New article!!! Interplay between arsenic and selenium biomineralization in Shewanella sp. O23S

Our article “Interplay between arsenic and selenium biomineralization in Shewanella sp. O23S” was published in Environmental Pollution (read). The paper explores the complex interaction between arsenic and selenium metabolism in a strain of Shewanella previously isolated from a gold mine. This work is the product of a successful collaboration with scientists from Poland (Paulina Wójtowicz), Hungary (Mihály Pósfai and Zsombor Molnár) and Spain (Encarnación Ruiz-Agudo; Diego Baragaño and José Luis Gallego).

The main findings are summerized below:

  • Shewanella sp. O23S reduced As and Se oxyanions to AsS and Se0(-S) biominerals.
  • AsS (realgar) and As2S3 (orpiment) were formed using cysteine as a source of H2S.
  • SeO42− and SeO32− reduction led to red Se0 with variable sulfur (-S) content.
  • All biominerals were extracellular, amorphous, polydispersed and negatively-charged.
  • The reduction of the two elements seems to involve seperate enzymes.
AsS biominerals produced by Shewanella sp. O23S
AsS biominerals produced by Shewanella sp. O23S
Elemental map of AsS and Se(0) biominerals

(Bio)minerals in Granada

In April 2022 Dr Staicu will visit the team of Prof. Mohamed Merroun (link) at University of Granada (Spain) for research activity and manuscript preparation on the biomineralization process in Bacillus cereus. The visit will also include manuscript preparation on chemogenic barite with Dr Encarnacion Ruiz-Agudo (link).

Alhambra seens from Albayzin (Carmen de la Victoria)

Veszprem Winter school talk

Dr Staicu will give a talk (January 28, 1:20 PM, GMT+1) on biominerals and bioremediation for the 17th Winter School in Mineral Sciences (Veszprem, Hungary) organized by Prof. Mihaly Posfai and his team. The talk will explore the formation of AsS and Se0 biominerals by a strain of Shewanella, as well as its bioremediation capacity on real industrial effluents rich in metals.

If you are interested to attend the event, please register at

Lake Balaton (winter) Source:

Selenium Summit21 participation

Dr Staicu will contribute the following communication “Cysteine-enhanced bioremediation of a polymetallic, arsenic- and selenium-laden industrial effluent” at the Selenium Summit2021 (26-28/11/2021, online), event organized by Electric Power Research Institute (EPRI).

The results that will be presented were recently published in Letters in Applied Microbiology (here).

New paper “Bioremediation of a polymetallic, arsenic-dominated reverse osmosis reject stream”

A new article “Bioremediation of a polymetallic, arsenic-dominated reverse osmosis reject stream” was published in Letters in Applied Microbiology by our team (Dr. Lucian Staicu and Paulina Wojtowicz) in collaboration with Prof. Mihaly Posfai and Zsombor Molnar (University of Pannonia, Veszprem, Hungary), Prof. Encarnacion Ruiz-Agudo (University of Granada, Spain) and Dr. Diego Baragano and Prof. Jose Luis Gallego (University of Oviedo, Spain).

The article explores the bioremediation potential of a real industrial effluent (retentate stream from a full-scale reverse osmosis plant treating mine water) using a metal-resistant bacterial culture, Shewanella sp. O23S. The results show cysteine metabolism significantly increases the removal yield of several pollutants such as As (27%), Co (80%), Cu (96%), Mo (78%), Se (88%), Sb (83%), and Zn (90%). The contribution of cysteine as a source of H2S to enhancing the removal yield was confirmed by its addition after seven days of incubations initially lacking it. Additionally, the cysteine-sourced H2S was confirmed by its capture onto headspace-mounted Pb-acetate test strips that were analyzed by X-ray diffraction. We show that real metal-laden industrial effluents can be treated to medium-to-high efficiency using a biological system (naturally-sourced inocula) and inexpensive reagents (yeast extract, lactate and cysteine).

This study provides evidence of the medium-to-high removal of metals and metalloids present in real industrial effluents by using naturally-sourced metal-resistant bacterial inocula. Apart from the applied research significance, the coupling of cysteine degradation to metal removal sheds light into the microbially-driven natural attention of industrial pollution in specific geochemical settings. The results warrant the scaling up of the process to treat larger effluent volumes and potentially recover valuable metals in the form of metal sulfides.

19th Symposium on Remediation (Jena, Germany)

The symposium “Biogeochemistry of minerals and strategic metals in remediation and energy transition” will explore topics related to bioremediation and phytoremediation, metal pollution, resource recovery of critical raw materials, and environmental microbiology and will be organized at University Friedrich-Schiller (Jena, Germany) on 4-5 October 2021.

Our contribution presents the cysteine-enhanced bioremediation of a polymetallic industrial effluent using a metal-resistant strain of Shewanella, being the product of a collaborative project of our team (Paulina Wojtowicz and Dr Lucian Staicu) with University of Oviedo (Dr Diego Baragano and Prof Jose Luis Gallego), University of Granada (Prof Encarnacion Ruiz-Agudo) and University of Pannonia (Zsombor Molnar and Prof. Mihaly Posfai). This study is currently in press at Letters in Applied Microbiology.

The symposium proceedings are uploaded below: