Download Inducible uptake and metabolism of glucose by the phosphorylative

Inducible uptake and metabolism of glucose by the
phosphorylative pathway in Pseudomonas putida CSV86
Aditya Basu & Prashant S. Phale
Biotechnology group, School of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai, India
Correspondence: Prashant S. Phale,
Biotechnology Group, School of Biosciences
and Bioengineering, Indian Institute of
Technology-Bombay, Powai, Mumbai 400
076, India. Tel.: 191 22 25767836; fax: 191
22 25723480; e-mail: [email protected]
Received 28 January 2006; revised 19 April
2006; accepted 20 April 2006.
First published online May 2006.
doi:10.1111/j.1574-6968.2006.00285.x
Editor: Wilfrid Mitchell
Keywords
Pseudomonas ; glucose metabolism; transport;
enzyme induction; aromatic compound
catabolism.
Abstract
Pseudomonas putida CSV86 utilizes glucose, naphthalene, methylnaphthalene,
benzyl alcohol and benzoate as the sole source of carbon and energy. Compared
with glucose, cells grew faster on aromatic compounds as well as on organic acids.
The organism failed to grow on gluconate, 2-ketogluconate, fructose and mannitol. Whole-cell oxygen uptake, enzyme activity and metabolic studies suggest that
in strain CSV86 glucose utilization is exclusively by the intracellular phosphorylative pathway, while in Stenotrophomonas maltophilia CSV89 and P. putida
KT2442 glucose is metabolized by both direct oxidative and indirect phosphorylative pathways. Cells grown on glucose showed five- to sixfold higher activity of
glucose-6-phosphate dehydrogenase compared with cells grown on aromatic
compounds or organic acids as the carbon source. Study of [14C]glucose uptake
by whole cells indicates that the glucose is taken up by active transport. Metabolic
and transport studies clearly demonstrate that glucose metabolism is suppressed
when strain CSV86 is grown on aromatic compounds or organic acids.
Introduction
A variety of aromatic compounds are present in fresh and
marine waters and in agricultural lands. The most effective
and economical way to remove these compounds from the
environment is by microbial degradation (Alexander, 1981).
The bottleneck in the efficient degradation of these compounds is the presence of simple carbon sources like organic
acids and sugars, which are preferentially utilized by microorganisms, and unless the simpler carbon sources are
completely depleted, the toxic aromatic compounds are not
degraded (Collier et al., 1996). In pseudomonads, glucose
utilization follows two routes: (i) the direct oxidative pathway, which converts glucose to gluconate, 2-ketogluconate
and then subsequently to 6-phosphogluconate by extracellular, high affinity, glucose dehydrogenase and gluconate
dehydrogenase (Quay et al., 1972; Midgley & Dawes, 1973;
Roberts et al., 1973; Lessie et al., 1979), and (ii) the
intracellular, low affinity, nucleotide-dependent phosphorylative pathway (Lessie & Neidhardt, 1967; Tiwari & Campbell, 1969; Eisenberg et al., 1974; Guymon & Eagon, 1974)
wherein glucose is converted to 6-phosphogluoconate by
glucokinase and glucose 6-phosphate dehydrogenase (Zwf).
The key intermediate for both pathways is 6-phosphogluconate, which enters the TCA cycle via glyceraldehyde-3FEMS Microbiol Lett 259 (2006) 311–316
phosphate and pyruvate through the Entner-Doudoroff
pathway (Fig. 1a) (Entner & Doudoroff, 1952; Tiwari &
Campbell, 1969). Depending on the physiological conditions, one or other of the pathways predominates (Lessie &
Phibbs, 1984).
It has been reported that degradation of aromatic compounds is repressed by glucose as well as by organic acids
(Worsey & Williams, 1975; Duetz et al., 1994; Holtel et al.,
1994; Schleissner et al., 1994; Muller et al., 1996, 1997;
McFall et al., 1997). Such preferential utilization of simple
carbon sources represses degradation of recalcitrant compounds in nature (referred to as carbon catabolite repression). Attempts have been made to overcome this repression
by generating mutants defective in glucose utilization which
will mineralize complex carbon sources like naphthalene
efficiently even in the presence of glucose (Samanta et al.,
2001).
Pseudomonas putida CSV86 has been shown to metabolize aromatic compounds preferentially over glucose and
cometabolize aromatic compounds and organic acids (Basu
et al., 2006). Here we report that strain CSV86 utilizes
glucose only by the intracellular, phosphorylative pathway.
