• MECHANISM OF OXIDATION OF REDUCED SULPHUR COMPOUNDS BY THIOBACILLI

      Karavaiko, G. I.; Pirovarova, T. A.; Institute of Microbiology, USSR Academy of Sciences, Moscow (1977-07)
      The mechanism of transport sulphur both outside and inside the cells was studied. Macroroentgen structural analysis and electronicmicroscopic researches showed that the membrane structures of thiobacilli carry out not only the oxidation function, but the transport function as well, which consists in the extraction of the formed sulphur from cell. This mechanism of sulphur deposition develops ac-— cording to the exocytosis type. The transport of elemental sulphur inside the cell involves the surface membrane structures (vesicles), while oxidation of the sulphur to sulphuric acid takes place on the outer surface of the cytoplasmic membrane. The vesicles are supposed also to participate in the primary dissolution of elemental sulphur at the site of contact of the cells with the mineral. The study of bacterial oxidation of sulphide minerals has shown the electrochemical nature of microbiological oxidation of sulphide minerals, which takes place at the level of its electronic structure. Pyrite with hole conductivity (with the cation deficit in composition) is oxidized by means of Thiobacillus ferrooxidans not only much more intensively, but also continuously as compared to pyrite with electron conductivity. Thiobacilli play a leading role in the oxidation of reduced sulphur compounds under natural conditions. The mechanism of this process however have not been studied sufficiently well so far. The main purpose of this work was to study the mechanism of sulphur transport, when sulphur was deposited or oxidized by thiobacilli, by means of cytological and cytochemical techniques. We believed that the mechanism,of sulphur transport either from, or into, the cell must be closely related to the submicroscopic organization of thiobacilli
    • A FACULTATIVE THERMOPHILIC THIOBACILLUS-LIKE BACTERIUM: OXIDATION OF IRON AND PYRITE

      Brierley, J. A.; Le Roux, N. W.; Department of Biology, New Mexico Institute of Mining and Technology Socorro, NM 87801, USA; Department of Industry, Warren Spring Laboratory Stevenage, Hertfordshire SG] 2BX, England (1977-07)
      A rod-shaped microbe, isolated from an Icelandic thermal spring grows well at 50° C and oxidises metal sulphides e.g., pyrite (FeS,), pentlandite ((NiFe) SQ) and chalcopyrite (CuFeS,). Initial isolation on a modified ferrous iron medium at pH 3.6 and 60° C indicated that the bacteria were capable of oxidising ferrous iron but that growth was poor. For good growth on sulphide minerals, yeast extract is a requirement. This paper reports on the oxidation of soluble ferrous iron and pyrite by this microbe. The microbe grows slowly at 30° C using ferrous iron but does not grow on pyrite; growth on the latter substrate begins at 40° C. Growth on iron occurs at 50° C, but not at 55° C; growth on pyrite is present at 55° C but not at 60° C. The microbe grows using sulphur as an energy source. The thermophile also grows when yeast extract provides the only apparent energy source. Pyrite-grown cells were used for manometric experiments. Using ferrous iron, the oxygen uptake was non-linear, decreasing with time; the rate increased with increasing pH from 1.3 to 3.2 and also increasing ferrous iron concentration to 8] mM Fe(II). The rate then remained the same at 111mM Fe(II). Using pyrite, the oxygen uptake was linear, the rate being a maximum at pH 2.6. Oxidation of pyrite was slight at pH 1.1 and 3.5. The greatest rate of pyrite oxidation occurred with 100 g c pyrite, the largest concentration tested. Oxygen uptake during the manometric tests with ferrous iron was not greatly affected by the absence of yeast extract; pyrite oxidation was slightly greater without yeast extract. The relevance of the activity of this microbe to biohydrometallurgy is discussed.
    • FERRIC IRON REDUCTION BY SULFUR- AND IRON-OXIDIZING BACTERIA

