Accession Number : ADA574806


Title :   Analysis of Redox Responses During TNT Transformation by Clostridium acetobutylicum ATCC 824 and Mutants Exhibiting Altered Metabolism


Descriptive Note : Journal article


Corporate Author : RICE UNIV HOUSTON TX DEPT OF BIOCHEMISTRY AND CELL BIOLOGY


Personal Author(s) : Cai, Xianpeng ; Servinsky, Matthew ; Kiel, James ; Sund, Christian ; Bennett, George N


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a574806.pdf


Report Date : Jan 2012


Pagination or Media Count : 16


Abstract : The transformation of trinitrotoluene (TNT) by several mutant strains of Clostridium acetobutylicum has been examined to analyze the maximal rate of initial transformation, determine the effects of metabolic mutations of the host on transformation rate and to assess the cell metabolic changes brought about during TNT transformation. Little difference in the maximal rate of TNT degradation in early acid phase cultures was found between the parental ATCC824 strain and strains altered in the acid forming pathways (phosphotransacetylase, or butyrate kinase) or in a high solvent producing strain (mutant B). This result is in agreement with the previous findings of a similar degradation rate in a degenerate strain, (M5) that had lost the ability to produce solvent. A series of antisense constructs were made that reduced the expression of hydA, encoding the Fe-hydrogenase, or hydE and hydF, genes encoding hydrogenase maturating proteins. While the antisense hydA strain had only 30% of the activity of wild type, the antisense hydE strain exhibited a TNT degradation rate around 70% that of the parent. Over expression of hydA modestly increased the TNT degradation rate in acid phase cells, suggesting the amount of reductant flowing into hydrogenase rather than the hydrogenase level itself was a limiting factor in many situations. The redox potential, hydrogen evolution and organic acid metabolites produced during rapid TNT transformation in early log phase cultures were measured. The redox potential of the acid producing culture decreased from -370 to -200 mV immediately after addition of TNT and the hydrogen evolution rate decreased, lowering the hydrogen to carbon dioxide ratio from 1.4 to around 1.1 for 15 minutes. During the time of TNT transformation, the treated acidogenic cells produced less acetate and more butyrate.


Descriptors :   *CLOSTRIDIUM , *METABOLISM , *TNT , *TRANSFORMATIONS , ACIDS , BUTYRATES , CHEMICALS , CODING , DEGRADATION , EVOLUTION(GENERAL) , FERMENTATION , GLUCOSE , HYDROGEN , PHOSPHORUS TRANSFERASES , PLASMIDS , SOLVENTS , STRAINS(BIOLOGY)


Subject Categories : Biochemistry
      Microbiology
      Ammunition and Explosives


Distribution Statement : APPROVED FOR PUBLIC RELEASE