The strain utilizes aromatic compounds and organic acids
faster compared with glucose, and the glucose-metabolizing
2006 Federation of European Microbiological Societies
Published by Blackwell Publishing Ltd. All rights reserved
c
312
(a)
A. Basu and P.S. Phale
Gluconate
Glucose
Gcd
Gad
Gct
Glucose
ATP
2-Ketogluconate
Kgt
2-Ketogluconate
Gluconate
Gck
ATP
ATP
Gnk
Kgk
2-Keto-6-P-gluconate
Glucose-6-P
Kgr
Zwf
NAD(P)H
NAD(P)
6-P-Gluconate
Pgd
2-Keto-3-Deoxy-6-P-Gluconate
Kdga
Glyceraldehyde-3-P
(b)
Glucose
Gluconate
x
Gcd
Gct
Glucose
ATP
Pyruvate
x
TCA Cycle
2-Ketogluconate
x
Gck
Glucose-6-P
Zwf
NAD(P)
6-P-Gluconate
Pgd
2-Keto-3-Deoxy-6-P-Gluconate
Kdga
Glyceraldehyde-3-P
Pyruvate
enzyme, Zwf, and glucose transport are inducible and
suppressed by growth on aromatics or organic acids.
Materials and methods
Growth conditions
Bacterial cultures used in this study were P. putida CSV86
(Mahajan et al., 1994), Stenotrophomonas maltophilia CSV89
(Phale et al., 1995) and P. putida KT2442. Cultures were
grown in 150 mL mineral salt medium [MSM; Basu et al.,
2003] at 30 1C on a rotary shaker (200 r.p.m.). The medium
was supplemented aseptically with appropriate amounts of
aromatic compounds (0.1%), glucose (0.25%) or organic
acids (0.25%) as carbon source. Growth was monitored
spectrophotometrically at 540 nm.
Metabolism of glucose
Glucose grown mid-log phase cells (200 mg) were harvested, washed twice with sterile distilled water, suspended
in 50 mL of 10 mM glucose prepared in sterile distilled water
2006 Federation of European Microbiological Societies
Published by Blackwell Publishing Ltd. All rights reserved
c
TCA Cycle
Fig. 1. Metabolic pathways involved in the
utilization of glucose by (a) pseudomonads and
(b) Pseudomonas putida CSV86. The enzymes
involved are: Gcd, Gad: glucose and gluconate
oxidase; Gct, Kgt: glucose- and 2-ketogluconate-transporter; Gck, Gnk, Kgk: glucose-,
gluconate- and 2-ketogluconate-kinase; Zwf:
glucose 6-phosphate dehydrogenase; Kgr:
2-keto 6-phospho gluconate reductase; Pgd:
6-phosphogluconate dehydratase; Kdga: 2Keto-3-deoxy-6-phospho gluconate aldolase
Cross indicates the inability of strain to utilize
gluconate and 2-ketogluconate as carbon
source.
and incubated at 30 1C for 3.5 h. The pH of the suspension
was constantly monitored and maintained at pH 7.0 with
KOH (6 M). After incubation, the cells were removed by
centrifugation. The supernatant was filtered through a
0.2 mm filter and lyophilized to a dry powder. Products
formed from glucose were resolved by TLC (one dimension)
and detected as described (Pujol & Kado, 2000).
Whole-cell oxygen uptake
Mid-log phase cells grown on the appropriate carbon source
were used. Respiration rates were measured at 30 1C using
oxygraph (Hansatech, UK) fitted with a Clark-type O2 electrode as described earlier (Basu et al., 2003). Respiration rates
were corrected for endogenous O2 consumption and expressed
as nmol O2 consumed min1 mg1 of cells (wet weight).
Preparation of cell-free extracts and enzyme
assays
Cell-free extracts were prepared as described earlier (Basu
et al., 2003). Protein was estimated using folin-phenol
FEMS Microbiol Lett 259 (2006) 311–316
313
Glucose metabolism in P. putida CSV86
reagent (Lowry et al., 1951). Glucose dehydrogenase (Matsushita & Ameyama, 1982), gluconate dehydrogenase (Matsushita et al., 1982) and glucose-6-phosphate dehydrogenase
(Lessmann et al., 1975) activities were monitored as described. Enzyme activities are expressed either as nanomoles
of substrate consumed or product formed or NADH formed
or consumed per min. Specific activities are expressed as
nmoles per min per mg of protein.
