Effect of pps disruption and constitutive expression of srfA on surfactin productivity, spreading and antagonistic properties of Bacillus subtilis 168 derivatives.
OBJECTIVE
To analyse the effects of plipastatin operon disruption and constitutive expression of surfactin operon in Bacillus subtilis 168 on surfactin productivity, in vitro invasive growth and antagonism against fungi.


RESULTS
The srfA native promoter was replaced by the constitutive promoter P(repU) in B. subtilis 168 after integration of a functional sfp gene. Moreover, the plipastatin synthesis was further disrupted in the B. subtilis 168 derivatives. In liquid media, an earlier and higher expression of P(repU), than that found with P(srfA), led to a specific surfactin production fivefold higher after 6 h of culture. On solid media, not only the invasive growth and the haemolytic activity but also the antifungal activity of the constitutive strains were improved when compared to the parental strain BBG111. As expected, the disruption of the plipastatin operon strongly reduced in vitro antifungal properties but, interestingly, enhanced specific surfactin production (1.47 g g(-1) of biomass), spreading behaviour and haemolytic activity of the strains.


CONCLUSIONS
This work demonstrates for the first time the interdependency of surfactin and plipastatin regarding their biosynthesis as well as their influence on the biological activities of the producing strain.


CONCLUSIONS
The constitutive overproduction of surfactin enhances the invasive growth and the in vitro antagonistic activity of the mutant strain. Both properties are known to play an important role in the biocontrol of plant diseases. Plipastatin operon disruption increases the surfactin productivity of mutant strains. These mutants are interesting for use in continuous bioprocesses for surfactin production or in bioremediation.
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Coutte
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Leclère
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Béchet
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Guez
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Lecouturier
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Chollet-Imbert
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Dhulster
Laboratoire de Procédés Biologiques, Génie Enzymatique et Microbien (ProBioGEM, UPRES EA 1026), Polytech'Lille, IUT A, Université des Sciences et Technologies de Lille, Boulevard Paul, Villeneuve d'Ascq Cedex, France.
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Jacques
D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis*; D005658:Fungi / Q000254:growth & development; D055666:Lipopeptides / Q000096:biosynthesis*; D056265:Microbial Interactions; D009842:Oligopeptides / Q000096:biosynthesis*; D009876:Operon; D010456:Peptides, Cyclic / Q000096:biosynthesis*
D005227:Fatty Acids; D055666:Lipopeptides; D009842:Oligopeptides; D010456:Peptides, Cyclic; C049901:plipastatin; C009365:surfactin peptide