      Brock, Thomas D.; Department of Bacteriology, University of Wisconsin, Madison, WI 53706 U.S.A. (1977-07)
      Acidophilic bacteria of the genera Thiobacillus and Sulfolobus reduce ferric iron when growing on elemental sulfur as an energy source. This process can be demonstrated aerobically in T. thiooxidans and S, acidocaldarius, but only anaerobically in T. ferrooxidans, since under aerobic conditions this latter organism reoxidizes the ferrous iron it produces as a result of ferric reduction. Since oxidation of sulfide minerals probably proceeds through the intermediary accumulation of elemental sulfur, the bacterial coupling of elemental’sulfur and ferric iron may be important in the overall process of sulfide mineral oxidation, especially when 0, is limiting. Considerations of the environment and ecology of leach dumps suggest that 0, is often limiting, and anaerobic conditions may develop. Thus, the bacterial catalysis of the elemental sulfur-ferric iron reaction may play a major role in the effective operation of a leaching process.
    • EINFLUSS VERSCHIEDENARTIGER SCHWEFELVERBINDUNGEN AUF DAS WACHSTUM UND DAS UEBERLEBEN VON TH. FERROOXIDANS

      Barbic, F.; Lucic, J.; Babic, M.; Institut fur die Technologie von Nuklearrohstoffen und anderen mineralischen Rohstoffen, Belgrad (1977-07)
      Various sulphur compounds were investigated as energy sources for the growth of Th. ferrooxidans. At the same time the tolerance of Th. ferrooxidans for various compounds was examined. Th. ferrooxidans responds in different ways to sulphur compounds, depending on their kind and concentration. Some of the sulphur compounds examined can replace iron as an energy source. The compounds examined can be lethal to Th. ferrooxidans depending on their concentration.
    • EVALUATION OF CONTINUOUS CHEMOSTAT CULTIVATION OF THIOBACILLUS FERROOXIDANS ON FERROUS IRON OR TETRATHIONATE

      Kelly, D. P.; Eccleston, M.; Jones, Carol A.; Department of Environmental Sciences, University of Warwick, Coventry CV4 7AL, England; Glaxo Research Ltd., Sefton Park, Stoke Poges, Buckinghamshire, England (1977-07)
      Thiobacillus ferrooxidans was cultured in continuous flow chemostats on FeSO, at pHl.6 and K was subject to one or other of non-competitive product inhibition (NCP1) or 254% at pH2.5. On iron as the limiting substrate, growth predominatly competitive product inhibition (PCP1). This resulted in premature washout at dilution rates dependent on the concentration of FeSO, in the medium feed. Growth yield, apparent maintenance energy requirement and maximum specific growth rate ae were determined over a wide range of dilution rates for cultures subject to either NCPl or PCP1l. With tetrathionate as the limiting substrate no inhibition effects were observed in the chemostat pH2.5, although tetrathionate is an inhibitory substrate at some pH values. Yield, apparent maintenance and ee page eater For both substrates, true growth yield, Yo (g dry wt per g atom Fe or g mole KS 96 oxidized) was determined from the experimental data and enabled calculation 24 of the Yarp (g dry wt per mole ATP available from each substrate) and the probable ° + ° : . . . ATP requirement for NAD reduction during iron oxidation.
    • EFFECT OF LIGHT ON THIOBACILLI

      Le Roux, N. W.; Marshall, Vivian M.; Warren Spring Laboratory, Stevenage, Herts., England (1977-07)
      The aim was to study the effect of visible and ultra-violet light on some members of the genus Thiobacillus. This genus is one more example of an aerobic organism which undergoes what appears to be the widespread phenomenon of light inhibition. Light inhibition of thiobacilli has been observed before and these other observations are presented. In the present study the effect of both visible and U-V light on three species was considered viz. T.thiooxidans, T.thioparus and T.ferrooxidans, the latter species being studied more thoroughly with respect to different intensities and wavelengths of light and the shielding effect of bacterial numbers and ferric iron. The photoreactivation of T.ferrooxidans cells after irradiation by U-V light was also examined, Using unfiltered, visible light, there was an inhibitory effect on all three of the thiobacilli irrespective of the energy source being used. When selected wavelengths were studied it was seen that the blue end of the visible spectrum was most inhibitory. A relationship between ferric iron concentration and protection from visible light» was shown and the beneficial protective effect of particulate suspensions was demonstrated. afforded by ferric iron and cell numbers was assessed. Photoreactivation of U-V irradiated cells by exposure to visible light showed that this phenomenon occurred using wavelengths of visible light which, by themselves, were inhibitory. Some practical implication of these findings are offered.
    • PATHWAYS OF THE UTILIZATION OF INORGANIC SULPHUR COMPOUNDS IN THIOBACILLUS FERROOXIDANS

