Bioaugmentation and coexistence of two functionally similar bacterial strains in aerobic granules |
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Authors: | He-Long Jiang Abdul Majid Maszenan Joo-Hwa Tay |
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Institution: | (1) Environmental Engineering Research Centre, School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, Singapore;(2) Present address: Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA |
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Abstract: | The survival of the inoculated microbial culture is critical for successful bioaugmentation but impossible to predict precisely.
As an alternative strategy, bioaugmentation of a group of microorganisms may improve reliability of bioaugmentation. This
study evaluated simultaneous bioaugmentation of two functionally similar bacterial strains in aerobic granules. The two strains,
Pandoraea sp. PG-01 and Rhodococcus erythropolis PG-03, showed high phenol degradation and growth rates in phenol medium, but they were characterized as having a poor aggregation
activity and weak bioflocculant-producing and biofilm-forming abilities. In the spatially homogeneous batch conditions, strain
PG-01 with higher growth rates outcompeted strain PG-03. However, the two strains could stably coexist in the spatially heterogeneous
conditions. Then the two strains were mixed and bioaugmented into activated sludge in two sequencing batch reactors, which
were operated with the different settling times of 5 and 30 min, respectively. Aerobic granules were developed only in the
reactor with a settling time of 5 min. Fluorescence in situ hybridization and denaturing gradient gel electrophoresis showed
that the two strains could coexist in aerobic granules but not in activated sludge. These findings suggested that the compact
structure of aerobic granules provided spatial isolation for coexistence of competitively superior and inferior strains with
similar functions. |
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Keywords: | Aerobic granules Bioaugmentation Coexistence Competition Phenol degradation Spatial effect |
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