Microbial biosurfactants: a review of recent environmental applications

Abstract

Microbial biosurfactants are low-molecular-weight surface-active compounds of high industrial interest owing to their chemical properties and stability under several environmental conditions. The chemistry of a biosurfactant and its production cost are defined by the selection of the producer microorganism, type of substrate, and purification strategy. Recently, biosurfactants have been applied to solve or contribute to solving some environmental problems, with this being their main field of application. The most referenced studies are based on the bioremediation of contaminated soils with recalcitrant pollutants, such as hydrocarbons or heavy metals. In the case of heavy metals, biosurfactants function as chelating agents owing to their binding capacity. However, the mechanism by which biosurfactants typically act in an environmental field is focused on their ability to reduce the surface tension, thus facilitating the emulsification and solubilization of certain pollutants ( in-situ biostimulation and/or bioaugmentation). Moreover, despite the low toxicity of biosurfactants, they can also act as biocidal agents at certain doses, mainly at higher concentrations than their critical micellar concentration. More recently, biosurfactant production using alternative substrates, such as several types of organic waste and solid-state fermentation, has increased its applicability and research interest in a circular economy context. In this review, the most recent research publications on the use of biosurfactants in environmental applications as an alternative to conventional chemical surfactants are summarized and analyzed. Novel strategies using biosurfactants as agricultural and biocidal agents are also presented in this paper.

Design of TiO2-Based Hybrid Systems with Multifunctional Properties

“…Microbial polymers are biosurfactants whose use is attracting increasing interest for the removal of metal(loid)s from soil, effluents, and wastewaters [ 2 , 3 ]. Surfactin, a cyclic lipopeptide produced by Bacillus subtilis, is considered one of the most effective biosurfactants [ 6 ]. Its low critical micelle concentration; high binding affinity for metal cations; foaming, emulsifying, and dispersing properties; high surface activity; and ability to interact and disrupt microorganisms’ cell membranes make surfactin an ideal candidate for water/soil bioremediation and antibacterial/antiviral applications [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ].…”

Bacterial-derived surfactants: an update on general aspects and forthcoming applications

“…Most data in literature describe bacterial BS production at laboratory scale using shake flasks and low volumes; however, some reports using bioreactors are available [86]. Stirred tank reactors (STR) operated in batch or fed-batch mode are usually applied for BS production [87][88][89]; however, conventional fermentation is dependent on the supply of dissolved oxygen by stirring and aeration that, when in high levels, can lead to shear stress damaging the cells and also to excessive foaming that reduces the efficiency of the process [90].…”

Multifunctional, stable and low-cost lipopeptide biosurfactant produced by Enterobacter cloacae UCP 1597

“…Thus, the use of appropriate techniques is essential to allow these biomolecules to be economically and competitively integrated in the market (Thavasi & Banat, 2019;Sarubbo, et al, 2022). Several techniques have been reported to recover biosurfactants after fermentation, the most reported of which is liquid phase solvent extraction using a variety of organic compounds (Venkataraman, et al, 2021;Eras-Muñoz, et al, 2022). In this work, the biosurfactant produced by E. cloacae UCP 1597 was extracted with ethyl acetate, obtaining a yield of 13.69 g/L, higher than those previously described for biosurfactants produced by this genus (Table 3).…”