As a result of an author oversight in the originally published version of this article, there were a few errors in the author list and affiliations: (1) Coauthor Evangelos Dioletis was omitted from the author list. E. Dioletis was responsible for conducting experiments and data analysis. (2) The last name of coauthor Irma Garcia-Martinez was misspelled. (3) Coauthor Wei-hong Yang was missing a second affiliation:

To further enhance oil recovery in reservoir after chemical flooding, an efficient activator formulation for promoting metabolism of endogenous microorganism was researched. Changes in community structure, growth and metabolites of endogenous microorganism were analyzed by methods of aerogenic experiments, physical simulation experiments, electron microscopy scanning (SEM), T-RFLP and Pyrophosphate sequencing. To evaluate whether endogenous microorganism activator screened in laboratory could activate endogenous microorganisms and enhance oil recovery in reservoirs after polymer flooding. The flooding effect and mechanism were studied, and this activator was used in a testing well group in Daqing oilfield. The results of the aerogenic experiments showed that the activator could activate the endogenous microorganisms in the injected water and make them produce a lot of biogas. The pressurized gas reached 2MPa after 60d static culture of activator in a high pressure vessel. The results showed that the activator could activate the endogenous microorganisms in the injected sewage and make them have a lot of growth and reproduction in the core and physical simulation of natural core flooding experiment. In the field test,the incremental oil production was 5957 t while the water content declined by 2.2% after injecting the activator, which provides an effective way to further enhance oil recovery in reservoir after chemical flooding.