Research Geotechnological Center, Far Eastern Branch of the Russian Academy of Sciences (Petropavlovsk-Kamchatsky, Russia)

Ocheretyana S. O., Senior Researcher, PhD in Biological Sciences, blossom-so@yandex.ru
Averyanova V. E., Junior Researcher, Purlac@inbox.ru

This study investigates the influence of various nutrient media on the cultivation of an autochthonous mixed bacterial culture isolated from oxidized ore at the Shanuch copper-nickel deposit. PCR diagnostics revealed the presence of Acidithiobacillus thiooxidans, A. ferrooxidans, and Sulfobacillus thermosulfidooxidans. These acidophilic bacteria are critical for the bacterial-chemical treatment of sulfide ores and concentrates from copper-nickel deposits. The sample, which had been preserved for seven years under low-temperature conditions without reinoculation, was subjected to experiments aimed at restoring autochthonous bacterial activity and increasing cell counts to enhance bioleaching efficiency. The study has found that the most effective conditions for bacterial growth included the addition of Na₂S₂O₃·5H₂O and yeast extract to the nutrient medium, maintaining a temperature of 30 °C, stirring at 150 rpm, aeration, and controlling the pH at 2.02. Various inoculum-to-medium ratios (1 : 4, 1 : 8, and 1 : 10) were tested to optimize the production of bacterial suspensions. The 1 : 10 dilution provided the most favorable results, with cell growth ranging from 211 to 230 times the initial concentration across different media. Additionally, at this dilution ratio, no significant decrease in the number of planktonic bacterial forms was observed after reaching high cell density.

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