Biomassa residual frutícola: uma abordagem metagenômica da microbiota autóctone e sua utilização na produção de biossurfactantes

Abstract

Biosurfactants are multifunctional compounds of microbial origin of industrial and environmental interest due to their surfactant and emulsifying properties of biodegradable nature and low toxicity. Several culture media and carbon sources are used in the production of these compounds, as well as a wide variety of microorganisms, isolated from multiple environments. The present work aims to promote a bioprospection in the microbiota associated with fruit residues (orange, mango and fruit mix) in order to identify the genetic composition of this microbiota related to the biosynthesis of biosurfactants. For this, the residues were evaluated through a metagenomic approach, where the genetic potential of their associated microbiota for biosurfactant biosynthesis was determined. The residues presented a common core that includes the genera Klebsiella, Enterobacter, Stenotrophomonas, Acinetobacter and Escherichia and similar functional profiles related to biosurfactant biosynthesis, presenting a genetic potential mainly for lipopeptide biosynthesis, with emphasis on genes related to the biosynthesis of putisolvins, mycosubitilin and iturin A. The taxonomic assignments to the genes present in higher abundance in the samples were related to the common core found. From the metagenome, 34 genomes (MAGs) were retrieved, 10 of which were of high quality, which were evaluated for genes related to the production of biosurfactants. MAGs showed genetic potential for the biosynthesis of biosurfactants, especially lipopeptides, corroborating the metagenomic analysis. The MAG OB01 taxonomically identified as Brevibacillus laterosporus stood out for the number of assigned genes. Subsequently, the microorganism isolated from mango residue, identified as Brevibacillus borstelensis ISM04, was used in the fermentation process for the production of biosurfactant using glycerol as a carbon source. The produced biosurfactant showed an emulsifying activity of 67 % in kerosene and showed thermal stability up to 80 °C and at pH range between 6 and 10, in addition, it did not show toxicity in tomato and lettuce seeds. The compound produced was partially characterized and the analyzes suggest that it is a lipopeptide biosurfactant.