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Appl Environ Microbiol, January 1998, p. 359-362, Vol. 64, No. 1
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Impact of Inoculation Protocols, Salinity, and pH
on the Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) and
Survival of PAH-Degrading Bacteria Introduced into Soil
Matthias
Kästner,*
Maren
Breuer-Jammali, and
Bernd
Mahro
Department of Biotechnology II, Technical
University of Hamburg-Harburg, 21071 Hamburg, Germany
Received 22 July 1997/Accepted 16 October 1997
 |
ABSTRACT |
Degradation of polycyclic aromatic hydrocarbons (PAHs) and survival
of bacteria in soil was investigated by applying different inoculation
protocols. The soil was inoculated with Sphingomonas paucimobilis BA 2 and strain BP 9, which are able to degrade
anthracene and pyrene, respectively. CFU of soil bacteria and of the
introduced bacteria were monitored in native and sterilized soil at
different pHs. Introduction with mineral medium inhibited PAH
degradation by the autochthonous microflora and by the strains tested.
After introduction with water (without increase of the pore water
salinity), no inhibition of the autochthonous microflora was observed
and both strains exhibited PAH degradation.
| |
TEXT |
Polycyclic aromatic hydrocarbons
(PAHs) are pollutants which are widely distributed in the ecosphere.
These compounds enter the environment either adsorbed onto particles by
emissions from combustion processes or from spilling of mineral or tar
oils. Pollution of soil by tar oil from coal liquefaction and
gasification facilities is the source of considerable contamination by
PAHs (5). Those sites are subject to remediation activities,
since PAHs are a serious risk to human health as a result of their
carcinogenic potential (30). For bioremediation of
contaminated environments, seeding by introduction of microorganisms
has been considered a valuable tool for increasing the rate and extent
of biodegradation of pollutants (2). Increased
biodegradation of xenobiotic pollutants by such treatments has been
demonstrated in several studies (3, 4, 10, 12, 21). However,
degradation by introduced bacteria could not be established in other
soils, and the reasons for the failures have not been further
investigated (9, 11, 19). The advantage of seeding is not
generally accepted, since inoculation experiments have shown ambiguous
results in comparison to degradation by indigenous microorganisms
(2, 7, 18). We have isolated several strains of bacteria
from a site contaminated with tar oil. The bacteria are able to grow on
PAHs and were found in the soil at levels of 102 to
105 CFU per g of soil (15). However, no PAH
degradation was observed after introduction of these strains into
artificially contaminated soil. The goal of the present study was to
investigate and overcome this inhibition of the introduced bacteria.
The activity and survival of the PAH-degrading bacteria were examined
by applying different inoculation protocols in native and sterilized
soils with different pHs.
Experimental methods.
The experiments were carried out with
soil from an Ah horizon of a Luvisol (German systematic) from a
noncontaminated rural area (16). All concentrations are dry
weights of soil. The experiments were conducted with 100 g of soil
in 1.5-liter jars at 25°C, as described previously (17).
The soil was sterilized three times by autoclaving of 500 g for 30 min followed by incubation for 24 h at 37°C. The pH of the soil
was determined to be 5.2. The pH was shifted to 7.0 by adding 80 mg of
CaO to 100 g of soil. After neutralization, the soil was
distributed into vessels and contaminated with PAHs as described
previously (17). The first set of experiments (see Table 1)
was conducted with 100 mg (each) of phenanthrene, anthracene,
fluoranthene, and pyrene per kg. All other experiments were conducted
with 25 mg of anthracene or pyrene per kg. The suspended bacteria were
added to the soil after contamination. The water content of the soil
was finally adjusted to 60% of the water-holding capacity (WHC).
Sampling, isolation, identification, culture conditions, and
physiological characteristics of the PAH-degrading bacteria used have
already been described (15). The phenanthrene- and
anthracene-degrading strain BA 2 was identified as Sphingomonas
paucimobilis, and the phenanthrene-, anthracene-, fluoranthene-,
and pyrene-degrading strain BP 9 was classified as a
Gordona-like species by the Deutsche Sammlung von
Mikroorganismen, Braunschweig, Germany (15).
