Heterogeneity of population of microorganisms grown in presence of iron oxide maghemite nanoparticles

¹ Irkutsk State University, Nizhnyaya Embankment St., 6, Irkutsk, 664011, Russia
² FSBEI HE Irkutsk State Medical University MOH, Red Revolt str., 1, Irkutsk, 664003, Russia
³ Institute of Electrophysics, Amundsen str., 106, Ekaterinburg, 620016, Russia
⁴ Ural Federal University, Mira St. 19 Ekaterinburg, 620000, Russia
⁵ Universidad del País Vasco UPV-EHU, Leioa, 48940 Spain

Corresponding author: denis_tp@inbox.ru

Published online: 4 July 2018

Abstract

In this work γ-Fe₂O₃ MNPs were obtained by laser target evaporation and water based suspensions were prepared. Maximum permissive dose of iron in water (MPD) is 0.3 mg/L. It was found that 100 MPD dose of iron induces formation of non-typical colonies after 72 or 96 hours exposition: against a background of small black colonies large white colonies appeared due to a disruption in tyrosine synthesis. Multiple re-cloning of the white colonies grown with MNPs showed that they retained their properties both under standard conditions (temperature of 24 °C) and at the temperatures up to 37o C. E.nigrum grown with MNPs demonstrated very scant extension of small colonies at the cultivation temperature of 24o C, their growth was completely blocked at 37°C. Significant changes in the structure of the population were noted. First of all, large cells with pronounced aggregation were observed among the black colonies. These aggregates consisted of large cells connected to each other by matrix. In the white colonies the appearance of very long threadlike cells connecting different groups of the cells establishing an intercellular communication was evident. Fe₂O₃ MNPs induce an increase in the heterogeneity of the population, expressed as a change in morpho-physiological states.