Implications of microbial enhanced oil recovery and waterflooding for geochemical interpretation of recovered oils.

Biosurfactants and waterflooding have been widely reported thus far for enhancing oil production. Nevertheless, there is a lack of literature to explore enhanced oil recovered methods effects on its chemical composition. The aim of this work is to investigate the effects of a biosurfactant produced by Bacillus safensis and brine injection on the recovered petroleum composition, and their implications for geochemical interpretation. Original and oils recovered from displacement tests were analyzed by gas chromatography and ultra-high-resolution mass spectrometry, emphasizing saturated and aromatic biomarkers and basic and acidic polar compounds. Geochemical parameters based on some saturated compounds were subtly affected by the recovery methods, showing their reliable applicability in geochemical studies. Contrarily, parameters based on some aromatic compounds were more affected by biosurfactant flooding, mostly the low molecular weight compounds. Thus, these aromatic parameters should be applied with caution after such methods. The distribution of basic and acidic polar compounds can also be modified affecting the geochemical interpretation. In the case of the basic ones, the biosurfactant greatly influenced the N class species with favorable loss of lower aromaticity compounds. In addition to water solubilization, the compositional changes described in this study can be related to fractionation due to adsorption on reservoir rocks.

Weathering impacts on petroleum biomarker, aromatic, and polar compounds in the spilled oil at the northeast coast of Brazil over time.

After the wide oil spill reached the northeast of Brazil, the resurgence of oil was recorded and to evaluate this oil in detail, two samples collected in the state of Pernambuco in 2019 and 2021 were submitted to multiple analytical techniques. For both, we have found similar saturated biomarkers and triaromatic steroid ratios, implying that they are from the same spilled source. The n-alkanes, isoprenoids, and cycloalkanes were almost completely degraded due to evaporation, photooxidation, and/or biodegradation processes. The preferential loss of less alkylated PAHs than the more alkylated ones suggests that biodegradation was the most active process. This hypothesis is reinforced by the formation of mono and dicarboxylic acids assessed by GC × GC-TOFMS and ESI(-) FT-ICR MS high-resolution techniques. Furthermore, based on the ESI(-) FT-ICR MS results, three new ratios were proposed to evaluate the progress of the biodegradation process over time: Ox>2/O, SOx/SO, and SOx/N.

Antiproliferative activity of Luehea candicans Mart. et Zucc. (Tiliaceae).

Luehea candicans Mart. et Zucc. (Tiliaceae) is known as 'açoita-cavalo' and is one of the most important medicinal plants found in the Brazilian cerrado. The crude methanolic extracts of the branches and leaves and their fractions were evaluated using the following cancer cell lines: MCF-7 (breast), NCI-ADR (breast expressing the multidrug resistance phenotype), NCI-460 (lung), UACC-62 (melanoma), 786-0 (kidney), OVCAR (ovarian), PCO-3 (prostate), HT-29 (colon) and K-562 (leukaemia). The crude methanolic extracts from the branches (B) and leaves (L) were able to inhibit the growth of the K-562 and 786-0 cell lines in a dose-dependent manner, with GI(50) values of 8.1 and 5.4 µg mL(-1), respectively. The hexane (L1), chloroform (L2) and methanol (L4) fractions derived from extract L showed a high selectivity and pronounced cytostatic activity against 786-0 (GI(50) ~ 40 µg mL(-1)). A significant amount of lupeol was isolated from fraction L2. The chloroform (B2) and methanol (B3) fractions derived from extract (B) exhibited less selectivity, showing the highest cytostatic activity against K-562, NCI-ADR, OVCAR, MCF-7 and NCI-460 cells, with GI(50) values between 27 and 40 µg mL(-1). Lupeol, betulin, a mixture of steroids, (-)-epicatechin, vitexin and liriodendrin were isolated from these active fractions.