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

Abstract

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 NaN 3 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 NaN 3 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. Staphylococcus aureus is a facultative Gram-positive coccus-shaped bacterium [27] that is best known for its ability to cause a range of illnesses [27,28]. Several recent studies report that S. aureus is involved in environmental metal remediation [4,29] and S. epidermidis which is closely related to S. aureus is able to anaerobically reduce Cr(VI) to Cr (III) [11]. However, there is no direct evidence that S. aureus can reduce Cr(VI). In this study, we screened the Lanzhou reach river bank soil for Cr(VI) reducers and isolated a novel subspecies of S. aureus strain LZ-01, which reduces Cr(VI) to Cr(III) aerobically. 16S rRNA sequencing and fatty lipids profiling showed that strain LZ-01 is closely related to S. aureus. Comparison of Vitek phenotype identification showed that there were 7 different reactions out of 64 between LZ-01 and type strains of Staphylococcus aureus. LZ-01 reduces Cr(VI) in a highly efficient manner suggesting that it may be useful for Cr(VI) reduction studies in Lanzhou reach. Journal of Bior emediation & Biodegradation Materials and Methods Soil sample collectionThe sampling site was 60 kilometers west of central Lanzhou city and adjacent to the upper reach of the Yellow River. The actual location was close to a petrochemical corporation waste water discharge site. The latitude and longitude of the sampling site is 36°06'N 103°39'E, (Figure 1). The pH of soils at the sampling site ranged from 5.0 to 6.0 with temperature around 18°C at the time of collection. The soil samples were collected from 15 cm below surface horizon and stored in sterile aluminum boxes a...

Enterococcus faecalisstrain LZ-11 isolated from Lanzhou reach of the Yellow River is able to resist and absorb Cadmium

“…Lanzhou reach of the Yellow River is heavily contaminated by industrial wastes. Bacteria previously isolated from this environment showed heavy metal resistance and remediation potential (Zhang et al 2013). In this Figure 2 Microbial growth of strain LZ-11 monitored by spectrophotometer (optical density, OD) at 600 nm under different Cd(II)concentrations.…”

“…Bacteria previously isolated from this environment showed heavy metal resistance and remediation potential (Zhang et al . ). In this study, we have isolated bacteria with high resistance to Cd(II).…”

Phosphate promotes uranium (VI) adsorption in Staphylococcus aureus LZ-01

“…It can also grow under acidic conditions at pH 5 (Zhang et al . ). These results indicated that strain LZ‐01 has high U(VI) resistance and is likely to be able to survive in nuclear waste.…”

“…Staphylococcus aureus LZ‐01 was isolated from the Lanzhou reaches of the Yellow River (36°06′N, 103°39′E) (Zhang et al . ). Staphylococcus aureus ATCC25923 and E. coli DH5 α were used as reference strains.…”

“…It has high chromate resistance and reduction abilities. It can also resist many other heavy metals (Zhang et al 2013). U(VI) and Cr(VI) are homologous, and previous studies showed that microbes use similar pathways to resist U(VI) and Cr(VI) (Li and Krumholz 2009;Martins et al 2010).…”