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1.
Extracellular enzymes in a polyhumic lake: important regulators in detritus processing 总被引:6,自引:3,他引:3
Eight extracellular enzymes and their corresponding natural substrates were studied in an acid polyhumic lake. Highest activities
were found for phosphatases (100–150 nmol 1−1 h−1), glucosidase (70–120 nmol 1−1 h−1), and aminopeptidases (20–30 nmol l−1 h−1), Significant relationships were found for natural polymeric substrate composition, variation and enzyme activities. Identified
carbohydrates and amino acids contributed 1–5% to the DOC pool and are assumed to undergo significant processing by microbial
glycosidases and aminopeptidases. Measured enzymes are partially modified in their activity by lake water acidity, temperature
and humic matter. Extracellular enzymes are regarded as important regulators in microbial detritus processing and substrate
utilization. 相似文献
2.
Hee Wook Ryu So Jong Kim Kyung-Suk Cho Tae Ho Lee 《Biotechnology and Bioprocess Engineering》2008,13(3):360-365
In the present study, toluene elimination in the polyurethane (PU) biofilter during long-term (145 day) operation was characterized,
and assessed the effects of changing the inlet loading and space velocity (SV). A very high elimination capacity of 3.7 kg·m−3·h−1 was obtained at an inlet loading of 4.0 kg·m–3·h−1 (inlet toluene concentration of 900 ppmv at a SV of 1,040 h−1). Backwashing with irrigation and compressed air allowed maintenance of a pressure drop of < 80 mm H2O·m−1-filter at an SV of 830 h−1 and an elimination efficiency of > 90% during the 145 day of operation. In conclusion, the PU biofilter can overcome the
problems of clogging caused by excess biomass growth and of low treatment capacities of conventional biofilters. 相似文献
3.
Particle size effects in bioleaching of pyrite by acidophilic thermophile Sulfolobus metallicus (BC) 总被引:4,自引:0,他引:4
The effect of mineral particle size on the bioleaching of pyrite by the acidophilic thermophile Sulfolobus metallicus was investigated in a batch bioreactor. Decreasing the particle size from a mean diameter of 202 micron (size fraction: 150–180 micron)
to a mean diameter of 42.5 micron (size fraction: 25–45 micron) enhanced the bioleaching rate from 0.05 kg m−3 h−1 to 0.098 kg m−3 h−1. The particle size distribution of the mineral in this range did not influence the morphology and growth kinetics of the
cells. The values of specific growth rate (μ) and yield factor (Y) were 0.018–0.025 h−1 and 0.67 × 1011–1.45 × 1011 cells (g iron)−1, respectively. Decreasing the particle size of the mineral to a mean diameter of 6.40 micron (size fraction <25 micron) adversely
influenced the activity of the cells. The presence of fine particles apparently damaged the structure of the cells, resulting
in their inability to oxidise pyrite.
Received: 11 December 1998 / Accepted: 9 April 1999 相似文献
4.
Production of 1,3-Propanediol by Clostridium butyricum VPI 3266 in continuous cultures with high yield and productivity 总被引:2,自引:0,他引:2
González-Pajuelo M Andrade JC Vasconcelos I 《Journal of industrial microbiology & biotechnology》2005,32(9):391-396
The effects of dilution rate and substrate feed concentration on continuous glycerol fermentation by Clostridium butyricum VPI 3266, a natural 1,3-propanediol producer, were evaluated in this work. A high and constant 1,3-propanediol yield (around
0.65 mol/mol), close to the theoretical value, was obtained irrespective of substrate feed concentration or dilution rate.
Improvement of 1,3-propanediol volumetric productivity was achieved by increasing the dilution rate, at a fixed feed substrate
concentration of 30, 60 or 70 g l−1. Higher 1,3-propanediol final concentrations and volumetric productivities were also obtained when glycerol feed concentration
was increased from 30 to 60 g l−1, at D=0.05–0.3 h−1, and from 60–70 g l−1, at D=0.05 and 0.1 h−1·30 g l−1 of 1,3-propanediol and the highest reported value of productivity, 10.3 g l−1 h−1, was achieved at D=0.30 h−1 and 60 g l−1 of feed glycerol. A switch to an acetate/butyrate ratio higher than one was observed for 60 g l−1 of feed glycerol and a dilution rate higher than 0.10 h−1; moreover, at D=0.30 h−1 3-hydroxypropionaldehyde accumulation was observed for the first time in the fermentation broth of C. butyricum. 相似文献
5.
