**3.2 Identification and surfactant properties of viscosin and massetolide E produced by** *Pseudomonas sp***. PDD-14b-2**

Two biosurfactants issued from the culture of a cloud bacterium *Pseudomonas* sp. PDD-14b-2 were purified using an Amberlite column and a puriFlash® system. The structure of these biosurfactants was identified as that of cyclic lipopeptides (viscosin and massetolide E) using high-resolution LC-MS/MS. **Figure 1A** presents the ESI-MS-MS spectrum of viscosin, the details of the fragmentation of this molecule are shown in **Figure 1B** and **C**.

Viscosin gave a ([M + H]<sup>+</sup> ) protonated molecule at m/z 1126.699 (theoretical m/z 1126.697) appropriate for a molecular formula of C54H95N9O16 (monoisotopic mass is 1125.69 g.mol<sup>−</sup><sup>1</sup> ).

**Figure 1.**

*(A) ESI-MS/MS (collision-induced dissociation) spectrum of parent ion of viscosin (m/z 1126.699), (B) Chemical structure (fragments) for viscosin, (C) Identification of the fragments of viscosin. The Y1 fragment could be either isoleucine (I) or leucine (L).*

**79**

**Figure 2.**

*CMC = 25 mN.m<sup>−</sup><sup>1</sup>*

a valine instead of a leucine.

strains isolated from marine environment.

 *at 21.6 mg.L<sup>−</sup><sup>1</sup>*

*Cloud Microorganisms, an Interesting Source of Biosurfactants*

In the same way and with the same precision (observed mass: m/z 1112.684; theoretical mass: m/z 1112.682), we identified the massetolide E (C53H93N9O16) whose structure is rather similar to that of viscosin, the last amino acid fragment is

*; (B) Syringafactin B/C CMC = 25 mN.m<sup>−</sup><sup>1</sup>*

 *at 1.2 gL<sup>−</sup><sup>1</sup> .*

*Determination of the surface tension curve and CMC value of biosurfactants by the pendant drop technique. The red dot represents the initial crude extracts (consisting of the supernatants of the pure cultures). The black dots at lower concentrations are those obtained from successive dilutions. The blue dashed line represents the value for pure water, and red dashed lines illustrate the graphical determination of the CMC. (A) Viscosin* 

The synthesis of viscosin has been reported by other *Pseudomonas* strains including *P. syringae*, *P. tolaasii*, *P. fuscovaginae*, *P. corrugate*, *P. fluorescens*, *P. libanensis*, and *P. putida* [16, 42–45]. Massetolides whose structures are very closely

These high-resolution MS data are consistent with those obtained by Gerard [41] who isolated and identified massetolides A–H and viscosin from two *Pseudomonas*

*DOI: http://dx.doi.org/10.5772/intechopen.85621*

*Cloud Microorganisms, an Interesting Source of Biosurfactants DOI: http://dx.doi.org/10.5772/intechopen.85621*

#### **Figure 2.**

*Surfactants and Detergents*

is 1125.69 g.mol<sup>−</sup><sup>1</sup>

**3.2 Identification and surfactant properties of viscosin and massetolide E** 

Two biosurfactants issued from the culture of a cloud bacterium *Pseudomonas* sp. PDD-14b-2 were purified using an Amberlite column and a puriFlash® system. The structure of these biosurfactants was identified as that of cyclic lipopeptides (viscosin and massetolide E) using high-resolution LC-MS/MS. **Figure 1A** presents the ESI-MS-MS spectrum of viscosin, the details of the fragmentation of this

1126.697) appropriate for a molecular formula of C54H95N9O16 (monoisotopic mass

*(A) ESI-MS/MS (collision-induced dissociation) spectrum of parent ion of viscosin (m/z 1126.699), (B) Chemical structure (fragments) for viscosin, (C) Identification of the fragments of viscosin. The Y1*

) protonated molecule at m/z 1126.699 (theoretical m/z

**produced by** *Pseudomonas sp***. PDD-14b-2**

molecule are shown in **Figure 1B** and **C**. Viscosin gave a ([M + H]<sup>+</sup>

).

