**5. Conclusions and perspectives**

354 Biomedical Science, Engineering and Technology

containing propylene glycol have excellent hygroscopic properties and are applied as moisturizer or softener in cosmetic products (Faivre & Rosilio, 2010). For example, a product containing 1 mol of sophorolipid and 12 mol of propylene glycol has excellent skin compatibility and is used commercially as a skin moisturizer (Yamane, 1987, as cited in Desai & Banat 1997). Sophorolipid is commercially used by Kao Co. Ltd. as a humectant for cosmetic makeup brands such as Sofina. This company has developed a fermentation process for sophorolipid production, and after a two-step esterification process, the product finds application in lipstick and as moisturizer for skin and hair products (Inoue et al., 1979 a, 1979b, as cited in Desai & Banat, 1997). Moreover, sophorolipids are also believed to stimulate the leptin synthesis through adipocytes, in this way reducing the subcutaneous fat

The French company Soliance (http://www.groupesoliance.com) produces sophorolipidbased cosmetics for the body and skin and the Korean MG Intobio Co. commercializes Sopholine cosmetics (Van Bogaert & Soetaert, 2010). They are also found in cleaning soap mixtures (EcoverTM products). Despite the high number of scientific publications and patents, industrial surfactin applications still remain quite limited (Jacques, 2010). Sold by SIGMA and SHOWA DENKO for analytical or laboratory purposes, the compound is also

During the last decades, many patents have been issued worldwide in relation with applications of biosurfactants and bioemulsifiers in the health care field (Shete et al., 2006). Bioemulsifiers produced by *Acinetobacter calcoaceticus*, for examples, have been used in shampoos and soaps against acne and eczema and in personal care products. The skin cleansing cream and lotion containing these bioemulsifiers have, among other properties, the ability to interfere with microbial adhesion on skin or hair (Hayes et al., 1989, 1990, 1991, 1992, as cited in Shete et al., 2006). Viscosin and analogues have been patented as antibacterial, antiviral, antitrypanosomal therapeutic compounds that inhibit the growth of *Mycobacterium tuberculosis*, Herpes simplex virus 2 and/or *Trypanosoma cruzi* (Burke et al., 1999, as cited in Shete et al., 2006). *Lactobacillus* biosurfactants have also been patented as inhibitors of adherence and colonization of bacterial pathogens on medical devices (Reid et

Another interesting patented area is related to antimicrobial biosurfactant peptides produced by probiotic strains able to selectively bind to collagen and inhibit infections around wounds at the site of implants and biofilms associated with infections in mammals (Howard et al., 2002, as cited in Shete et al., 2006). Sophorolipids, in particular have been the object of many patents as moisturizing agents and for the amelioration of skin physiology, skin restructuration and repair (Shete et al., 2006). Sophorolipids are also used for the treatment of skin, as an activator of macrophages, and as agent in fibrinolytic healing, desquamating and depigmenting process (Maingault, 1999 as cited in Shete et al., 2006). A germicidal composition containing fruit acids, a surfactant and a sophorolipid biosurfactant, able to kill in 30 seconds 100% of *E. coli*, *Salmonella* and *Shigella*, has been patented for

Rhamnolipids in comparison have been patented in a process to make some liposomes and emulsions (Ishigami & Suzuki 1997; Ramisse et al., 2000) both important in the cosmetic industry. More recently an activator and anti-aging agent containing MEL as active ingredient has been patented (Suzuki et al., 2010). Another recent invention is directed to polymeric acylated biosurfactants that can self-assemble or auto-aggregate into polymeric micellar structures useful in topically-applied dermatologic products (Owen & Fan, 2010).

cleaning fruits, vegetable, skin and hair (Pierce & Heilman, 2001).

overload (Pellecier & André, 2004, as cited in Van Bogaert & Soetaert, 2010).

available in several Japanese cosmetic products.

al., 2000).

As evidenced by the growing number of publications on the topic of biosurfactants, there is an increasing interest in the study of these molecules and their potential applications. The demand for new specialty surfactants in the agriculture, cosmetic, food, pharmaceutical, and environmental industries is steadily increasing and biosurfactants, as effective and environmentally compatible compounds, perfectly meet this demand (Banat et al., 2000, 2010; Mukherjee et al., 2006).

The most important limitation for the commercial use of biosurfactants is the complexity and high cost of production, which has limited the development of their use on a large scale (Soberón-Chávez & Maier, 2010). However, the proven antimicrobial, anti-adhesive, immune-modulating properties of biosurfactants and the recent successful applications in gene therapy, immunotherapy and medical insertion safety suggest that it is worth persisting in this field. Moreover, in pharmaceutical and biomedical sectors, the high cost of production could be compensated for by the small amounts of product required. In fact, it has been elucidated that biosurfactants used as pharmaceutical agents are needed only in very low concentrations (Cameotra & Makkar, 2004). Prerequisites for making biosurfactant production more profitable and economically feasible include optimized growth/production conditions and novel and efficient multi-step downstream processing methods as well as the use of recombinant varieties of microorganisms or selected hyperproducing mutants, which can grow on a wide range of cheap renewable substrates (Muthusamy et al., 2008).

Recent advances in the area of biomedical application are probably going to take the lead due to higher potential economic returns. Moreover, due to their self-assembly properties, new and fascinating applications in nanotechnology are predicted for biosurfactants (Kitamoto et al., 2009; Palanisamy, 2008; Reddy et al., 2009). In-depth studies of their natural roles in microbial competitive interactions, cell-to-cell communication, pathogenesis, motility and biofilm formation and maintenance could suggest improved and interesting future applications.
