Heavy Crude Oil Biodegradation And The Characteristics Of Bioemulsifier Produced By Strain Geobacillus Spp.ZY-10

To investigated the potential application of strain ZY-10 in the filed of microbial enhanced oil recovery,the physiological and biochemical character,phylogenetic position and the capabilities of crude oil and alkanes biodegradation of strain ZY-10,and the character of bioemulsifier pruoduced by strain ZY-10 was studied.Morphological,physiological and biochemical analyses as well as 16S rDNA gene sequence comparison demonstrated that strain ZY-10 should be grouped in the genus Geobacillus.The 16S rDNA sequence of strain ZY-10 exhibited the highest similarity(99.1%)to that of the type strain Geobacillus stearothermophilus(former name Bacillus stearothermophilus).The major cellular fatty acid of the isolate is iso-15:0(28.55%),iso-16:0(24.93%)and iso-17:0(23.53%),different from that of the recognized species in the genus Geobacillus.The physiological and biochemical characteristic,such as indole production,tolerance to NaN3,some carbohydrates fermentation,etc.also makes the isolate different from the recognized species in the genus Geobacillus.The crude biosurfactant was precipitated by ammonium sulfate and more effective instabiliz-ing oil-in-water emulsions but not lower the surface tension as much.Emulsification acti-vity and surface tension reducing capability could be affected by salinity.Protein andlipid group could been detected in the crude bioemulsifier.In the crude oil fermentation experiment,absorption column chromatography was used to separate the extracted crude oil into saturated hydrocarbons,aromatic hydrocarbons,resins and as altenes.Strain ZY-10 could utilize saturated hydrocarbons,aromatic hydrocarbons and resins,increase the content of resins under the condition of 1.05%salinity,but merely utilize saturated and resins under the condition of 2.5%salinity.Ultraviolet absorption spectra analysis showed that strain ZY-10 could utilize the aromatic hydrocarbons less than three rings in the crude oil.After heavy crude oil was biotreated by strain ZY-10,gas chromatography analysis showed that the content of long-chain alkanes was decreased and the content of short-chain alkanes was increased.When tridecane,hexadecane,octacosane and hexatriacontane was used as carbon source respectively,strain ZY-10 could rapidly utilize tridecane and the best growth was observed for hexadecane.Strain ZY-10 could convert long-chain alkanes into low-molecular-weight hydrophobic compounds.The potential for the endogenous bacterias to degrade crude oil and produce methane was performed under anaerobic condition.The result demonstrated that endogenous bacterias from crude oil could slowly degrade crude oil and produce methane.