Stimulating the indigenous microorganisms to remove heavy metals from marine sediments

Jinjun KanDepartment of Earth Sciences
University of Southern California
Los Angeles CA 90089Microbial activities play critical roles in metal remediation in natural environments. Adding organic or inorganic amendments will stimulate growth of indigenous microorganisms and then the microbes contribute to sorb, degrade, transform or immobilize metals from the environments. In this current study, we evaluated microbial stimulation of adding inorganic (e.g. apatite) and organic (e.g. chitin, acetate) amendments to marine sediments. Significant bacterial biomass and activities were induced by amendments of apatite, chitin and acetate. Molecular fingerprints of bacterial communities by denaturant gradient gel electrophoresis (DGGE) showed that distinct bacterial populations occurred in different amendments, and the stimulated microorganisms contained three major bacterial groups, Alphaproteobacteria (Roseobacter), Gammaproteobacteria and Bacteroidetes. Alphaproteobacteria (Roseobacter) dominated in water columns while Bacteroidetes were predominant population in the sediments. Most probable number (MPN) analyses showed that sulfate-reducing bacteria were significantly induced in the treatments with chitin, apatite+chitin. Testing N-acetylglucosamine and acetate as potential carbon source has also recovered sulfate-reducing bacteria. Sulfide-producing and metal-reducing bacteria were also recovered by using thiosulfate as an electron-acceptor. The results indicate that amendments stimulate geochemically important bacteria and further investigations on their physiological properties are critical to recognize their actual roles in the metal remediation process.

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