Microbes of biotechnological importance in acidic saline lakes in the Yilgarn Craton, Western Australia

Acidic salt lakes are environments that harbor an array of biologically challenging conditions. Through 16S rRNA, 18S rRNA, and ITS amplicon sequencing of eight such lakes across the Yilgarn Craton of Western Australia, we aim to understand the microbial ecology of these lakes with a focus on iron- and sulfur-oxidizing and reducing microorganisms that have theoretical application in biomining industries. In spite of the biological challenges to life in these lakes, the microbial communities were highly diverse. Redundancy analysis of soil samples revealed sulfur, ammonium, organic carbon, and potassium were significant diversities of the microbial community composition. The most abundant microbes with a hypothetical application in biomining include the genus 9 M32 of the Acidithiobacillus family, Alicyclobacillus and Acidiphilium, all of which are possible iron- and/or sulfur-oxidizing bacteria. It is evident through this study that these lakes harbor multiple organisms with potential in biomining industries that should be exploited and studied further

Upregulation of the Nifhdken Operon in Leptospirillum Species Subjected to Soluble Nitrogen Starvation

Background: Members of the genus Leptospirillum routinely dominate bioleaching systems. Understanding their metabolic complexity is necessary for the improvement of bioleaching technologies. Nitrogen is an essential element required for the cellular growth of all microorganisms. In this study Leptospirillum species were assessed for their nitrogen fixation capabilities under aerobic and anaerobic conditions, in the absence of soluble ammonia

Bioprospecting for and the applications of halophilic acidophiles in bioleaching operations

The economic recovery of metals from sulfide ores has become a topic of increasing interest due to the escalating demand for critical minerals and the reducing grade of available ores. Bioleaching is the use of acidophilic iron and sulfur-oxidising microorganisms to facilitate the extraction of base metals from primary sulfide ores and tailings. One significant issue limiting the use of bioleaching is the availability of freshwater due to the sensitivity of these microbes to chloride. The use of saline tolerant acidophilic iron- and-sulfur oxidising microorganisms will go a long way to addressing this issue. There are three possible means of sourcing suitable microorganisms; adaptation, genetic engineering and bioprospecting, with bioprospecting showing the greatest possibilities. Bioprospecting in search of native organisms for bioleaching operations has led researchers to numerous locations around the world and the isolation of iron- and sulfur-oxidising acidophiles that are capable of tolerating high levels of salinity has been of particular interest in these investigations

The recovery of nucleic acid from biomining and acid mine drainage microorganisms

The cornerstone of biological molecular techniques is the extraction of the intra- or extra-cellular component of interest. However, inefficiencies in the extraction method can lead to results that are not representative of the microbial population under investigation. It is particularly difficult to extract clean and pure samples of the cellular component of interest from the microbial inhabitants of low-pH, sulfidic environments, such as those found in biomining or acid mine drainage (AMD). A number of nucleic acid (NA) extraction methods were tested using microorganisms commonly found in biomining and AMD environments, including archaea and Gram-negative and Gram-positive bacteria. The different stages in the methods of NA extraction were investigated separately, including the: (i) removal of cells from pyrite, (ii) cell lysis and nucleic acid extraction, (iii) nucleic acid precipitation and (iv) RNA purification using, as appropriate, microscopy, spectrophotometry, agarose gel electrophoresis of NA, PCR, quantitative-PCR and quantitative reverse transcriptase-PCR to assess the quality and quantity of the DNA and RNA.The relative percentage of NA recovered from each microorganism using the optimised method discussed in this paper returned the following percentage of NA per cell: At. ferrooxidans 91% ± 1.4%; At. caldus 91% ± 2.7%; L. ferriphilum 98% ± 1.2%; F. acidiphilum 83% ± 2.9%; and S. thermosulfidooxidans 79% ± 0.7%. Differences in lysis methods and NA precipitation greatly impacted the quality and quantity of the extracted NA. A method for the reliable, representative and reproducible extraction of NA from five strains of biomining and AMD microorganisms from pyrite and from liquid culture is described

Amanita wadulawitu (Basidiomycota), a new species from Western Australia, and an expanded description of A. kalamundae

A new species of Amanita Pers. is documented from Western Australia. Amanita wadulawitu L.E.McGurk, E.M.Davison & E.L.J.Watkin is described from the Perth IBRA subregion. Amanita kalamundae O.K.Mill. is redescribed to include additional collections, drawing attention to the presence of clamp connections in the lamellae and at the base of basidia. A BLASTn search has shown that there are no exact matches of the nuclear ribosomal internal transcribed spacer (ITS) region of either species in GenBank

Carbon fixation genes in biomining microorganisms

Background and aims: Studying metabolic pathways will help provide a better understanding of the role of different microorganisms within biomining environments. The majority of microorganisms involved in biomining are autotrophs which rely on atmospheric carbon fixation for growth. The aim of this study is to investigate genes involved with carbon fixation in a range of biomining microorganisms

Draft Genome Sequence of the Iron-Oxidizing, Acidophilic, and Halotolerant “Thiobacillus prosperus” Type Strain DSM 5130

“Thiobacillus prosperus” is a halotolerant mesophilic acidophile that gains energy through iron and sulfur oxidation. Its physiology is poorly understood. Here, we describe the principal genomic features of the type strain of T. prosperus, DSM 5130. This is the first public genome sequence of an acidophilic halotolerant bacterium

Crevice corrosion of duplex stainless steels in the presence of natural marine biofilms

The evaluation of crevice corrosion of high alloy stainless steels used in offshore applications is of major importance as it is one of the most deleterious forms of localized corrosion which may result in sudden marine corrosion failure. The resistance of UNS S31803 duplex stainless steel (DSS) to crevice corrosion in natural seawater was evaluated by immersion and electrochemical tests. Artificially creviced specimens were tested before, during and after immersion in natural seawater under stagnant conditions for up to eight weeks allowing indigenous marine microorganisms to adhere to the alloy surface and form a biofilm. The changes in biofilm community structure and the influence of biofilm on the crevice corrosion of DSS specimens in seawater were investigated at two different exposure times (4 and 8 weeks) using a combination of potentiodynamic and potentiostatic measurements, surface inspection and bacterial community profile analysis by 16S rRNA gene PCR-DGGE and DNA sequencing. Results indicate that our selection approach to evaluate crevice corrosion yields highly reproducible results. Crevice corrosion was observed only in electrochemically polarized specimens that had been exposed to natural seawater containing bacteria. The possible mechanisms involved in the biofilm enhanced crevice corrosion are discussed