Vaupotic J 《Radiation and environmental biophysics》2008,47(4):527-534
Levels of radon were surveyed in the air at underground workplaces of eight major Slovenian wineries. Geometric mean and geometric
standard deviation values, respectively, obtained with different devices were 81 Bq m−3 and 2.3 with alpha scintillation cells, 114 Bq m−3 and 2.0 by exposing etched track detectors for 1–5 months, and 183 Bq m−3 and 2.6 from 1–4-weeks continuous measurements. The equilibrium factor was 0.25–0.67, and the unattached fraction of radon
short-lived decay products was in the range 0.09–0.20. Effective doses were calculated and compared based on radon data obtained
with different techniques. 相似文献
6.
P. Becker I. Abu-Reesh S. Markossian G. Antranikian H. Märkl 《Applied microbiology and biotechnology》1997,48(2):184-190
A thermostable lipase was produced in continuous cultivation of a newly isolated thermophilic Bacillus sp. strain IHI-91 growing optimally at 65 °C. Lipase activity decreased with increasing dilution rate while lipase productivity
showed a maximum of 340 U l−1 h−1 at a dilution rate of 0.4 h−1. Lipase productivity was increased by 50% compared to data from batch fermentations. Up to 70% of the total lipase activity
measured was associated to cells and by-products or residual substrate. Kinetic and stoichiometric parameters for the utilisation
of olive oil were determined. The maximal biomass output method led to a saturation constant K
S of 0.88 g/l. Both batch growth data and a washout experiment yielded a maximal specific growth rate, μmax, of 1.0 h−1. Oxygen uptake rates of up to 2.9 g l−1h−1 were calculated and the yield coefficient, Y
X/O, was determined to be 0.29 g dry cell weight/g O2. From an overall material balance the yield coefficient, Y
X/S, was estimated to be 0.60 g dry cell weight/g olive oil.
Received: 8 January 1997 / Received revision: 30 April 1997 / Accepted: 4 May 1997 相似文献
7.
Two-phase olive mill waste (TPOMW) is a semisolid sludge generated by the olive oil industry. Its recycling as a soil amendment,
either unprocessed or composted, is being promoted as a beneficial agricultural practice in the Mediterranean area. One of
the major difficulties when composting TPOMW is the compaction of the material due to its dough-like texture, which leads
to an inadequate aeration. For this reason, the addition of bulking agents is particularly important to attain a proper composting
process. In this study we followed the evolution of two composting mixtures (A and B) prepared by mixing equal amounts of
TPOMW and sheep litter (SL) (in a dry weight basis). In pile B grape stalks (GS) were added (10% dry weight) as bulking agent
to study their effect on the development of the composting process and the final compost quality. The incorporation of grape
stalks to the composting mixture changed the organic matter (OM) degradation dynamics and notably reduced the total amount
of lixiviates. The evolution of several maturation indices (C/N, germination index, water soluble carbon, humification indices,
C/N in the leachates) showed a faster and improved composting process when GS were added. Moreover, chemical (NH4
+, NO3
−, cation exchange capacity, macro and micronutrients, heavy metals) and physical properties (bulk and real densities, air
content, total water holding capacity, porosity) of the final composts were analysed and confirmed the superior quality of
the compost where GS were added. 相似文献
8.