      Tuovinen, Olli H.; Department of General Microbiology, University of Helsinki, Malminkatu 20, SF-00100 Helsinki 10, Finland (1977-07)
      During growth on ferrous-iron Thiobactllus ferrooxidans assimilated sulphate into cellular material. Sulphate was rapidly bound by the cells and activated into adenosine 5'-sulphatophosphate prior to its reduction to sulphite and sulphide. The sulphate activation was mediated by the ATP-sulphurylase enzyme. The heterotrophic strain of 7. ferrooxidans assimilated sulphate via the same route. Sulphate was not assimilated by the bacteria during growth on thiosulphate. Adenosine 3'- phosphate 5'-sulphatophosphate was not formed and APS-kinase activity not detected in T. ferrooxtdans grown on ferrous-iron, thiosulphate or glucose. Thiosulphate oxidation was preceded by its cleavage to sulphide and sulphite and the outer S-atom of thiosulphate was also incorporated into cellular material. Tetrathionate was formed from thiosulphate by the thiosulphate-oxidizing enzyme but this pathway was not studied any further. The thiosulphate-oxidizing enzyme activity was not detected in iron-grown 7m. ferrooxtdans. Enzymes mediating the oxidation of thiosulphate linked to oxidative and substrate-level phosphorylation were present in 7. ferrooxtdans grown autotrophically on ferrous-iron or thiosulphate or heterotrophically on glucose.
    • CHALCOCITE OXIDATION BY CONCENTRATED CELL SUSPENSIONS OF THIOBACILLUS FERROOXIDANS

      Beck, Jay V.; Department of Microbiology, Brigham Young University Provo, Utah, USA (1977)
      Suspensions of intact cells of Thiobacillus ferrooxidans catalyze a rapid oxidation of finely ground chalcocite to covellite and soluble copper as shown in the following equation: 2Cu2S + 0» + 2HyS0, ————> 2CuS + 2CuS0, + 2Hy0 This reaction occurs spontaneously, but bacterial action increases the oxidation rate about 40 times. The oxidation reaction consumes protons thus causing an increased pH. Both spontaneous and biologically catalyzed oxidations cease when the pH reaches 4.6 - 4.7. In the presence of bacteria and under experimental conditions as described, a period of only about five hours is required to completely convert 0.3 gm of chalcocite to covellite with a 50% solubilization of the chalcocite copper.
    • EXPERIMENTS ON COMBINED ELECTRO AND BACTERIAL LEACHING (Short Communication)

      Tepper, K. P.; Näveke, R.; Lehrstuhl für Mikrobiologie, Technische Universitat Braunschweig Braunschweig, FRG (1977)
      The influence of direct current and of current with changing the poles two times per sec at intensities of 0,2...15 mA and at tensions of 12...170 Von leaching of pyrite dispersed in quartzite in percolators with Thiobacillus ferrooxidans was studied. The solution of iron was accelerated by bacteria without current and by current without bacteria, but in combination the acceleration did not exceed the sum of both single effects. The results suggest that there is no direct elec- trophysiological influence of current on bacteria under conditions of our experiments. At present we try to utilize indirect electrochemical effects of current on bacterial leaching of chalcopyrite.
    • STUDIES IN THE BACTERIAL LEACHING OF NICKEL ORES

