Naoko Okibe

Microorganisms were enumerated and isolated on selective solid media from a pilot-scale stirred-tank bioleaching operation in which a polymetallic sulfide concentrate was subjected to biologically accelerated oxidation at 45 degrees C. Four distinct prokaryotes were isolated: three bacteria (an Acidithiobacillus caldus-like organism, a thermophilic Leptospirillum sp., and a Sulfobacillus sp.) and one archaeon (a Ferroplasma-like isolate). The relative numbers of these prokaryotes changed in the

The oxidative dissolution of pyrite (FeS2) by pure and mixed cultures of moderately thermophilic acidophiles was studied in shake flask cultures and in pH-controlled bioreactors, incubated at 45 degrees C. Various combinations of seven eubacteria (a Leptospirillum sp. (MT6), Acidimicrobium ferrooxidans, Acidithiobacillus caldus, an Alicyclobacillus sp. (Y004), and three Sulfobacillus spp.) and one archaeon (Ferroplasma sp. MT17) were examined. Pyrite dissolution was determined by measuring chang

The effect of controlling the redox potential (Eh) on chalcopyrite bioleaching kinetics was studied as a new aspect of redox control during chalcopyrite bioleaching, and its mechanism was investigated by employing the “normalized” solution redox potential (Enormal) and the reaction kinetics model. Different Eh ranges were established by use of different acidophiles (Sulfobacillus acidophilus YTF1; Sulfobacillus sibiricus N1; Acidimicrobium ferrooxidans ICP; Acidiplasma sp. Fv-AP). Cu dissolution

Applicability of the bioscorodite method (use of the thermo-acidophilic Fe(II)-oxidizing archaeon Acidianus brierleyi for arsenic (As) oxidation and immobilization at 70 °C) was tested for synthetic copper refinery wastewaters of a wide range of dilute initial As(III) concentrations ([As(III)]ini = 3.3–20 mM) with varying initial [Fe(II)]/[As(III)] molar ratios ([Fe(II)]ini/[As(III)]ini = 0.8–6.0). Crystallization of scorodite (FeAsO4·2H2O) tends to become increasingly challenging at more dilute

Corynebacterium glutamicum, like its counterpart industrial workhorses E. coli and Bacillus subtilis, does exhibit strong, carbon source-inducible promoters, and the functionality of two of which was demonstrated in this study. While this study may be most relevant in the ongoing efforts to establish technologies of the biorefinery, it should also be of interest to general microbiologists exploring the versatility of industrial micro-organisms. In so doing, the study should impact future advance

pCGR2 and pCG1 belong to different subfamilies of the pCG1 family of Corynebacterium glutamicum plasmids. Nonetheless, they harbour homologous putative antisense RNA genes, crrI and cgrI, respectively. The genes in turn share identical positions complementary to the leader region of their respective repA (encoding plasmid replication initiator) genes. Determination of their precise transcriptional start- and end-points revealed the presence of short antisense RNA molecules (72 bp, CrrI; a

In order to tackle the dual challenge of utilizing highly refractory chalcopyrite (CuFeS2) while saving scarce freshwater resources, this study aimed to systematically understand the individual role of chemical lixiviant and bioleaching microorganisms in the complex Fe3+-Cu2+-SO42−-Cl− chalcopyrite leaching system. In general freshwater bioleaching conditions, the Eh level sharply increased, and the “high-Eh-bioleaching” became the major leaching driving force. In this case, the lowest Cu yield