Previous Article | Next Article 
Journal of Bacteriology, February 2002, p. 853-856, Vol. 184, No. 3
0021-9193/01/$04.00+0 DOI: 10.1128/JB.184.3.853-856.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Evidence for a Fourth Hydrogenase in Desulfovibrio fructosovorans
Laurence Casalot,1,2 Gilles De Luca,3 Zorah Dermoun,1,4 Marc Rousset,1 and Pascale de Philip1,4*
Laboratoire de Bioénergétique et Ingénierie des Protéines, UPR 9036-CNRS, 13402 Marseille Cedex 09,1
Département dEcophysiologie Végétale et de Microbiologie, CEA/Cadarache, 13108 Saint-Paul-lez-Durance Cedex,3
Université de Provence, 13331 Marseille Cedex 03,4
Laboratoire de Microbiologie, IRD, ESIL, 13288 Marseille Cedex 09, France2
Received 9 April 2001/
Accepted 24 October 2001

ABSTRACT
A strain devoid of the three hydrogenases characterized for
Desulfovibrio fructosovorans was constructed using marker exchange
mutagenesis. As expected, the H
2-dependent methyl viologen reduction
activity of the strain was null, but physiological studies showed
no striking differences between the mutated and wild-type strains.
The H
+-D
2 exchange activity measured in the mutated strain indicates
the presence of a fourth hydrogenase in
D. fructosovorans.

INTRODUCTION
Molecular hydrogen plays an important role in the energy-generating
metabolism of sulfate reducers belonging to the genus
Desulfovibrio. Desulfovibrio species can alternatively utilize hydrogen as
the sole source of electron and energy (
2,
3) or can produce
hydrogen when growing fermentatively on a suitable carbon source
in the absence of sulfate as an electron acceptor (
17). Furthermore,
hydrogen is successively produced and consumed during the degradation
of organic compounds in the presence of sulfate (
7,
22,
23).
It has not yet been established whether hydrogen plays only
a role in the regulation of the redox state of the electron
transfer chains (
11) or a central role as a key intermediate
in the electron transfer across the membrane (
14,
15). Hydrogenases
are the key enzymes of energy-generating metabolism because
of their ability to catalyze the splitting or the synthesis
of molecular hydrogen. The number (generally more than one),
the type ([Fe], [NiFe], or [NiFeSe] on the basis of their metal
contents), and the cellular location of hydrogenases vary considerably
from one
Desulfovibrio species to another (
6,
25). This diversity
makes the role of these various hydrogenases difficult to determine.
With the aim to study the role of hydrogenases in Desulfovibrio, we chose D. fructosovorans DSM 3604 (16) as a model. In this species, three hydrogenases have been already characterized: a periplasmic [NiFe] hydrogenase which represents about 1% of the total proteins (8, 20), a cytoplasmic NADP-reducing hydrogenase (13), and a periplasmic [Fe] hydrogenase (4). In order to elucidate the relative importance of these various hydrogenases in the energy-generating metabolism of D. fructosovorans, deletions were first made by marker exchange mutagenesis of the genes encoding the [NiFe] hydrogenase (19) and the NADP-reducing hydrogenase (12). All mutants (single or double) showed significant growth on organic substrates as well as on medium containing H2 as the sole energy source.

