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Biotransformation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) by a prospective consortium and its most effective isolate Serratia marcescens
Author(s) -
Young Douglas M.,
Unkefer Pat J.,
Ogden Kimberly L.
Publication year - 1997
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19970305)53:5<515::aid-bit9>3.0.co;2-k
Subject(s) - biotransformation , serratia marcescens , anoxic waters , bacteria , chemistry , microbiology and biotechnology , biodegradation , food science , chromatography , environmental chemistry , biology , biochemistry , escherichia coli , organic chemistry , enzyme , genetics , gene
The biotransformation of hexahydro‐1,3,5‐trinitro‐1,3,5 triazine (RDX) has been observed in liquid culture by a consortium of bacteria found in horse manure. Five types of bacteria were found to predominate in the consortium and were isolated. The most effective of these isolates at transforming RDX was Serratia marcescens . The biotransformation of RDX by all of these bacteria was found to occur only in the anoxic stationary phase. The process of bacterial growth and RDX biotransformation was quantified for the purpose of developing a predictive type model. Cell growth was assumed to follow Monod kinetics. All of the aerobic and anoxic growth parameters were determined: μ max , K s , and Y x/s . RDX was found to competitively inhibit cell growth in both atmospheres. Degradation of RDX by Serratia marcescens was found to proceed through the stepwise reduction of the three nitro groups to nitroso groups. Each of these reductions was found to be first order in both component and cell concentrations. The degradation rate constant for the first step in this reduction process by the consortium was 0.022 L/g cells · h compared to 0.033 L/g cells · h for the most efficient isolate. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 515–522, 1997.