Assessment of Neutalization Potential by Myxococcus xanthus in Acidified Medium

초록

Acid neutralization by Myxococcus xanthus was studied depending upon varying pH and acid types. While neutralization, the microbial viability against various types of heavy metals was assessed. For 48 hours of incubation, pH, biomass, microbial activity and NH4+ concentration were monitored. It revealed that the minimum pH at which M. xanthus can take part in neutralizing was found to be from pH 4.5. The initial pH of 4.5, 5.0, and 6.0 previously adjusted with H2SO4 was turned into the final pH of 7.6, 7.8, and 7.9, respectively (Fig.1). It was supposed to be derived from the generation of OH- that have been subsequently occurred while NH3 was converted into NH4+ under the metabolism of M. xanthus. At various acid types, their pH have become 7.5, 7.6, and 8.0 which were equivalently forming NH4+ of 14.2, 14.2, and 16.3 mM at H2SO4, HCl and HNO3 used (Fig.2). It simply implied that the presence of N-sources can the most effectively help neutralization of M. xanthus. In the presence of various heavy metals, M. xanthus can still actively grow to neutralize although in the medium contaminated with As and Pb so that their final pH were 7.9 and 8.0, respectively. At the same time, their biomass and microbial activity, NH4+ were also correspondingly enhanced. This study suggests that M. xanthus can be very useful for attempting to restoring impaired mine areas contaminated with certain types of heavy metal.