Article (Scientific journals)
Automated Microscopic Analysis of Metal Sulfide Colonization by Acidophilic Microorganisms.
Bellenberg, Soren; Buetti-Dinh, Antoine; Galli, Vanni et al.
2018In Applied and Environmental Microbiology, 84 (20)
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Keywords :
biofilm dispersal; biofilm formation; biofilms; bioleaching; diffusible soluble factor; fluorescent image analysis; image analysis; microbe-mineral interaction; microbe-mineral interactions; quorum sensing
Abstract :
[en] Industrial biomining processes are currently focused on metal sulfides and their dissolution, which is catalyzed by acidophilic iron(II)- and/or sulfur-oxidizing microorganisms. Cell attachment on metal sulfides is important for this process. Biofilm formation is necessary for seeding and persistence of the active microbial community in industrial biomining heaps and tank reactors, and it enhances metal release. In this study, we used a method for direct quantification of the mineral-attached cell population on pyrite or chalcopyrite particles in bioleaching experiments by coupling high-throughput, automated epifluorescence microscopy imaging of mineral particles with algorithms for image analysis and cell quantification, thus avoiding human bias in cell counting. The method was validated by quantifying cell attachment on pyrite and chalcopyrite surfaces with axenic cultures of Acidithiobacillus caldus, Leptospirillum ferriphilum, and Sulfobacillus thermosulfidooxidans. The method confirmed the high affinity of L. ferriphilum cells to colonize pyrite and chalcopyrite surfaces and indicated that biofilm dispersal occurs in mature pyrite batch cultures of this species. Deep neural networks were also applied to analyze biofilms of different microbial consortia. Recent analysis of the L. ferriphilum genome revealed the presence of a diffusible soluble factor (DSF) family quorum sensing system. The respective signal compounds are known as biofilm dispersal agents. Biofilm dispersal was confirmed to occur in batch cultures of L. ferriphilum and S. thermosulfidooxidans upon the addition of DSF family signal compounds.IMPORTANCE The presented method for the assessment of mineral colonization allows accurate relative comparisons of the microbial colonization of metal sulfide concentrate particles in a time-resolved manner. Quantitative assessment of the mineral colonization development is important for the compilation of improved mathematical models for metal sulfide dissolution. In addition, deep-learning algorithms proved that axenic or mixed cultures of the three species exhibited characteristic biofilm patterns and predicted the biofilm species composition. The method may be extended to the assessment of microbial colonization on other solid particles and may serve in the optimization of bioleaching processes in laboratory scale experiments with industrially relevant metal sulfide concentrates. Furthermore, the method was used to demonstrate that DSF quorum sensing signals directly influence colonization and dissolution of metal sulfides by mineral-oxidizing bacteria, such as L. ferriphilum and S. thermosulfidooxidans.
Disciplines :
Biotechnology
Author, co-author :
Bellenberg, Soren
Buetti-Dinh, Antoine
Galli, Vanni
Ilie, Olga
Herold, Malte ;  University of Luxembourg > Luxembourg Centre for Systems Biomedicine (LCSB)
Christel, Stephan
Boretska, Mariia
Pivkin, Igor V.
Wilmes, Paul ;  University of Luxembourg > Luxembourg Centre for Systems Biomedicine (LCSB)
Sand, Wolfgang
Vera, Mario
Dopson, Mark
External co-authors :
yes
Language :
English
Title :
Automated Microscopic Analysis of Metal Sulfide Colonization by Acidophilic Microorganisms.
Publication date :
2018
Journal title :
Applied and Environmental Microbiology
ISSN :
1098-5336
Publisher :
American Society for Microbiology, Washington, United States - District of Columbia
Volume :
84
Issue :
20
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
FNR - Fonds National de la Recherche [LU]
Commentary :
Copyright (c) 2018 American Society for Microbiology.
Available on ORBilu :
since 03 January 2019

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