Nocardioides sp. JS614
   
   
 

Vinyl chloride (VC), a frequent groundwater contaminant (16) , is a concern to human health and the environment due its human carcinogenic effects (1, 11) .   VC in groundwater is often produced as a result of incomplete reductive dechlorination of the widely used chlorinated solvents tetrachloroethene (PCE) and trichloroethene (TCE), also common groundwater contaminants (4, 13) .   VC tends to accumulate and persist in anaerobic groundwater zones but has been shown to degrade readily if the VC plume migrates in aerobic groundwater zones (3, 5, 12) .   Several strains of VC-assimilating bacteria, including strain JS614, have recently been isolated (2, 7, 18) indicating that these organisms are widespread in the environment and may participate in natural attenuation of VC at certain sites.  

Nocardioides strain JS614 is unique among growth-coupled VC-degraders . All other known, aerobic VC-assimilating bacteria are either Mycobacteria (2, 7, 8) or Pseudomonads (18, 19) . In addition to its phylogenetic distinction, strain JS614 is unique among VC-assimilating bacteria due to a relatively high VC yield coefficient, high VC utilization rate, and peculiar VC starvation sensitivity (2) .

JS614 has significantly higher growth yields on VC and ETH than other VC-assimilating bacteria . The VC and ETH growth yields of five mycobacterial VC degraders are very similar (averaging 6.4 g protein/mol VC and 12.0 g protein/mol ETH) (2) . The growth yield on VC of Pseudomonas strain DL1 is also similar to that of the mycobacterial VC degraders (2) . In contrast, the growth yields on VC and ETH of strain JS614 are 10.3 g protein/mol VC and 21.2 g protein/mol ETH respectively (2) . The fact that strain JS614 derives approximately 60-76% more energy from VC and ETH than other VC degraders implies that the pathway of VC-assimilation in strain JS614 may be different than all other known VC-assimilating bacteria.

JS614 displays severe VC starvation sensitivity in comparison to Mycobacterium JS60 . VC-grown JS614 cultures starved of VC for longer than one day do not degrade VC for at least 40 days after refeeding (2) . In contrast, VC-grown JS60 cultures did not display an appreciable VC lag period after VC starvation periods of up to one week (2) . This suggests that regulation and maintenance of the VC pathway in strain JS614 is significantly different than in mycobacterial or pseudomonad VC degraders and may indicate the energy dependent detoxification of a potentially toxic VC metabolic intermediate. The physiological basis of this starvation sensitivity is still under investigation, but the monooxygenase system appears to play a major role in the VC starvation response and not the epoxide transformation system, as was previously speculated (2) .

JS614 harbors a large plasmid that encodes VC/ETH pathway genes. Pulsed Field Gel Electrophoresis experiments have detected a 300 kb linear megaplasmid in strain JS614 (14) . PCR experiments using primers specific for putative JS614 monooxygenase and epoxide transforming genes indicate that these genes are located on the large plasmid (14) . Sequencing of this large catabolic plasmid will provide information about VC/ETH pathway genes and may uncover other potential metabolic capabilities of this isolate.

The genomic characterization of a Nocardioides strain is warranted since members of this genus have been found to degrade a variety of hazardous agricultural and industrial pollutants such as atrazine (17) , butane (6) , p-nitrophenol (20) , trinitrophenol (15) , jet fuel (10) , phenanthrene (9) , and VC (2) .

References

1. Bucher, J. R., G. Cooper, J. K. Haseman, C. W. Jameson, M. Longnecker, F. Kamel, R. Maronpot, H. B. Matthews, R. Melnick, R. Newbold, R. W. Tennant, C. Thompson, and M. Waalkes. 2001. Ninth report on carcinogens. U.S. Dept. of Health and Human Services, National Toxicology Program. [ http://ehis.niehs.nih.gov/roc/ninth/known/vinylchloride.pdf] .

2. Coleman, N. V., T. E. Mattes, J. M. Gossett, and J. C. Spain. 2002. Phylogenetic and kinetic diversity of aerobic vinyl chloride-assimilating bacteria from contaminated sites. Appl. Environ. Microbiol. 68: 6162-6171.

3. Davis, J. W., and C. L. Carpenter. 1990. Aerobic degradation of vinyl chloride in groundwater samples. Appl. Environ. Microbiol. 56: 3878-3880.

