Ionic Behavior Assessment of Surface-Active Compounds from Corn Steep Liquor by Exchange Resins

Purification of lipopeptide biosurfactant extracts obtained from a complex residual food stream using Tricine-SDS-PAGE electrophoresis

Protocols to identify lipopeptide biosurfactant extracts contained in complex residual streams are very important, as fermented agri-food matrices are potential sources of these valuable compounds. For instance, corn steep liquor (CSL), a secondary stream of the corn wet-milling industry, is composed of a mixture of microbial metabolites, produced during the corn steeping process, and other natural metabolites released from corn, that can interfere with the purification and analysis of lipopeptides. Electrophoresis could be an interesting technique for the purification and further characterization of lipopeptide biosurfactant extracts contained in secondary residual streams like CSL, but there is little existing literature about it. It is necessary to consider that lipopeptide biosurfactants, like Surfactin, usually are substances that are poorly soluble in water at acidic or neutral pH, forming micelles what can inhibit their separation by electrophoresis. In this work, two lipopeptide biosurfactant extracts obtained directly from CSL, after liquid-liquid extraction with chloroform or ethyl acetate, were purified by applying a second liquid extraction with ethanol. Following that, ethanolic biosurfactant extracts were subjected to electrophoresis under different conditions. Lipopeptides on Tricine-SDS-PAGE (polyacrylamide gels) were better visualized and identified by fluorescence using SYPRO Ruby dye than using Coomassie blue dye. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of lipopeptide isoforms separated by electrophoresis revealed the presence of masses at 1,044, 1,058, and 1,074 m/z, concluding that Tricine-SDS-PAGE electrophoresis combined with MALDI-TOF-MS could be a useful tool for purifying and identifying lipopeptides in complex matrices.

Effect of a Biosurfactant Extract Obtained from a Corn Kernel Fermented Stream on the Sensory Colour Properties of Apple and Orange Juices

In this work, we assessed the effect of a biosurfactant extract, which possesses preservative properties, on the sensory properties, regarding colour, of two fruit juices: pasteurized apple juice and natural orange juice. This biosurfactant extract was obtained from corn steep liquor, a secondary stream of the corn wet-milling industry. The biosurfactant extract is composed of natural polymers and biocompounds released during the spontaneous fermentation of corn kernels during the steeping process of corn. The reason for this study is based on the importance of colour as a visual attribute that can determine the consumer's preferences; it is important to study the effect of the biosurfactant extract under evaluation before including it in juice matrices. For this, a surface response factorial design was employed and the effects of the biosurfactant extract concentration (0-1 g/L), the storage time (1-7 days), and the conservation temperature (4-36 °C) on the CIELAB colour parameters (L*, a*, b*) of the juice matrices were evaluated, as well as the total colour differences (ΔE*) regarding the control juices and the saturation index (Cab*). Moreover, the CIELAB coordinates of each conducted treatment were converted into RGB values to obtain visual colour differences that can be appreciated by testers or consumers.

Optimization of the Operational Conditions to Produce Extracellular and Cell-Bound Biosurfactants by Aneurinibacillus aneurinilyticus Using Corn Steep Liquor as a Unique Source of Nutrients

The relevance of this work lies in the fact that it is the first time that corn steep liquor (CSL) has been proposed as a unique source of nutrients for producing biosurfactants in a controlled fermentation and Aneurinibacillus aneurinilyticus, isolated from CSL, has been evaluated for producing extracellular and cell-bound biosurfactants in a controlled fermentation, using secondary raw materials as a source of nutrients. In the present study, A. aneurinilyticus was inoculated into the culture medium containing sterilized CSL solutions (100–400 g L−1) and incubated using different temperatures (20–60 °C) and fermentation times (8–30 days). The dependent variables under study were the concentration of extracellular biosurfactants and cell-bound biosurfactant production in terms of critical micellar concentration (CMC), as well as the C/N ratio for cell-bound biosurfactant extracts. It was observed that CSL could increase the concentration of extracellular biosurfactants produced by A. aneurinilyticus if these were fermented during 19 days at 40 °C, using 250 g L−1 of CSL; a mean value of 6 g L−1 for extracellular biosurfactants and favorable CMC concentrations enabled the detection of cell-bound biosurfactant extracts under these conditions. Hence, these conditions could be considered optimal for producing both extracellular and cell-bound biosurfactants from CSL.