**78**

**Figure 1.**

*fragment could be either isoleucine (I) or leucine (L).*

*Determination of the surface tension curve and CMC value of biosurfactants by the pendant drop technique. The red dot represents the initial crude extracts (consisting of the supernatants of the pure cultures). The black dots at lower concentrations are those obtained from successive dilutions. The blue dashed line represents the value for pure water, and red dashed lines illustrate the graphical determination of the CMC. (A) Viscosin CMC = 25 mN.m<sup>−</sup><sup>1</sup> at 21.6 mg.L<sup>−</sup><sup>1</sup> ; (B) Syringafactin B/C CMC = 25 mN.m<sup>−</sup><sup>1</sup> at 1.2 gL<sup>−</sup><sup>1</sup> .*

In the same way and with the same precision (observed mass: m/z 1112.684; theoretical mass: m/z 1112.682), we identified the massetolide E (C53H93N9O16) whose structure is rather similar to that of viscosin, the last amino acid fragment is a valine instead of a leucine.

These high-resolution MS data are consistent with those obtained by Gerard [41] who isolated and identified massetolides A–H and viscosin from two *Pseudomonas* strains isolated from marine environment.

The synthesis of viscosin has been reported by other *Pseudomonas* strains including *P. syringae*, *P. tolaasii*, *P. fuscovaginae*, *P. corrugate*, *P. fluorescens*, *P. libanensis*, and *P. putida* [16, 42–45]. Massetolides whose structures are very closely

related to those of viscosin are less frequently described; massetolide A was produced by *P. fluorescens* SS101 [46].

We measured the surface tension of the isolated viscosin and determined its CMC using the pendant drop method (**Figure 2A**). This CMC is extremely low (21.6 mg.L<sup>−</sup><sup>1</sup> for a minimum surface tension of 25 mN.m<sup>−</sup><sup>1</sup> ) showing that this molecule has very strong biosurfactant properties. Very few authors measured the CMC of viscosin; Saini [42] found a value of 54 mg.L<sup>−</sup><sup>1</sup> for a minimum surface tension of 27.5 mN.m<sup>−</sup><sup>1</sup> for viscosin isolated from *P. libanensis* M9 while de Bruijn [46] measured a CMC of 10–15 mg.L<sup>−</sup><sup>1</sup> for a surface tension around 30 mN.m<sup>−</sup><sup>1</sup> for viscosin isolated from *P. fluorescens* SBW25. These CMC values are within the same range of order of our results for the case of *Pseudomonas sp*. PDD-14b-2.

Viscosin is one of the most effective biosurfactants among the cyclic lipopeptides of pseudomonads together with arthrofactin (minimum surface tension of 24 mN.m<sup>−</sup><sup>1</sup> , CMC of 13.5 mg.L<sup>−</sup><sup>1</sup> ) [45]. In spite of its very low CMC, viscosin has not yet been produced and exploited at an industrial scale. Some studies report viscosin as a surface-active, bioemulsifier with anticancer properties and massetolide as a biocontrol agent [16]. Raaijmakers [22] pointed out natural functions of viscosin and massetolide A including their role in mobility and biofilm formation.

### **3.3 Identification and surfactant properties of syringafactins produced by** *Xanthomonas campestris* **PDD-32b-52 and by** *Pseudomonas syringae* **PDD-32b-74**

Using the same technique as described before, we produced and purified syringafactins (linear lipopeptides) by cultivation of two strains isolated from clouds (*Xanthomonas campestris* PDD-32b-52 and *Pseudomonas syringae* PDD-32b-74). Their amino acid sequence was identified by LC-MS-MS (**Figure 3**) using the same methodology for fragment assignments as described for viscosin (**Figure 3B** and **C**). Six types of syringafactins (A, B, C, D, E, and F) could be identified; syringafactins B/C and E/F were isolated as mixtures.