The cultures for the inocula were incubated in 250-ml serum bottles on
a shaker (150 rpm) at 25°C. The mineral medium contained, per liter,
2.13 g of Na2HPO4, 1.3 g of
KH2PO4, 0.5 g of NH4Cl, 0.2 g of MgSO4 · 7H2O, 1 ml of
trace element solution, and 3 ml of vitamin solution (pH 6.9). Strain
BA 2 was cultivated in the presence of 50 mg of anthracene per liter,
and strain BP 9 was cultivated with 200 mg of pyrene per liter. The
cultures were harvested in log phase by centrifugation, and the pellets
were washed twice with decreasing concentrations of the mineral medium for introduction protocols B and C. Protocol A (introduction with mineral medium) was performed by resuspending the pellet in 5 ml of
mineral medium. Protocol B (introduction with deionized water) was
carried out by resuspending the pellet in 5 ml of deionized water. This
solution was mixed with 100 g of contaminated soil and the water
content was adjusted to 60% of the WHC. In protocol C (slurry phase
introduction), the pellet was resuspended in 50 ml of water. The water
was mixed with 100 g of soil, and the slurry was dried to 60% of
the WHC at 20°C within 24 h. The bacteria were introduced to a
final concentration of 2 × 108 cells/g of soil.
Microorganisms were extracted from the soil by mixing 1 g of soil
with 10 ml of sterile Na2P2O7
solution (2.8 g/liter) and 3 g of glass beads (diameter, 5 mm) in
50-ml tubes for 2 h in a horizontal position on a shaker (350 rpm). The soil particles were allowed to sediment for 30 min. The
supernatant was diluted and plated on solid media. Total CFU were
determined after 8 days by counting the colonies on mineral medium
without additional carbon sources. The total CFU of the native Ah soil amounted to 107/g. PAH-degrading bacteria were determined
by clear-zone-forming colonies on mineral media coated with a crystal
layer of the respective PAH (15). In addition, due to their
characteristic visible shape and color, colonies of strain BP 9 were
counted separately from other colonies on the media. Colonies of strain
BA 2 could be detected only by anthracene degradation. No PAH-degrading
organisms were detected in the native Ah soil. PAH concentrations in
the soil were analyzed by ultrasonic extraction with ethylacetate. This
was followed by alkaline hydrolysis to extract PAH residues not
extractable by organic solvents (8). PAHs were quantified by
high-performance liquid chromatography as described previously (17). The presented data are summarized from both extraction procedures and are means of triplicate analyses.
Results and discussion.
Native Ah soil showed degradation of
anthracene and phenanthrene, whereas fluoranthene and pyrene were not
degraded (Table 1). Due to sequestering
into soil micropores, a slight abiotic loss was observed in sterilized
Ah soil. To improve the PAH degradation, the soil was inoculated with
PAH-degrading bacteria. The Gordona-like strain BP 9, which
is able to degrade the respective PAHs (see "Experimental
methods"), was introduced by protocol A with mineral medium. However,
no decrease in the PAHs was observed in the seeded culture (Table 1).
Moreover, degradation of phenanthrene and anthracene by the
autochthonous soil microflora was completely inhibited. Only slight
degradation was observed in sterilized soil. However, 108
CFU/g of viable pyrene-degrading colonies of BP 9 were detected after 5 days, and 106 CFU/g were still present after 35 days in the
native soil. The decline in CFU of strain BP 9 was more rapid in
sterilized soil (only 3 × 104 CFU/g after 5 days),
indicating better survival in native soil. Similar results were
obtained with the anthracene-degrading strain BA 2 (Fig.
1). After introduction by protocol A with
mineral medium, no anthracene degradation was observed and the
degradation by the autochthonous microflora was also inhibited.