Variations of soil enzyme activities in a temperate forest soil 总被引:3,自引:0,他引:3
Soil enzyme activities (dehydrogenase, urease, phosphatase, and arylsulfatase) in a temperate forest soil were determined
in relation to landscape position and seasons. Overstory of the area is dominated by Quercus mongolica, Kalopanax pictus, Carpicus cordata, and Acer pseudo-sieboldianum. The activities were measured in three patches, namely a north-facing backslope, a ridge, and a south-facing backslope in
autumn and spring over 2 years. In addition, spatially more detailed analysis for phosphatase was conducted before and after
litterfall production in six patches. Dehydrogenase, urease, phosphatase, and arylsulfatase activities varied 1.8–18.5 μg
INT-formazan g−1 h−1, 45.4–347.0 μg NH4
+ g−1 h−1, 0.9–4.5 mmol pNP g−1 h−1, and 0.7–2.6 mmol pNP g−1 h−1, respectively. In general, higher enzyme activities were found in the northern aspect than in the southern aspect. This variation
appears to be related to differences in chemical properties (e.g., Fe, Al, and Mg) of soil as well as distribution of leaf
litter. Two patterns were discernible in relation to seasonal variations. Dehydrogenase and urease exhibited a positive correlation
with mean air temperature, suggesting that temperature would be a major controlling variable for those enzymes. In contrast,
higher activities were detected in autumn for phosphatase and arylsulfatase activities, which appeared to be closely related
to litter production and distribution. Overall results of this study indicate that soil enzyme activities in a forest floor
are influenced by several variables such as temperature, nutrient availability, and input of leaf litter, which are closely
related to landscape position. 相似文献
9.
Zhiyong Sun Juliana A. Ramsay Martin Guay Bruce A. Ramsay 《Applied microbiology and biotechnology》2009,82(4):657-662
Unsaturated medium-chain-length polyhydroxyalkanoates (MCL-PHA) were produced at a productivity of 0.63–1.09 g PHA l−1 h−1 with final PHA content ranging from 42.6 to 55.8% in single-stage, carbon-limited, fed-batch fermentations of Pseudomonas putida KT2440. A mixture of nonanoic acid (NA) and 10-undecenoic acid (UDA=) was fed exponentially to control growth rate. Varying the specific growth rate (0.14 h−1 vs. 0.23 h−1) at similar substrate feed ratios (NA:UDA= = 5:1) had little effect on the final PHA content and relative composition. However, decreasing the NA:UDA= ratio decreased the final amount of PHA produced from 56% with NA:UDA= = 5.07:1 to only 42% at NA:UDA= = 2.47:1. The molar fraction of all 3-hydroxyalkanoate monomers in the PHA product was relatively constant throughout each
fermentation, indicating that the final product was homogeneous rather than a mixture of different copolymers. A linear relationship
between unsaturation of the PHA produced and unsaturation of the carbon feed was found, which demonstrates the feasibility
of producing unsaturated MCL-PHAs with controlled polymeric composition in a fed-batch process. 相似文献
10.
Importance of point sources on regional nitrous oxide fluxes in semi-arid steppe of Inner Mongolia, China 总被引:3,自引:0,他引:3
J. Holst C. Liu Z. Yao N. Brüggemann X. Zheng X. Han K. Butterbach-Bahl 《Plant and Soil》2007,296(1-2):209-226
The aim of the present work was to estimate the contribution of different point and diffuse sources to the regional N2O emission strength of steppe in the Xilin river catchment, Inner Mongolia, People’s Republic of China. Transect studies showed
that the topographic effect on N2O emissions from upland soils was negligible and that upland steppe is only a very weak net source of N2O during the growing season (0.8 ± 0.4 μg N2O–N m−2 h−1). Slightly higher emissions were found for riparian areas (1.8 ± 0.3 μg N2O–N m−2 h−1), which cover ∼4% of the landscape. Even faeces or urine additions stimulated N2O emissions from steppe soils only weakly (<2.5 μg N2O–N m−2 h−1 for a 5 days period). Due to low moisture contents, N2O emissions from dung heaps were also rather low (6.2 ± 0.8 μg N2O–N kg−1 dry matter h−1). In contrast, three orders of magnitude higher N2O emissions were found at sheepfolds (2.45 mg N2O–N m−2 h−1 on average). By calculating N2O emissions on a landscape scale, we show that point sources, and especially sheepfolds, become the dominating regional N2O source during the growing season if stocking rates are >1 sheep ha−1. Our results indicate that the common grazing management in the Xilin river region leads to a translocation of nitrogen from
large source areas towards defined spots. This finding is further supported by measurements of NH3 concentrations at different sites. Since most of the nitrogen accumulated in these hot spots is finally lost through burning
of the dried excrements by the farmers for heating and cooking purposes, the ecosystem faces a significant human perturbation
of regional N cycling, which may contribute to an accelerated degradation of steppe in the Xilin river region.