The ESI-MS-MS data obtained in this work and used to assign the syringafactin structures are fully consistent with those initially published by Berti [47]. Syringafactins are the only linear lipopeptides described up to now and are poorly documented. They were first isolated from *P. syringae* pv. tomato DC3000 [47] and more recently from *P. syringae* pv. syringae B728a 5b [48]. We show here that they can be produced by another strain of *Pseudomonas syringae* (*P. syringae* PDD-32b-74) and also by a strain of *Xanthomonas* (*X. campestris* PDD-32b-52).

The measured CMC of syringafactin B/C was 1.2 g.L<sup>−</sup><sup>1</sup> for a minimum surface tension of 25 nM.m<sup>−</sup><sup>1</sup> (**Figure 2B**) proving the surfactant properties of this molecule. To our knowledge, this is the first report of a CMC value for this compound. This CMC is much higher than that of viscosin and closer to that of syringomycin, a cyclic lipopeptide, produced by *Pseudomonas syringae* B301D (CMC of 1.25. mg.L<sup>−</sup><sup>1</sup> and minimum surface tension of 33 mN.m<sup>−</sup><sup>1</sup> ) [45].

Biotechnological applications of syringafactins are not described yet, only natural functions related to their secretions by *Pseudomonas syringae* isolates present on the phyllosphere are described (enhancement of bacterial fitness on leaf surfaces during fluctuating humidity, swarming motility) [47, 48].

#### **3.4 Modeling the conformation of biosurfactants at the water-air interface**

Both descriptions can be used to simulate interfacial systems: an atomistic description that performs very well for relatively small and simple systems and a

**81**

**Figure 3.**

through a bottom-up approach.

*Cloud Microorganisms, an Interesting Source of Biosurfactants*

CG model that is designed for complex interfacial systems involving surfactants for example. Nevertheless, these two descriptions may even be complementary. Indeed, the CG model can be built from the configurations obtained at the atomistic level

*(A) ESI-MS/MS (collision-induced dissociation) spectrum of parent ion of syringafactin B/C (m/z 1095.752), (B) Chemical structure (Fragments) for syringafactin, (C) MS/MS fragmentation for the syringafactin B/C with R1: H and R2: Leu (b7 fragment is dehydrated), (D) Formula and exact masses of the different syringafactins.*

**Figure 4A** shows the structure of viscosin at the water-air interface with the distribution of the hydrophobic and hydrophilic zones. **Figure 4B** presents the density

*DOI: http://dx.doi.org/10.5772/intechopen.85621*

*Cloud Microorganisms, an Interesting Source of Biosurfactants DOI: http://dx.doi.org/10.5772/intechopen.85621*

*Surfactants and Detergents*

(21.6 mg.L<sup>−</sup><sup>1</sup>

30 mN.m<sup>−</sup><sup>1</sup>

PDD-14b-2.

24 mN.m<sup>−</sup><sup>1</sup>

**PDD-32b-74**

tension of 25 nM.m<sup>−</sup><sup>1</sup>

produced by *P. fluorescens* SS101 [46].

surface tension of 27.5 mN.m<sup>−</sup><sup>1</sup>

related to those of viscosin are less frequently described; massetolide A was

for a minimum surface tension of 25 mN.m<sup>−</sup><sup>1</sup>

the CMC of viscosin; Saini [42] found a value of 54 mg.L<sup>−</sup><sup>1</sup>

de Bruijn [46] measured a CMC of 10–15 mg.L<sup>−</sup><sup>1</sup>

, CMC of 13.5 mg.L<sup>−</sup><sup>1</sup>

B/C and E/F were isolated as mixtures.

and minimum surface tension of 33 mN.m<sup>−</sup><sup>1</sup>

We measured the surface tension of the isolated viscosin and determined its CMC using the pendant drop method (**Figure 2A**). This CMC is extremely low

for viscosin isolated from *P. fluorescens* SBW25. These CMC values

molecule has very strong biosurfactant properties. Very few authors measured

are within the same range of order of our results for the case of *Pseudomonas sp*.