Solubilization of cuprous oxide in water using biosurfactant extracts from corn steep liquor: a comparative study

In this work the chemical characterization (elemental analysis and the content of phospholipids) and surface-active properties of two biosurfactants (BS) extracted with both chloroform or ethyl acetate from corn steep liquor were compared. The phospholipids content for the BS extracted with chloroform (BS1) was considerably higher (8.15%) than that obtained for the BS extracted with ethyl acetate (BS2), 0.11%. When comparing the FTIR spectra of the two BS studied in this work with the spectrum of the commercial surfactant lecithin, a greater similarity (75%) was observed with the spectrum of the BS1. The biosurfactant extract (BS2) provided the most favorable conditions for the solubilization of cuprous oxide (Cu-Ox) in water (12.54% of copper dissolved), in comparison with BS1. The results achieved were considerably better than those obtained with chemical surfactants (Tween 80, SDS and CTAB) on solubilizing Cu-Ox, resulting in the latter cases on percentages of Cu dissolved always lower than 0.21%. In addition, a factorial design was performed obtaining the optimum conditions to solubilize Cu-Ox, where the maximum water solubility of Cu-Ox (13.17%) was achieved using 3.93 g/L of BS2 with a contact time of 19.86 min and using a concentration of Cu-Ox of 1.96 g/L. Thus, the BS2 extract could have a promising future as solubilizing agent in the formulation of more sustainable Cu-Ox based pesticides. Moreover, it was confirmed that the presence of phospholipids prevents the solubilization of copper-based pesticides in water.

Characterization and Cytotoxic Effect of Biosurfactants Obtained from Different Sources

In this work, five biosurfactant extracts, obtained from different sources, all of them with demonstrated antimicrobial properties, were characterized and subjected to a cytotoxic study using mouse fibroblast cells (NCTC clone 929). Biosurfactant extracts obtained directly from corn steep water (CSW) showed similar surfactant characteristics to those of the extracellular biosurfactant extract produced by Bacillus isolated from CSW and grown in tryptic soy broth, observing that they are amphoteric, consisting of viscous and yellowish liquid with no foaming capacity. Contrarily, cell-bound biosurfactant extracts produced from Lactobacillus pentosus or produced by Bacillus sp isolated from CSW are nonionic, consisting of a white powder with foaming capacity. All the biosurfactants possess a similar fatty acid composition. The cytotoxic test revealed that the extracts under evaluation, at a concentration of 1 g/L, were not cytotoxic for fibroblasts (fibroblast growth > 90%). The biosurfactant extract obtained from CSW with ethyl acetate, at 1 g/L, showed the highest cytotoxic effect but above the cytotoxicity limit established by the UNE-EN-ISO10993-5. It is remarkable that the cell-bound biosurfactant produced by L. pentosus, at a concentration of 1 g/L, promoted the growth of the fibroblast up to 113%.

Can a Corn-Derived Biosurfactant Improve Colour Traits of Wine? First Insight on Its Application during Winegrape Skin Maceration versus Oenological Tannins

In winemaking, oenological tannins are used to preserve wine colour by enhancing the antioxidant activity, taking part in copigmentation, and forming polymeric pigments with anthocyanins. As a novel processing aid, in this study, a biosurfactant extract was evaluated as a solubilizing and stabilizing agent of anthocyanins in red wine. The biosurfactant extract under evaluation was obtained from a fermented residual stream of the corn milling industry named corn steep liquor (CSL). Two red winegrape varieties (Vitis vinifera L. cv. Aglianico and Cabernet sauvignon) were studied for anthocyanin content and profile, and colour traits, during simulated skin maceration for 7 days at 25 °C, as well as polymerization and copigmentation at the end of maceration. A model wine solution was used as a control, which was added either with the CSL biosurfactant or with four different oenological tannins (from grape skin, grape seed, quebracho, and acacia). The results showed that CSL biosurfactant addition improved the colour properties of skin extracts by the formation of more stable compounds mainly through copigmentation interactions. These preliminary results highlighted that the effectiveness of CSL biosurfactant is variety-dependent; however, there is no significant protection of individual anthocyanin compounds as observed for delphinidin and petunidin forms using quebracho tannin.

Characterization of extracellular and cell bound biosurfactants produced by Aneurinibacillus aneurinilyticus isolated from commercial corn steep liquor

