Removal of hydrogen sulfide by immobilized Thiobacillus thioparus in a biotrickling filter packed with polyurethane foam.

In the work described here, a biotrickling filter with Thiobacillus thioparus (ATCC 23645) immobilized on polyurethane foam is proposed for the removal of hydrogen sulfide contained in air. The effect of surface velocity of the recirculation medium (5.9-1.2 m/h), sulfate concentration inhibition (3.0-10.7 g/L), pH (6.0-8.2), empty bed residence time (EBRT) (150-11 s) for constant loads of 11.5 and 2.9 g S/m(3)/h, and pressure drop of the system were investigated. The total amount of biomass immobilized on the carrier was 8.2+/-1.3x10(10) cells/g. The optimal values of the operating variables were: pH between 7.0 and 7.5, surface velocity of 5.9 m/h and sulfate concentration below 5 g/L. The critical EC value was 14.9 g S/m(3)/h (removal efficiency of 99.8%) and the EC(max) was 55.0 g S/m(3)/h (removal efficiency of 79.8%) for an EBRT of 150 s. For loads of 2.89+/-0.05 and 11.5+/-0.1 g S/m(3)/h, the removal efficiency was higher than 99% for an EBRT over 90 s.

[Thiobacillus sajanensis sp. nov., a new obligately autotrophic sulfur-oxidizing bacterium isolated from Khoito-Gol hydrogen-sulfide springs, Buryatia].

Four strains of rod-shaped gram-negative sulfur-oxidizing bacteria were isolated from Khoito-Gol hydrogen-sulfide springs in the eastern Sayan Mountains (Buryatia). The cells of the new isolates were motile by means of a single polar flagellum. The strains were obligately chemolithoautotrophic aerobes that oxidized thiosulfate (with the production of sulfur and sulfates) and hydrogen sulfide. They grew in a pH range of 6.8-9.5, with an optimum at pH 9.3 and in a temperature range of 5-39 degrees C, with an optimum at 28-32 degrees C. The cells contained ubiquinone Q-8. The DNA G+C content of the new strains was 62.3-64.2 mol %. According to the results of analysis of their 16S rRNA genes, the isolates belong to the genus Thiobacillus within the subclass Betaproteobacteria. However, the similarity level of nucleotide sequences of the 16S rRNA genes was insufficient to assign the isolates to known species of this genus. The affiliation to the genus Thiobacillus was confirmed by DNA-DNA hybridization of the isolates with the type strain of the type species of the genus Thiobacillus, T. thioparus DSM 505T (= ATCC 8158T). Despite the phenotypic similarity, the hybridization level was as low as 21-29%. In addition, considerable differences were revealed in the structure of the genes encoding RuBPC, the key enzyme of autotrophic CO2 assimilation, between the known Thiobacillus species and the new isolates. Based on molecular-biological features and certain phenotypic distinctions, the new isolates were assigned to a new Thiobacillus species, T. sajanensis sp. nov., with the type strain 4HGT (= VKM B-2365T).

Modeling and analysis of biooxidation of gold bearing pyrite-arsenopyrite concentrates by Thiobacillus ferrooxidans.

The results of modeling the biooxidation of a mixed sulfidic concentrate by Thiobacillus ferrooxidans is reported here. A kinetic model, which accounts for the dissolution of sulfide matrix due to both bacterial attachment onto the mineral surface and indirect leaching, has been proposed. A comprehensive system approach is employed for modeling the complex biooxidation process by (a) the decomposition of the complete system into several subsystems, (b) modeling individual systems, and (c) integrating the subsystems model in a final system model. The model for subsystems was developed by writing mass balance equations for the different species involved. The bacterial balance accounts for its growth, both on solid substrate and in solution, and for the attachment to and detachment from the surface. The kinetic parameters of the model were determined by designing the experiments in such a manner that only one subsystem was operational. This model was tested in both laboratory scale batch and continuous biooxidation processes. The model predictions agreed with the experimental data reasonably well. A further analysis of the model was carried out to predict the conditions for efficient biooxidation. Studies on the effect of residence time and pulp density on steady-state behavior showed that there is a critical residence time and pulp density below which washout conditions occur. Operation at pulp densities lower than 5% and residence times lower than 72 h was found unfavorable for efficient leaching.

Ferrous sulphate oxidation using Thiobacillus ferrooxidans cells immobilised on sand for the purpose of treating acid mine-drainage.