Viscosin is one of the most effective biosurfactants among the cyclic lipopeptides of pseudomonads together with arthrofactin (minimum surface tension of

yet been produced and exploited at an industrial scale. Some studies report viscosin as a surface-active, bioemulsifier with anticancer properties and massetolide as a biocontrol agent [16]. Raaijmakers [22] pointed out natural functions of viscosin

Using the same technique as described before, we produced and purified syringafactins (linear lipopeptides) by cultivation of two strains isolated from clouds (*Xanthomonas campestris* PDD-32b-52 and *Pseudomonas syringae* PDD-32b-74). Their amino acid sequence was identified by LC-MS-MS (**Figure 3**) using the same methodology for fragment assignments as described for viscosin (**Figure 3B** and **C**). Six types of syringafactins (A, B, C, D, E, and F) could be identified; syringafactins

The ESI-MS-MS data obtained in this work and used to assign the syringafactin structures are fully consistent with those initially published by Berti [47]. Syringafactins are the only linear lipopeptides described up to now and are poorly documented. They were first isolated from *P. syringae* pv. tomato DC3000 [47] and more recently from *P. syringae* pv. syringae B728a 5b [48]. We show here that they can be produced by another strain of *Pseudomonas syringae* (*P. syringae* PDD-32b-74)

ecule. To our knowledge, this is the first report of a CMC value for this compound. This CMC is much higher than that of viscosin and closer to that of syringomycin, a cyclic lipopeptide, produced by *Pseudomonas syringae* B301D (CMC of 1.25. mg.L<sup>−</sup><sup>1</sup>

Biotechnological applications of syringafactins are not described yet, only natural functions related to their secretions by *Pseudomonas syringae* isolates present on the phyllosphere are described (enhancement of bacterial fitness on leaf surfaces

**3.4 Modeling the conformation of biosurfactants at the water-air interface**

Both descriptions can be used to simulate interfacial systems: an atomistic description that performs very well for relatively small and simple systems and a

(**Figure 2B**) proving the surfactant properties of this mol-

) [45].

and also by a strain of *Xanthomonas* (*X. campestris* PDD-32b-52). The measured CMC of syringafactin B/C was 1.2 g.L<sup>−</sup><sup>1</sup>

during fluctuating humidity, swarming motility) [47, 48].

and massetolide A including their role in mobility and biofilm formation.

**3.3 Identification and surfactant properties of syringafactins produced by** *Xanthomonas campestris* **PDD-32b-52 and by** *Pseudomonas syringae*

) showing that this

for a minimum

for a minimum surface

for a surface tension around

for viscosin isolated from *P. libanensis* M9 while

) [45]. In spite of its very low CMC, viscosin has not

**80**

**Figure 3.**

*(A) ESI-MS/MS (collision-induced dissociation) spectrum of parent ion of syringafactin B/C (m/z 1095.752), (B) Chemical structure (Fragments) for syringafactin, (C) MS/MS fragmentation for the syringafactin B/C with R1: H and R2: Leu (b7 fragment is dehydrated), (D) Formula and exact masses of the different syringafactins.*

CG model that is designed for complex interfacial systems involving surfactants for example. Nevertheless, these two descriptions may even be complementary. Indeed, the CG model can be built from the configurations obtained at the atomistic level through a bottom-up approach.

