“Geomicrobiology: Natural and anthropogenic settings” editorial project was officially launched and will be published this year by Springer. The book is coordinated by Prof. Larry Barton (University of New Mexico, USA) and by Dr. Lucian Staicu (University of Warsaw, Poland) and will include 20 chapters on relevant topics in the field of Geomicrobiology. The contributors are top-notch researchers of international reputation.
The four sections are as follows:
Microbes driving changes in the terrestrial and aquatic environments
Microbes thriving in extreme environments
Microbes in Biotechnology
Microbial community structure: A selection of geochemical environments
The review article “Allotropy of selenium nanoparticles: Colourful transition, synthesis, and biotechnological applications” was published in Microbial Biotechnology. Elemental selenium (Se0 ) nanomaterials undergo allotropic transition from thermodynamically-unstable to more stable phases. This process is significantly different when Se0 nanoparticles (NPs) are produced via physico-chemical and biological pathways. While the allotropic transition of physico-chemically synthesized Se0 is fast (minutes to hours), the biogenic Se0 takes months to complete. The biopolymer layer covering biogenic Se0 NPs might be the main factor controlling this retardation, but this still remains an open question. Phylogenetically-diverse bacteria reduce selenium oxyanions to red amorphous Se0 allotrope, which has low market value. Then, red Se0 undergoes allotropic transition to trigonal (metallic grey) allotrope, the end product having important industrial applications (e.g. semiconductors, alloys). Is it not yet clear whether biogenic Se0 presents any biological function, or it is mainly a detoxification and respiratory by-product. The better understanding of this transition would benefit the recovery of Se0 NPs from secondary resources and its targeted utilization with respect to each allotropic stage. This review article presents and critically discusses the main physico-chemical methods and biosynthetic pathways of Se0 (bio)mineralization. In addition, the article proposes a conceptual model for the resource recovery potential of trigonal selenium nanomaterials in the context of circular economy.
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.