Mangrove microniches determine the structural and functional diversity of enriched petroleum hydrocarbon-degrading consortia

In this study, the combination of culture enrichments and molecular tools was used to identify bacterial guilds, plasmids and functional genes potentially important in the process of petroleum hydrocarbon (PH) decontamination in mangrove microniches (rhizospheres and bulk sediment). In addition, we aimed to recover PH-degrading consortia (PHDC) for future use in remediation strategies. The PHDC were enriched with petroleum from rhizosphere and bulk sediment samples taken from a mangrove chronically polluted with oil hydrocarbons. Southern blot hybridization (SBH) assays of PCR amplicons from environmental DNA before enrichments resulted in weak positive signals for the functional gene types targeted, suggesting that PH-degrading genotypes and plasmids were in low abundance in the rhizosphere and bulk sediments. However, after enrichment, these genes were detected and strong microniche-dependent differences in the abundance and composition of hydrocarbonoclastic bacterial populations, plasmids (IncP-1 alpha, IncP-1 beta, IncP-7 and IncP-9) and functional genes (naphthalene, extradiol and intradiol dioxygenases) were revealed by in-depth molecular analyses [PCR-denaturing gradient gel electrophoresis and hybridization (SBH and microarray)]. Our results suggest that, despite the low abundance of PH-degrading genes and plasmids in the environmental samples, the original bacterial composition of the mangrove microniches determined the structural and functional diversity of the PHDC enriched.Deutsche Forschungsgemeinschaft [SM59/4-1, 4-2]; FAPERJ-Brazil; European Commission [003998, 211684]; Alexander-von-Humboldt-Stiftung; CONICET (Argentina)info:eu-repo/semantics/publishedVersio

The impact of gasification wastewater on soil microorganisms and the growth of oat and red clover

Process water generated during the biomass gasification is abundant in organic compounds such as polycyclic aromatic hydrocarbons (PAHs). Doses of wastes used in the study were the following: 10, 20, 40, 80, and 160 cm3 of process water per 100 g of dry soil mass. Obtained results showed, that, analyzed wastes can be classified as acute toxicity compounds. Cytometric analysis showed that with the wastewater concentrations of 40 and 80 cm3 per 100 g of soil, the number of microorganisms during the initial days after the contamination was markedly increased; however after 16 days it dropped to the quantity similar to the initial number. Regarding plants the contamination of soil with small volumes (10 cm3/100 g of soil and 20 cm3/100 g of soil) led to the stimulation of the oat aboveground part's growth by 6 and 23% compared to the control sample, respectively. The use of higher concentrations weakened the plants growth or arrested it completely. As a result it was also concluded, that red clover can be a better bioindicator in the analyses of toxicity of this type of wastes than oat. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 56–59, 2016Web of Science351595