Construction and molecular characterization of a triple mutant depleted of all three hydrogenases.
In order to perform the marker exchange experiment, a 5-kb fragment
containing the two structural genes (
hydAB) coding for the [Fe]
hydrogenase of
D. fructosovorans (obtained by PCR amplification
performed on genomic DNA by using oligonucleotides 1 [5'-AAACGGCGACGCCGTGGTCGGCAAGGTCAA-3']
and 2 [5'-CGATGTCGGTGCCCGGATATTT-3']) was cloned in pMosblue-T-vector
(Amersham) to give the recombinant plasmid pMBE9 (Fig.
1). A
1.3-kb fragment containing the gentamicin resistance gene (
acc1)
was obtained by PCR amplification performed on pML122 (
10),
using two oligonucleotides, one introducing a
BspEI restriction
site (in boldface) (Gm 1, 5'-TTAAA
TCCGGATGAAGGCACGAACCCAGTT-3')
and one located downstream from the
BstEII restriction site
(Gm 2, 5'-GACGCTTAGCACCTCTGATAGTT-3'). The amplification product
was digested with
BstEII and
BspEI and cloned into pMBE9 with
a deletion of the
BstEII-
BspEI fragment containing
hydAB, to
give pE9Gm (Fig.
1). This recombinant suicide plasmid was introduced
into the DM4 strain (
hynABC Kan
r;
hndD Cm
r) (
12) depleted of
the [NiFe] and NADP-reducing hydrogenases, using an electrotransformation
procedure as previously described (
19). The electrotransformed
cells were first grown for 6 h without any antibiotics and then
subcultured in the presence of antibiotics (50 µg of kanamycin
ml
-1, 34 µg of thiamphenicol ml
-1, and 20 µg of
gentamicin ml
-1) in liquid medium. The start of growth was observed
within 2 weeks. Afterwards, recombinant cultures were isolated
on plates under the anaerobic atmosphere of a glove box (N
2-H
2,
95:5 [vol/vol]) and incubated in hyperbaric (2
x 10
5 Pa) (N
2-CO
2,
80:20 [vol/vol]) anaerobic jars. The genotype of the isolated
gentamicin-resistant strain, called TM4, was then analyzed by
Southern blot hybridization.
The blot of total DNA digested with
EcoRI and
BglII was first
hybridized with a DNA fragment encompassing the majority of
the
hydA gene (probe A) (Fig.
2A). After removal of the probe,
the blot was subsequently hybridized with the
acc1 gene (probe
B) (Fig.
2B). The pMBE9 and pE9Gm plasmids digested with
BspEI
(unique restriction site) were used as controls with the two
probes. Restriction analysis of the region containing the wild-type
hydAB genes revealed the existence of one
EcoRI site and two
BglII sites, producing three fragments (0.65, 0.8, and 1 kb)
which specifically hybridized with probe A (Fig.
1). The hybridization
pattern of the genomic DNA from wild-type
D. fructosovorans showed the 0.8- and 0.65-kb bands (Fig.
2A). The absence of
the 1-kb band can be explained by the very short sequence (52
bp) of this fragment hybridizing with probe A. In strain TM4,
the replacement of
hydAB by
acc1 leads to the loss of one
EcoRI
site and one
BglII site (Fig.
1). Thus, a 1.3-kb fragment should
hybridize with probe A. The hybridization pattern of genomic
DNA from the TM4 strain (Fig.
2A) showed that a double crossing
over, rather than a single crossing over event, occurred. With
probe B (Fig.
2B), two bands (1.3 and 2.2 kb) were revealed
in the genomic DNA of the mutated strain TM4. Indeed, one
BglII
restriction site is located in the middle of the gentamicin
resistance reporter gene (Fig
1). As expected, pE9Gm hybridized
specifically with probe B, and neither the genomic DNA from
wild-type
D. fructosovorans nor the pMBE9 plasmid was detected.
The results of the Southern blot experiments demonstrated that
the
hydAB genes were deleted and replaced by the
acc1 gene.
The TM4 mutant obtained is
hydAB Gm
r in addition to the
hynABC Km
r and
hndD Tm
r of the primary DM4 strain.

Methyl viologen reduction activity of the triple mutant.
Hydrogenase activity in
D. fructosovorans is usually determined
by measurement of hydrogen-dependent methyl viologen reduction
activity in soluble cellular extract obtained from cultures
grown on a 30 mM fructose50 mM sulfate medium (
4,
5,
12,
19). The presence of the hydrogenase activities in the
D. fructosovorans strains was tested in native polyacrylamide gel
electrophoresis (Fig.
3). None of the three hydrogenase activities
which are observed in the wild-type strain were visualized in
the TM4 soluble cellular extract. In addition, total methyl
viologen reduction activities measured in soluble cellular extracts
of different strains are given in Table
1. As expected, no hydrogenase
activity was detected in the TM4 strain by using methyl viologen
as a redox mediator.
Complementation experiments were performed by cloning
hydAB in shuttle vectors harboring chloramphenicol or streptomycin
resistance (
18). A synthetic linker (5'-
AGCTTGGCCGGCCCTGCA-3'/5'-
GGGCCGGCCA-3'),
designed to introduce an
FseI (boldface) site between the polylinker
PstI (italics) and
HindIII (underlined) sites, was cloned into
plasmid pBMC6 digested with
PstI and
HindIII (
18) to give the
recombinant plasmid pC6Fse. A 2.6-kb
BbrPI/
FseI fragment from
pMBE9 containing
hydAB was cloned in pC6Fse digested with
SmaI
and
FseI. This recombinant plasmid, pC6HF, was used to construct
pS7HF. A 2.7-kb
HindIII/
Asp718 fragment of pC6HF containing
hydAB was blunted using Klenow enzyme (Roche Molecular Biochemicals)
and cloned into the
SmaI-digested pBMS7 plasmid harboring the
streptomycin resistance gene (
18). Electrotransformation of
the TM4 strain was performed with the replicative pS7HF plasmid,
and transformant TM4(pS7HF) colonies were isolated in medium
containing 50 µg of kanamycin ml
-1, 34 µg of thiamphenicol
ml
-1, 20 µg of gentamicin ml
-1, and 300 µg of streptomycin
ml
-1. On a native gel with soluble cellular extracts prepared
from the TM4(pS7HF) strain, a unique hydrogenase activity corresponding
to the [Fe] hydrogenase was revealed (Fig.
3).

