Utilização de caroço de manga como substrato alternativo para produção de biossurfactante

Abstract

Surfactants are amphiphilic molecules with properties of adsorption and formation of micelles, which guarantee the ability to reduce surface tension, emulsion formation, phase dispersion, and other purposes. However, conventional surfactants are still produced from petroleum, which is harmful to the environment and the populations that consume it. Because of this, biosurfactants have been the subject of studies, as they are molecules similar to synthetic surfactants and produced by microorganisms, being biodegradable and less toxic, and for their production renewable sources can be used, such as agro-industrial residues that in addition to being a source of carbon it is a valuation of residual biomass. Brazil, as a large agricultural producer, generates agro-industrial residues on a large scale, and its use as a substrate in fermentation can significantly reduce the cost of production of biosurfactants. Within this agricultural sector, Brazil is the seventh world producer of mango and its residual biomass has considerable amounts of oils and sugars to be used in the production of biosurfactants. Thus, the production of biosurfactant by autochthonous bacteria isolated from self-fermented residual mango biomass and by Pseudomonas aeruginosa was evaluated, using dehydrated, ground, and pre-treated mango seed as substrate. The mango seed was characterized with lipid content of 3.25% and in the pre-treatment, by autoclave, it released 67 ± 0.01 mg/g of total reducing sugars. The isolate identified as Brevibacillus borstelensis was the only one capable of producing emulsifying agents, presenting a maximum emulsion index of 48.65% with glucose, however, the P. aeruginosa strain showed the best results, with an emulsion index of 57.7% with glucose and positive results in the droplet collapse, oil displacement and hydrocarbon plaque tests, which was selected for the biosurfactant production assays with the pre-treated mango seed. Through experimental planning, it was possible to optimize the production of biosurfactant at pH 6, with 3 g/L of substrate and without the addition of soybean oil and glycerol, reaching a maximum emulsion index of 66.86%, with 9, 16% higher than glucose control. The extracted biosurfactant showed a negative ionic charge and belongs to the class of glycolipids. Therefore, pre-treated mango seed can be an alternative substrate for biosurfactant production by Pseudomonas aeruginosa