Responsible Editor: Per Ambus. 相似文献
11.
Ibrahim Rajoka M. Tariq Kiani M.A. Khan Sohail Awan M.S. Hashmi Abu-Saeed 《World journal of microbiology & biotechnology》2004,20(3):297-301
Microbial protein was produced from defatted rice polishings using Candida utilis in shake-flasks and a 14-l fermentor to optimize fermentation conditions before producing biomass in a 50-l fermentor. The
organism supported maximum values of 0.224 h−1, 0.94, 1.35, 1.75, 2.12 g l−1 h−1, 0.62 g cells g−1 substrate utilized and 0.38 g g−1 for specific growth rate, true protein productivity, crude protein productivity, cell mass productivity, substrate consumption
rate, cell yield, crude protein yield, respectively in 50-l fermentor studies using optimized cultural conditions. Maximum
values compared favourably or were superior to published data in literature. The biomass protein in the 50-l fermentor contained
22.3, 27.8, 19.2, 9.5, 38.12, 8.5 and 0.27% true protein, crude protein, crude fibre, ash, carbon, cellulose and RNA content,
respectively. The dried biomass showed a gross metabolizable energy value of 2678 kcal kg−1 and contained all essential and non-essential amino acids. Yeast biomass as animal feed may replace expensive feed ingredients
currently being used in poultry feed and may improve the economics of feed produced in countries like Pakistan.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
The influence of brackish phytoplankton cell classes upon the response of urea decomposition was investigated in Lake Nakaumi.
The urea decomposition rate was 5 to 350 μmol urea m−3 h−1 in the light and 3 to 137 μmol urea m−3 h−1 in the dark. The urea decomposition rates in the light were obviously higher than in the dark. An extremely high rate (350
μmol urea m−3 h−1) was observed in Yonago Bay. The rate in the smaller fraction (<5 μm) exceeded that in the middle (5–25 μm) and larger fractions
(>25 μm). The chlorophyll- and photosynthesis-specific rates for urea decomposition in the light were 0.5 to 3.9 μmol urea
mg chl.a
−1 h−1 and 0.3 to 1.3 μmol urea mg photo.C−1. The specific urea decomposing activities were higher in the smaller fraction than in the other two fractions. The present
results suggest that in brackish waters urea decomposition occurred with coupling to the standing crop and photosynthetic
activity of phytoplankton.
Received: May 22, 1999 / Accepted: August 15, 1999 相似文献
13.
J. Carlos Roseiro P. J. Partidário N. Lobo M. J. Marçal 《Applied microbiology and biotechnology》1999,52(4):546-552
The change of dilution rate (D) on both Methylophilus methylotrophus NCIMB11348 and Methylobacterium sp. RXM CCMI908 growing in trimethylamine (TMA) chemostat cultures was studied in order to assess their ability to remove
odours in fish processing plants. M. methylotrophus NCIMB11348 was grown at dilution rates of 0.012–0.084 h−1 and the biomass level slightly increased up to values of D around 0.07 h−1. The maximum cell production rate was obtained at 0.07 h−1 corresponding to a maximum conversion of carbon into cell mass (35%). The highest rate of TMA consumption was 3.04 mM h−1 occurring at D=0.076 h−1. Methylobacterium sp. RXM CCMI908 was grown under similar conditions. The biomass increased in a more steep manner up to values of D around 0.06 h−1. The maximum cell production rate (0.058 g l−1h−1) was obtained in the region close to 0.06 h−1 where a maximum conversion of the carbon into cell mass (40%) was observed. The maximum TMA consumption was 2.33 mM h−1 at D=0.075 h−1. The flux of carbon from TMA towards cell synthesis and carbon dioxide in both strains indicates that the cell is not excreting
products but directing most of the carbon source to growth. Carbon recovery levels of approximately 100% show that the cultures
are carbon-limited. Values for theoretical maximum yields and maintenance coefficients are presented along with a kinetic
assessment based on the determination of the substrate saturation constant and maximum growth rate for each organism.