Anthracene-degrading colonies at >102 CFU/g were still
detected after 30 days. Thus, the introduced bacteria were able to
survive and to compete with the indigenous microflora. Introduction of
strain BA 2 by protocol C in slurry phase with water did not inhibit
degradation by the native soil (Fig. 1). However, degradation was not
improved by strain BA 2. The results suggest that the inhibition of PAH
degradation in the native soil was caused by the salt content of the
mineral medium used in protocol A. Therefore, introduction protocol B with water was performed without increasing the salt content of the
soil. Both strains were tested with protocol B. Anthracene degradation
by the autochthonous microflora was not inhibited. However, no improved
anthracene degradation by strain BA 2 was observed in native or
sterilized soil (pH 5.2) (Fig. 2),
whereas a sixfold increase in pyrene degradation was caused by BP 9 (Fig. 3). The lack of degrading activity
of strain BA 2 in the native soil suggested additional inhibition by
the pH level. This hypothesis was tested by neutralizing the soil pH
with CaO. Cultures at pH 7 showed a 10-fold-increased degradation rate
in the soil after introduction by protocol B (Fig. 2). Pyrene
degradation by strain BP 9 was not significantly affected by the soil
pH, and similar rates were observed in sterilized soil cultures (data
not shown).
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FIG. 1.
Degradation of anthracene in contaminated soil after
inoculation with S. paucimobilis BA 2 by different
procedures. Symbols:  , native soil (control);  , introduction
protocol A (addition of strain BA 2 with mineral medium);  ,
introduction protocol C (addition of strain BA 2 by slurry
application). dw, dry weight.
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FIG. 2.
Degradation of anthracene by S. paucimobilis
BA 2 in contaminated soils with different pHs. Symbols: , native
soil (control); , introduction protocol B (addition of strain BA 2 with water);  , sterilized native soil;  , introduction protocol B
with sterilized soil. dw, dry weight.
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FIG. 3.
Degradation of pyrene by strain BP 9 in contaminated
soils with different pHs. Symbols: , native soil (control); ,
introduction protocol B (addition of strain BP 9 with water). dw, dry
weight.
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|
The results demonstrate that introduction by protocol B with water is
the appropriate method to overcome the inhibition observed
by use of
protocol A with mineral medium. We present, to our knowledge,
the first
evidence that the salinity of the introduction medium
may repress the
PAH degradation activity of the introduced bacteria
and of the
autochthonous soil microflora. This confirms the essential
impact of
the inoculation protocol on the activity of bacteria
in soil.
Introduction of bacteria into soil has usually been conducted
with
buffers or media (
26) without focused attention on
introduction
media and details of the protocol. A
Mycobacterium sp. introduced
into contaminated soils simply
as free cells in Tris buffer increased
the mineralization of pyrene
from 1 to 55% (
12). PAH degradation
in other soils was only
slightly enhanced by inoculation (
10).
Previous studies have
presented liquid inoculation methods, such
as simple spraying or mixing
procedures, or semisolid inoculation
methods, such as immobilization
techniques (
26). Immobilization
is considered to promote
better survival and activity of the introduced
organisms (
3,
6,
21,
29). However, an immobilized phenanthrene-degrading
Pseudomonas sp. did not enhance degradation in soil
slurries.
Additional substrates (
28) or inorganic nutrients
(
11) had
a greater impact on degradation and survival. Our
results imply
that inoculation by media may have caused several
failures in
the introduction of degradation activities and may have
supported
the higher effectiveness of immobilized cells. The possible
reasons
for such failures have not been extensively discussed
(
9).
However, changes in environmental conditions of the
soil by the
inoculation procedure have been considered, and no attempts
to
overcome these limitations have been reported.
The focus of previously published inoculation experiments has been the
inoculum size (
1,
23). The data can be summarized
by the
fact that increasing the inoculum size increases degradation
activity
(
13). Inoculation levels of 10
7 to
10
8 cells/g are considered sufficient to establish
degradation activity
(
13,
14); therefore, 2 × 10
8 CFU/g were applied in this work. After addition of
strain BP
9, total CFU and pyrene-degrading CFU were doubled in native
soil
(pH 5.2) during initial degradation until day 7. Neutralization
of
the soil led to 10-fold-increased CFU after 7 days. CFU began
to
decrease after 7 days, and decline factors of
100 CFU within
30 days
have also been observed by other authors (
22,
27).
The
decline in pyrene-degrading CFU of strain BP 9 was significantly
more
rapid than that in total CFU (
500 at pH 7 and
1,000 at
pH 5.2).
Considerable amounts of the BP 9 colonies lost the ability
to degrade
pyrene after extraction from soil. This phenomenon,
and whether it is
an effect of soil cultures or is inherent to
the organisms, should be
investigated further.