The presence of biosurfactants produced by a Bacillus strain in corn steep liquor (CSL), a wastewater stream of the corn milling process, has been recently discovered. However, the species responsible for their production has not been identified at the moment. Therefore, in this work, the Bacillus strain isolated from CSL, with capacity to produce biosurfactants, was subjected to amplification and sequence analysis of the 16S rRNA, being identified as Aneurinibacillus aneurinilyticus. This strain has been proved to be endospore forming and thermophile, what would explain its presence in the commercial CSL. It was observed that the strain under evaluation has the ability to produce both cell-bound and extracellular biosurfactant extracts, which were characterized in this work. The electrospray ionization mass spectrometry (ESI) analysis of the biosurfactant extracts revealed that the extracellular biosurfactant produced by Aneurinibacillus aneurinilyticus is composed by a mixture of lipopeptides, containing C16 and C18 fatty acids and amino acids, including valine, phenylalanine, proline, cysteine, histidine, aspartic acid/asparagine, alanine, glycine, leucine/isoleucine, with biomarkers between 1025-458 m/z. Conversely, the cell-bound biosurfactant extract produced by Aneurinibacillus aneurinilyticus was composed by the cyclic decapeptide gramicidin S, with a characteristic peak at 571 m/z, and lipopeptides with characteristic peaks between 1034-705 m/z, containing alanine, glycine, cysteine, serine, proline, aspartic acid/asparagine, similarly to the amino acid sequence of the extracellular biosurfactant extract.

Characterization and properties of the biosurfactant produced by PAH-degrading bacteria isolated from contaminated oily sludge environment

The aim of the present study was to investigate biosurfactant production ability of five different polyaromatic hydrocarbon (PAH)-metabolizing bacteria, such as Ochrobactrum anthropi IITR07, Pseudomonas mendocina IITR46, Microbacterium esteraromaticum IITR47, Pseudomonas aeruginosa IITR48, and Stenotrophomonas maltophilia IITR87. These bacteria showed biosurfactant production using 2% glucose as rich substrate; strain IITR47 yielded the highest with 906 and 534 mg/L biosurfactant in the presence of naphthalene and crude oil as the unique carbon sources. P. aeruginosa IITR48 showed the least surface tension at 29 N/m and the highest emulsification index at 63%. The biosurfactants produced were identified as glycolipid and rhamnolipid based on Fourier transform infrared spectroscopy analysis. In particular, the biosurfactant produced by bacteria S. maltophilia IITR87 efficiently emulsified mustard oil with an E24 value of 56%. It was observed that, all five biosurfactants from these degrader strains removed 2.4-, 1.7-, 0.9-, 3.8-, and 8.3-fold, respectively, crude oil from contaminated cotton cloth. Rhamnolipid derived from IITR87 was most efficient, exhibiting highest desorption of crude oil. These biosurfactants exhibited good stability without significantly losing its emulsification ability under extreme conditions, thus can be employed for bioremediation of PAHs from diverse contaminated ecosystem. Graphical Abstract.

Fungistatic and Fungicidal Capacity of a Biosurfactant Extract Obtained from Corn Steep Water

Biosurfactants are surface-active compounds that are produced by microorganisms, which in addition to their surfactant capacity, can possess interesting antimicrobial activities that are used in their incorporation into the agrifood industry. In this work, the preservative capacity of a novel biosurfactant extract obtained from a residual stream of the corn-milling industry was evaluated against two different fungi (Aspergillus brasiliensis and Candida albicans) under different biosurfactant concentrations (0.33–0.99 mg/mL), temperatures (4–40 °C), and incubation times (5–11 days). All the assays started with the same concentration of fungi (2 × 10⁶ CFU/mL). The results showed that temperature played an important role in the bactericidal and fungistatic effects of this biosurfactant extract. It was observed that at a low biosurfactant concentration (0.33 mg/mL) and low or high temperatures in the range tested, this biosurfactant extract possessed an important fungicidal effect (complete inhibition) on A. brasiliensis, while at intermediate temperatures, it achieved a fungistatic effect (50% of inhibition). Regarding C. albicans, it was observed that this strain was more resistant than A. brasiliens, although it was possible to achieve growth inhibitions of 76.3% at temperatures of 40 °C after 8 days of incubation with a biosurfactant concentration of 0.99 mg/mL. This work supports the possible application of biosurfactants extracted from corn steep water as preservatives and antimicrobial agents against fungal contaminations on agrifood products.

Novel Multifunctional Biosurfactant Obtained from Corn as a Stabilizing Agent for Antidandruff Formulations Based on Zn Pyrithione Powder

The cosmetic industry provides a wide variety of shampoos to treat dandruff, containing insoluble ingredients such as Zn pyrithione. However, the solubility of this active ingredient is quite limited in both water and oil media; thus, antidandruff formulations must include a large amount of chemically synthesized stabilizing ingredients to avoid their precipitation. In this work, the stabilization of Zn pyrithione in O/W emulsions using a biosurfactant (BS) extract and Tween 80 is studied. The study includes an incomplete factorial design based on the tea tree oil/water ratio and both surfactant and biosurfactant concentrations. The formulations are characterized in terms of particle size, stability after 30 days, and solubility of Zn pyrithione. The formulation that provided the most favorable results contains Tween 80 (5%) and BS extract (2.5%), with an O/W ratio of 0.01. This provides the smallest particle size (40.5 μm), good stability after 30 days (91.0%), and the highest solubility of Zn pyrithione (59%). The results obtained enable the use of the combination of BS extract and Tween 80 as bio/surfactants of antidandruff shampoo formulations, along with another antiseptic agent such as tea tree oil. Furthermore, this is the first work where a biosurfactant is considered to be a stabilizing agent in antidandruff formulations.