Physiological studies.
Growth parameters of the wild-type and mutated strains were
determined on fructose-sulfate medium as previously described
(Table
2) (
12). High-pressure liquid chromatography (Bio-Rad
Aminex Fast Acid Analysis HPAH column) analysis of the metabolism
products in the culture medium did not give any evidence of
intermediate accumulation or that an alteration in the metabolism
had occurred during the growth of the mutant strain compared
to the wild-type strain (data not shown). Fructose was completely
oxidized into acetate and CO
2. The growth rate and the molar
growth yield of strain TM4 were lower than those of the wild-type
strain (Table
2), but surprisingly, no striking differences
were observed compared to the results obtained in previous studies
with the double mutant strain DM4 (
12). Thus, the depletion
of three hydrogenases did not have more of an effect on energy-generating
metabolism than the depletion of two hydrogenases. It is possible
to assume that the [Fe] hydrogenase is not necessary for growth
on fructose-sulfate medium.
The wild-type and TM4 strains were grown mixotrophically on
medium containing H
2 as the sole energy source, 50 mM acetate
and CO
2 as carbon sources, and 20 mM sulfate as a terminal electron
acceptor. Under these conditions (cultures were gassed periodically
with H
2-CO
2 [80:20, vol/vol] at a pressure of 2
x 10
5 Pa), the
growth was linear rather than exponential (Fig.
4), which prevented
us from determining the growth rates. Surprisingly, except for
a slower growth at the beginning, the kinetics of the mutated
strain was quite similar to those of the wild type and DM4.
In all cases, the growth stopped when sulfate was exhausted,
and the molar growth yields relative to sulfate were found to
be 6.17 ± 0.74 g mol
-1, 6.05 ± 0.3 g mol
-1, and
5.48 ± 0.73 g mol
-1 for the wild-type, DM4, and TM4 strains,
respectively. This growth, with H
2 as the sole electron donor,
can be explained only by the presence of an enzyme able to split
the H
2 molecule, i.e., a fourth hydrogenase.

Search for a remaining hydrogenase activity in the triple mutant.
The proton-deuterium (H
+-D
2) exchange reaction in whole-cell
suspensions was measured by a mass spectrometric method (
9).
Cells were grown in 20 mM fructose20 mM fumarate medium
to an optical density at 600 nm of 1.3. Fumarate, rather than
sulfate, was used to prevent formation of sulfur precipitates.
Argon was bubbled in the reaction vessel filled with 1 ml of
50 mM Tris-HCl (pH 8) until saturation to eliminate the majority
of O
2, and then 0.5 ml of the culture was added to the reaction
vessel and D
2 was bubbled until saturation. Changes in concentrations
of gases (D
2, HD, H
2, and O
2) were automatically scanned and
recorded immediately after the vessel was closed, as described
previously (
24). Production of H
2 and HD was used to calculate
the exchange activity. The results presented in Table
1 show
that an exchange reaction occurred in the triple mutant strain
(TM4), which was about 10-fold lower than that in the wild-type
strain but equivalent to the activity measured in the double
mutant strain (DM4).
As methyl viologen reduction activity was null for soluble cellular extracts of the TM4 strain grown on fructose-sulfate medium and H+-D2 exchange activity could be measured in whole cells of the same strain grown on fructose-fumarate medium (Table 1), we measured methyl viologen reduction in cultures grown on fructose-fumarate medium. Results obtained with whole-cell suspensions and soluble cellular extracts were quite similar (data not shown). Interestingly, a significant methyl viologen reduction activity was measured in the triple mutant TM4, representing 4% of the wild-type activity (Table 1). Thus, H+-D2 exchange activity and methyl viologen reduction activity in cells grown on fructose-fumarate indicated the presence of a fourth hydrogenase in D. fructosovorans. This activity was not seen in strain TM4 grown on fructose-sulfate medium. Thus, it can be assumed that the induction or the derepression of a gene encoding a fourth hydrogenase occurred when TM4 was cultivated in fructose-fumarate medium. In this medium, the metabolism of the bacteria is mostly fermentative, as the amount of exogenous fumarate (electron acceptor) is limiting. Thus, the energy-generating metabolism may be quite different than that in fructose-sulfate medium. It is possible to assume that the fermentative growth has induced the expression of one enzyme presenting an hydrogenase activity in order to dispose of an excess of reducing power. On the other hand, this hydrogenase is likely to be responsible for the growth on H2 as a sole energy source.
The presence of multiple hydrogenases in bacteria is relatively widespread. Escherichia coli possesses four hydrogenases (1). In D. vulgaris, three hydrogenases of different types have been characterized ([Fe], [NiFe], and [NiFeSe]) (6), and a gene encoding a potential fourth one has been isolated (21). Thus, it is not surprising for D. fructosovorans to possess a fourth hydrogenase activity. The enzyme responsible for the fourth hydrogenase activity may be a cryptic hydrogenase induced to compensate for the mutations. Alternatively, we cannot rule out the possibility that this enzyme might not be a typical hydrogenase but might be an enzyme exhibiting this activity under particular conditions.

