**1. Introduction**

244 Practical Applications in Biomedical Engineering

Pharmaceutical, 2002,235,121-7

weights. Carbohydrate Polymer, 2003, 45, 527-530

Currient. Science, 2004, 87(9), 1176-1178.

[61] Ikinci G, Senel S, Akincibay H, Kas S, Ercis S, Wilson CG, Hincal A.A.: Effect of chitosan on a periodontal pathogen Porphyromonas gingivalis. Intrnational Journal of

[62] Zheng LY, Zhu JF. Study on antimicrobial activity of chitosan with different molecular

[63] Yadav AV, Bhise .B. Chitosan: a potencial biomaterial effective against typhoid.

Several compounds with tensioactive properties are synthesized by living organisms, from plants (e.g. *saponins*) to microorganisms (e.g. *glycolipids*) and humans (e.g. surface-active lipoprotein complex), being considered natural surfactants [1]. Additionally, these compounds have been produced through biotechnological processes broadening their diversity and potential applications [2]. Surfactants are usually organic compounds that are amphiphilic, meaning they contain both hydrophobic groups (tails) and hydrophilic groups (heads), and that act preferably in the interface of fluid phases with different levels of polarity and bridges of hydrogen, such as oil/water or air/water interfaces. Many microbes appear to produce a complex mixture of biosurfactants, particularly during their stationary growth on water-immiscible substrates. Generally, biosurfactants are secondary metabolites with the typical amphiphilic structure of a surfactant, where the hydrophobic moiety is either a long-chain fatty-acid, hydroxyl fatty acid, or -alkyl--hydroxy fatty acid and the hydrophilic moiety can be a carbohydrate, an amino acid, a cyclic peptide, a phosphate, a carboxylic acid, or alcohol, among others [1].

Physical and chemical properties, surface tension reduction, and stability of the emulsion formed are important characteristics in biosurfactant that make possible its use in countless biological applications. Most work on biosurfactant applications has been focused on their use in environmental applications owing to their diversity, environmentally friendly nature, suitability for large-scale production and selectivity [3]. Biosurfactants have several advantages over chemical surfactants, such as lower toxicity, higher biodegradability and effectiveness at extreme temperatures or pH values [4]. Many of the potential applications that have been considered for biosurfactants depend on whether they can be produced

© 2012 de Campos-Takaki et al., licensee InTech. This is an open access chapter 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, provided the original work is properly cited. © 2012 de Campos-Takaki et al., licensee InTech. This is a paper 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, provided the original work is properly cited.

economically; however, much effort in process optimization and at the engineering and biological levels have been carried out [5]. Despite their potential and biological origin only a few studies have been carried out on applications related to the biomedical field [6]. Some biosurfactants are suitable alternatives to synthetic medicines and antimicrobial agents and may be used as safe and effective therapeutic agents [6].

Antimicrobial and Anti-Adhesive Potential of a Biosurfactants Produced by *Candida* Species 247

during exponential growth, presumably as a result of increased cell wall hydrophobicity

The conditioning film on the biomaterial surface (and on the bacterial cell surface) plays an important role, as it changes the physicochemical properties of the interacting surfaces. Albumin is a strong adhesion inhibitor, for unknown reasons, although changes in

The adhesion of microorganisms to a surface is one of the first stages in the development of a biofilm and is believed to be influenced by a number of factors. As the substrate is essential in the development of a biofilm, an understanding of how substrate properties affected the adherence of bacterial cells my assist in designing or modifying substrates inhibitory to bacterial adhesion. Many of these molecules are proteinaceous constitution, such as serum albumin, fibrogen and collagen, and some have been shown to affect

The formation of infectious biofilm on biomaterial appeared to involve several sequential steps. Immediately after exposure of a device to body fluids, such as blood, saliva, or urine, macromolecular components adsorb to form a conditioning film [15]. The most microbial surfactants are complex molecules, comprising different structures that include peptides, glycolipids, glycopeptides, fatty acids and phospolipids, as reviewed recently. Among the many classes of biosurfactants, lipopeptides are particularly interesting because their high surface activities and antibiotic potential. Lipopeptides are molecules act as antibiotics, antiviral and antitumoral agents, and enzyme inhibitors. Those molecules enhance or decrease the bacterial surface hydrophobicity following that the surface is less or more hydrophobic[16]. Morikawa et al. [17] identified and characterized a biosurfactant,

Glycolipids are the most common class of biosurfactans of which the most effective from the point of view of surface active properties arethe trehalose lipids of *Mycobacterium* and related bacteria, the rhamnolipids of *Pseudomonas* sp and the sophorolipids of yeasts [18]. Otto et al. [19] described the production of sophorose lipids from deproteinized whey concentrate by a two-stage process. Several antimicrobial, immunological and neurological properties have been attributed to mannosylerythritol lipid (MEL), a yeast glycolipid

Several biosurfactants which exhibit antimicrobial activity against various microorganisms have been previously described. They include surfactin and iturin produced by *Bacillus subtilis* strains [20], rhamnolipids from *Pseudomonas* species [21], mannosylerythritol lipids

Among the genus *Bacillus, B. subtilis* produces a broad spectrum of bioactive lipopeptides which have a great potential for biotechnological and biopharmaceutical applications. The

hydrophobiciy and sterical hindrance are proposed as mechanisms [14].

during this growth phase

subsequent bacterial adhesion [13].

arthrofactin, produced by *Arthrobacter.*

biosurfactant, produced from vegetable oils by *Candida* strains.

from *C. antarctica* [22] and biosurfactants produced by some fungi [23].

**3. Antimicrobial activity of biosurfactant** 

Furthermore, biosurfactants have been found to inhibit the adhesion of pathogenic organisms to solid surfaces or to infection sites hampering biofilm formation that is the cause of many diseases, as for example cystic fibrosis [7]. Therefore, prior adhesion of biosurfactants to solid surfaces might constitute a new and effective means of combating colonization by pathogenic microorganisms and subsequent biofilm formation [8,9].

Pre-coating vinyl urethral catheters by running a surfactin solution through them before inoculation with media resulted in a decrease in the amount of biofilm formed by *Salmonella typhimurium*, *S. enterica*, *Escherichia coli* and *Proteus mirabilis* [10]. Given the importance of opportunistic infections with *Salmonella* species, including urinary tract infections of AIDS patients, these results have great potential for practical applications. In addition, the use of lactobacilli as a probiotic for the prevention of urogenital infections has been widely studied [11].

Microbial surfactants are not yet competitive with those produced by the chemical industry, but efforts should be made on the different production aspects to find suitable and economic substrates and to develop new strategies to increase the volumetric productivity. We have shown that the co-utilization of ground-nut oil refinery residue and corn steep liquor is an attractive choice for biosurfactant production. The biosurfactant adhesive mechanism is based in the inhibition of microorganisms to different surfaces can interact with interfaces of the molecule. In this sense, they are an alternative to synthetic surface-active agents because of their low toxicity and biodegradability [7,12].

Considering the lack of studies with yeasts biosurfactants for medical purposes, and is an attractive characteristics showed by produced by the *Candida lipolytica* (Rufisan) and *Candida sphaerica* (Lunasan). In this sense the revision shown the role and applications of rufisan and lunasan biosurfactant as a antimicrobial and antiadhesive activities were investigated against pathogenic and nonpathogenic microorganisms, and indicated the therapeutic perspectives.. Results gathered in the current work showed the potential of those molecules in this field of application; however, its use still remains limited, possibly as due to high production costs, as well as on their toxicity towards human systems.
