Assessment of the Influence Of Ca²⁺ and PH on Bacterial Growth of Acidithiobacillus Ferrooxidans

ABSTRACT

The capability of Acidithiobacillus ferrooxidans to oxidize ferrous ions is successfully used for treatment of gas and water pollutions and in biometallurgy This bacterium forms solid bofilms, which are included in waste water and tail gas treatment and bioleaching technologies

In our previous work the oxidation capacity of the bacteria was assessed only based on the average velocity of ferric ion production without investigation of the biomass growth process.

Based on some mathematical models which describe the initial processes of biofilm formation and functioning, the significance of the specific cell growth was shown. It is important to know more about the cultivation regimes of the suspended cells of the strain for the subsequent choice of appropriate cultivation regime for bacteria adaptation to high substrate levels

This work is a part of studies on the influence of different regimes of cultivation on bacterial physiology. Three series of experiments were elaborated for studying the influence of different pH and Ca concentrations on cells growth of the strain. For studying the bacterial growth, samples were taken from the culture media troughout the cultivation process, at 0, 9, 24, 28, 34, 48, 53 hours. The probes were processed using the method of limited dilutions and the cells were grown on solid media in BIOCENTER 2001 for 25 days, and developed colonies were counted.

The experimental data showed some statistically significant differences in the studied parameters measured in different cultural media at the beginning and last phases of culture growth.

Keywords:

• suspended cells
• cultivation regime
• Acidithiobacillus ferrooxidans
• Ca²⁺
• pH