The growth curves of strains in the MSMP are shown in Fig. 1.
The growth attained its maximum level, approximately 350 and
400mgL−1, in the liquid cultures for HWBI (Fig. 1(a)) and HWBII
(Fig. 1(b)), respectively after 48 h cultivation. After that, the cell
biomass was steady, with a slight decrease. The results showed
that the strains can use PAM as their sole carbon source. This has
also been shown in a study from Nakamiya and Kinoshita [14].
The time course of the PAM degradation of HWBI in the MSMP
is shown in Fig. 2(a). 49% of the initial PAM in the culture broth
was degraded in the first 24 h cultivation, with a 74% removal of
PAM achieved following 96 h cultivation. The time course of PAM
degradation by HWBII in theMSMPis shown in Fig. 2(b). The degradation
ratio of PAM was 20% after the first 24 h cultivation, while
76% of the initial PAM in the culture was degraded following 96 h
cultivation.
The results show that while the two isolates degraded PAM at
different rates, PAM removal by the two strains could both achieve
more than 70% degradation after 96 h. No significant change was
observed in PAM concentration after 96 h by either organism