Biosurfactants are surfactants of microbial origin. Biosurfactants are active compounds produced at the microbial cell surface and reduce surface tension. Usually, surfactants are substances that reduce interfacial tension between two phases, i.e., oil and water or vice versa, and water and air, making it a soluble emulsion. The different origins of surfactants are
1. Natural origin: these are surfactants produced by microbes like bacteria, fungi, and yeast.
2. Synthetic origin: these are surfactants that are produced by a chemical process.
3. Biodegradable: these surfactants are environment-friendly and decompose quickly.
Properties of biosurfactants:
1. Microorganisms produce surface-active molecules
2. Helps in attachment to the surfaces
3. It is stable across various temperatures and pHs, as sometimes the interaction of chemical compounds of surfactants with nutritional components of food alters the pH and salinity of the food composition
4. It is suitable for human consumption as it is non-toxic
5. High emulsifying, solubilizing, and adsorption power
6. Used to clean vegetables by removing heavy metals and boost fish immunity
7. Popularly used in bakeries, salad dressing
8. Inhibits the growth of pathogens
Biosurfactants have both hydrophilic and hydrophobic moieties, so they reduce the surface and interfacial tension between two liquids, oil and water. These are produced by the microbial fermentation process, and the energy consumed is much less, which makes them more sustainable. Bioremediation is a process of degradation that involves the use of microbes, and biosurfactants play a crucial role in this process. By employing this technique, it is helpful in the remediation of soil, oil spills, and industrial wastewater treatment. Besides remediation, it is also important in the food industry. Apart from being biodegradable and sustainable, they are also cost-effective. The best part is that the byproducts released during their production are used as biofuels, organic fertilizers, and animal feed.
With the advancement of technologies, the production of biosurfactants can be increased at the industrial level by employing techniques like metabolic engineering and synthetic biology. Metabolic engineering is the targeted alteration of metabolic pathways in organisms, whereas synthetic biology is the redefining or modifying of the microbes.
Why is there a buzz for the use of biosurfactants?
To know in detail, an article titled “Recent Advances in the Application of Microbial Biosurfactants in Food Industries: Opportunities and Challenges” published in Elsevier journal was referred to, and the findings are listed below.
Generally, the synthetic surfactants used widely in the food industry contain chemical compounds that can destroy gut health. Our gut plays a crucial role in digestion and absorption. Due to the intake of synthetic surfactants, the protective mucosal layer protecting the epithelium of the intestine in the stomach gets damaged. The function of the mucosal layer is to provide a hydrophobic barrier and prevent the entry of toxins, nanoparticles, and water-soluble minerals through negatively charged ions. So now what the synthetic surfactant does is damage the mucosal layer, which reduces its function. The reduced function can lead to gut-related problems.
Surfactant reduces cohesive forces between molecules when suspended in a liquid medium, thereby reducing surface tension. Reduction of surface tension is correlated with critical micelle formation (CMC). CMC is defined as the concentration at which surfactant starts forming micelles. Some studies have also reported that biosurfactants have a lower or similar CMC to synthetic surfactants. The lower the CMC, the more effective the surfactant. The selection of biosurfactant-producing strains is based on three properties: 1) capacity to reduce surface tension 2) Oil spreading technique and 3)emulsifying power. Biosurfactants produced from Bacillus subtilis strains are higher than those of Glucopone® 215 and Glucopone® 650, which are used for food processing. These biosurfactants are anti-adhesive, which means they prevent the formation of pathogenic bacteria on any non-biological or biological surface.
Lipopeptides from Bacillus species and rhamnolipids from Pseudomonas aeruginosa prevent the deterioration of food by penetrating the membrane and preventing microbial growth, thereby maintaining its quality. They work by preventing the adhesion of pathogenic bacteria to the food components by altering the hydrophobicity of the surface. Biosurfactants produced by microbes like Bacillus licheniformis and Lactobacillus brevis act on the food surface and inhibit the pathogenic Listeria monocytogenes and Candida albicans from growing on the food surfaces. If these microbes enter the body, they can cause gut-related disorders.
Rhamnolipid biosurfactants obtained from pseudomonas aeruginosa and saccharomyces cerevisiae have excellent emulsifying power and stability even under extreme conditions. Because of these properties, it is widely used in the food industry for maintaining solubility in salad dressings, butter, icing creams, and other confectionaries and textures. The important aspect is that the lipopeptide has a cyclic ring structure, that cannot be easily destroyed by the host enzymes, which is crucial for its use in the food industry.
Lipopeptides are usually categorized into three classes. They are surfactin, fengycin, and iturin. Surfactin and fengycin have antifungal and immune-modulating activities, whereas iturin has bactericidal activity. Because of these properties, it can be used to improve food quality.
Applications of biosurfactants:
It can be used as an emulsifier to improve the stability and texture of food products, a lubricant to provide smooth flow, a foamer to help in forming and stabilizing foam in beverages, a disperser to evenly distribute the flavoring agent, and for moisture retention, and to improve the shelf life of food products with its antimicrobial properties.
Limitations of biosurfactants:
1. Variability in the production of microbial strains
2. Scalability in the fermentation process
3. Purification costs
4. Lack of regulatory standards to secure safety and efficacy
REFERENCES:
1. Safe microbial substitute can replace synthetic surfactants in the food industry. (n.d.). https://pib.gov.in/PressRelease
2. Roy, A., Khan, M. R., & Mukherjee, A. K. (2024). Recent advances in the application of microbial biosurfactants in food industries: Opportunities and challenges. Food Control, 163, 110465. https://doi.org/10.1016/j.foodcont.2024.110465
3. Lopez, Z. (n.d.). Microbial biosurfactants: Green alternatives for industrial applications in bioremediation and food processing. www.alliedacademies.org. https://doi.org/10.35841/aamcr-8.1.191
(Input from various sources)
(Rehash/Dr. Siddiqua Parveen/MSM)
