الفهرس 
Title: Isolation and characterization of Bacteria from Crude Egyptian Petroleum Oil Reservoirs and Their Potential Use in Enhanced Oil Recovery
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Abstract
A broad range of bacteria have been detected in or isolated from oil field samples either by culture-based or molecular techniques. Facultatively aerobic, aerobic and other types of microorganisms have been detected in oil samples. Using microorganisms and their byproducts in a technique called 2microbial enhanced oil recovery(MEOR)3 can help recover huge amounts of crude oil from depleted oil reservoirs. In an attempt to study the nature of the bacteria indigenous to the Egyptian oil reservoirs and its characteristics, direct isolation using LB, TSB and MSM was performed on17 different samples of crude oil, formation water and condensate collected from 12 different Egyptian crude oil reservoirs.To this end, 51 bacterial isolates were collected, identified byGram staining, biochemical tests, VITEK 2 and 16S rRNA gene sequencing. The identified isolates belonged to several different genera, but mostly to the genera Bacillus (19 strains) and Pseudomonas (8 strains).Generally, bacteria found in oil reservoirs possess unique metabolic functions that allows them to utilize hydrocarbons and produce biosurfactants and biopolymers among other compounds, which make them the ideal candidate for the development of the MEOR technology. Here we screened the isolates for their ability to produce biosurfactants by different methods: the DROP collapse, penetration assay and oil spreading technique. Several isolateswere positive with more than one of the used methods; however, only two of themhad highest scores with all threemethods.These two isolates were identified as Bacillus subtilis and Pseudomonas aeruginosa.In addition to screening the collected isolates for the production of biosurfactants, we also screened them for their ability to produce biopolymer, using YM culture media and fermentation media.Thirty-sevenstrains were found to producebiopolymer, in amounts ranging from 34 to 357.3 mg. The isolates that produced the largest amounts of biopolymer were identified as Bacillus safensis, Bacillus licheniformis and Rhizobium radiobacter. A sample of the extracellular polymeric substance (EPS) collected in this study was chosen for further characterization and identification.This sample was produced by Bacillus licheniformis, pH of the media after fermentation was 7.02 and the weight of the product was 234.3 mg.