Screening, identification and experimental design to optimization of the selenite bioremediation by new isolated Bacillus sp. Selena 3 in water

Hadis Tavafi; Parisa  Tajer-Mohammad-Ghazvini; Arash Babaei

doi:10.18502/ijm.v15i2.12481

Hadis Tavafi Department of Biology, Faculty of Science, Malayer University, Malayer, Iran
Parisa Tajer-Mohammad-Ghazvini Nuclear Fuel Cycle Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
Arash Babaei Department of Biology, Faculty of Science, Malayer University, Malayer, Iran

DOI: https://doi.org/10.18502/ijm.v15i2.12481

Keywords: Bacillus; Metalloids pollution; Selenite bioremediation

Abstract

Background and Objectives: Heavy metals pollution is one of the most important concerns in the world. Selenium is one of the most important elements for the life, but if the absorption of this element in cells increases, it acts as a toxic element.

Materials and Methods: In this study, bacterial isolates were screened and isolated from selenium-contaminated soil and water. Twenty -five out of 42 isolates were able to reduce Selenite. Also, the response surface method (RSM) was used to evaluate and optimize the biological reduction of selenite by Selena 3. Factors of bacterial inoculation percentage, time, and amount of selenium oxyanion salt concentration were studied at five levels of -α, -1, 0, +1, and +α.

Results: Bacillus sp. Selena 3 was able to reduce 80 mM sodium selenite in less than 4 hours compared to other bacteri- al isolates. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of sodium selenite Bacillus sp. Selena 3 was reported as 160 and 320 mM, respectively. The results showed that with increasing duration, the percentage of selenite reduction by bacteria increases and the percentage of bacterial inoculation does not have much effect on its reduction.

Conclusion: Due to the ability of Bacillus sp. Selena 3 for rapid reduction in significant concentration of selenium oxyanion (SeO 2-), this bacterium can be used as an efficient candidate in removing selenite from the environment.