Some authors (
6) have argued that pure cultures of bacteria
introduced into soil often do not persist due to limited
competitiveness,
since degradation was observed only in sterilized soil
(
9,
19). Those considerations imply that survival leads
automatically
to activity. However, we have shown that bacteria
survived in
soil without developing their degradation capacities. PAH
degradation
by the autochthonous microflora was even suppressed after
introduction
of the bacteria with mineral medium. The observed
inhibition was
not caused by limited bioavailability. Attempts to
improve PAH
degradation in this soil by addition of compost were
successful
(
17). The inhibition was caused by the
introducing medium, which
changed the salinity of the pore water in the
soil to the range
of marine environments. The impact of salinity on PAH
degradation
in estuarine sediments has already been described
(
25). No attention
has been paid to this detail of soil
inoculation in previous publications.
The observed effects depended on
the soil type used, since the
degradation of PAHs in soil from a
contaminated site was not inhibited
after introducing the same bacteria
with mineral medium (
20).
Therefore, we have to conclude
that the inoculation protocol plays
an essential role in establishing
the degrading activity of specialized
strains in soils.
An important factor for the degradation activity of introduced bacteria
is the pH of the soil. The shift of the pH from 5.2
to 7.0 enabled PAH
degradation by strain BA 2 (Fig.
2). Neutralization
of soil is
generally discussed to be favorable for the degradation
of mineral oil
components by bacteria (
18). However, a pH of
5.2 should not
lead to total inhibition of activity. That PAHs
were available in low
concentrations might explain the higher
impact of pH on the degradation
of PAHs. Small pH shifts have
dramatic effects on the degradation of
low concentrations of xenobiotics
in oligotrophic aquatic environments
(
31). Remarkable differences
in the amounts of
mineralization from radiolabeled glucose available
at high and low
concentrations have recently been demonstrated
in soils
(
24). We have to consider that metabolism of the
oligotrophic
autochthonous (humus-degrading) microflora of soil might
be more
sensitive to changes in environmental conditions than
metabolism
of zymogenic (opportunistic) microflora or of introduced
bacteria.
Therefore, environmental conditions in soil have to be
adjusted
carefully to develop the degradation potential of introduced
bacteria
and of the indigenous microflora. If the degradation potential
is inherent to the indigenous soil microflora, the addition of
"specialists" may only reduce the time necessary for
biodegradation.
| |
ACKNOWLEDGMENTS |
We thank V. Kasche for stimulating discussions.
The research on this subject was financed by the Deutsche
Forschungsgemeinschaft (DFG) within the interdisciplinary research project "Remediation of Contaminated Soil" (SFB 188).
| |
FOOTNOTES |
*
Corresponding author. Present address: Institute of
Microbiology, Department of Technical Microbiology,
Friedrich-Schiller-University, Philosophenweg 12, 07743 Jena, Germany.
Phone: (49) 3641-949300. Fax: (49) 3641-949302. E-mail:
kaestner{at}merlin.biologie.uni-jena.de.
Present address: Bremen Polytechnic, Institute of Environmental
Technology, Department of Civil Engineering, 28199 Bremen, Germany.
| |
REFERENCES |
| 1.
|
Acea, M. J.,
C. R. Moore, and M. Alexander.
1988.
Survival and growth of bacteria introduced into soil.
Soil Biol. Biochem.
4:509-515.
|
| 2.
|
Atlas, R. M.
1991.
Bioremediation of fossil fuel contaminated soils, p. 14-32. In
R. E. Hinchee, and R. F. Olfenbuttel (ed.), In situ bioreclamation.
Butterworth-Heinemann, Boston, Mass.
|
| 3.
|
Briglia, M.,
E.-L. Nurmiaho-Lassila,
G. Vallini, and M. Salkinoja-Salonen.
1990.
The survival of the pentachlorophenol-degrading Rhodococcus chlorophenolicus PCP-1 and Flavobacterium sp. in natural soil.
Biodegradation
1:273-281.
|
| 4.
|
Brodkorb, T. S., and R. L. Legge.
1992.
Enhanced biodegradation of phenanthrene in oil tar-contaminated soils supplemented with Phanerochaete chrysosporium.
Appl. Environ. Microbiol.
58:3117-3121[Abstract/Free Full Text].
|
| 5.
|
Cerniglia, C. E.
