Biodegradation of Monochloroacetic Acid by Immobilization of Xanthobacter Autotrophicus GJ10 in Polyacrylamide Gel

ABSTRACT

The degradation of monochloroacetic acid (MCA) by Xanthobacter autotrophicus GJ10 has been studied. The following processes have been explored: the growth kinetics, the MCA degradation, the glycolic acid production and its further conversion into chlorides. Immobilization experiments have been conducted with microbial cells entrapped in polyacrylamide gels. Different ratio of the monomer—acrylamide (AA) and the cross-linking agent N, N'-methylene-bis-acrylamide (MBAA) was immobilization examined, as the above constituents were varied from 5% to 15% (w/v) and from 0.5% to 1.5%, respectively. The gels were used in a repeated-batch process, which were compared with the free culture degradation kinetics, as the quantity of the immobilized cells was 40 times higher than that of the free culture at analogous conditions and substrates.

Best results were achieved with polyacrylamide gel containing: 10% (w/v) concentration of the monomer AA, 0.1% (w/v) of the cross-linking agent MBAA, 0.67 ml 5% ammonium persulfate (NH₄)₂S₂O⁸ and 0.5 ml 2.5% N,N,N',N'-tetramethylethylene diamine (TEMED) for 10 ml gel. That culture degrades completely MCA with 10 mM starting concentration. The kinetics of gel's exhaustion was investigated in repetitive runs.

Keywords:

• immobilization
• monochloroacetic acid
• polyacrylamide