      Bosecker, K.; Bundesanstalt für Geowissenschaften und Rohstoffe Hannover (1977)
      The applicability of bacterial leach technique in the extraction of nickel from naturally occurring nickel minerals and from sulfide and silicate nickel ores has been investigated. The nickel minerals gerstorffite, niccolite, and pentlandite could be leached with Thiobacillus thiooxidans whereas silicate nickel ores seemed to be inefficient to leaching with Thiobacillus. Within 100 days less than 1 % of the nickel was extracted from silicate ores. Sulfide nickel ores have been leached with Th. ferrooxidans and Th. thiooxidans. In air-lift-percolators within 100 days 17 % of the nickel were extracted using pure cultures of Th. thiooxidans, but only 5.6 % were recovered after leaching with Th. ferrooxidans. Within 30 days 38 %, 66 %,and 70 % of the nickel were extracted from ground material (Harzburger Gabbro) by submerged fermentation in shaking Erlenmeyer flasks adding pure cultures of Th. thiooxidans, Th. ferrooxidans and a mixed culture of both strains, respectively, to the culture medium.
    • UTILIZATION OF METAL BEARING INDUSTRIAL WASTE MATERIALS BY MICROBIOLOGICAL LEACHING

      Szolnoki, J.; Hungarian Academy of Sciences, Laboratory for Geochemical Research, Budapest, Hungary (1977)
      Chemoautotrophic sulphur-bacteria were isolated from mine drainage waters /Th. ferrooxidans/, which are able to oxidize the ferrous-iron into ferric-iron in biocatalytic way in a heavy acidic medium. These bacteria were adapted to high metal especially to high iron, aluminium and sodium concentrations. The ferric-sulphate produced by the bacterial oxidation is a strong leaching agent. The optimal parameters were determined under which the acidic ferric-sulphate bearing solution is favourable from the point of view of practical utilization. During the biological oxidation process a part of dissolved iron precipitated in form of ferric-hydroxide which is also utilizable material.
    • THE COMPOSITION, MORPHOLOGY AND ACTION UPON CHALCOPYRITE OF AUTOTROPHS RECOVERED FROM FUMAROLES

      Wyckoff, Ralph W. G.; Davidson, Franklin D.; Department of Physics, University of Arizona Tucson, Arizona, USA (1977)
      Studies have been made of the composition, morphology and ability to metabolize sulfides of certain autotrophic microorganisms collected from the neighborhood of fumaroles. Some are thermophilic and resemble the Sulfolobus described in the United States by Brock and the Brierleys. Others, living at lower temperatures, resemble but are in certain respects different from thiobacteria. They have been more effective than sulfur bacteria in attacking chalcopyrite and their reaction with this mineral is described. Attention is given to their pleomorphism and to their possibly primitive nature. Differences noted between strains from different localities emphasize the desirability of obtaining and testing samples from many sources, Our
    • INFLUENCE OF URANIUM EXTRACTANTS ON PYRITE OXIDATION ABILITY OF Thiobacillus ferrooxidans

      Torma, A. E.; Itzkovitch, I. J.; Department of Metallurgical and Materials Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA and Department of Metallurgy, Ontario Research Foundation, Mississauga, Ontario, Canada, L5K 1B3. (1977)
      Microbiological leaching as applied to uranium ores involves the metabolic oxidation by Thiobacillus ferrooxidans of associated pyrite to sulfuric acid and ferric sulfate. The sulfuric acid and ferric sulfate generated are effective leachants for common uranium minerals. Dissolved uranium can be recovered from the aqueous leach solutions by solvent extraction or ion exchange techniques. The present study explored the effects of potential solvent extraction reagents for uranium on pyrite oxidation ability of Thiobacillus ferrooxidans. For the solvents studied it was found that in all cases the dissolved organic matter decreased the pyrite oxidation activity of the bacteria, the surface tensionof the leach solutions and the oxygen saturation concentration. The following order of inhibition was established for the solvents and modifiers studied: aliquat 336 > nonyl phenol > kerosene 140 > alamine 310 > adogen 381 > di (2-ethylhexyl) phosphoric acid > adogen 365 > tri-n-butyl phosphate > ¥sodecanol > alamine 308 > alamine 336 > alamine 304. Suggestions to integrate solvent extraction and bacterial leaching for uranium by treating the recirculating raffinate are described.
    • METAL EXTRACTION FROM INDUSTRIAL WASTE WITH THIOBACILLI

