Influence of Sulfobacillus thermosulfidooxidans on Initial Attachment and Pyrite Leaching by Thermoacidophilic Archaeon Acidianus sp. DSM 29099

At the industrial scale, bioleaching of metal sulfides includes two main technologies, tank leaching and heap leaching. Fluctuations in temperature caused by the exothermic reactions in a heap have a pronounced effect on the growth of microbes and composition of mixed microbial populations. Currently, little is known on the influence of pre-colonized mesophiles or moderate thermophiles on the attachment and bioleaching efficiency by thermophiles. The objective of this study was to investigate the interspecies interactions of the moderate thermophile Sulfobacillus thermosulfidooxidans DSM 9293T and the thermophile Acidianus sp. DSM 29099 during initial attachment to and dissolution of pyrite. Our results showed that: (1) Acidianus sp. DSM 29099 interacted with S. thermosulfidooxidansT during initial attachment in mixed cultures. In particular, cell attachment was improved in mixed cultures compared to pure cultures alone; however, no improvement of pyrite leaching in mixed cultures compared with pure cultures was observed; (2) active or inactivated cells of S. thermosulfidooxidansT on pyrite inhibited or showed no influence on the initial attachment of Acidianus sp. DSM 29099, respectively, but both promoted its leaching efficiency; (3) S. thermosulfidooxidansT exudates did not enhance the initial attachment of Acidianus sp. DSM 29099 to pyrite, but greatly facilitated its pyrite dissolution efficiency. Our study provides insights into cell-cell interactions between moderate thermophiles and thermophiles and is helpful for understanding of the microbial interactions in a heap leaching environment

Phylogenetic distribution of the capsid assembly protein gene (g20) of cyanophages in paddy floodwaters in Northeast China.

Numerous studies have revealed the high diversity of cyanophages in marine and freshwater environments, but little is currently known about the diversity of cyanophages in paddy fields, particularly in Northeast (NE) China. To elucidate the genetic diversity of cyanophages in paddy floodwaters in NE China, viral capsid assembly protein gene (g20) sequences from five floodwater samples were amplified with the primers CPS1 and CPS8. Denaturing gradient gel electrophoresis (DGGE) was applied to distinguish different g20 clones. In total, 54 clones differing in g20 nucleotide sequences were obtained in this study. Phylogenetic analysis showed that the distribution of g20 sequences in this study was different from that in Japanese paddy fields, and all the sequences were grouped into Clusters α, β, γ and ε. Within Clusters α and β, three new small clusters (PFW-VII∼-IX) were identified. UniFrac analysis of g20 clone assemblages demonstrated that the community compositions of cyanophage varied among marine, lake and paddy field environments. In paddy floodwater, community compositions of cyanophage were also different between NE China and Japan

Three-dimensional principal coordinate analysis of <i>g20</i> clone sequences of cyanophage communities obtained from marine waters (<i>blue circles</i>), lake freshwaters (<i>red circles</i>), and paddy fields (<i>green circles</i>).

<p>The <i>percentages</i> in the axis labels represent the percentages of variation explained by the principal coordinates.</p

Neighbor-joining phylogenetic tree showing the relationship of <i>g20</i> amino acid sequences from paddy floodwaters in NE China with those from Japanese paddy floodwaters (Wang et al. 2010) and paddy field soils (Wang et al.2011).

<p><i>Brown</i> and <i>white square boxes</i> indicate <i>g20</i> clones obtained from paddy field soils in Japan and paddy floodwaters in Japan, respectively; <i>green triangles</i> indicate <i>g20</i> clones obtained from paddy floodwaters in NE China; <i>JP</i> and <i>CN</i> represent Japan and China, respectively; <i>PFW</i> and <i>PFS</i> represent paddy floodwater and paddy field soil, respectively. Bootstrap values <50 are not shown. The scale bar represents the number of amino acid substitutions per residue.</p

