) was obtained at a superficial gas velocity of 127.5 m h−1 (corresponding to a residence time of 28 s) and a toluene inlet concentration of 4.0 g m−3. Under these operating conditions, toluene removal efficiency was only 0.238, which suggested that effective operation required
higher residence times. Removal efficiencies higher than 0.9 were achieved at organic loads less than 113.7 g m−3 h−1. A macro-kinetic study, performed using concentration profiles along the bioreactor, revealed this process was limited by
diffusion at organic loads less than 100 g m−3 h−1 and by biological reaction beyond this threshold.
Received: 10 October 1999 / Received revision: 15 February 2000 / Accepted: 18 February 2000 相似文献
15.
Growth of Streptomyces hygroscopicus under conditions of simulated microgravity in a rotating-wall bioreactor resulted in a pellet form of growth, lowered dry
cell weight, and inhibition of rapamycin production. With the addition of Teflon beads to the bioreactor, growth became much
less pelleted, dry cell weight increased but rapamycin production was still markedly inhibited. Growth under simulated microgravity
favored extracellular production of rapamycin, in contrast to a greater percentage of cell-bound rapamycin observed under
normal gravity conditions.
Received: 20 September 1999 / Received revision: 18 November 1999 / Accepted: 19 November 1999 相似文献
16.
Colonisation of phase II compost by biotypes of Trichoderma harzianum and their effect on mushroom yield and quality 总被引:1,自引:0,他引:1
H. S. S. Sharma M. Kilpatrick F. Ward G. Lyons L. Burns 《Applied microbiology and biotechnology》1999,51(5):572-578
Colonisation assessments confirmed that Trichoderma harzianum biotypes Th1, Th2a, Th2b and Th3 inoculated into two distinct compost types at spawning became established by first flush
assessment; the extension rate of two Th2 isolates was over 1000 times that of Th1 and Th3. Results subsequently confirmed
that while Th1 and Th3 did not significantly affect yield, Th2 could reduce mushroom quality and productivity by as much as
80%. Analysis of compost type also indicated that the speed and magnitude of T. harzianum colonisation was influenced by key compost characteristics, most notably, moisture, ash content and degree of fermentation.
This study has shown that compost parameters which have a positive influence on Agaricus growth and productivity also resulted in increased compost colonisation by T. harzianum. Commercially acceptable yields obtained from uninoculated compost confirmed that production of a high quality, productive
substrate does not confer inherent immunity to colonisation by T. harzianum.
Received: 25 September 1998 / Received revision: 30 November 1998 / Accepted: 5 December 1998 相似文献
17.
M. Rutgers A. M. Breure J. G. van Andel W. A. Duetz 《Applied microbiology and biotechnology》1997,48(5):656-661
A polychlorophenol-degrading bacterium, Sphingomonas sp. strain P5, was grown in 2,6-dichlo-rophenol(26-DCP)-limited, 2,3,6-trichlorophenol(236-TCP)-limited, 2,4,6-trichlorophenol(246-TCP)-limited,
2,3,4,6-tetrachlorophenol(2346-TeCP)-limited, and pentachlorophenol(PCP)-limited chemostat cultures at a dilution rate of
0.02 ± 0.002 h−1. The cultures were analyzed for the yield coefficient for growth on chlorophenol during steady-state conditions. The average
growth yields coefficients (as carbon conversion efficiencies) were 0.252, 0.230, 0.219, 0.157, and 0.121 mol C mol C−1 for 26-DCP, 236-TCP, 246-TCP, 2346-TeCP, and PCP respectively. The differences in growth yield can be interpreted in terms
of the energetics of chlorinated carbon metabolism; i.e. substitution of the phenol moiety reduces the available metabolic
energy by one electron per chlorine. The growth yield coefficients on chlorinated phenols were lower than the yield coefficients
of heterotrophic growth reported in the literature on non-chlorinated and aliphatic compounds. Metabolic origins for low growth
yield coefficients on (chlorinated) aromatic compounds are postulated.
Received: 7 April 1997 / Received revision: 7 July 1997 / Accepted: 12 July 1997 相似文献
18.
C. Löser H. Seidel A. Zehnsdorf U. Stottmeister 《Applied microbiology and biotechnology》1998,49(5):631-636
Microbial hydrocarbon degradation in soil was studied during periodical aerobic/anaerobic switching and under purely aerobic
conditions by using a pilot-scale plant with diesel-fuel-contaminated sand. The system worked according to the percolation
principle with controlled circulation of process water and aeration. Periodical switching between 4 h of aerobic and 2 h of
anaerobic conditions was achieved by repeated saturation of the soil with water. Whatever the cultivation mode, less than
50% of the diesel was degraded after 650 h because the hydrocarbons were adsorbed. Contrary to expectations, aerobic/anaerobic
changes neither accelerated the rate of degradation nor reduced the residual hydrocarbon content of the soil. Obviously the
pollutant degradation rate was determined mainly by transport phenomena and less by the efficiency of microbial metabolism.
The total mass of oxygen consumed and carbon dioxide produced was greater under aerobic/anaerobic changing than under aerobic
conditions, although the mass of hydrocarbons degraded was nearly the same. As shown by an overall balance of microbial growth
and by a carbon balance, the growth yield coefficient was smaller during aerobic/anaerobic changes than under aerobic conditions.
Received: 25 November 1997 / Received revision: 15 January 1998 / Accepted: 18 January 1998 相似文献
19.
F. Eismann F. Becker P. Kuschk U. Stottmeister 《Applied microbiology and biotechnology》1996,46(5-6):604-609
Biotreatment experiments with solutions of autoxidized phenolic compounds as well as coal-conversion wastewater stored for
30 years and rich in humic matter were performed under nitrate-reducing, sulphate-reducing and methanogenic conditions. The
removal of total organic carbon in fractions of different molecular mass and of monomeric phenolic compounds in the wastewater
was determined. A comparison of biotransformation potentials and rates indicated a relationship between these aspects and
the availability of electron acceptors in the system. The capacities of the microbial consortia increased significantly with
the energy microorganisms could gain from their respective respiration process and can be expressed by the order: aerobic
process – nitrate reduction – sulphate reduction – methanogenesis.
Received: 25 April 1996 / Received revision: 23 July 1996 / Accepted: 5 August 1996. 相似文献
20.
Z. M. Wang K. M. Devos C. J. Liu R. Q. Wang M. D. Gale 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(1):31-36
An RFLP-based map consisting of 160 loci was constructed in an intervarietal cross of foxtail millet [Setaria italica (L.) P. Beauv.], Longgu 25×Pagoda Flower Green. The map comprises nine linkage groups, which were aligned with the nine foxtail
millet chromosomes using trisomic lines, and spans 964 cM. The intraspecific map was compared to an interspecific map, constructed
in a S. italica×S. viridis cross. Both the order of the markers and the genetic distances between the loci were highly conserved. Deviations from the
expected 1 : 2 : 1 Mendelian segregation ratios were observed in both the intra- and inter-specific populations. The segregation
data indicate that chromosome VIII in the Longgu 25×Pagoda Flower Green cross carries a gene that strongly affects gamete
fertility.
Received: 18 December 1996 / Accepted: 4 August 1997 相似文献