Log OD 540 nm
10
1
0.1
[14C]Glucose uptake, binding assay
Uptake of [U-14C]glucose was studied by modifying the
method described previously (Sly et al., 1993). Cells were
grown till late-log phase, harvested, washed twice and
resuspended in MSM to an absorbance of 0.20 at 540 nm.
Cell suspension was incubated at 30 1C for 10 min in a
shaking water bath. To the prewarmed cell suspension
(10 mL), 5 nmol of [14C]glucose (BRIT, India, sp. ac.
140 mCi mmol1) was added, and samples (100 mL) were
withdrawn and rapidly filtered through 0.45 mm cellulose
ester filters (Pall). The filters were immediately washed twice
with sterile MSM (1 mL), air dried and vigorously mixed in
scintillation cocktail (0.4% PPO and 0.025% POPOP in
toluene). Radioactivity was measured using a liquid scintillation counter (Rackbeta LKB1209) and expressed as pmoles
[14C]glucose accumulated.
All the experiments were performed at least three times
in triplicate and the observed standard deviation was less
than 5%.
Results and discussion
Pseudomonas putida CSV86 metabolizes naphthalene via the
catechol meta-cleavage pathway, and benzyl alcohol via the
catechol ortho-cleavage pathway (Mahajan et al., 1994;
Basu et al., 2003). It also utilizes benzoic acid, and p-and
o-hydroxy benzoic acid and p-and o-hydroxybenzyl alcohols
(Basu et al., 2003). Besides aromatic compounds, strain
CSV86 also utilizes glucose and glycerol, but it failed to
grow on gluconate, 2-ketogluconate, fructose and mannitol.
The growth profile on various carbon sources is shown in
Fig 2. The observed specific growth rate (m, h1) and
doubling time (h) on various carbon sources were found to
be: naphthalene (0.51, 1.36), salicylate (0.34, 2.04), benzyl
alcohol (0.54, 1.28), benzoate (0.59, 1.17) glucose (0.22,
3.15) and succinate (0.76, 0.91). Growth profile and kinetic
analysis clearly demonstrated that CSV86 utilized aromatic
compounds and organic acids faster than glucose. The
observed m and doubling time values on glucose for strains
S. maltophilia CSV89 and P. putida KT2442 were 0.52 and
1.33; and 0.55 and 1.26, respectively, indicating that strain
CSV86 utilizes glucose at a lower rate.
To elucidate the glucose metabolic pathway, O2 uptake
and enzyme activity studies were carried out. Strain CSV86
FEMS Microbiol Lett 259 (2006) 311–316
0.01
0
5
10
15
Time (h)
20
25
Fig. 2. Growth profile of Pseudomonas putida CSV86 on naphthalene
( ), salicylate (,), benzyl alcohol (&), benzoate (}), glucose (n) and
succinate ( ).
grown on glucose showed O2 uptake with glucose but failed
to respire on gluconate and 2-ketogluconate. Naphthaleneand succinate-grown cells showed poor O2 uptake when
incubated with glucose. Strains CSV89 and KT2442 showed
O2 uptake in the presence of glucose, gluconate and 2ketogluconate (Table 1). These results suggest that, unlike
the other strains, CSV86 does not have the ability to
metabolize gluconate and 2-ketogluconate. These observations were supported by measurements of enzyme activities
and analysis of the products formed during metabolism of
glucose. Specific activities for various enzymes involved in
glucose metabolism are depicted in Table 2. Cell-free extracts prepared from all three strains showed activity of Zwf.
Compared with glucose-, succinate- and naphthalenegrown cells of CSV86 showed five- to six-fold lower activity
of Zwf, suggesting that the enzyme is inducible. Strain
CSV86 showed activity of glucose oxidase but failed to show
activity of gluconate oxidase, while strains CSV89 and
KT2442 showed activity for both enzymes. TLC analysis of
metabolites produced during metabolism of glucose by
CSV86 detected very little gluconate and no 2-ketogluconate; however, strains CSV89 and KT2442 showed spots
corresponding to gluconate (Rf 0.18, light blue) and 2ketogluconate (Rf 0.18, dark brown), data not shown.
