Comparison the effects of bioaugmentation versus biostimulation on marine microbial community by PCR-DGGE: A mesocosm scale

In order to better understand the effects of biostimulation and bioaugmentation processes on a marine microbial community, three different mesocosm experiments were planned. Natural seawater (10.000 L) was artificially polluted with crude oil (1 L) and (1) inorganic nutrients (Biostimulating Mesocosm, BM), (2) inorganic nutrients and an inoculum of Alcaniuorax borkumensis SK2 (Single Bioaugmentation Mesocosm, SBM), (3) inorganic nutrients and inoculums of A. borkumensis SK2 and Thalassolituus oleivorans MIL-1 (Consortium Bioaugmentation Mesocosm, CBM). During the experimental period (20 days), samples were taken from each mesocosm and the community structure was analyzed by PCR DCCE. The 16S rRNA gene DCCE banding patterns and sequence analysis demonstrated that biostimulation had the lowest effect on microbial biodiversity in the mesocosms; however, the biodiversity of the marine microbial community dramatically decreased in the CBM (Shannon index was 0.6 in T3). The community structures among the three mesocosms were also markedly different, and major bacteria derived from DGGE bands were related to uncultured Gamma Proteobacteria. The biodegradation results show that the Single Bioaugrnentation Mesocosm (SBM) system had the highest percentage of degradation (95%) in comparison to the BM mesocosm (80%) and GEM (70%). C) 2015 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.