A solution containing a denitrifying bacteria Micrococcus denitrificans at a concentration of 1 × 10-6 kg/dm3 is introduced into a semibatch reactor where the growth rate is given by r = k([X][O2][S]/Ks + [S]), where [O2] is the oxygen concentration (mol/dm3). An excess of substrate [S] was used. If after 3 h of operation, the concentration of the bacteria is 3 × 10-5 kg/dm3, what is the specific growth rate of the bacteria?