A Multifunctional Biosurfactant Extract Obtained from Corn Steep Water as Bactericide for Agrifood Industry

The increase of crop production along with stricter requirements on food security have augmented the demand of new and eco-friendly bactericides. Most of the bactericides used at the moment consist of persistent organic substances, representing a risk for environmental and human health. For instance, agriculture bactericides used for crop protection includes copper-based, dithiocarbamate and amide bactericides, which are not biodegradable, resulting in the necessity of further research about the production of new active principles that attack microorganisms without producing any harmful effect on human health or environment. The biosurfactant extract evaluated in this work as a bactericide, is obtained from corn steep water, a residual stream of corn wet milling industry, which is fermented spontaneously by probiotic lactic acid bacteria that possess the capacity to produce biosurfactants. In previous works, it has been demonstrated that this biosurfactant extract is able to promote the growth of Lactobacillus casei in drinkable yogurts, though its antimicrobial activity against pathogenic strains has not been evaluated at the moment. The results obtained in this work have proved that this biosurfactant extract is effective as bactericide against Pseudomonas aeruginosa and Escherichia coli, at concentrations of 1 mg/mL, opening the door to its use in agrifood formulations for reducing the use of chemical pesticides and preservatives.

Effect of biosurfactant extract obtained from the corn-milling industry on probiotic bacteria in drinkable 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. © 2018 Society of Chemical Industry.

The effect of the presence of biosurfactant on the permeation of pharmaceutical compounds through silicone membrane

The permeation of ten model drugs through silicone membrane was analysed to investigate the effect of the presence of a biosurfactant obtained from corn steep liquor. The ten selected pharmaceutical compounds were chosen to include a diverse range of physicochemical properties, such as variable hydrophobicities, pKa's, molecular masses and degrees of ionisation. When compared with compound permeation alone, the additional inclusion of biosurfactant in the donor phase altered the rate and extent of permeation. It significantly enhanced permeation for five of the compounds, whereas it decreased permeation for four of the compounds and remained approximately the same for the tenth compound. These effects were observed at both biosurfactant concentrations considered, namely 0.005 mg/mL, i.e. below the critical micellar concentration (CMC) and 0.500 mg/mL, i.e. above the CMC of the biosurfactant. Upon analysing permeation change with respect to physicochemical properties of the compounds, it was determined that compounds with a relative molecular mass below 200 resulted in an increase in permeation with biosurfactant present, and those above 200 resulted in a decrease in permeation with biosurfactant present. This effect was therefore attributed to the formation of a drug-biosurfactant interaction that enhanced permeation of smaller compounds, yet retarded permeation for those with a higher molecular mass. These in vitro findings can be considered an indication of potential novel formulation options that incorporate biosurfactant to create transdermal products that have bespoke permeation profiles.

Study of the synergic effect between mica and biosurfactant to stabilize Pickering emulsions containing Vitamin E using a triangular design

HYPOTHESIS

Vitamin E has interesting biological functions for the cosmetic and pharmaceutical industry because it can act as a fat-soluble antioxidant, as well as peroxyl radical scavenger. However, this vitamin is formed by a group of compounds that include tocopherols (γ-tocopherols, α-tocopherol) characterized by their poor solubility in water, what implies the need of using stabilizing agents such as biosurfactants or minerals, in order to make them soluble or stable in formulations composed by water and oil.

EXPERIMENTS

In this work, it has been evaluated the synergic effect between a mining silicate mineral (mica) and a biosurfactant extract, obtained from corn steep liquor, to stabilize emulsions containing water and a non-aqueous soluble antioxidant consisting of Vitamin E, through the use of a triangular design.

FINDINGS

The results show that the presence of biosurfactant extract improves the emulsion volume up to 70% after 22 days, for an emulsion composed of Vitamin E and biosurfactant, whereas the mica component was able to increase the emulsion stability until values of 80% after 30 days of experiment, for those emulsions containing 10% of mica. Hence, both novel ingredients produce a synergistic effect on the Pickering emulsions carried out in the study.

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

Biosurfactants obtained from corn steep liquor were applied to dyed hair and showed good adsorption while maintaining the dyed hair structure in a good state.