      Ebner, H. G.; Universitat Dortmund, Technische Chemie B, Dortmund, FRG (1977)
      During the last two decades a lot of research has been carried out on microbiological leaching of low-grade ores. Since the UNCTAD conferences on raw materials have shown that besides the energy resources also the metallic resources of the world are limeted and what is even worse not renewable the idea of recycling has become more and more attractive. This means that waste raterials will have to be processed to regain valuable metals. Bacterial leaching of inorganic industrial waste or tailings can be regarded at least under two beneficial aspects: 1. toxic substances from the wastes will be removee thus the cost for their disposal can be lowered and the environment will be protected, 2. valuable metals can be gained from the wastes. This part is probably even more economic because of the rising prices for raw-materials in the near future.
    • BACTERIAL LEACHING OF A LOW-GRADE CHALCOPYRITE ORE WITH DIFFERENT LIXIVIANTS

      Ehrlich, Henry L.; Department of Biology, Rensselaer Polytechnic Institute Troy, NY 12181 (1977)
      A chalcopyrite-containing ore was shown to be able to retain measurable amounts of Cu2* ions from a 9 mM copper sulfate solution at pH values of 1.5 or above, which was percolated through it. The ore also exhibited significant buffering capacity when titrated with 0.01 N H,S0, or 0.01 N NaOH. Thiobacillus ferrooxidans strain Cu,S-2 accelerated leaching of the ore when using iron-free 1lixiviant at pH 1.5 or ferrous iron-containing lixiviant at pH 1.5. The total copper recovered in 20 weeks from inoculated percolation columns fed with ferrous lixiviant was the same as that recovered from inoculated columns fed with iron-free lixiviant, namely about 20% of the total copper in the ore, but the amount of copper recovered from uninoculated, sterile columns when using ferrous lixiviant was only about a third (3.2%) of that obtained with iron-free lixiviant fed to uninoculated, sterile columns in the same length of time (10.2%). When the ore was fed ferric lixiviant at pH 1.5, the bacteria exerted a strong retarding effect on the leaching process. In their absence, about 2.5 times as much copper (about 52% of the total copper in the ore) was recovered in 20 weeks than in their presence. The amount of copper recovered with bacteria in this case equalled approximately the amount recovered with bacteria using iron-free or ferrous ironcontaining lixiviants.
    • UN PROBLEME POSE PAR DES PALEOBACTERIES : LA CRISTALLISATION DE LA GALENE DES DEPOTS STRATIFORMES EST-ELLE MICROBIOLOGIOUE ?

      Devigne, Jean-Pierre; Laboratoire de Sédimentologie, Batiment 504 Université Paris-Sud, 91405 Orsay Cedex, France (1977)
      SEM study of divers rocks (sandstones, clays, marls, dolomites. etc...) mineralised by galena has resulted jn the discovery of fossil bacteria within the galena crystals. Two significant facts result trom these studies : the first concerns the clearly developped and exclusive association of galena and certain paleobacteria and their absence within surrounding sediment. Current studies confirm that this mutual attraction is not an exception; it is already established that certain species of aerobic, anaerobic, autotroohic and heterotrophic bacteria are not adversly affected by leadrich environments. Our research has enabled us to follow the absorption of this cation within individual germs of Sarcina flava. Certain results obtained in vitro suggest that this metal may be utilised by organisms during their microbio-synthetic activities prior to its rejection in the form of black, cryptocrystalline sulphur, PbS. and in other cases, either as carbonate, as an oxide, or an organo-metallic complex. The second significant fact concerns the imprisoning of paleobacteria within the galena crystals irrespective of their age and mmposition or environment of denosition? By varying the focus of the SEM it was possible to penetrate several microns jnto the crystals. Invariably, this has lead to the observation that the crystals of galena have envelopped a multitude of bacteria. The absence of all traces of physial imperfections (fractures, etc..) which could have facilited their postcrystallisation emplacement seems to indicate not only that the bacteria in question have lived in this environment and are themselves enriched in Pb but also that the cristallisation of the galena is an early 108 J.-P. Devigne diagenetic phenomena. These observations pose the following questions to which we have attempted to reply : should one consider this crystallisation as a simple chemical or physical reaction, or should we consider that the paleobacteria are the instigators of this process, at least during the initial phases of crystal germ formation ? In this latter case the imprisoning of the lead-associated paleomicrobes within the crystal structure is only the result of progressive crystal qrowth.
    • THE PRACTICAL ASPECTS OF LABORATORY LEACHING STUDIES

