Ms. Nawaz et al., Influence of selected physical parameters on the biodegradation of acrylamide by immobilized cells of Rhodococcus sp., BIODEGRADAT, 9(5), 1998, pp. 381-387
The influences of concentration of acrylamide, pH, temperature, duration of
storage of encapsulated cells and presence of different metals and chelato
rs on the ability of immobilized cells of a Rhodococcus sp, to degrade acry
lamide were evaluated. Immobilized cells (3 g) rapidly degraded 64 and 128
mM acrylamide in 3 and 5 h, respectively, whereas free cells took more than
24 h to degrade 64 mM acrylamide. An acrylamide concentration of 128 mM in
hibited the growth of the free cells. Immobilized bacteria were slow to deg
rade acrylamide at 10 degrees C. Less than 60% of acrylamide was degraded i
n 4 h. However, 100% of the compound was degraded in less than 3 h at 28 de
grees C and 45 degrees C. The optimum pH for the degradation of acrylamide
by encapsulated cells was pH 7.0. Less than 10% of acrylamide was degraded
at pH 6.0, while ca. 60% of acrylamide was degraded at pH 8.0 and 8.5. Copp
er and nickel inhibited the degradation, suggesting the presence of sulfhyd
ryl (-SH) groups in the active sites of the acrylamide degrading amidase. T
ron enhanced the rates of degradation and chelators (EDTA and 1,10 phenanth
roline) reduced the rates of degradation suggesting the involvement of iron
in its active site(s) of the acrylamide-degrading-amidase. Immobilized cel
ls could be stored up to Iq days without any detectable loss of acrylamide-
degrading activity.