**Figure 4A** shows the structure of viscosin at the water-air interface with the distribution of the hydrophobic and hydrophilic zones. **Figure 4B** presents the density

**Figure 4.**

*(A) Structure of viscosin. (B) Viscosin at the water-air interface in a water box using all-atoms simulation (CHARMM force field).*

#### **Figure 5.**

*(A) CG structure of syringafactin A represented. (B) Typical configuration of a liquid-vapor water interface with 32 surfactants at each interface.*

profiles of the water box containing viscosin. These profiles were obtained by running a trajectory over 20 ns and establish a bidimensional structure of the biosurfactant at the water-air interface. The hydrophobic parts defined by the leucine (L); valine (V); isoleucine (I); and alanine, cysteine and glycine (ACG) amino acids of the surfactant populate the side of the interfacial region toward the vapor phase. The hydrophilic parts defined by the group of glutamic acid (E) and serine (S) amino acids are rather located at the interface at the position of the Gibbs dividing plane. The density profiles have been calculated by using atomistic models with 30 surfactant molecules at each interface. We also show that the liquid-water region is quite well developed over a region of 40 Å. This is a necessary condition to simulate the behavior of surfactants at least at the atomistic level.

These atomistic simulations take a very long time to equilibrate the interfacial region.

It is well known that the use atomistic force field models is problematic for simulating complex liquid-vapor interfacial systems with surfactants that relax over time and length scales inaccessible for these atomistic descriptions. An alternative is to simplify the model by using a CG description [49, 50] for which the key element called a bead represents several atoms or molecules. By using these CG models [51–53], we can improve the description of the systems by using larger system sizes. The modeling of the interfacial systems with surfactants can then be conducted by CG models [51–53]. **Figure 5A** shows the CG representation of syringafactin A and

**83**

*Cloud Microorganisms, an Interesting Source of Biosurfactants*

**Figure 5B** represents an equilibrated liquid-vapor water interface with 32 biosur-

*Profiles of the normal PN (z) (MPa) and tangential PT(z) (MPa) components of the pressure tensor, the difference (PN (z) − PT (z)) (left axis) and the integral* γ*(z) (right axis) as a function of the z-axis (direction normal to the interface). These profiles are calculated in the liquid-vapor interface of water with four surfactants at each interface.*

One of the key properties in the modeling of the liquid-vapor systems is the interfacial tension. It is now well known that the calculation of this property is under control at the atomistic level [54–57]. It is far from being the same for the CG simulations. Indeed, an accurate calculation of the interfacial tension requires to check that the mechanical equilibrium of the CG liquid-vapor equilibrium is respected. **Figure 6** shows the profiles of the normal (PN) and tangential (PT) components of the pressure tensor along the direction normal to the interface calculated in the liquid-vapor interface of water with four surfactants at each interface. The profile of the difference (PN − PT) exhibits two peaks at both interfaces and no con-

the local interfacial tension along the direction normal to the interface. As expected from mechanical equilibrium and observed in **Figure 6** (blue curve), this profile is flat in the bulk phases with two symmetric contributions at both interfaces. The

from experiments. Whereas the prediction of the surface tension, calculated from atomistic simulations, is quantitative, it is still subject to some adjustments due to the CG nature of the interactions. It means that the CG model must be calibrated on this property to predict in the future both the interfacial tension and its dependence on the concentration of surfactants [51]. Indeed, recent studies [52, 53] show that the degree of coarse-graining impacts on the description of the interface. A good reproduction of the interfacial tension requires a new parametrization of the CG model by considering the interfacial tension in the experimental database.

Nevertheless, the use of CG models has the advantage of providing very wellequilibrated interfacial regions. **Figure 7** shows the density profiles along the z-axis for the liquid-vapor interface of water with both 4 and 32 syringafactin molecules at each interface. We observe that the surfactant molecules populate the interfaces with sharp peaks at weak concentrations (**Figure 7a**). At strong concentrations, we observe that the thickness of the interface increases. In any case, the interfacial region is well recovered by surfactants with no preferential coverage between the lipid and protein parts of the syringafactin molecule. We only observe a slight

*2* ∫*0*

and does not deviate very much

*Lz(PN(z) − PT(z))dz* is

tribution in the water bulk liquid and vapor phases. *γ(z) = \_1*

resulting interfacial tension is about 60 mN.m<sup>−</sup><sup>1</sup>

increase of coverage of the lipid part on the vapor side.

