Production and characterization of rhamnolipids by Pseudomonas aeruginosa isolated in the Amazon region, and potential antiviral, antitumor, and antimicrobial activity.

Biosurfactants encompass structurally and chemically diverse molecules with surface active properties, and a broad industrial deployment, including pharmaceuticals. The interest is growing mainly for the low toxicity, biodegradability, and production from renewable sources. In this work, the optimized biosurfactant production by Pseudomonas aeruginosa BM02, isolated from the soil of a mining area in the Brazilian Amazon region was assessed, in addition to its antiviral, antitumor, and antimicrobial activities. The optimal conditions for biosurfactant production were determined using a factorial design, which showed the best yield (2.28 mg/mL) at 25 °C, pH 5, and 1% glycerol. The biosurfactant obtained was characterized as a mixture of rhamnolipids with virucidal properties against Herpes Simplex Virus, Coronavirus, and Respiratory Syncytial Virus, in addition to antimicrobial properties against Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecium), at 50 µg/mL. The antitumor activity of BS (12.5 µg/mL) was also demonstrated, with potential selectivity in reducing the proliferation of breast tumor cells, after 1 min of exposure. These results demonstrate the importance of studying the interconnection between cultivation conditions and properties of industrially important compounds, such as rhamnolipid-type biosurfactant from P. aeruginosa BM02, a promising and sustainable alternative in the development of new antiviral, antitumor, and antimicrobial prototypes.

Optimization of enhanced oil recovery using ASP solution.

Many studies have been conducted to focused on developing an optimal alkali/surfactant/polymer (ASP) composition to increase the recovered fraction of oil in reservoirs that have already undergone water injection. To analyze the effect of alkali (Na2CO3), surfactant (lauryl sodium sulfate), and polymer (commercial xanthan gum) concentration on oil recovery, a complete factorial experimental design was performed with combinations of three variables (alkali, surfactant, and polymer) and three central point replications (2³ + 3). The experiments were carried out on a core holder using rock samples from the Botucatu formation. The simulated oil reservoirs have an average permeability of 348 mD and a temperature of 60 °C. The crude oil was acquired from the Carmópolis field, with 25.72 °API. Synthetic production water containing 40,000 mg L-1 of NaCl and 13,000 mg L-1 of Na2SO4 was injected through an HPLC pump to saturate the rock samples and to recover the oil in the secondary step. From the experimental results, it was verified that the surfactant and polymer concentrations are the most statistically significant independent variables and that first-order interactions are not statistically significant for the process. The oil recovery factors in the secondary stage ranged between 30 and 36 % of the OOIP, which are within the range reported in the literature. The optimal composition of the ASP fluid obtained a recovered fraction of oil of 62 % in the advanced step. Other combinations reported in the literature used higher concentrations of alkali, surfactant, and polymer with lower recoveries and higher cost in the injection design. Thus, the present study highlights the necessity to investigate the performance of each component of the ASP solution. In addition, the results obtained in this study are very attractive for possible full-scale applications.