1984.
Microbial degradation of polycyclic aromatic hydrocarbons.
Adv. Appl. Microbiol.
30:31-71[Medline].
|
| 6.
|
Crawford, R. L.,
K. T. O'Reilly, and H.-L. Tao.
1989.
Microorganism stabilization for in situ degradation of toxic chemicals, p. 203-211. In
D. Kamely, A. Chakrabarty, and G. S. Omenn (ed.), Biotechnology and biodegradation. Advances in applied biotechnology series, vol. 4.
Gulf Publishing Company, Houston, Tex.
|
| 7.
|
Dott, W.,
D. Feidieker,
P. Kämpfer,
H. Schleibinger, and S. Strechel.
1989.
Comparison of autochthonous bacteria and commercially available cultures with respect to their effectiveness in fuel oil degradation.
J. Ind. Microbiol.
4:365-374.
|
| 8.
|
Eschenbach, A.,
M. Kästner,
R. Bierl,
G. Schaefer, and B. Mahro.
1994.
Evaluation of a new and more effective method to extract polycyclic aromatic hydrocarbons from soil samples.
Chemosphere
28:683-692.
|
| 9.
|
Goldstein, R. M.,
L. M. Mallory, and M. Alexander.
1985.
Reasons for possible failure of inoculation to enhance biodegradation.
Appl. Environ. Microbiol.
50:977-983[Abstract/Free Full Text].
|
| 10.
|
Grosser, R. J.,
D. Warshawsky, and J. R. Vestal.
1991.
Indigeous and enhanced mineralization of pyrene, benzo[a]pyrene, and carbazole in soils.
Appl. Environ. Microbiol.
57:3462-3469[Abstract/Free Full Text].
|
| 11.
|
Harkness, M. R.,
J. B. McDermott,
D. A. Abramowicz,
J. J. Salvo,
W. P. Flanagan,
M. L. Stephens,
F. J. Mondello,
R. J. May,
J. H. Lobos,
K. M. Carroll,
M. J. Brennan,
A. A. Bracco,
K. M. Fish,
G. L. Warner,
P. R. Wilson,
D. K. Dietrich,
D. T. Lin,
C. B. Morgan, and W. L. Gately.
1993.
In situ stimulation of aerobic PCB biodegradation in Hudson River sediments.
Science
259:503-507[Abstract/Free Full Text].
|
| 12.
|
Heitkamp, M. A., and C. E. Cerniglia.
1989.
Polycyclic aromatic hydrocarbon degradation by a Mycobacterium sp. in microcosms containing sediment and water from a pristine ecosystem.
Appl. Environ. Microbiol.
55:1968-1973[Abstract/Free Full Text].
|
| 13.
|
Jacobsen, C. S., and J. C. Petersen.
1992.
Growth and survival of Pseudomonas cepacia DBO1(pRO101) in soil amended with 2,4-dichlorophenoxyacetic acid.
Biodegradation
2:245-252.
|
| 14.
|
Jacobsen, C. S., and J. C. Petersen.
1992.
Mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) in soil inoculated with Pseudomonas cepacia DBO1(pRO101), Alcaligenes eutrophus AEO106(pRO101) and Alcaligenes eutrophus JMP134(pJP4): effects of inoculation level and substrate concentration.
Biodegradation
2:253-263.
|
| 15.
|
Kästner, M.,
M. Breuer-Jammali, and B. Mahro.
1994.
Enumeration and characterization of the soil microflora from hydrocarbon-contaminated soil sites able to mineralize polycyclic aromatic hydrocarbons.
Appl. Microbiol. Biotechnol.
41:267-273.
|
| 16.
|
Kästner, M.,
S. Lotter,
J. Heerenklage,
M. Breuer-Jammali,
R. Stegmann, and B. Mahro.
1995.
Fate of 14C-labeled anthracene and hexadecane in compost manured soil.
Appl. Microbiol. Biotechnol.
43:1128-1135[Medline].
|
| 17.
|
Kästner, M., and B. Mahro.
1996.
Microbial degradation of polycyclic aromatic hydrocarbons in soils affected by the organic matrix of compost.
Appl. Microbiol. Biotechnol.
44:668-675[Medline].
|
| 18.
|
Leahy, J. G., and R. R. Colwell.