4. Distefano, T. D. 1999. The effect of tetrachloroethene on biological dechlorination of vinyl chloride: Potential implication for natural bioattenuation. Water Research 33: 1688-1694.

5. Edwards, E. A., and E. E. Cox. 1997. Field and laboratory studies of sequential anaerobic-aerobic chlorinated solvent biodegradation, p. 261-265. In B. C. Alleman, and Leeman, A. (ed.), In Situ and On-Site Bioremediation, vol. 3. Battelle Press, Columbus, OH.

6. Hamamura, N., and D. J. Arp. 2000. Isolation and characterization of alkane-utilizing Nocardioides sp. strain CF8. FEMS Microbiol. Lett. 186: 21-26.

7. Hartmans, S., and J. A. M. de Bont. 1992. Aerobic vinyl chloride metabolism in Mycobacterium aurum L1. Appl. Environ. Microbiol. 58: 1220-1226.

8. Hartmans, S., J. A. M. de Bont, J. Tramper, and K. C. A. M. Luyben. 1985. Bacterial degradation of vinyl chloride. Biotech. Lett. 7: 383-388.

9. Iwabuchi, T., Y. Y. Inomata, A. Katsuta, and S. Harayama. 1998. Isolation and characterization of marine Nocardioides capable of growing and degrading phenanthrene at 42 degrees C. J. Marine Biotech. 6: 86-90.

10. Jung, C. M., C. Broberg, J. Giuliani, L. L. Kirk, and L. F. Hanne. 2002. Characterization of JP-7 jet fuel degradation by the bacterium Nocardioides luteus strain BAFB. J. Basic Microbio. 42: 127-131.

11. Kielhorn, J., C. Melber, U. Wahnschaffe, A. Aitio, and I. Mangelsdorf. 2000. Vinyl chloride: still a cause for concern. Environ. Health Perspect. 108: 579-88.

12. Lee, M. D., J. M. Odom, and R. J. J. Buchanan. 1998. New perspectives on microbial dehalogenation of chlorinated solvents: insights from the field. Annu. Rev. Microbiol. 52: 423-452.

13. Lorah, M. M., and L. D. Olsen. 1999. Degradation of 1,1,2,2-tetrachloroethane in a freshwater tidal wetland: field and laboratory evidence. Environ. Sci. Technol. 33: 227-234.

14. Mattes, T. E., N. V. Coleman, J. M. Gossett, and J. C. Spain. 2005. Physiological and molecular genetic analyses of vinyl chloride and ethene biodegradation in Nocardioides sp. JS614. Arch. Microbiol. 183: 95-106.

15. Rajan, J., K. Valli, R. E. Perkins, F. S. Sariaslani, S. M. Barns, A. L. Reysenbach, S. Rehm, M. Ehringer, and N. R. Pace. 1996. Mineralization of 2,4,6-trinitrophenol (picric acid): Characterization and phylogenetic identification of microbial strains. J. Ind. Microbiol. 16: 319-324.

16. Squillace, P. J., M. J. Moran, W. W. Lapham, C. V. Price, R. M. Clawges, and J. S. Zogorski. 1999. Volatile organic compounds in untreated ambient groundwater of the United States, 1985-1995. Environ. Sci. Technol. 33: 4176-4187.

17. Topp, E., W. M. Mulbry, H. Zhu, S. M. Nour, and D. Cuppels. 2000. Characterization of s-triazine herbicide metabolism by a Nocardioides sp. isolated from agricultural soils. Appl. Environ. Microbiol. 66: 3134-3141.

18. Verce, M. F., R. L. Ulrich, and D. L. Freedman. 2000. Characterization of an isolate that uses vinyl chloride as a growth substrate under aerobic conditions. Appl. Environ. Microbiol. 66: 3535-3542.

19. Verce, M. F., R. L. Ulrich, and D. L. Freedman. 2001. Transition from cometabolic to growth-linked biodegradation of vinyl chloride by a Pseudomonas sp. isolated on ethene. Environ. Sci. Technol. 35: 4242-4251.

20. Yoon, J. H., Y. G. Cho, S. T. Lee, n. i. Suzuki, T. Nakase, and Y. H. Park. 1999. Nocardioides nitrophenolicus sp. nov., a p-nitrophenol-degrading bacterium. Int J Syst Bacteriol 49: 675-680.