Citrobacter freundii, is aerobic gram-negative bacilli. In the Biotech industry, C. freundii produces many important enzymes including phosphatase, α-galactosidase and selenocysteine beta-lyase. While Klebsiella pneumoniae is a nosocomial pathogen. In spite of its potential pathogenicity, it has several metabolic potentials, such as able to produce 1,3-propanediol dehydrogenase, 2,3-butanediol, guluronate layse and these could be used in biotechnology applications. The micro-nutrients act, as cofactors, required in micro quantity may lead excess production of desired proteins, enzymes and other value added products. The metal ions may also act on metabolic pathway of gene expression, protein folding and enzymatic activity in cells. In this study pH and temperature of C. freundii and K. pneumoniae were optimized and microelements viz., Zn2+, Mn2+, Cu2+, Fe2+ and Ti2+ ions used to investigate the effect on growth and soluble proteins production by C. freundii and K. pneumoniae. We observed that Fe2+ ions helped dramatically in the growth of K. pneumoniae at concentrations of 60mg/ml and 80mg/ml (maximum) while Mn2+ at 60mg/ml. Therefore, Fe2+ and Mn2+ ions may be used in medium for promoting the growth and soluble protein production by K. pneumonia. The interesting outcome of this study on K. pneumoniae is that Ti2+ ions did not allowed increase in growth at none of the concentrations. Therefore, it may be used as anti-pneumoniae agent. 80mg/ml (maximum) followed by 60mg/ml of Fe2+ and Cu2+ ions in medium helped growth of C. freundii progressively. Hence, Fe2+ and Cu2+ ions may be used for promoting the growth. While Ti2+ and Zn2 ions could be used as antibacterial agent against C. freundii as they inhibited growth Therefore, 80mg/ml of FeSO4 and ZnSO4 may be used in medium to increase growth and soluble protein production.