Therefore, TLC analysis, whole-cell respiration and enzyme
activity studies suggest that CSV86 does not metabolize
glucose via gluconate and 2-ketogluconate, thus indicating
the absence of the direct oxidative pathway. However, the
presence of Zwf activity suggests that CSV86 utilizes glucose
by the phosphorylative pathway. Based on these results, the
proposed pathway for glucose metabolism in P. putida
CSV86 is shown in Fig. 1b. In strains CSV89 and KT2442,
both the phosphorylative and direct oxidative pathways
appear to be operational for glucose metabolism (Fig. 1a).
To study glucose transport, [14C]glucose uptake by cells
grown under different conditions was monitored. Glucose2006 Federation of European Microbiological Societies
Published by Blackwell Publishing Ltd. All rights reserved
c
314
A. Basu and P.S. Phale
Table 1. Oxygen uptake rates with various substrates for Pseudomonas putida CSV86, Stenotrophomonas maltophilia CSV89 and P. putida KT2442
O2 uptake rates (nmol min1 mg1)
Pp CSV86w
Sm CSV89z
Pp KT2442‰
Substrate
Glcz
Naph
Suc
Glc
Glc
Glucose
Gluconate
2-Ketogluconate
2.31
ND
ND
0.4
NDk
ND
0.3
ND
ND
4.93
0.78
0.37
4.12
4.61
1.0
Oxygen uptake has been corrected for endogenous cell respiration.
w
P. putida CSV86.
S. maltophilia CSV89.
‰
P. putida KT2442.
z
Cells were grown on: Naph, Naphthalene; Glc, Glucose; Suc, Succinate.
k
ND, not detected by this method.
z
Table 2. Specific activities of glucose metabolizing enzymes in Pseudomonas putida CSV86 grown on naphthalene (0.1%) and glucose (0.25%), and
Stenotrophomonas maltophilia CSV89 and P. putida KT2442 grown on glucose (0.25%)
Specific activity (nmol min1 mg1 protein)
Pp CSV86
Enzyme
Naph
Glc
Suc
Sm CSV89
Pp KT2442
Glucose oxidase
Gluconate oxidase
Glucose-6-phosphate dehydrogenase (Zwf)
13
ND
14
15.7
ND
63.4
14
ND
11
17.1
285.9
95.1
16
25
170
grown CSV86 cells showed high rates of glucose uptake (Fig.
3). Addition of sodium azide (25 mM) after 1 min, inhibited
glucose uptake, and cells preincubated for 10 min with
sodium azide (25 mM) or formaldehyde (25 mM) did not
show any uptake. These results demonstrate that glucose
uptake in CSV86 is by active transport. Cells grown on
succinic acid or naphthalene alone showed very low glucose
uptake compared with glucose-grown cells. Similar results
were observed when cells were grown on benzyl alcohol or
pyruvate (data not shown). These results suggest that
glucose transport in CSV86 is suppressed when cells are
grown on organic acids or aromatic compounds.
Metabolic studies clearly demonstrated that glucose is
metabolized in P. putida CSV86 by the phosphorylative
pathway and not by the direct oxidative pathway. It has been
shown that pseudomonads sequester glucose as gluconate
and under glucose limitation conditions gluconate is utilized as the carbon source (Schleissner et al., 1997). However, this is not the case with strain CSV86 as it failed to
accumulate gluconate in the medium, and did not utilize
it as a carbon source. Although a very small amount of
gluconate was formed during glucose metabolism, the
inability to utilize it as the carbon source could be due to
either lack of gluconate transport or gluconate metabolizing
enzymes, or both. CSV86 utilizes glucose at slower rate
2006 Federation of European Microbiological Societies
Published by Blackwell Publishing Ltd. All rights reserved
c
[14C]Glucose uptake (pmol)
ND, not detected.
30
20
10
0
0
5
10
15
20
Time (min)
25
30
35
Fig. 3. [14C]Glucose uptake by Pseudomonas putida CSV86 cells grown
on naphthalene ( ), succinate (,) and glucose (&). Inhibition of
[14C]glucose uptake was observed when cells were exposed to sodium
azide (25 mM) after one min (arrow,B) or pretreated for 10 min with
sodium azide (25 mM, ) or formaldehyde (25 mM, %).
compared with aromatic compounds and organic acids. The
slow utilization of glucose may be due to regulation of
glucose metabolizing enzymes and/or the transport process.
