The 20th Symposium on remediation in Jena “Microbes matter – Environmental systems” will be held on 29-30/09/2022 at Friendrich Schiller University, Jena, Germany. “The program consists of six sessions highlighting environmental interactions with metals focusing on processes that include microbially as well as chemically driven reactions with metals spanning the geological, hydrogeochemical, mineralogical, materials sciences and microbiological aspects and implications to remediation and land use” (Thorsten Schäfer & Erika Kothe). Dr Staicu will give a talk on “Arsenic and selenium biomineralization: biominerals to bioremediation online” on Friday, Sepember 30.
Dr Staicu will deliver a talk on microbial biomineralization at symposium “Membrane proteins involved in extracellular electron transfer” organized by Américo G. Duarte and Catarina M. Paquete from ITQB-NOVA, Lisbon, Portugal (29/09/2022).
The article “Genomic insight into iron acquisition by sulfate-reducing bacteria in microaerophilic environments” was published in BioMetals (read). Historically, sulfate-reducing bacteria (SRB) have been considered to be strict anaerobes, but reports in the past couple of decades indicate that SRB tolerate exposure to O2 and can even grow in aerophilic environments. With the transition from anaerobic to microaerophilic conditions, the uptake of Fe(III) from the environment by SRB would become important. In evaluating the metabolic capability for the uptake of iron, the genomes of 26 SRB, representing eight families, were examined. All SRB reviewed carry genes (feoA and feoB) for the ferrous uptake system to transport Fe(II) across the plasma membrane into the cytoplasm. In addition, all of the SRB genomes examined have putative genes for a canonical ABC transporter that may transport ferric siderophore or ferric chelated species from the environment. Gram-negative SRB have additional machinery to import ferric siderophores and ferric chelated species since they have the TonB system that can work alongside any of the outer membrane porins annotated in the genome. Included in this review is the discussion that SRB may use the putative siderophore uptake system to import metals other than iron.
This work is the product of a successful collaboration with scientists from United States (Larry Barton) and Portugal (Americo Duarte).
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.
Dr Staicu contributed an oral presentation on “Industrial microbial mat-sourced Shewanella strain: versatile polymetallic and anaerobic respirer” at the Biofilms10 conference (May 9-11) hosted by UFZ Leipzig, Germany (link). Abstract (here)
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).
On March 16 Dr Staicu delivered a talk for BSc students from Faculty of Journalism and Communication, University of Bucharest, Romania entitled “Despre textul stiințific/On scientific text”). The meeting included a presentation and a discussion with the students about scientific articles and the scientific text.
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.
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).