The review, led by Aditya Thapliyal, Aishwary Purohit, Souvik Kumar Paul and Amar Jyoti Das, critically assesses the microbial conversion of sugarcane bagasse into rhamnolipids within circular bioeconomy frameworks. Its central message is that turning bagasse into biosurfactants is not merely an environmental nicety but a technically plausible route to cheaper, more sustainable surfactant production, provided that the right combination of pretreatment, microbial strain engineering, fermentation strategy and downstream processing can be assembled at scale. The authors frame the work explicitly against United Nations Sustainable Development Goal 9 on industry, innovation and infrastructure, and SDG 12 on responsible consumption and production.

The environmental case begins with the waste problem itself. Bagasse that is not burned for energy is frequently dumped or left in the open, where wind disperses it and open burning releases ash, greenhouse gases, particulate matter, nitrogen oxides and carbon monoxide. Inhaled bagasse ash can penetrate deep into the respiratory tract, while landfilling and open dumping generate leachate and harbour pathogens and pests. These hazards have prompted strict regulation: India’s Air Act of 1981 and its 1987 amendment prohibit open burning of agricultural residues, while Brazil has legislated the phased elimination of pre-harvest cane burning under State Law No. 11,241/2002 and the Green Ethanol Agreement, and the United States regulates bagasse combustion under the Clean Air Act. Redirecting bagasse into bioprocesses thus addresses both a pollution problem and a resource opportunity.

Chemically, bagasse is well suited to microbial upgrading. Roughly half of its mass is cellulose, about a quarter hemicellulose and a quarter lignin, with a notably low ash content compared with residues such as rice straw or wheat straw. The cellulose and hemicellulose fractions can be hydrolysed into fermentable sugars, chiefly glucose and xylose, that microorganisms can convert into rhamnolipids. Because bagasse is generated continuously and centrally at sugar mills, it offers a consistent, scalable and inexpensive carbon source, in sharp contrast to the refined glucose, glycerol and vegetable oils that dominate conventional rhamnolipid fermentation and drive up costs.

Rhamnolipids themselves are glycolipid biosurfactants composed of one or two rhamnose sugar units linked to beta-hydroxy fatty acid chains. This amphiphilic architecture lets them cut the surface tension of water from about 72 millinewtons per metre to roughly 25 to 30, and they do so at low critical micelle concentrations, meaning small amounts are effective. They remain stable across wide ranges of pH, temperature and salinity, and they are readily biodegradable and far less toxic than synthetic surfactants. These properties underpin their use in bioremediation, microbial enhanced oil recovery, anti-biofilm pharmaceutical applications, cosmetics, food processing and agriculture as biocontrol agents and formulation stabilizers.

The dominant natural producer, however, is a problem. Pseudomonas aeruginosa synthesizes rhamnolipids through the rhlA, rhlB and rhlC enzymes, regulated by quorum sensing, but it is an opportunistic pathogen classified at biosafety level 2 and is not on the US FDA’s GRAS list, forcing costly containment and purification for food, cosmetic and pharmaceutical uses. The review highlights how metabolic engineering is mitigating this. Replacing the native rhlAB promoter with the stronger constitutive poprL promoter in engineered strain WJPAB raised yields to 57.83 grams per litre, a 91 percent increase over wild type, while systematic gene deletions in strain 8D lifted production from 8.567 to 14.53 grams per litre. Heterologous expression of the rhlAB operon in safe hosts such as Pseudomonas putida KT2440 has produced 40.2 grams per litre in optimized fed-batch fermentation, and non-pathogenic producers including Pseudomonas chlororaphis, Acinetobacter calcoaceticus and Burkholderia thailandensis offer further regulatory advantages, albeit often at lower native yields.

Getting the sugars out of bagasse is the first technical hurdle. Pretreatment options include physical milling, steam explosion, chemical methods using dilute sulphuric acid to hydrolyse hemicellulose or alkali treatments with sodium hydroxide and lime to remove lignin, and biological delignification with fungi such as Trametes versicolor and Phanerochaete chrysosporium. Each approach involves trade-offs: chemical pretreatments can generate fermentation inhibitors, steam explosion is energy intensive, and biological methods are slow. Once sugars are released, fermentation can proceed in batch, fed-batch or continuous modes, with fed-batch generally preferred because it sustains high cell density and supports secondary metabolite production. Carbon catabolite repression, in which glucose suppresses xylose utilization through the Crc/Hfq regulatory system, and careful optimization of the carbon-to-nitrogen ratio, with a ratio of around 22 reported as optimal for one Pseudomonas strain, are key determinants of yield.

Practical demonstrations of the concept are encouraging. Camilios-Neto and colleagues achieved 45 grams per litre of rhamnolipids from Pseudomonas aeruginosa UFPEDA 614 grown on a solid mixture of bagasse and corn bran supplemented with glycerol and soybean oil. El-Housseiny’s gamma-irradiated P. aeruginosa mutant produced 46.85 grams per litre over ten days on bagasse and sunflower seed meal with glycerol, roughly 5.5 times more than submerged fermentation. A co-culture of P. aeruginosa and Saccharomyces cerevisiae on steam-exploded bagasse simultaneously yielded 9.1 grams per litre of rhamnolipids and 8.4 grams per litre of ethanol. Downstream, recovery relies on acid precipitation at low pH, solvent extraction with ethyl acetate, foam fractionation that exploits the molecules’ own surface activity, and membrane ultrafiltration, each balancing cost, purity and environmental burden.

The review insists that neither economic viability nor sustainability claims can rest on substrate choice alone, and it makes a strong case for integrating techno-economic analysis and life cycle assessment. Reported production costs vary almost a hundredfold, from about 7.64 US dollars per kilogram for digestate-based processes to 600 dollars per kilogram in some simulated scenarios, while glucose-based production can reach 56 dollars per kilogram. Fermentation consistently emerges as the dominant environmental hotspot, contributing roughly 76 percent of the global warming potential in one assessment, driven by aeration, mixing and thermal energy demands, while purification steps such as acetone precipitation or solvent extraction account for 35 to 43 percent of the environmental burden in others. Because substrate substitution alone shifts these numbers relatively little, the authors argue that process intensification, energy recovery from residual biomass, solvent recycling and industrial symbiosis with sugar mills offer the greatest sustainability gains.

The market context makes the timing compelling. The global biosurfactant market, in which rhamnolipids are a major component, is projected to grow from about 14.15 kilotons in 2026 to nearly 71 kilotons by 2031, a compound annual growth rate of over 38 percent, driven by consumer demand for eco-friendly ingredients in personal care, agriculture, food and bioremediation. If metabolic engineering, tailored pretreatment, co-product biorefineries and rigorous life cycle assessment continue to converge, the review concludes, sugarcane bagasse could shift from a burning liability to the foundation of economically and environmentally resilient bio-based surfactant production, turning one of agriculture’s largest waste streams into a cornerstone of the circular bioeconomy.

Subject of Research: Microbial production of rhamnolipid biosurfactants from sugarcane bagasse waste in circular bioeconomy frameworks

Article Title: From waste to rhamnolipid biosurfactant production using sugar industry waste in circular bioeconomy frameworks

Article References: Thapliyal, A., Purohit, A., Paul, S. K., & Das, A. J. (2026). From waste to rhamnolipid biosurfactant production using sugar industry waste in circular bioeconomy frameworks. Discover Green Chemistry, 1(1), Article 31. https://doi.org/10.1007/s44509-026-00030-2

Image Credits: AI Generated

DOI: 10.1007/s44509-026-00030-2

Keywords: sugarcane bagasse, rhamnolipids, biosurfactants, circular economy, fermentation, Pseudomonas aeruginosa, lignocellulosic biorefinery, metabolic engineering, life cycle assessment, techno-economic analysis, waste valorization, sustainable development goals

In this context, microfluidic emulsification emerges as a cutting-edge technology revolutionizing how emulsions are created and utilized in various industries, from pharmaceuticals to food production. This technique enables precise control over droplet size and distribution, allowing for the development of stable micro-emulsions and nano-emulsions. By harnessing microfluidics, researchers can achieve more uniform formulations that display enhanced performance and reduced resource consumption compared to traditional methods. The combination of sustainable surfactant engineering and microfluidic emulsification offers a glimpse into an innovative future where resource efficiency and environmental stewardship go hand in hand.

The need for sustainable surfactants is driven by the widespread use of conventional surfactants that have detrimental impacts on the environment. These synthetic compounds, often derived from petrochemicals, contribute to pollution and are not always biodegradable. The toxicity associated with many traditional surfactants poses a risk to aquatic life and ecosystems at large. As such, researchers have been investigating bio-based surfactants that leverage renewable resources. These bio-surfactants, extracted from natural sources such as plants and microorganisms, promise to reduce ecological footprints while maintaining efficacy in various applications.

Microfluidic emulsification plays a crucial role in this transition. By utilizing a microfluidic device, researchers can finely tune the generation of emulsions at a microscale level. This level of control enables the design of surfactant-stabilized emulsions with tailored properties, essential for diverse applications. For instance, in the cosmetic industry, where texture and performance are paramount, achieving the right emulsion can significantly enhance product appeal and effectiveness. With the advent of microfluidics, the enhancement of emulsion stability and performance can lead to improved product lifespan and reduced waste.

Additionally, microfluidic emulsification provides an efficient platform for the encapsulation of bioactive compounds. Encapsulation is vital for protecting sensitive ingredients from degradation while ensuring their sustained release. In the food industry, for instance, flavor and nutrient encapsulation can enhance product quality and extend shelf life. The more precise the emulsion, the better the encapsulation of these critical components, leading to more effective formulations that meet consumer demands for quality and sustainability.

The practical applications of sustainable surfactants and microfluidic emulsification are extensive. The agricultural sector, for example, could greatly benefit from bio-based surfactants that serve as eco-friendly agents for pesticide formulations. By utilizing naturally derived surfactants, farmers can protect crops while minimizing the potential for environmental contamination. Moreover, the precise control offered by microfluidic emulsification can optimize the delivery of active ingredients, ensuring that they are effectively distributed and absorbed by crops.

In addition to agriculture, the medical field stands to gain significantly from advancements in this area. Drug delivery systems that incorporate microfluidic technology can improve therapeutic efficacy by precisely controlling release profiles. By utilizing sustainable surfactants, researchers can also develop formulations that are safer for patients and more environmentally friendly. This integration of sustainability with cutting-edge technology reflects a growing trend towards greener practices in the pharmaceutical industry.

Conversely, the exploration of sustainable surfactant engineering is not limited to bio-surfactants derived from natural sources. Researchers are also investigating novel synthetic pathways that utilize waste products and by-products from other industries. This approach not only contributes to waste reduction but also showcases the potential for circular economy practices in surfactant production. By finding innovative ways to transform what would otherwise be discarded into valuable surfactant materials, the industry could drastically reduce its reliance on unsustainable sources.

The intersection of these two fields — sustainable surfactant engineering and microfluidic emulsification — leads to a cooperative mechanism for advancing sustainability. Researchers emphasize that collaboration across disciplines is essential to push boundaries and achieve new heights in green technology. As engineers, chemists, and environmental scientists come together, they can cultivate cross-disciplinary innovations that prioritize sustainability and pave the way for future developments.

As these technologies gain traction, it is critical to communicate their benefits to stakeholders across industries. Increased awareness and understanding of sustainable surfactants and microfluidic emulsification can help stimulate investments and research funding. By showcasing successful case studies and implementing pilot programs, advocates can demonstrate the efficacy of these approaches and encourage broader adaptation within traditional systems.

Industry leaders and policymakers also play a vital role in nurturing this innovation ecosystem. By implementing supportive regulations and incentives for utilizing sustainable practices, they can significantly accelerate the transition towards greener solutions. Commitment from governments to support sustainable manufacturing initiatives can drive research and development efforts, further strengthening the foundation for future breakthroughs.

However, the adoption of sustainable surfactants and microfluidic emulsification technologies is not without challenges. There are still technical hurdles that require attention, including optimizing scalability and resource availability. Addressing these challenges necessitates a concerted effort among researchers and industry stakeholders to develop frameworks and strategies that can promote successful transitions.

As we stand on the brink of a revolution in surfactant technology, the implications reach far beyond just industry sustainability; they encompass environmental stewardship and innovation. By prioritizing the shift towards sustainable surfactants and microfluidic emulsification methods, society can harness the power of science and technology for good. The transition promises a healthier planet and a pioneering pathway for future advancements, proving that engineering and environmental responsibility can coexist harmoniously.

These advancements mark a pivotal moment as we look ahead to a sustainable future, one where the innovations in surfactant engineering and emulsification can transform industries and redefine standards. As researchers and practitioners continue to navigate the landscape of sustainable chemistry, the collaborative spirit and commitment to green practices will be key drivers of success.

The future of surfactants is indeed bright, and as knowledge expands, so does the opportunity to create a sustainable world that reflects our collective responsibility towards the environment. Embracing these innovations is not simply a trend but a crucial step towards impactful change in how we produce and interact with chemical products across various industries.

Through this transformative journey in sustainable surfactant engineering and microfluidic emulsification, we are witnessing the birth of an exciting chapter in the world of materials science. As these methods continue to evolve and gain acceptance, the ripple effects will undoubtedly be felt globally, leading us toward a paradigm shift rooted in sustainability and innovation.

Subject of Research: Sustainable surfactant engineering and microfluidic emulsification.

Article Title: Sustainable surfactant engineering and microfluidic emulsification for green encapsulation.

Article References:

Syofii, I., Irwansyah, R. & Whulanza, Y. Sustainable surfactant engineering and microfluidic emulsification for green encapsulation.
Discov Sustain (2025). https://doi.org/10.1007/s43621-025-02395-z

Image Credits: AI Generated

DOI:

Keywords: Sustainable surfactants, microfluidic emulsification, green chemistry, bio-based surfactants, emulsion technology.