*DOI: http://dx.doi.org/10.5772/intechopen.85621*

factants in the interfacial region.

**Figure 6.**

*Cloud Microorganisms, an Interesting Source of Biosurfactants DOI: http://dx.doi.org/10.5772/intechopen.85621*

#### **Figure 6.**

*Surfactants and Detergents*

**82**

**Figure 5.**

**Figure 4.**

*(CHARMM force field).*

*with 32 surfactants at each interface.*

at least at the atomistic level.

*(A) CG structure of syringafactin A represented. (B) Typical configuration of a liquid-vapor water interface* 

*(A) Structure of viscosin. (B) Viscosin at the water-air interface in a water box using all-atoms simulation* 

profiles of the water box containing viscosin. These profiles were obtained by running a trajectory over 20 ns and establish a bidimensional structure of the biosurfactant at the water-air interface. The hydrophobic parts defined by the leucine (L); valine (V); isoleucine (I); and alanine, cysteine and glycine (ACG) amino acids of the surfactant populate the side of the interfacial region toward the vapor phase. The hydrophilic parts defined by the group of glutamic acid (E) and serine (S) amino acids are rather located at the interface at the position of the Gibbs dividing plane. The density profiles have been calculated by using atomistic models with 30 surfactant molecules at each interface. We also show that the liquid-water region is quite well developed over a region of 40 Å. This is a necessary condition to simulate the behavior of surfactants

These atomistic simulations take a very long time to equilibrate the interfacial region. It is well known that the use atomistic force field models is problematic for simulating complex liquid-vapor interfacial systems with surfactants that relax over time and length scales inaccessible for these atomistic descriptions. An alternative is to simplify the model by using a CG description [49, 50] for which the key element called a bead represents several atoms or molecules. By using these CG models [51–53], we can improve the description of the systems by using larger system sizes. The modeling of the interfacial systems with surfactants can then be conducted by CG models [51–53]. **Figure 5A** shows the CG representation of syringafactin A and

*Profiles of the normal PN (z) (MPa) and tangential PT(z) (MPa) components of the pressure tensor, the difference (PN (z) − PT (z)) (left axis) and the integral* γ*(z) (right axis) as a function of the z-axis (direction normal to the interface). These profiles are calculated in the liquid-vapor interface of water with four surfactants at each interface.*

**Figure 5B** represents an equilibrated liquid-vapor water interface with 32 biosurfactants in the interfacial region.

One of the key properties in the modeling of the liquid-vapor systems is the interfacial tension. It is now well known that the calculation of this property is under control at the atomistic level [54–57]. It is far from being the same for the CG simulations. Indeed, an accurate calculation of the interfacial tension requires to check that the mechanical equilibrium of the CG liquid-vapor equilibrium is respected. **Figure 6** shows the profiles of the normal (PN) and tangential (PT) components of the pressure tensor along the direction normal to the interface calculated in the liquid-vapor interface of water with four surfactants at each interface. The profile of the difference (PN − PT) exhibits two peaks at both interfaces and no contribution in the water bulk liquid and vapor phases. *γ(z) = \_1 2* ∫*0 Lz(PN(z) − PT(z))dz* is the local interfacial tension along the direction normal to the interface. As expected from mechanical equilibrium and observed in **Figure 6** (blue curve), this profile is flat in the bulk phases with two symmetric contributions at both interfaces. The resulting interfacial tension is about 60 mN.m<sup>−</sup><sup>1</sup> and does not deviate very much from experiments. Whereas the prediction of the surface tension, calculated from atomistic simulations, is quantitative, it is still subject to some adjustments due to the CG nature of the interactions. It means that the CG model must be calibrated on this property to predict in the future both the interfacial tension and its dependence on the concentration of surfactants [51]. Indeed, recent studies [52, 53] show that the degree of coarse-graining impacts on the description of the interface. A good reproduction of the interfacial tension requires a new parametrization of the CG model by considering the interfacial tension in the experimental database.

