Produção e caracterização de biossurfactantes obtidos por Bacillus subtilis (UFPEDA86) e Bacillus pumilus em extrato aquoso de algaroba

Abstract

Biosurfactants are molecules with amphipathic characteristics, that is, they contain a hydrophilic (polar) and a hydrophobic (non-polar) component in their molecular structure, which promote the reduction of surface and interfacial tension between liquids, solids and gases. They have many applications in various sectors, including agriculture, cosmetics, food, pharmacy, environment and petrochemicals. Compared to synthetic surfactants, biosurfactants have characteristics such as biodegradability, low toxicity, tolerances to wide ranges of temperature, salinity and pH, making them applicable in food products, cosmetics and medicines. However, due to high production costs, research is being carried out with strategies that aim to replace conventional substrates with low-cost and preferably renewable alternatives to production of biosurfactants. In the present work, the production of biosurfactant from Bacillus subtilis (UFPEDA 86) and Bacillus pumilus was conducted using mesquite aqueous extract as substrate, at 1% (v/v) concentration. The cultures were carried out in Erlenmeyer flasks shaken in an orbital rotating incubator at 200 rpm, 37°C and an aeration ratio of 0.4. Samples were taken at regular times to monitor microbial growth, substrate consumption, biosurfactant production and kinetic parameters during the 96h process. The recovery of biosurfactants obtained in the processes was carried out by acid precipitation (HCl at 6N) and characterization through analysis of the functional groups identified in FTIR. In cultivation using the B. subtilis UFPEDA 86 strain, a cell concentration in the exponential phase ([X]) of 0.78 g/L, cell productivity (Px) of 12.07 mg/L.h, maximum specific growth rate (μmax) of 0.0569 h-1, biosurfactant concentration produced 2.83 g/L with an emulsification capacity of 72.1% in lubricating oils. In B. pumilus production, a maximum cell concentration was obtained in the exponential phase (Xmax) of 1.07 g/L, cell productivity (Px) was 8.59 mg/L.h and maximum specific growth rate (μmax) is 0.0063 h-1. In relation to the biosurfactant produced, a concentration of 4.73 g/L was obtained with a good emulsification capacity of 85.4% in lubricating oils. Therefore, with the results obtained so far, it is possible to consider that the B. subtilis UFPEDA 86 and B. pumilus strains could produce lipopeptide-type biosurfactant from mesquite extract, as an alternative substrate, under the proposed conditions.