L. Rodríguez-López

Sewage Sludge Polycyclic Aromatic Hydrocarbon (PAH) Decontamination Technique Based on the Utilization of a Lipopeptide Biosurfactant Extracted from Corn Steep Liquor

A decontamination technique based on the utilization of a lipopeptide biosurfactant extracted from corn steep liquor has been developed to eliminate polycyclic aromatic hydrocarbons (PAHs) from sewage sludge. High concentrations of PAHs were used during experiments observing that 408.3 mg/kg of naphthalene was almost completely mobilized and biodegraded, only 1.7% of naphthalene remained in the sewage sludge, whereas anthracene and pyrene were reduced up to 51.7 and 69.4%, respectively. The biodegradation of PAHs was fitted to several kinetic models (zero- and first-order kinetic models), observing good correlation coefficient values when biodegradation was described by the first-order kinetic model. Experimental results suggest that biosurfactant extracted from corn steep liquor may have great potential, as an ecofriendly washing agent, for the treatment of sewage sludge contaminated with PAHs. Therefore, in situ application of natural biosurfactants may be considered to be a good remediation alternative as they are not hazardous for water and soil organisms.

Adsorption of natural surface active compounds obtained from corn on human hair

In this work, an aqueous solution containing surface-active compounds, extracted from corn steep liquor (CSL), was added to human hair and its adsorption was studied by applying an incomplete factorial design. The independent variables established in the study were temperature (20–50 °C), pH (5–7) and treatment time (2–30 min); whereas the dependent variable studied was the adsorption capacity of hair. It was observed that the adsorption of the biosurfactant onto hair was very fast, occurring few minutes after starting the experiments. The time was, in the range studied, the least significant independent variable while temperature had an important effect on the adsorption of this biosurfactant onto hair. It was observed that the capacity of hair to adsorb the biosurfactant was improved at low temperatures. Moreover, pH had an intermediate significant effect, mainly at middle or high temperatures, meanwhile at low temperatures, the pH, in the range studied, almost did not affect the adsorption process. At the higher concentration of biosurfactant, hair was able to adsorb the biosurfactant with a maximum capacity of 3679 μg g−1.

Biological Surfactants vs. Polysorbates: Comparison of Their Emulsifier and Surfactant Properties

Abstract In this work two biological surfactants, a cell-bound biosurfactant produced by Lactobacillus pentosus and a biosurfactant obtained from a fermented stream corn milling industry, were compared with two chemical surfactants (polysorbate 20 and polysorbate 80) in terms of surface tension reduction, critical micellar concentration (CMC), oil spreading and emulsifying capacity. Biological surfactants showed a similar ability to reduce the surface tension of water as polysorbates, which was in conformance with the results obtained in the drop collapse test. Regarding the ability to spread the oil on water, both biosurfactants produced similar results as polysorbates after 1 h. However, after 24 h, polysorbates and biosurfactant from corn stream were more effective than L. pentosus biosurfactant, producing greater free oil areas. Concerning the emulsifying activity, in terms of relative emulsion volume (EV), the biosurfactant produced from L. pentosus gave the best results (EV = 100%), after 1 day of emulsion formation, keeping this value over 50% after 15 days of emulsion formation; whereas polysorbates gave EV values lower than 50%. The CMC values of the biosurfactant from corn stream and of polysorbates were closer in comparison with the CMC value of L. pentosus biosurfactant, observing that the characteristics and properties of the biosurfactant from corn stream are more similar to polysorbates than to L. pentosus biosurfactant. Thus, it could be speculated that biosurfactant from corn stream would be a good substitute for polysorbates.

Effect of biosurfactant extract obtained from the corn-milling industry on probiotic bacteria in drinkable yogurt: Effect of biosurfactant extract on yogurt

BACKGROUND Recent studies have proven that biosurfactants (BS) obtained from controlled fermentation have shown surfactant and antimicrobial properties. In this work a biosurfactant extract obtained from a raw agroindustrial stream from the corn-milling industry was introduced into a drinkable probiotic yogurt containing Lactobacillus casei. RESULTS The effect of the biosurfactant extract on the probiotic population was determined under different biosurfactant concentration, temperature, and time conditions. This extract was able to reduce the surface tension of water by 30 mN/m and it was observed that its addition to a drinkable probiotic yogurt did not negatively affect the biomass of L. casei during incubation. It also had a positive effect on the population of L. casei, increasing the growth of the probiotic bacterium in the yogurt under optimum temperature conditions for the growth of L. casei, in the range of 30-40 °C. Likewise, the biosurfactant extract did not modify the homofermentative pathway of L. casei; hence no acetic acid was detected in the presence of the biosurfactant extract in the drinkable yogurt. CONCLUSION This is the first time that a biosurfactant extract, obtained from natural sources, has been introduced into a food product like a drinkable probiotic yogurt, producing a positive effect in the growth of probiotic bacterium.

Influence of micelle formation on the adsorption capacity of a biosurfactant extracted from corn on dyed hair

Human hair contains fatty acids (palmitic, palmitoleic, oleic and stearic acid) that prevent hair dryness and avoid lower hair density of the scalp that can be caused when hair is dyed. These acids are also present in the composition of the amphoteric biosurfactant obtained from corn steep liquor, an agro-industrial stream generated by the corn wet-milling industry. This biosurfactant has a molecular weight of 1542 Da, with a similar mass spectrum to that of Fengycin, a biosurfactant produced by Bacillus subtilis strains. Few studies exist in the literature on the interaction of hair and biosurfactants, nor are there studies on the influence of micelle formation on biosurfactant adsorption capacity. Moreover, this is supposedly the first work in which a biosurfactant is applied to dyed hair. Different concentrations of biosurfactant were applied to dyed hair between 20–50 °C during 2–30 min of treatment. Theoretical models were obtained, which allowed the prediction of the amount of biosurfactant that can be entrapped by dyed hair. A maximum capacity of 10 549 μg g−1 was achieved at 295 mg L−1 of biosurfactant, thus it could be observed that dyed hair mainly adsorbed the biosurfactant above its critical micellar concentration, at which point the biosurfactant is in micellar form. Furthermore, this treatment maintains the dyed hair structure in a good state.