RESUMO
Rapid growth in the oil industry has been accompanied concomitant increases in risks of spills or leaks triggered by natural or anthropogenic causes that cause soil changes and plant damage. Bio-scavenging and phytoremediation plants are important tools for identifying pollutants and mitigating environmental damage. The objective of this study was to evaluate the phytoremediation potential of Ricinus communis cultivated in soils contaminated with mineral oil, and to determine the possible visual, anatomical and physiological effects. R. communis seeds were pre-germinated in individual pots containing Red Latosol contaminated with Lubrax Essential SL (15W-40) mineral oil at concentrations of 0 (control), 5, 10, and 15 g kg-1. After exposure to treatments, emergency evaluations were performed, and after 45 days of cultivation, visual, morphoanatomical, physiological and oil removal effects were evaluated. There was no difference in emergence showed between treatments. Visual effects were characterized by necrosis and chlorosis formation in R. communis, evidenced on the 45th day of cultivation in all treatments tested, followed by parenchymal tissue alterations with collapsed cell formation and damage to photosynthesis with increasing doses. We found that R. communis removed up to 81% of hydrocarbons in soils, classifying it as potential phytoremediator of contaminated soils. The strong correlation between the variables suggests that R. communis can be used as an indicator of pollutant action.
Assuntos
Biodegradação Ambiental , Óleo Mineral/metabolismo , Ricinus/fisiologia , Poluentes do Solo/metabolismoRESUMO
Discarded PE-based products pose a social and environmental threat because of their recalcitrance to degradation, a consequence of the unique set of PE's physicochemical properties. In this study we isolated nine novel PE-degrading bacteria from plastic debris found in soil of the savanna-like Brazilian Cerrado. These bacterial strains from the genera Comamonas, Delftia, and Stenotrophomonas showed metabolic activity and cellular viability after a 90-day incubation with PE as the sole carbon source. ATR/FTIR indicated that biodegraded PE undergone oxidation, vinylene formation, chain scission, among other chemical changes. Considerable nanoroughness shifts and vast damages to the micrometric surface were confirmed by AFM and SEM. Further, phase imaging revealed a 46.7% decrease in the viscous area of biodegraded PE whereas Raman spectroscopy confirmed a loss in its crystalline content, suggesting the assimilation of smaller fragments. Intriguingly, biodegraded PE chemical fingerprint suggests that these strains use novel biochemical strategies in the biodegradation process. Our results indicate that these microbes are capable of degrading unpretreated PE of very high molecular weight (191,000gmol-1) and survive for long periods under this condition, suggesting not only practical applications in waste management and environmental decontamination, but also future directions to understand the unraveled metabolism of synthetic polymers.
Assuntos
Comamonas/metabolismo , Delftia/metabolismo , Polietileno/análise , Poluentes do Solo/análise , Stenotrophomonas/metabolismo , Aderência Bacteriana , Brasil , Comamonas/isolamento & purificação , Delftia/isolamento & purificação , Viabilidade Microbiana , Óleo Mineral/análise , Óleo Mineral/metabolismo , Modelos Teóricos , Polietileno/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Stenotrophomonas/isolamento & purificaçãoRESUMO
Several species of the genus Exophiala are found as opportunistic pathogens on humans, while others cause infections in cold-blooded waterborne vertebrates. Opportunism of these fungi thus is likely to be multifactorial. Ecological traits [thermotolerance and pH tolerance, laccase activity, assimilation of mineral oil, and decolorization of Remazol Brilliant Blue R (RBBR)] were studied in a set of 40 strains of mesophilic Exophiala species focused on the salmonis-clade mainly containing waterborne species. Thermophilic species and waterborne species outside the salmonis-clade were included for comparison. Strains were able to tolerate a wide range of pHs, although optimal growth was observed between pH 4.0 and 5.5. All strains tested were laccase positive. Strains were able to grow in the presence of the compounds (mineral oil and RBBR) with some differences in assimilation patterns between strains tested and also were capable of degrading the main chromophore of RBBR. The study revealed that distantly related mesophilic species behave similarly, and no particular trend in evolutionary adaptation was observed.
Assuntos
Exophiala/isolamento & purificação , Exophiala/fisiologia , Micoses/microbiologia , Micoses/veterinária , Infecções Oportunistas/microbiologia , Infecções Oportunistas/veterinária , Animais , Antraquinonas/metabolismo , Exophiala/crescimento & desenvolvimento , Exophiala/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Lacase/análise , Óleo Mineral/metabolismo , VertebradosRESUMO
Microbial-derived surfactants are molecules of great interest due to their environmentally friendly nature and low toxicity; however, their production cost is not competitive when compared to synthetics. Marine microorganisms are exposed to extremes of pressure, temperature, and salinity; hence, they can produce stable compounds under such conditions that are useful for industrial applications. A screening program to select marine bacteria able to produce biosurfactant using low-cost substrates (mineral oil, sucrose, soybean oil, and glycerol) was conducted. The selected bacterial strain showed potential to synthesize biosurfactants using mineral oil as carbon source and was identified as Brevibacterium luteolum. The surface-active compound reduced the surface tension of water to 27 mN m(-1) and the interfacial tension (water/hexadecane) to 0.84 mN m(-1) and showed a critical micelle concentration of 40 mg L(-1). The biosurfactant was stable over a range of temperature, pH, and salt concentration and the emulsification index (E24) with different hydrocarbons ranging from 60 to 79 %. Structural characterization revealed that the biosurfactant has a lipopeptide nature. Sand washing removed 83 % of crude oil demonstrating the potential of the biosurfactants (BS) for bioremediation purposes. The new marine B. luteolum strain showed potential to produce high surface-active and stable molecule using a low-cost substrate.