1990.
Microbial degradation of hydrocarbons in the environment.
Microbiol. Rev.
54:305-315[Abstract/Free Full Text].
|
| 19.
|
Liu, S. Y.,
M.-H. Lu, and J.-M. Bollag.
1990.
Transformation of metachlor in soil inoculated with Streptomyces sp.
Biodegradation
1:9-17.
|
| 20.
|
Mahro, B.,
G. Schaefer, and M. Kästner.
1994.
Pathways of microbial degradation of polycyclic aromatic hydrocarbons in soil, p. 203-217. In
R. E. Hinchee, A. Leeson, L. Semprini, and S. K. Ong (ed.), Bioremediation of chlorinated and polycyclic aromatic hydrocarbons.
Lewis Publishers, Boca Raton, Fla.
|
| 21.
|
Middledorp, P. J. M.,
M. Briglia, and M. Salkinoja-Salonen.
1990.
Biodegradation of pentachlorophenol in natural soil by inoculated Rhodococcus chlorophenolicus.
Microb. Ecol.
20:123-139.
|
| 22.
|
Ogunseitan, O. A.,
I. L. Delgado,
Y.-L. Tsai, and B. H. Olson.
1991.
Effect of 2-hydroxybenzoate on the maintenance of naphthalene-degrading pseudomonads in seeded and unseeded soil.
Appl. Environ. Microbiol.
57:2873-2879[Abstract/Free Full Text].
|
| 23.
|
Ramadan, M. A.,
O. M. El-Tayeb, and M. Alexander.
1990.
Inoculum size as a factor limiting success of inoculation for biodegradation.
Appl. Environ. Microbiol.
56:1392-1396[Abstract/Free Full Text].
|
| 24.
|
Shen, J., and R. Bartha.
1996.
Metabolic efficiency and turnover of soil microbial communities in biodegradation tests.
Appl. Environ. Microbiol.
62:2411-2415[Abstract/Free Full Text].
|
| 25.
|
Shiaris, M. P.
1989.
Seasonal biotransformation of naphthalene, phenanthrene, and benzo[a]pyrene in surficial estuarine sediments.
Appl. Environ. Microbiol.
55:1391-1399[Abstract/Free Full Text].
|
| 26.
|
Trevors, J. T.,
P. Kuikman, and J. D. van Elsas.
1994.
Review article. Release of bacteria into soil: cell numbers and distribution.
J. Microbiol. Methods
19:247-259.
|
| 27.
|
Wagner-Döbler, I.,
R. Pipke,
K. N. Timmis, and D. F. Dwyer.
1992.
Evaluation of aquatic sediment microcosms and their use in assessing possible effects of introduced microorganisms on ecosystem parameters.
Appl. Environ. Microbiol.
58:1249-1258[Abstract/Free Full Text].
|
| 28.
|
Weir, S. C.,
S. P. Dupuis,
M. A. Providenti,
H. Lee, and J. T. Trevors.
1995.
Nutrient-enhanced survival of and phenanthrene mineralization by alginate-encapsulated and free Pseudomonas sp. UG14Lr cells in creosote-contaminated soil slurries.
Appl. Microbiol. Biotechnol.
43:964-951.
|
| 29.
|
Wiesel, I.,
S. M. Wübker, and H.-J. Rehm.
1993.
Degradation of polycyclic aromatic hydrocarbons by an immobilized mixed bacterial culture.
Appl. Microbiol. Biotechnol.
39:110-116.
|
| 30.
|
Wislocki, P. G., and A. Y. H. Lu.
1988.
Carcinogenicity and mutagenicity of proximate and ultimate carcinogens of polycyclic aromatic hydrocarbons, p. 1-30. In
S. K. Yang, and B. D. Silverman (ed.), Polycyclic aromatic hydrocarbon carcinogenesis: structure-activity relationships, vol. 1.
CRC Press, Boca Raton, Fla.
|
| 31.
|
Zaidi, B. R.,
G. Stucki, and M. Alexander.
1988.
Low chemical concentration and pH as factors limiting the success of inoculation to enhance biodegradation.
Environ. Toxicol. Chem.
7:143-151.
|
Appl Environ Microbiol, January 1998, p. 359-362, Vol. 64, No. 1
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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