Isolation and identification of a bacteria strain Enterobacter cloacae I7 for degradation of hydrolyzed polyacrylamide

MA Fang¹, LI Jie-xun^2,3, WEI Li¹, CHEN Zhong-xi^3,4, SHAIK FIRDOZ⁵, ZHAO Guang¹

1.School of Municipal and Environmental Engineering,Harbin Institute of Technology,Harbin 150090,China;2.College of Petroleum Engineering,Daqing Petroleum Institute,Daqing 163318,China;3.Daqing Oilfield Corporation,PetroChina, Daqing 163453,China;4.Water Treatment and Oilfield Chemistry Research Department,Daqing Oilfield Engineering Co.Ltd, PetroChina,Daqing 163712,China;5.Indian Institute of Technology,Roorkee,Uttarakhand 247667,INDIA



Abstract:

A bacteria strain for the degradation of hydrolyzed polyacrylamide (HPAM) was isolated from a curing pot in HPAM distribution station of Daqing Oilfield using Hungate anaerobic technique.The isolate was investigated from morphological,physiological,biochemical and molecular characterization.It is a Gram-negative,short-bacillus,non-spore-forming anaerobic bacteria with an optimum growth at 8.0 pH at 40℃.It can reduce sulfate to H2S.Alignment of 16S ribosomal DNA and 16S-23S ribosomal DNA intergenic spacer sequences suggests that this isolate is closely related to the Enterobacter cloacae.The isolate is identified as a new strain belonging to Enterobacter genus,temporarily named as Enterobacter cloacae I7.Analysis results of infrared spectroscopy (IR) show that the bacteria can use HPAM as the only carbon source,change the structure of HPAM polymer surface,and realize the hydrolysis of amide to carboxyl group by hydrolysis mechanism.It can degrade the side chain and change some functional groups,which obviously decreases the viscosity.GC-MS analysis indicates that the determined low-molecular weight degradation products of HPAM are polyacrylamide fragments with duplet bond,epoxy as well as carbonyl group,but most of them are acrylamide oligomer derivatives.

Key words:  PAM-degrading bacteria strain  Hungate anaerobic technique  biodegradation  Enterobacter cloacae I7

DOI：10.11916/j.issn.1005-9113.2009.05.015

Clc Number:X172

Fund: