aState Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, PR China
bThe fourth oil production Company of Daqing Oilfield Limited Company, PetroChina, Daqing 163511, Heilongjiang, PR China
cSchool of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PR China
dShanghai Collaborative Innovation Center of Biomanufacturing Technology, Shanghai 200237, PR China
Received 14 July 2015, Revised 25 October 2015, Accepted 28 October 2015, Available online 31 October 2015
Biofilms increase dragging force for liquid transportation, cause power consumption, and result in equipment corrosion in polymer-flooding oilfields. To reveal the responsible microorganisms for biofilm formation and stability of high-molecular-weight polyacrylamide (PAM), a biofilm, developed on the sieve of a piston plunger pump in a water transport and injection pipeline with partial hydrolyzed polyacrylamide (HPAM) in Daqing Oilfield, was collected and analyzed by molecular microbiology, chemical and physical methods. Diverse bacterial groups (11 families) were detected in the biofilm, includingPseudomonadaceae, Rhodocyclaceae, Desulfobulbaceae, Alcaligenaceae,Comamonadaceae, Oxalobacteraceae, Bacteriovoracaceae, Campylobacteraceae, Flavobacteriaceae, Clostridiales Incertae Sedis XIII and Moraxellaceae. Three archaeal orders of methanogens including Methanomicrobiales, Methanosarcinales andThermoplasmatales were also detected separately. HPAM was degraded into lower molecular weight polymers and organic fragments with its amide groups hydrolyzed into carboxylic groups by the microorganisms. The microenvironment of the biofilm contained diverse bacterial and archaeal communities, correlating with the extracellular polymeric substance (EPS) and HPAM biodegradation. The results are helpful to provide information for biofilm control in oil fields.