Journal of Bioremediation & Biodegradation

Abstrait

A Novel Subspecies of Staphylococcus aureus from Sediments of Lanzhou Reach of the Yellow River Aerobically Reduces Hexavalent Chromium

Xiaowei Zhang, Lee R Krumholz, Zhengsheng Yu, Yong Chen, Pu Liu and Xiangkai Li

Background: Lanzhou reach of the Yellow River is contaminated by heavy metals including chromium perennially. The microbial community within the sediment is very active. Yet the study on the bacteria in this distinctive microbial community is still scarce. Results: LZ-01, a Gram-positive hexavalent chromium-reducing bacterium was isolated from the soil sample collected at a petrochemical corporation wastewater discharge site of Lanzhou reach. It was able to aerobically reduce 94.5% of 0.4 mM Cr (VI) to Cr(III) in 120 hours. Cd (II) and NaN3 treatment both repressed Cr(VI) reduction in LZ-01 and Cr(III) precipitates were detected both on the cell membrane and in the cytoplasm by Transmission Electron Microscopy (TEM) imaging. LZ-01 also demonstrated resistance to 4 mM As (V) and 9 mM U (VI). LZ-01 was closely related to Staphylococcus aureus revealed by 16S rRNA sequence analysis. Comparison of cellular fatty acid components and Vitek phenotype identification provided further evidences that LZ-01 is a novel subspecies of S. aureus. Conclusions: A chromate-reducing bacterium LZ-01 identified as a novel subspecies of S. aureus was isolated from Lanzhou reach of the Yellow River. Cd (II) and NaN3 treatment and TEM images suggested that Cr(VI) was reduced not only intracellularly but also on the cell membrane. All the results indicate that the isolate has a great potential for bioremediation of Cr (VI)-contaminated environment.