Received: 25 February 1999 / Received revision: 14 May 1999 / Accepted: 17 May 1999 相似文献
14.
Batch experiments were conducted to evaluate the biodegradation rates of limonene, α-pinene, γ-terpinene, terpinolene and
α-terpineol at 23 °C under aerobic conditions. Biodegradation was demonstrated by the depletion of monoterpene mass, CO2 production and a corresponding increase in biomass. Monoterpene degradation in liquid cultures devoid of soil followed Monod
kinetics. The maximum specific growth rate (μmax) was 0.02 h−1 and 0.06 h−1 and the half-velocity constant (K
s ) varied from 32 mg/l to 3 mg/l for the limonene and α-terpineol respectively. The recovery of monoterpenes by solvent extraction
from autoclaved and azide-amended soil-slurry samples decreased over time and ranged from 69% to 73% for 120 h of incubation
period. Although a significant fraction of monoterpene hydrocarbon could not be extracted, mineralization of these compounds
in the soil-slurry systems took place, as shown by CO2 production. The soil-normalized degradation rates for the hydrocarbon monoterpenes ranged from 0.6 μg g−1 h−1 to 2.1 μg g−1 h−1. A kinetic model – which combined monoterpene biodegradation in the liquid phase and net desorption – was developed and applied
to data obtained from soil-slurry assays.
Received: 10 September 1996 / Received revision: 16 December 1996 / Accepted: 10 January 1997 相似文献
15.
Velasquez-Orta SB Yu E Katuri KP Head IM Curtis TP Scott K 《Applied microbiology and biotechnology》2011,90(2):789-798
This study determined the influence of substrate degradation on power generation in microbial fuel cells (MFCs) and microbial
community selection on the anode. Air cathode MFCs were fed synthetic medium containing different substrates (acetate, glucose
and starch) using primary clarifier sewage as source of electroactive bacteria. The complexity of the substrate affected the
MFC performance both for power generation and COD removal. Power output decreased with an increase in substrate complexity
from 99 ± 2 mW m−2 for acetate to 4 ± 2 mW m−2 for starch. The organic matter removal and coulombic efficiency (CE) of MFCs with acetate and glucose (82% of COD removal
and 26% CE) were greater than MFCs using starch (60% of COD removal and 19% of CE). The combined hydrolysis–fermentation rate
obtained (0.0024 h−1) was considerably lower than the fermentation rate (0.018 h−1), indicating that hydrolysis of complex compounds limits current output over fermentation. Statistical analysis of microbial
community fingerprints, developed on the anode, showed that microbial communities were enriched according to the type of substrate
used. Microbial communities producing high power outputs (fed acetate) clustered separately from bacterial communities producing
low power outputs (fed complex compounds). 相似文献
16.
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
17.
The objective of this study was the application of the experimental design technique to optimize the conditions for the bioremediation
of contaminated soil by means of composting. A low-cost material such as compost from the Organic Fraction of Municipal Solid
Waste as amendment and pyrene as model pollutant were used. The effect of three factors was considered: pollutant concentration
(0.1–2 g/kg), soil:compost mixing ratio (1:0.5–1:2 w/w) and compost stability measured as respiration index (0.78, 2.69 and
4.52 mg O2 g−1 Organic Matter h−1). Stable compost permitted to achieve an almost complete degradation of pyrene in a short time (10 days). Results indicated
that compost stability is a key parameter to optimize PAHs biodegradation. A factor analysis indicated that the optimal conditions
for bioremediation after 10, 20 and 30 days of process were (1.4, 0.78, 1:1.4), (1.4, 2.18. 1:1.3) and (1.3, 2.18, 1:1.3)
for concentration (g/kg), compost stability (mg O2 g−1 Organic Matter h−1) and soil:compost mixing ratio, respectively. 相似文献
18.
