A study of the biological and functional properties of microorganisms with high resistance to manganese (II)

Abstract

The issue of water treatment of the central water supply, as well as wastewater, from excessive content of heavy metals (HMs) remains relevant at the present time. The presence of heavy metals, even in trace amounts, has a negative impact not only on the environment, but also on all human organic systems. At the moment, iron and manganese are among the main pollutants entering the human body via drinking water. Studies were carried out on the biological and functional properties of microorganisms isolated from highly magnetic soil, which previously demonstrated high resistance to manganese (II). Microbial strains with maximum resistance to Mn (II) were identifi ed as: Bacillus simplex 55.2, B. simplex 13.2 and Listeria murrayi 13.4. The growth dynamics of B. simplex 55.2 and B. megaterium 69.5 was studied under conditions of periodic cultivation in a liquid medium containing 2 mmol/L Mn (II). It was shown that after 7 day’s cultivation, the weight of the biomass of B. megaterium 69.5 increased by 5.5 times, B. simplex 55.2 increased by 3.7 times relative to the values after 1 day cultivation, the optical density of the culture medium B. megaterium 69.5 increased 4 times, B. simplex 55.2 increased 2 times compared with the initial sowing dose. The specifi c growth rate of B. megaterium 69.5 after 7 days cultivation was higher than that of B. simplex 55.2 by about 2 times, and the degree of removal of Mn (II) from the aquatic environment was less. B. simplex 55.2 reduced the content of Mn (II) by 66%, B. megaterium 69.5 reduced by 50%. It was established that B. megaterium 69.5, B. simplex 55.2, B. simplex 13.2 and L. murrayi 13.4 are able to grow in conditions of high alkalinity and mineralization of the medium (pH 7–10; 10% NaCl). Taking into account that these microorganisms are able to remove high concentrations of Mn (II) from the aquatic environment, they are promising for their use in water treatment biotechnology.

Keywords

• manganese (ii) ions
• manganese-oxidizing microorganisms
• resistance
• periodic cultivation
• biomass growth