In strain CSV86 the activity of Zwf was found to be
inducible; five- to six-fold higher activity was observed when
cells were grown on glucose compared with naphthalene and
FEMS Microbiol Lett 259 (2006) 311–316
315
Glucose metabolism in P. putida CSV86
succinate. The Zwf activity was 35% and 65% lower in
CSV86 compared with strains CSV89 and KT2442, respectively. As reported for other pseudomonads (Midgley &
Dawes, 1973), glucose transport in CSV86 was sensitive to
sodium azide and formaldehyde demonstrating the active
transport of glucose, while significantly reduced glucose
uptake by cells grown on aromatic compounds and organic
acid indicates that this transport system is also inducible.
Based on these results, we conclude that in P. putida CSV86
the metabolism of glucose is regulated at least at enzyme and
transport level. The absence of the direct oxidative pathway
and the low activity of Zwf in CSV86 may be responsible for
the slow growth rate on glucose. Few strains have been
previously reported to have only the phosphorylative pathway or to be defective in glucose metabolism (Lessie &
Phibbs, 1984).
It has been reported that glucose and organic acid repress
the utilization of various aromatic compounds by pseudomonads (Holtel et al., 1994; Schleissner et al., 1994; Muller
et al., 1996; Rentz et al., 2004) and attempts have been made
to improve the utilization of aromatic compounds in the
presence of glucose by conjugal transfer of naphthalene and
salicylate degradation genes into P. putida strains generated
by mutagenesis which are deficient in glucose metabolism
(Samanta et al., 2001). Such strains would utilize aromatic
compounds with a higher specific growth rate compared
with glucose and hence would be an asset for bioremediation. However, the viability of such strains in the environment is not known. Pseudomonas putida CSV86 is a natural
isolate and grows on aromatic compounds with a higher
specific growth rate than on glucose. It also showed a
preference for aromatic compounds over glucose and cometabolizes aromatic compounds and organic acids (Basu
et al., 2006). These unique properties, coupled with further
characterization and subtle modification, may make this
strain a potential candidate for bioremediation and environmental clean up.
Acknowledgements
A. B. thanks the University Grants Commission, India for
the award of a senior research fellowship.
References
Alexander M (1981) Biodegradation of chemicals of
environmental concern. Science 211: 132–138.
Basu A, Dixit SS & Phale PS (2003) Metabolism of benzyl alcohol
via catechol ortho-pathway in methylnaphthalene-degrading
Pseudomonas putida CSV86. Appl Microbiol Biotechnol 62:
579–585.
FEMS Microbiol Lett 259 (2006) 311–316
Basu A, Apte SK & Phale PS (2006) Preferential utilization of
aromatic compounds over glucose by Pseudomonas putida
CSV86. Appl Environ Microbiol 72: 2226–2230.
Collier DN, Hager PW & Phibbs PV Jr (1996) Catabolite
repression control in the Pseudomonads. Res Microbiol 147:
551–561.
Duetz WA, Marques S, de JC, Ramos JL & van Andel JG (1994)
Inducibility of the TOL catabolic pathway in Pseudomonas
putida (pWW0) growing on succinate in continuous culture:
evidence of carbon catabolite repression control. J Bacteriol
176: 2354–2361.
Eisenberg RC, Butters SJ, Quay SC & Friedman SB (1974)
Glucose uptake and phosphorylation in Pseudomonas
fluorescens. J Bacteriol 120: 147–153.
Entner N & Doudoroff M (1952) Glucose and gluconic acid
oxidation of Pseudomonas saccharophila. J Biol Chem 196:
853–862.
Guymon LF & Eagon RG (1974) Transport of glucose, gluconate,
and methyl alpha-D-glucoside by Pseudomonas aeruginosa.
J Bacteriol 117: 1261–1269.
Holtel A, Marques S, Mohler I, Jakubzik U & Timmis KN (1994)
Carbon source-dependent inhibition of xyl operon expression
of the Pseudomonas putida TOL plasmid. J Bacteriol 176:
1773–1776.
Lessie TG & Neidhardt FC (1967) Formation and operation of the
histidine-degrading pathway in Pseudomonas aeruginosa.
J Bacteriol 93: 1800–1810.
Lessie TG & Phibbs PV Jr (1984) Alternative pathways of
carbohydrate utilization in pseudomonads. Annu Rev
Microbiol 38: 359–388.
Lessie TG, Berka T & Zamanigian S (1979) Pseudomonas cepacia
mutants blocked in the direct oxidative pathway of glucose
degradation. J Bacteriol 139: 323–325.
Lessmann D, Schimz KL & Kurz G (1975) D-glucose-6-phosphate
dehydrogenase (Entner–Doudoroff enzyme) from
Pseudomonas fluorescens. Purification, properties and
regulation. Eur J Biochem 59: 545–559.