The continuous fermentation of 1,3-propanediol from glycerol by Clostridium butyricum was subjected to cell recycling by filtration using hollow-fibre modules made from polysulphone. The performance of the culture
system was checked at a retention ratio (dilution rate/bleed rate) of 5, dilution rates between 0.2 h−1 and 1.0 h−1 and glycerol input concentrations of 32 g l−1 and 56 g l−1. The near-to-optimum propanediol concentration of 26.5 g l−1 (for 56 g l−1 glycerol) was maintained up to a dilution rate of 0.5 h−1 and then decreased while the propanediol productivity was highest at 0.7 h−1. The productivity could be increased by a factor of four in comparison to the continuous culture without cell recycling.
By application of the model of Zeng and Deckwer [(1995) Biotechnol Prog 11: 71–79] for cultures under substrate excess, it
was shown that the limitations resulted exclusively from product inhibition and detrimental influences from the cell recycling
system, such as shear stress, were not involved.
Received: 20 October 1997 / Received revision: 12 December 1997 / Accepted: 14 December 1997 相似文献
19.
Energetic cost of hovering flight in a nectar-feeding bat measured with fast-response respirometry 总被引:1,自引:1,他引:0
Y. Winter 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(6):434-444
Hover-feeding glossophagine bats provide, in addition to the hummingbirds, a second vertebrate model for the analysis of
hovering flight based on metabolic measurement and aerodynamic theory. In this study, the power input of hovering Glossophaga soricina bats (11.9 g) was measured by standard respirometry and fast-response (<0.2 s) oxygen analysis. Bats needed 5–7 s after a
rest-to-flight transition to return to a respiratory steady state. Therefore, only hovering events preceeded by a 7-s flight
interval were evaluated. V˙O2 during hovering fluctuated with a frequency of 3–5 Hz, which corresponded in frequency to the licking movement of the tongue.
During hovering, bats often may have hypoventilated as indicated by reduced V˙O2 and a respiratory exchange ratio (RER) well below the steady-state value of 1. Steady-state oxygen consumption (and derived
power input) during hovering was estimated to be 27 (25–29) ml O2 g−1 h−1 (158 W kg−1 or 1.88 W) in the 11.9-g bats as indicated by three independent findings: (1) V˙O2 was 26 ml O2 g−1 h−1 after 6.5 s of hovering, (2) the mean RER during single hovering events was at its steady-state level of 1 only at oxygen
uptake rates of 25–29 ml g−1 h−1, and (3) when the oxygen potentially released from estimated oxygen stores was added to the measured oxygen uptake, the upper
limit for oxygen consumption during hovering was found to be 29 ml O2 g−1 h−1. Hovering power input was about 1.2 times the value of minimum flight power input (Winter and von Helversen 1998) and thus
well below the 1.7–2.6 difference in power output postulated by aerodynamic theory (Norberg et al. 1993). Mass specific power
input was 40% less than in hummingbirds. Thus, within the possible modes of hovering flight, Glossophaga bats seem to operate at the high-efficiency end of the spectrum.
Accepted: 28 April 1998 相似文献
20.
Biodegradation of BTEX by a microbial consortium isolated from a closed municipal landfill was studied using respirometric
techniques. The kinetics of biodegradation were estimated from experimental oxygen uptake data using a nonlinear parameter
estimation technique. All of the six compounds were rapidly degraded by the microbial culture and no substrate inhibition
was observed at the concentration levels examined (200 mg L−1 as COD). Microbial growth and contaminant degradation were adequately described by the Monod equation. Considerable differences
were observed in the rates of BTEX biodegradation as seen from the estimates of the kinetic parameters. A three-fold variation
was seen in the values of the maximum specific growth rate, μmax. The highest value of μmax was 0.389 h−1 for p-xylene while o-xylene was characterized by a μmax value of 0.14 h−1, the lowest observed in this study. The half saturation coefficient, K
s, and the yield coefficient, Y, varied between 1.288–4.681 mg L−1 and 0.272–0.645 mg mg−1, respectively. Benzene and o-xylene exhibited higher resistance to biodegradation while toluene and p-xylene were rapidly degraded. Ethylbenzene and m-xylene were degraded at intermediate rates. In biodegradation experiments with a multiple substrate matrix, substrate depletion
was slower than in single substrate experiments, suggesting an inhibitory nature of substrate interaction.
Received 15 February 1998/ Accepted in revised form 5 July 1998 相似文献