ACKNOWLEDGMENTS
We gratefully acknowledge Odile Valette for technical help,
Bernard Dimon and Patrick Carrier for the mass spectrometric
measurements, the Laboratoire des Champignons Filamenteux (INRA)
for access to the high-pressure liquid chromatograph, and Jean-Pierre
Belaïch for help and support.

FOOTNOTES
* Corresponding author. Mailing address: BIP-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 09, France. Phone: 33 (0)4 91 16 43 40. Fax: 33 (0)4 91 71 33 21. E-mail:
dephilip{at}ibsm.cnrs-mrs.fr.


REFERENCES
1
- Andrews, S. C., B. C. Berks, J. McClay, A. Ambler, M. A. Quail, P. Golby, and J. R. Guest. 1997. A 12-cistron Escherichia coli operon (hyf) encoding a putative proton-translocating formate hydrogenlyase system. Microbiology 143:36333647.[Abstract/Free Full Text]
2
- Badziong, W., R. K. Thauer, and J. G. Zeikus. 1978. Isolation and characterization of Desulfovibrio growing on hydrogen plus sulfate as the sole energy source. Arch. Microbiol. 116:4149.[CrossRef][Medline]
3
- Brandis, A., and R. K. Thauer. 1981. Growth of Desulfovibrio species on hydrogen and sulfate as sole energy source. J. Gen. Microbiol. 126:249252.
4
- Casalot, L., C. E. Hatchikian, N. Forget, P. de Philip, Z. Dermoun, J. P. Bélaïch, and M. Rousset. 1998. Molecular study and partial characterization of iron-only hydrogenase in Desulfovibrio fructosovorans. Anaerobe 4:4555.
5
- De Luca, G., P. de Philip, M. Rousset, J. P. Belaïch, and Z. Dermoun. 1998. The NADP-reducing hydrogenase of Desulfovibrio fructosovorans: evidence for a native complex with hydrogen-dependent methyl viologen-reducing activity. Biochem. Biophys. Res. Commun. 248:591596.[CrossRef][Medline]
6
- Fauque, G., H. D. Peck, Jr., J. J. Moura, B. H. Huynh, Y. Berlier, D. V. Der Vartanian, M. Teixeira, A. E. Przybyla, P. A. Lespinat, and I. Moura. 1988. The three classes of hydrogenases from sulfate-reducing bacteria of the genus Desulfovibrio. FEMS Microbiol. Rev. 4:299344.[Medline]
7
- Hatchikian, E. C., M. Chaigneau, and J. Le Gall. 1976. Analysis of gas production by growing culture of the three species of sulfate-reducing bacteria, p.109118. In H. G. Schlegel, G. Gottschalk, and N. Pfenning (ed.), Microbial production and utilization of gases. Goltza, K. G., Göttingen, Germany.
8
- Hatchikian, E. C., S. A. Traore, M. Fernandez, and R. Cammack. 1990. Characterization of the nickel-iron periplasmic hydrogenase from Desulfovibrio fructosovorans. Eur. J. Biochem. 187:635643.[Medline]
9
- Jouanneau, Y., B. C. Kelley, Y. Berlier, P. A. Lespinat, and P. Vignais. 1980. Continuous monitoring, by mass spectrometry, of H2 production and recycling in Rhodopseudomonas capsulata. J. Bacteriol. 143:628636.[Abstract/Free Full Text]
10
- Labes, M., A. Pühler, and R. Simon. 1990. A new family of RSF1010-derived expression and lac-fusion broad-host-range vectors for Gram-negative bacteria. Gene 89:3746.[CrossRef][Medline]
11
- Lupton, F. S., R. Conrad, and J. G. Zeikus. 1984. Physiological function of hydrogen metabolism during growth of sulfidogenic bacteria on organic substrates. J. Bacteriol. 159:843849.[Abstract/Free Full Text]
12
- Malki, S., G. De Luca, M. L. Fardeau, M. Rousset, J. P. Bélaïch, and Z. Dermoun. 1997. Physiological characteristics and growth behavior of single and double hydrogenase mutants of Desulfovibrio fructosovorans. Arch. Microbiol. 167:3845.[CrossRef][Medline]