Nevertheless, the use of CG models has the advantage of providing very wellequilibrated interfacial regions. **Figure 7** shows the density profiles along the z-axis for the liquid-vapor interface of water with both 4 and 32 syringafactin molecules at each interface. We observe that the surfactant molecules populate the interfaces with sharp peaks at weak concentrations (**Figure 7a**). At strong concentrations, we observe that the thickness of the interface increases. In any case, the interfacial region is well recovered by surfactants with no preferential coverage between the lipid and protein parts of the syringafactin molecule. We only observe a slight increase of coverage of the lipid part on the vapor side.

#### **Figure 7.**

*Density distributions of the water and different parts of the syringafactin molecules at two surfactant concentrations: (a) 4 surfactant molecules and (b) 32 surfactant molecules at each interface. The lipid head is represented by the first three beads of the lipid chain whereas the protein part is represented by a typical bead of this part.*

On this aspect of modeling complex interfacial systems, we can conclude that the development of CG models will open the way to new force fields capable of quantitatively predicting the surface tension and main properties such as the CMC. The prediction of the CMC, already operational for some CG models [51], will require additional adjustments for new molecules with various intramolecular interactions. The development of CG force fields using mesoscale simulation methods [58–60] is an active area of research. Different methodologies coexist to develop these CG interactions: a bottom-up approach consisting in deriving the force field from atomistic simulations and a top-down approach aiming to build the parameters of the model from mapping onto macroscopic properties such as the interfacial tension.

## **4. Conclusions**

This work is the first report of a detailed study of biosurfactants produced by *Pseudomona*s and *Xanthomonas* strains isolated from cloud samples. We have used a convenient method to purify these compounds based on adsorption on Amberlite coupled with a puriFlash® chromatographic technique; the different steps were monitored using the pendant drop method. High-resolution LC-MS-MS allowed assigning unambiguously the structure of viscosin, massetolide E, and different syringafactins. The measurements of CMC of viscosin and syringafactin showed that viscosin is a particularly powerful biosurfactant. Finally, two approaches of molecular dynamics were used to model the conformation of these biosurfactants at the water-air interface: an atomistic description for viscosin (CHARMM force field) and a CG model for syringafactin A (MARTINI force field). This last approach is particularly original and promising. To our knowledge, these studies constitute the first modeling of interfacial properties of such complex biosurfactants.

In addition to fundamental knowledge of biosurfactant properties, this work shows that cloud microorganisms can provide an unexplored source of biosurfactants. Rather few strains, mainly *Pseudomonas*, were shown to produce viscosin, massetolides, and syringafactins, and two new isolates from this genus are described here. We report here the first production of syringafactins by a strain of *Xanthomonas*. Considering that more than 30 strains of our microbial collection isolated from clouds were very active biosurfactant producers (σ ≤ 30 mN.m<sup>−</sup><sup>1</sup> ) [27], further investigation is very promising to isolate and study other unusual or even new biosurfactants.

**85**

provided the original work is properly cited.

, Isabelle Canet1

Clermont-Ferrand, Clermont-Ferrand, France

, Patrice Malfreyt1

2 Slovak Academy of Sciences, Bratislava, Slovakia

\*Address all correspondence to: a-marie.delort@uca.fr

, Boris Eyheraguibel1

*Cloud Microorganisms, an Interesting Source of Biosurfactants*

This work was funded by the French-USA program ANR-NSF SONATA and the

*DOI: http://dx.doi.org/10.5772/intechopen.85621*

French-Slovak Program Stefanik N° 35588ZE.

The authors declare no conflict of interest.

**Acknowledgements**

**Conflict of interest**

**Author details**

Pascal Renard1

Iveta Uhliarikova<sup>2</sup>

Mounir Traïkia1

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

, Martine Sancelme1

1 Université Clermont Auvergne, CNRS, Sigma-Clermont, Institut de Chimie de

, Lionel Nauton1

and Anne-Marie Delort1

, Maria Matulova2

\*

, Julien Devemy1

,

,
