Production of a biosurfactant from S. cerevisiae and its application in salad dressing

The Physicochemical and Functional Properties of Biosurfactants: A Review

Surfactants, also known as surface-active agents, have emerged as an important class of compounds with a wide range of applications. However, the use of chemical-derived surfactants must be restricted due to their potential adverse impact on the ecosystem and the health of human and other living organisms. In the past few years, there has been a growing inclination towards natural-derived alternatives, particularly microbial surfactants, as substitutes for synthetic or chemical-based counterparts. Microbial biosurfactants are abundantly found in bacterial species, predominantly Bacillus spp. and Pseudomonas spp. The chemical structures of biosurfactants involve the complexation of lipids with carbohydrates (glycolipoproteins and glycolipids), peptides (lipopeptides), and phosphates (phospholipids). Lipopeptides, in particular, have been the subject of extensive research due to their versatile properties, including emulsifying, antimicrobial, anticancer, and anti-inflammatory properties. This review provides an update on research progress in the classification of surfactants. Furthermore, it explores various bacterial biosurfactants and their functionalities, along with their advantages over synthetic surfactants. Finally, the potential applications of these biosurfactants in many industries and insights into future research directions are discussed.

Antibacterial activity of bioemulsifiers/biosurfactants produced by Levilactobacillus brevisS4 and Lactiplantibacillus plantarumS5 and their utilization to enhance the stability of cold emulsions of milk chocolate drinks

Chocolate milk drink, one of the most popular and widely consumed milk products among the population, independent of their age, has as its main challenge the problem of its physical instability. The aim of this study was to assess the stabilizing effect of bioemulsifiers/biosurfactants (BE/BS) from two lactobacilli strains in a cold chocolate milk drink. The strains Levilactobacillus brevis S4 and Lactiplantibacillus plantarum S5 isolated from pendidam were screened for their ability to produce BE/BS. The produced BE/BS were characterized, their antimicrobial activities were assessed, and their ability to stabilize cold chocolate milk drinks was determined. The results obtained showed BE/BS yields of 3.48 and 4.37 g/L from L. brevis S4 and L. plantarum S5, respectively. These BE/BS showed emulsifying and surface activities that remained stable after treatment at different temperatures, pH, and salinity. The emulsions formed using BE/BS were stable for 72 h at room temperature (25 ± 1°C). The BE/BS exhibited antimicrobial activity against Staphylococcus aureus S1 and Escherichia coli E1. When applied to cold chocolate milk drinks at 0.2% (w/v), the BE/BS from L. brevis S4 and L. plantarum S5 showed interesting solubility indexes and water absorption capacities, which led to the successful stabilization of the drinks. The results of this study demonstrate the stabilizer potential of BE/BS from L. brevis S4 and L. plantarum S5 and suggest their use in the dairy and food industries.

Microbial surfactants: characteristics, production and broader application prospects in environment and industry

Microbial surfactants are green molecules with high surface activities having the most promising advantages over chemical surfactants including their ability to efficiently reducing surface and interfacial tension, nontoxic emulsion-based formulations, biocompatibility, biodegradability, simplicity of preparation from low cost materials such as residual by-products and renewable resources at large scales, effectiveness and stabilization under extreme conditions and broad spectrum antagonism of pathogens to be part of the biocontrol strategy. Thus, biosurfactants are universal tools of great current interest. The present work describes the major types and microbial origin of surfactants and their production optimization from agro-industrial wastes in the batch shake-flasks and bioreactor systems through solid-state and submerged fermentation industries. Various downstream strategies that had been developed to extract and purify biosurfactants are discussed. Further, the physicochemical properties and functional characteristics of biosurfactants open new future prospects for the development of efficient and eco-friendly commercially successful biotechnological product compounds with diverse potential applications in environment, industry, biomedicine, nanotechnology and energy-saving technology as well.

Are all yeast biosurfactants really capable of lowering surface tension below 30 mN/m ?

