ABSTRACT
Petroleum reservoir is an ecosystem having extreme environmental conditions of temperature, pressure and salinity. They possess highly anoxic conditions. Major microbial communities present in this environment include fermentative bacteria, sulphate reducing bacteria (SRB), syntrophic bacteria and methanogens. Phylogenetic diversity of microorganisms as well as their ecological role play an important role in the petroleum reservoir ecosystem. Past and present efforts to characterize microbial communities in oil field ecosystem by culture or cultivation-dependent and -independent approaches are discussed with highlights of microbial ecology of petroleum oil reservoir ecosystem(s). Novel strategies used to study culture independent diversity of microorganisms using metagenomic techniques have also been narrated.
ABSTRACT
Wide spread use of Di-(2-ethylhexyl) phthalate (DEHP) has made it a ubiquitous contaminant in today’s environment, responsible for possible carcinogenic and endocrine disrupting effects. In the present investigation an integrative toxico-proteomic approach was made to study the estrogenic potential of DEHP. In vitro experiments carried out with DEHP (0.1-100 μM) induced proliferations (E-screen assay) in human estrogen receptors-α (ERα) positive MCF-7 and ERα negative MDA-MB-231 breast cancer cells irrespective of their ERα status. Further, DEHP suppressed tamoxifen (a potent anti-breast cancer drug) induced apoptosis in both cell types as shown by flowcytometric cell cycle analysis. Label-free quantitative proteomics analysis of the cell secretome of both the cell lines indicated a wide array of stress related, structural and receptor binding proteins that were affected due to DEHP exposure. The secretome of DEHP treated MCF-7 cells revealed the down regulation of lactotransferrin, an ERα responsive iron transport protein. The results indicated that toxicological effects of DEHP did not follow an ERα signaling pathway. However, the differential effects in MCF-7 and MDA-MB-231 cell lines indicate that ERα might have an indirect modulating effect on DEHP induced toxicity.