Effect of abiotic factors on sulfidogenic activity of bacteria Desulfuromonas sp.

O M Сhaіka,T B Peretyatko

doi:10.15421/022025

Abstract

Sulfur-reducing bacteria are promising agents for the development of new methods of wastewater treatment with the removal of ions of heavy metals and organic compounds. Study of the effect of various environmental factors on the growth and sulfidogenic activity of sulfur-reducing bacteria allows one to investigate the adaptability of these microorganisms to stress factors. The paper deals with the effect of рН, different concentrations of elemental sulfur, hydrogen sulfide and presence of various electron acceptors on the growth and sulfidogenic activity of bacteria Desulfuromonas sp. YSDS-3. The calculation of C/S ratio for sulfur-reducing bacteria Desulfuromonas sp. YSDS-3 was made, with the comparison with similar parameters of sulfate-reducing bacteria. In the medium with elemental sulfur, concentration of hydrogen sulfide increased with the concentration of elemental sulfur. Bacteria Desulfuromonas sp. YSDS-3 accumulated their biomass in the most effective way at the concentration of elemental sulfur of 10–100 mM. In the medium with polysulfide form of sulfur at the neutral pH, bacteria produced hydrogen sulfide and accumulated biomass the best. Hydrogen sulfide at the concentration of 3 mM did not inhibit the bacterial growth, but further increase in the hydrogen sulfide concentration inhibited the growth of bacteria. The bacteria did not grow at the hydrogen sulfide concentration of 25 mM and above. As the concentration of elemental sulfur and cell density increases, sulfidogenic activity of the bacteria grows. Presence of two electron acceptors (S and K2Cr2O7, S and MnO2, S and Fe (III)) did not affect the accumulation of biomass of the bacteria Desulfuromonas sp. YSDS-3. However, under such conditions the bacteria accumulated 1.5–2.5 times less hydrogen sulfide than in the test medium. After 12–24 h of cultivation, different concentrations of elemental sulfur had a significant effect on the sulfidogenic activity. However, during 3–16 days of cultivation, the percentage of effect of elemental sulfur concentration decreased to 31%, while the percentage of effect of cell density increased threefold. Presence in the medium of the electron acceptors (Cr (VI), MnO2, Fe (III)) alternative to elemental sulfur led to a significant decrease in the content of hydrogen sulfide produced by sulfur-reducing bacteria.

Highlights

Microorganisms play an important role in the biosphere, in particular, in the processes of biotransformation of organic and inorganic substances, biogeochemical cycles of metallic and non-metallic elements, transformation of metals, minerals, soil and sediment formation (Bertrand et al, 2014; Liet et al, 2018; Crane, 2019)
We found that bacteria Desulfuromonas sp
In the presence of elemental sulfur, the C/S ratio is 0.212–0.241, which is 2.5 times lower compared to sulfate-reducing bacteria Desulfomicrobium sp

Summary

Introduction

Microorganisms play an important role in the biosphere, in particular, in the processes of biotransformation of organic and inorganic substances, biogeochemical cycles of metallic and non-metallic elements, transformation of metals, minerals, soil and sediment formation (Bertrand et al, 2014; Liet et al, 2018; Crane, 2019). By performing dissimilation recovery of sulfur, sulfur-reducing bacteria oxidize various organic compounds, purifying water reservoirs from organic matter (Qiuet et al, 2017; Moroz et al, 2018). These bacteria oxidize various organic substrates using metals of variable valency as electron acceptors and turn them into forms which are non-toxic or less toxic for living organisms (Smith & Gadd, 1993). Sulfur-reducing bacteria resistant to high concentrations of heavy metal ions are involved in the reduction deposition of toxic metal ions Usage of these microorganisms can neutralize the toxicity of the hydrogen sulfide produced by them and heavy metal ions due to their binding to produce insoluble sulfides (Lovley, 2004; Qiuet et al, 2017; Suna et al, 2020). Carbohydrates (glucose, sucrose, cellulose, starch), volatile fatty acids (formiate, acetate, butyrate), alcohols (ethanol, methanol), amino acids, proteins and even inorganic components (Alves et al, 2011; Richter et al, 2012; Vasyliv et al, 2015; Knoche et al, 2016) are used to generate the electric current in the microbial anodic fuel cells

Methods

Results

Discussion

Conclusion