Biodegradation kinetics of the nitramine explosive CL-20 in soil and microbial cultures

N. S. Panikov, M. V. Sizova, D. Ros, C. Christodoulatos, W. Balas, S. Nicolich

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The cyclic nitramine explosive CL-20 (C6H6N 12O12, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12 -hexaazaisowurtzitane) is a relatively new energetic compound which could be a persistent organic pollutant. To follow its biodegradation dynamics, CL-20 was added to soil alone or together with organic co-substrates and N-source and incubated under oxic and anoxic conditions. Without co-substrates, the CL-20 degradation was detectable only under anoxic conditions. The highest degradation rate was found under aerobic conditions and with the addition of co-substrates, succinate and pyruvate being more efficient than acetate, glucose, starch or yeast extract. When added to intact soil, CL-20 degradation was not affected by the N content, but in soil serially diluted with N-free succinate-mineral medium, the process became N-limited. About 40% of randomly selected bacterial colonies grown on succinate agar medium were able to decompose CL-20. Based on 16S rDNA gene sequence and cell morphology, they were affiliated to Pseudomonas, Rhodococcus, Ochrobactrum, Mycobacterium and Ralstonia. In the pure culture of Pseudomonas sp. MS-P grown on the succinate-mineral N(+) medium, the degradation kinetics were first order with the same apparent kinetic constant throughout growth and decline phases of the batch culture. The observed kinetics agreed with the model that supposes co-metabolic transformation of CL-20 uncoupled from cell growth, which can be carried out by several constitutive cellular enzymes with wide substrate specificity.

Original languageEnglish
Pages (from-to)317-332
Number of pages16
JournalBiodegradation
Volume18
Issue number3
DOIs
StatePublished - Jun 2007

Keywords

  • CL-20
  • Co-metabolism
  • Growth stoichiometry
  • Kinetics order
  • Microbial community
  • Remediation strategy

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