Sabrina Pinto Salamoni

Capability of a selected bacterial consortium for degrading diesel/biodiesel blends (B20): Enzyme and biosurfactant production

The search for alternative sources of energy, such as biodiesel, has been stimulated, since this biofuel is highly susceptible for biodegradation and has low toxicity, thus, reducing the impact in ecosystems. The objective of this study was to select a bacterial consortium with potential for degrading diesel/biodiesel blends (B20) obtained from areas contaminated with hydrocarbons/esters. In order to evaluate the biodegrability of the blend, six enzyme assays were conducted: alkane hydroxylase, Catechol 1,2-dioxygenase, Catechol 2,3-dioxygenase, Protocatechol 3,4-dioxygenase, ρ-NPA hydrolysis (esterase), and release of fatty acids through titration (lipase), with estimative of total protein and biosurfactant production (surface tension measurement and emulsifying index E24). The best results obtained allowed the selection of four bacteria isolates (Bacillus megaterium, Bacillus pumilus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia) for compiling a consortium, which will be used for bioaugmentation strategies in soils contaminated with these fuels. This consortium exhibited high potential for biodegradation of biodiesel, and might be an efficient alternative for cleaning up these contaminated environments.

Chemical constituents and pharmacological profile of Gunnera manicata L. extracts

Gunnera perpensa L. (Gunneraceae) is a native South African plant widely used in traditional medicine as an antibacterial and antifungal. In southern Brazil there is the native species called Gunnera manicata L. that also belongs to the Gunneraceae. Nevertheless, there is no information about chemical and pharmacological properties of South American Gunnera species. Therefore this study aimed at assessing the phytochemical and pharmacological profiles of aqueous and methanol Brazilian G. manicata extracts. The results showed that antimicrobial activity in an agar diffusion assay was effective against Staphylococcus aureus and Candida albicans . Phenolic compounds were investigated by liquid chromatography coupled with a tandem mass spectrometer (LC-MS/MS) and all extracts presented gallic acid and only the methanol extract obtained from the leaves exhibited hyperoside. Rutin, quercetin and chlorogenic acid were not found in the samples analysed. Total phenolic content was higher in methanol extract and total flavonoid content was low in all extracts. Antioxidant activity was evaluated by the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical test, and all samples presented good to moderate antioxidant activity. These results encourage complementary studies on the chemical composition of the plant extracts focusing on isolation and structure elucidation of their active compounds.