Neighbor-joining phylogenetic tree showing the relationships of <i>g20</i> amino acid sequence from paddy floodwaters in NE China with from those from lake freshwaters (Dorigo et al. 2004; Short and Suttle 2005; Wilhelm et al. 2006; Zhong and Jacquet 2013; Yeo and Gin, unpublished data which were submitted in Jan 15, 2013), paddy floodwaters in Japan (Wang et al. 2010), paddy field soils in Japan (Wang et al. 2011) and marine waters (Fuller et al. 1998; Zhong et al. 2002; Marston and Sallee 2003; Wang and Chen 2004; Mann et al. 2005; Short and Suttle 2005; Li and Li, unpublished data which were submitted in Jun 16, 2013).

<p><i>Green triangles</i> and <i>blue circles</i> indicate <i>g20</i> clones obtained from lake freshwater and marine water, respectively; <i>Black</i> and <i>white square boxes</i> indicate <i>g20</i> clones obtained from paddy field soils in Japan and paddy floodwaters in Japan, respectively; <i>White triangles</i> indicate <i>g20</i> clones obtained from paddy floodwaters in NE China. The <i>number in parentheses</i> denotes the accession number of amino acid sequences in the NCBI website. Bootstrap values <50 are not shown. The scale bar represents the number of amino acid substitutions per residue.</p

Closest relatives of sequenced <i>g20</i> clones from different paddy floodwaters at the amino acid level.

<p>Closest relatives of sequenced <i>g20</i> clones from different paddy floodwaters at the amino acid level.</p

Three-dimensional principal coordinate analysis of <i>g20</i> clone sequences of cyanophage communities obtained from paddy floodwaters in NE China (<i>dark green circles</i>) and from Japanese paddy floodwaters (<i>light green circles</i>) and paddy soils (<i>brown circles</i>).

<p>The <i>percentages</i> in the axis labels represent the percentage of variation explained by the principal coordinates.</p

Biofilm Formation and Interspecies Interactions in Mixed Cultures of Thermoacidophilic Archaea Acidianus spp. and Sulfolobus metallicus

The understanding of biofilm formation by bioleaching microorganisms is of great importance for influencing mineral dissolution rates and to prevent acid mine drainage (AMD). Thermo-acidophilic archaea such as Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to perform leaching at high temperatures, thereby enhancing leaching rates. In this work, leaching experiments and visualization by microscopy of cell attachment and biofilm formation patterns of the crenarchaeotes Sulfolobus metallicus DSM 6482T and the Acidianus isolates DSM 29038 and DSM 29099 in pure and mixed cultures on sulfur or pyrite were studied. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes as well as fluorescently labeled lectins were used to visualize different components (e.g. DNA, proteins or glycoconjugates) of the aforementioned species. The data indicate that cell attachment and the subsequently formed biofilms were species- and substrate-dependent. Pyrite leaching experiments coupled with pre-colonization and further inoculation with a second species suggest that both species may negatively influence each other during pyrite leaching with respect to initial attachment and pyrite dissolution rates. In addition, the investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. Physical contact between the two species seems to occur, as revealed by specific lectins able to specifically bind single species within mixed cultures.Fil: Castro, Camila Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Zhang, Ruiyong. Universitat Duisburg - Essen. Aquatische Biotechnologie Biofilm Centre; AlemaniaFil: Liu, Jing. Universitat Duisburg - Essen. Aquatische Biotechnologie Biofilm Centre; AlemaniaFil: Bellenberg, Sören. Universitat Duisburg - Essen. Aquatische Biotechnologie Biofilm Centre; AlemaniaFil: Neu, Thomas R.. Helmholtz Centre For Environmental Research-ufz; AlemaniaFil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; ArgentinaFil: Sand, Wolfgang. Universitat Duisburg - Essen. Aquatische Biotechnologie Biofilm Centre; AlemaniaFil: Vera, Mario. Universitat Duisburg - Essen. Aquatische Biotechnologie Biofilm Centre; Alemani