13
- Malki, S., I. Saimmaime, G. De Luca, M. Rousset, Z. Dermoun, and J. P. Bélaïch. 1995. Characterization of an operon encoding an NADP-reducing hydrogenase in Desulfovibrio fructosovorans. J. Bacteriol. 177:26282636.[Abstract/Free Full Text]
14
- Noguera, D. R., G. A. Brusseau, B. E. Rittmann, and D. A. Stahl. 1998. A unified model describing the role of hydrogen in the growth of Desulfovibrio vulgaris under different environmental conditions. Biotechnol. Bioeng. 59:733746.
15
- Odom, J. R., and H. D. Peck, Jr. 1981. Hydrogen cycling as a general mechanism for energy coupling in the sulfate-reducing bacteria Desulfovibrio sp. FEMS Microbiol. Lett. 12:4750.[CrossRef]
16
- Ollivier, B., R. Cord-Ruwisch, E. C. Hatchikian, and J. L. Garcia. 1988. Characterization of Desulfovibrio fructosovorans sp. nov. Arch. Microbiol. 150:2631.[CrossRef]
17
- Postgate, J. R. 1952. Growth of sulfate-reducing bacteria in sulfate-free media. Research (London) 5:189190.
18
- Rousset, M., L. Casalot, B. J. Rapp-Giles, Z. Dermoun, P. de Philip, J. P. Bélaïch, and J. D. Wall. 1998. New shuttle vectors for the introduction of cloned DNA in Desulfovibrio. Plasmid 39:114122.[CrossRef][Medline]
19
- Rousset, M., Z. Dermoun, M. Chippaux, and J. P. Bélaïch. 1991. Marker exchange mutagenesis of the hydN genes in Desulfovibrio fructosovorans. Mol. Microbiol. 5:17351740.[CrossRef][Medline]
20
- Rousset, M., Z. Dermoun, C. E. Hatchikian, and J. P. Bélaïch. 1990. Cloning and sequencing of the locus encoding the large and small subunit genes of the periplasmic [NiFe] hydrogenase from Desulfovibrio fructosovorans. Gene 94:95101.[CrossRef][Medline]
21
- Stokkerman, J., W. van Dongen, A. Kaaa, W. van den Berg, and C. Veeger. 1989. hyd
, a gene from Desulfovibrio vulgaris (Hildenborough), encodes a polypeptide homologous to the periplasmic hydrogenase. FEMS Microbiol. Lett. 49:217222.[Medline]
22
- Traore, A. S., C. E. Hatchikian, J. P. Bélaïch, and J. Le Gall. 1981. Microcalorimetric studies of the growth of sulfate-reducing bacteria: energetics of Desulfovibrio vulgaris growth. J. Bacteriol. 154:101199.
23
- Tsuji, K., and T. Yagi. 1980. Significance of hydrogen burst from growing cultures of Desulfovibrio vulgaris Miyazaki and the role of hydrogenase and cytochrome c3 in energy production system. Arch. Microbiol. 125:3542.[CrossRef]
24
- Vignais, P. M., B. Dimon, N. A. Zorin, A. Colbeau, and S. Elsen. 1997. HupUV proteins of Rhodobacter capsulatus can bind H2: evidence from the H-D exchange reaction. J. Bacteriol. 179:290292.[Abstract/Free Full Text]
25
- Voordouw, G., V. Nivière, F. G. Ferris, P. M. Fedorak, and D. W. S. Westlake. 1990. Distribution of hydrogenase genes in Desulfovibrio spp. and their use in the identification of species from the oil field environment. Appl. Environ. Microbiol. 56:37483754.[Abstract/Free Full Text]
Journal of Bacteriology, February 2002, p. 853-856, Vol. 184, No. 3
0021-9193/01/$04.00+0 DOI: 10.1128/JB.184.3.853-856.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Mikheenko, I. P., Rousset, M., Dementin, S., Macaskie, L. E.
(2008). Bioaccumulation of Palladium by Desulfovibrio fructosivorans Wild-Type and Hydrogenase-Deficient Strains. Appl. Environ. Microbiol.
74: 6144-6146
[Abstract]
[Full Text]