Lowry OH, Rosebrough NJ, Farr AL & Randall RJ (1951) Protein
measurement with the Folin phenol reagent. J Biol Chem 193:
265–275.
Mahajan MC, Phale PS & Vaidyanathan CS (1994) Evidence for
the involvement of multiple pathways in the biodegradation of
1- and 2-methylnaphthalene by Pseudomonas putida CSV86.
Arch Microbiol 161: 425–433.
Matsushita K & Ameyama M (1982) D-Glucose dehydrogenase
from Pseudomonas fluorescens, membrane-bound. Methods
Enzymol 89: 149–154.
Matsushita K, Shinagawa E & Ameyama M (1982) D-Gluconate
dehydrogenase from bacteria, 2-keto-D-gluconate-yielding,
membrane-bound. Methods Enzymol 89: 187–193.
McFall SM, Abraham B, Narsolis CG & Chakrabarty AM (1997)
A tricarboxylic acid cycle intermediate regulating transcription
of a chloroaromatic biodegradative pathway: fumaratemediated repression of the clcABD operon. J Bacteriol 179:
6729–6735.
2006 Federation of European Microbiological Societies
Published by Blackwell Publishing Ltd. All rights reserved
c
316
Midgley M & Dawes EA (1973) The regulation of transport of
glucose and methyl alpha-glucoside in Pseudomonas
aeruginosa. Biochem J 132: 141–154.
Muller C, Petruschka L, Cuypers H, Burchhardt G & Herrmann
H (1996) Carbon catabolite repression of phenol degradation
in Pseudomonas putida is mediated by the inhibition of the
activator protein PhlR. J Bacteriol 178: 2030–2036.
Phale PS, Mahajan MC & Vaidyanathan CS (1995) A pathway for
biodegradation of 1-naphthoic acid by Pseudomonas
maltophilia CSV89. Arch Microbiol 163: 42–47.
Pujol CJ & Kado CI (2000) Genetic and biochemical
characterization of the pathway in Pantoea citrea leading to
pink disease of pineapple. J Bacteriol 182: 2230–2237.
Quay SC, Friedman SB & Eisenberg RC (1972) Gluconate
regulation of glucose catabolism in Pseudomonas fluorescens.
J Bacteriol 112: 291–298.
Rentz JA, Alvarez PJ & Schnoor JL (2004) Repression of
Pseudomonas putida phenanthrene-degrading activity by plant
root extracts and exudates. Environ Microbiol 6: 574–583.
Roberts BK, Midgley M & Dawes EA (1973) The metabolism of
2-oxogluconate by Pseudomonas aeruginosa. J Gen Microbiol
78: 319–329.
Samanta SK, Bhushan B & Jain RK (2001) Efficiency of
naphthalene and salicylate degradation by a recombinant
2006 Federation of European Microbiological Societies
Published by Blackwell Publishing Ltd. All rights reserved
c
A. Basu and P.S. Phale
Pseudomonas putida mutant strain defective in glucose
metabolism. Appl Microbiol Biotechnol 55: 627–631.
Schleissner C, Olivera ER, Fernandez-Valverde M & Luengo JM
(1994) Aerobic catabolism of phenylacetic acid in
Pseudomonas putida U: biochemical characterization of a
specific phenylacetic acid transport system and formal
demonstration that phenylacetyl-coenzyme A is a catabolic
intermediate. J Bacteriol 176: 7667–7676.
Schleissner C, Reglero A & Luengo JM (1997) Catabolism of
D-glucose by Pseudomonas putida U occurs via extracellular
transformation into D-gluconic acid and induction of a
specific gluconate transport system. Microbiology 143:
1595–1603.
Sly LM, Worobec EA, Perkins RE & Phibbs PV Jr (1993)
Reconstitution of glucose uptake and chemotaxis in
Pseudomonas aeruginosa glucose transport defective mutants.
Can J Microbiol 39: 1079–1083.
Tiwari NP & Campbell JJ (1969) Enzymatic control of the
metabolic activity of Pseudomonas aeruginosa grown in glucose
or succinate media. Biochim Biophys Acta 192: 395–401.
Worsey MJ & Williams PA (1975) Metabolism of toluene
and xylenes by Pseudomonas (putida (arvilla) mt-2): evidence
for a new function of the TOL plasmid. J Bacteriol 124:
7–13.
FEMS Microbiol Lett 259 (2006) 311–316