3.3. Biosurfactant production
Biosurfactants are fully or partly extracellular polymers. They are produced by some microorganisms to make the uptake of lipophilic compounds easier, since they accumulate at interfaces with different polarities. This feature prevents the formation of hydrogen bonds and certain hydrophobic–hydrophilic interactions, causes molecular rearrangements and reduces the surface tension, a property related to the attraction and repulsion forces among molecules of a fluid (Souza et al., 2014). As a result of low solubility, bioavailability and high hydrophobicity of certain aromatic compounds (such as PHE), microorganisms are usually forced to release biosurfactants to uptake them. Since this is the case, the surface tension of the culture medium was measured before and after PHE biodegradation assays. The results showed that there was a reduction in surface tension from 73.6mN m−1 to 48.5mN m−1 after the assays were completed. This reduction clearly indicated that B.thuringiensis has ability to produce biosurfactants (Singh et al.,2014). In order to evaluate its potential application in biore-mediation, the oil spreading technique was performed. Thistechnique also demonstrated a high level of biosurfactant pro-duction by B. thuringiensis. These results agreed with thosefrom Kavitha et al. (2014) and Pereira et al. (2013) who reportedthat several species of the genus Bacillus were able to producebiosurfactants.
3.3. Biosurfactant production Biosurfactants are fully or partly extracellular polymers. They are produced by some microorganisms to make the uptake of lipophilic compounds easier, since they accumulate at interfaces with different polarities. This feature prevents the formation of hydrogen bonds and certain hydrophobic–hydrophilic interactions, causes molecular rearrangements and reduces the surface tension, a property related to the attraction and repulsion forces among molecules of a fluid (Souza et al., 2014). As a result of low solubility, bioavailability and high hydrophobicity of certain aromatic compounds (such as PHE), microorganisms are usually forced to release biosurfactants to uptake them. Since this is the case, the surface tension of the culture medium was measured before and after PHE biodegradation assays. The results showed that there was a reduction in surface tension from 73.6mN m−1 to 48.5mN m−1 after the assays were completed. This reduction clearly indicated that B.thuringiensis has ability to produce biosurfactants (Singh et al.,2014). In order to evaluate its potential application in biore-mediation, the oil spreading technique was performed. Thistechnique also demonstrated a high level of biosurfactant pro-duction by B. thuringiensis. These results agreed with thosefrom Kavitha et al. (2014) and Pereira et al. (2013) who reportedthat several species of the genus Bacillus were able to producebiosurfactants.
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