The results showed that species specific for 16SrRNA
gene of A. hydrophila could not be detected when Mg2+
concentration was 1.5 mM. The amplification efficiencies
improved by increasing Mg2+ concentration to 3.5 mM.
Nevertheless, excessive Mg2+ concentration resulted in
the nonspecific amplification and decreased specificity.
Consequently, Mg2+ concentration of 3.0 mM was optimum
for multiplex PCR reaction (Figure 4).