The study discusses pitfalls in attempts to determine reliable surface tension values for the culture media and their extracts for two biosurfactant-producing yeast strains: Rhodotorula graminis and Rhodotorula babjevae. The values obtained from an Axisymmetric Drop Shape Analysis (ADSA) tensiometer showed systematically more and more shallow dynamic surface tension decays, suggesting a deterioration of their surface activity. The rate of this apparent surface activity loss was shown to depend on the sample history, with slower changes observed in vigorously shaken samples. On the other hand, the force-based Wilhelmy plate method provided apparently stable surface tension values of the order of 30 mN/m, in accordance with numerous previous literature reports on similar yeast biosurfactants. Both observations can be justified by the presence of an oil emulsified by biosurfactants produced by the yeast. We show that the odd (apparent) surface tension results are in fact the measurement artifacts resulting from slow demulsification and subsequent oil-spreading assisted by the yeast biosurfactants. The apparent surface tension reduction is thus indeed caused by the presence of biosurfactants, but its value does not represent their real adsorption in a thermodynamic sense. Consequently, the often reported in the literature very low surface tension values for the yeast culture media, of the order of 30 ± 5 mN/m, should be treated with caution, especially if the emulsion stabilized with the biosurfactant had not been fully destabilized prior to the measurement.

Cookies and muffins containing biosurfactant: textural, physicochemical and sensory analyses

Interest in products with more natural ingredients increases the potential for application of Biosurfactants in foods. The aim of the present study was to assess the toxicity of biosurfactant produced by Saccharomyces cerevisiae URM6670 and the effect of the incorporation of this biosurfactant on the physicochemical and textural characteristics of cookies and muffins, performing unprecedented assessment of the sensorial effects of this application. The toxicity analysis revealed that the biosurfactant is classified as a mild irritant, with irritation indices lower than 4.9. The physical analysis of the incorporation of the biosurfactant in the formulation revealed that the addition of 1% to cookies significantly increased the diameter and spread factor. In muffins, significant changes in these properties were found beginning at 0.25% biosurfactant. The moisture content in cookies was reduced by a maximum of 74%, while in muffins this reduction was approximately 6%. The lipid content increased significantly with the addition of 1% of the biosurfactant (11% in cookies and 25% in muffins). The textural analysis revealed that the biosurfactant at 1% led to a significant increase in firmness as a consequence of the reduction in the moisture content. In muffins, the same concentration increased the firmness and variables related to chewability. The sensory analysis revealed that the muffins with biosurfactant had greater acceptance compared to the cookies. Thus, the biosurfactant demonstrated potential application in bakery products due to low toxicity and positive evaluation in important sensorial parameters for its commercialisation.

Effect of a Multifunctional Biosurfactant Extract Obtained from Corn Steep Liquor on Orange and Apple Juices

Biosurfactant extracts are multifunctional ingredients composed of natural polymers that can be used in the food industry as stabilizing and antimicrobial agents, although their inclusion in food matrices has been scarcely explored. In this work, a biosurfactant extract, with antimicrobial properties, obtained from a fermented stream of the corn wet-milling industry was introduced into an apple and orange juice matrix to evaluate the changes produced in the sugar consumption, pH, and biomass formation at different temperatures (4–36 °C) and storage time (1–7 days). It was observed that the addition of biosurfactant extract reduced the hydrolysis rate of polymeric sugars, decreasing the concentration of soluble sugars from 85.4 g/L to 49.0 g/L in apple juice after 7 days at 20 °C in the absence and presence of biosurfactant extract, respectively. In general, soluble sugars increased in juices for 5–6 days and after those sugars decreased at different rates depending on the temperature of storage. Differences in sugar solubilization and degradation were more significant in apple juice than in orange juice at 20 °C and 7 days of storage, achieving for orange juice values of 101 and 102 g/L in the absence and presence of biosurfactant extract, respectively. Biomass growth was almost unaffected by the biosurfactant extract concentration and the optimal conditions for biomass production were detected at intermediated temperatures after 6–7 days of storage for both apple and orange juices, obtaining maximum concentrations of 1.68 g/L and 1.54 g/L for apple juice and orange juice, respectively, in the absence of biosurfactant extract. The pH during storage was kept in the range of 3.35–3.48 for apple juice and of 3.40–3.77 for orange juice.