      Bruynesteyn, A.; Duncan, D. W.; B. C. Research 3650 Wesbrook Mall Vancouver, B. C., Canada V6S 2L2 Telex: 04-507748 (1977)
      To construct and operate leach dumps under optimum conditions, it is necessary to study the leaching characteristics of leach ores. Knowing how a particular Jeach ore will behave under commercial conditions will make it possible to design both the physical and operational parameters of a leach dump so that the ore will yield a maximum amount of metal in minimum time. The paper discusses a two phase investigation program consisting of a preliminary low cost investigation to determine a mineral's general amenability to the leaching process and a series of large column tests which can be used to provide the necessary practical data for commercial applications, examples of which are discussed.
    • THE LEACHING BEHAVIOUR OF VARIOUS ZINC SULPHIDE MINERALS WITH THREE THIOBACILLUS SPECIES

      Khalid, A. M.; Ralph, B. J.; School of Biological Technology, University of New South Wales, Kensington, New South Wales, Australia (1977)
      The availability of high-grade specimens of sphalerite, wurtzite and marmatite prompted a comparative study of the leaching rates of these minerals in the presence of Thiobacillus ferrooxidans, T. thiooxidans and T. thioparus. In this preliminary study, samples of the finely-ground minerals, of equivalent surface area, were subjected to attack by populations of equal magnitude of each of the three bacterial species in shake flasks at 30 C. The microorganisms were acclimatised to the particular substrates. The results indicate that (1) Wurtzite is much more slowly degraded than marmatite or sphalerite by all three organisms. (ii) Marmatite is leached more rapidly by T. ferrooxidans and T, thiooxidans than sphalerite, in both the presence and absence of soluble iron. (iii) Iron-free synthetic zinc sulphide is leached more rapidly by T. thiooxidans than by T. ferrooxidans or T. thioparus. The hexagonal crystalline structure of zinc sulphide in wurtzite appears to be more recalcitrant to microbial degradation than the cubical form of sphalerite, and the substitution of iron for some of the zinc in the marmatitic form of zinc sulphide appears to greatly facilitate biodegradation.
    • CHEMICAL AND MICROBIALLY-ASSISTED LEACHING OF ATHABASCA OIL SANDS COKE

      Zajic, J. E.; Jack, T. R.; Sullivan, E. A.; Faculty of Engineering Science The University of Western Ontario London, Ontario Canada (1977)
      The vast deposits of oil sands in the Province of Alberta Canada bear significant quantities of vanadium, nickel, titanium and iron in the bitumen component. During the production of oil from this bitumen, the metals are concentrated in the coke and coke ash refinery by-products. This study is concerned with the removal of metals, particularly vanadium, from the coke and coke ash obtained from different coking processes. The feasibility of marketable metal recovery by both chemical and microbially assisted leaching techniques has been assessed. Further the environmental impact of the solid waste disposal of untreated coke and coke ash has been evaluated by investigating the mechanism and extent of metal leaching under natural conditions and by investigating the toxicity of these "natural" leachates in a novel bioassay system. The study presents the data obtained in a critical evaluation of the leaching of metals from coke and coke ash in both economic and ecological contexts.
    • PILOT-PLANT BACTERIAL FILM OXIDATION (BACFOX PROCESS) OF RECYCLED ACIDIFIED URANIUM PLANT FERROUS SULPHATE LEACH SOLUTION

      Livesey-Goldblatt, E.; Tunley, T. H.; Nagy, I. F. (1977)
      Laboratory tests have established that a rapid oxidation of an acidified solution of ferrous sulphate to ferric can be achieved by passage of an air saturated solution over a film of Thiobacillus ferro-oxidans, Pilot-plant units of various types were constructed and operated to assess their oxidising efficiency using ferrous solutions ranging from 3,5 to 12 gram Fe II/litre and 3,1 to 10,5 gram H280,/litre. The best results were obtained with a plastic corrugated packing media to support the film of bacteria submerged in the iron sulphate solution thoroughly air saturated by forced aeration. The maximum specific rate of oxidation of Fe II to Fe III achieved was 7,5 gram per square metre of bacterial surface per hour.