Broad-Spectrum Antifungal, Biosurfactants and Bioemulsifier Activity of Bacillus subtilis subsp. spizizenii—A Potential Biocontrol and Bioremediation Agent in Agriculture

Abstract

In this study, the antifungal, biosurfactant and bioemulsifying activity of the lipopeptides produced by the marine bacterium Bacillus subtilis subsp. spizizenii MC6B-22 is presented. The kinetics showed that at 84 h, the highest yield of lipopeptides (556 mg/mL) with antifungal, biosurfactant, bioemulsifying and hemolytic activity was detected, finding a relationship with the sporulation of the bacteria. Based on the hemolytic activity, bio-guided purification methods were used to obtain the lipopeptide. By TLC, HPLC and MALDI-TOF, the mycosubtilin was identified as the main lipopeptide, and it was further confirmed by NRPS gene clusters prediction based on the strain’s genome sequence, in addition to other genes related to antimicrobial activity. The lipopeptide showed a broad-spectrum activity against ten phytopathogens of tropical crops at a minimum inhibitory concentration of 400 to 25 μg/mL and with a fungicidal mode of action. In addition, it exhibited that biosurfactant and bioemulsifying activities remain stable over a wide range of salinity and pH and it can emulsify different hydrophobic substrates. These results demonstrate the potential of the MC6B-22 strain as a biocontrol agent for agriculture and its application in bioremediation and other biotechnological fields.

The Physicochemical and Functional Properties of Biosurfactants: A Review

“…However, their application has encountered certain limitations due to their low resistance to extreme conditions of temperatures and pH in modern food technologies. Based on a study by Lima et al [100], a lipopeptide from Candida glabrata demonstrated the ability to successfully reduce the surface tension from ~50 to 28 mN/m and exhibited the capability to maintain emulsions stable over a broad range of temperatures (0-120 • C), pH values (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), and saline concentrations (2-12%). As a result, biosurfactants have emerged as a promising alternative for several applications.…”

“…In the case of the lipopeptide-derived Bacillus altitudinis, it exhibited reduced antifungal activities beyond 100 • C and at both acidic and basic pH levels [119]. Cheffi et al [26] observed the stability of lipopeptides from Halomonas venusta across various salinity (up to 120 g/L), temperature (4-121 • C) and pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) values by measuring the oil displacement and surface tension.…”

“…Surfactants are amphiphilic molecules that possess both hydrophilic and hydrophobic moieties and are frequently referred to in the literature as surface-active agents. The non-polar part of a surfactant is typically comprised of a hydrocarbon chain, while the polar part (hydrophilic head group) consists of peptides, carbohydrates, phosphates, and proteins [ 1 , 2 ]. This unique molecular structure enables surfactants to possess a wide range of properties, namely their capacity to reduce the surface and interfacial tensions between various phases: liquid–solid, liquid–air, and liquid–liquid.…”

Biosurfactants: Promising Biomolecules for Agricultural Applications

“…The lipopeptides produced by the marine bacterium B. subtilis subsp. spizizenii MC6B-22 showed broad-spectrum activity against ten phytopathogens of tropical crops at a minimum inhibitory concentration of 400 to 25 µg/mL and with a fungicidal mode of action, demonstrating the potential of the MC6B-22 strain as a biocontrol agent for agriculture [140]. The efficacy of Bacillus species associated with plant roots as antifungal biocontrol agents was evaluated.…”