Thiobacillus ferrooxidans was immobilised on sand (size 0.85 mm to 1.18 mm) for use in a repeated batch and continuously operated packed-bed bioreactor which has not been previously reported in the literature. Repeated batch operation resulted in the complete oxidation of ferrous to ferric iron. The bacteria were active immediately after 3-4 weeks in a non-aqueous medium; i.e. the sand was allowed to dry out, demonstrating the stability of the system. A lag phase of 28 days was recorded when the sand was stored dried in a sealed container for 16 weeks compared with a lag phase of 13 days for a sample frozen for 18 weeks. After a period of 10 days, continuous operation of the reactor at a dilution rate of 0.64 h(-1) resulted in 95-99% oxidation of ferrous iron or 0.31-0.33 kg m(-3) h(-1). With the use of a scanning electron microscope, images were recorded of Thiobacillus ferrooxidans on sand.

Purification and some properties of ubiquinol oxidase from obligately chemolithotrophic iron-oxidizing bacterium, Thiobacillus ferrooxidans NASF-1.

Ubiquinol-oxidizing activity was detected in an acidophilic chemolithotrophic iron-oxidizing bacterium, T. ferrooxidans. The ubiquinol oxidase was purified 79-fold from plasma membranes of T. ferrooxidans NASF-1 cells. The purified oxidase is composed of two polypeptides with apparent molecular masses of 32,600 and 50,100 Da, as measured by gel electrophoresis in the presence of sodium dodecyl sulfate. The absorption spectrum of the reduced enzyme at room temperature showed big peaks at 530 and 563, and a small broad peak at 635 nm, indicating the involvement of cytochromes b and d. Characteristic peaks of cytochromes a and c were not observed in the spectrum at around 600 and 550 nm, respectively. This enzyme combined with CO, and its CO-reduced minus reduced difference spectrum showed peaks at 409 nm and 563 nm and a trough at 431 nm. These results indicated that the oxidase contained cytochrome b, but the involvement of cytochrome d was not clear. The enzyme catalyzed the oxidations of ubiquinol-2 and reduced N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride. The ubiquinol oxidase activity was activated by the addition of albumin and lecithin to the reaction mixture and inhibited by the respiratory inhibitors KCN, HQNO, NaN3, and antimycin A1, although the enzyme was relatively resistant to KCN, and the divalent cation, Zn2+, compared with ubiquinol oxidases of E. coli.

Reclassification of some species of Thiobacillus to the newly designated genera Acidithiobacillus gen. nov., Halothiobacillus gen. nov. and Thermithiobacillus gen. nov.

The species of the genus 'Thiobacillus' fall into the alpha-, beta- and gamma-subclasses of the Proteobacteria, the type species Thiobacillus thioparus being located in the beta-subclass. 'Thiobacillus' species exhibit almost as much diversity in DNA composition and physiology as is found collectively in all other proteobacterial groups. On the basis of physiological characters and 16S rRNA gene sequence comparisons, eight of the existing Thiobacillus species are proposed for reassignment to three newly designated genera within the gamma-subclass of the Proteobacteria, namely Acidithiobacillus, Halothiobacillus and Thermithiobacillus.

Colonial heterogeneity of Thiobacillus versutus.

In acetate-limited chemostat cultures started with single-colony cultures of Thiobacillus versutus, a mutant appeared after approximately 85 volume changes. The inhomogeneity of the culture was detected by the development of two different types of colonies on agar plates. When a pure culture of the mutant was grown in a chemostat, parent colonies appeared after almost the same period of time. Electron micrographs of the mutant grown on butyrate showed the presence of fibrils surrounding the cells. The cells of the parent strain were bald when grown under the same conditions. The growth kinetics of the parent and the mutant were investigated in batch cultures with a variety of substrates and were found to be identical. Major differences between the two strains were observed during growth on mannitol; the mutant attained a lower yield and excreted large amounts of extracellular polysaccharides.

[Morphogenetic features of Sulfobacillus thermosulfidooxidans]. / Osobennosti morfogeneza Sulfobacillus thermosulfidooxidans.

The morphogenesis of Sulfobacillus thermosulfidooxidans BKM B-1269 was studied by electron microscopy at the vegetative stage of growth on a medium with pyrite as the source of energy. Young growing cultures of this organism were found to be very polymorphous: along with rod-like cells of various dimensions (0.6--0.8x1.0--3.0 mcm) which were predominant, coccoid, pyriform, clavate and dumbbell-like cells were also encountered. Certain cells have a tendency for branching. The cells can divide by sudden breaking of the parent cell along a partition being formed. These breaks are often incomplete, thus giving rise to cellular aggregates in the shape of palisades, bent chains, rings and Y-formations. The above characteristics of S. thermosulfidooxidans morphogenesis suggest that the genus Sulfobacillus is related to Corynebacterium-like organisms and actinomycetes. However, this genus differs in its morphology from bacilli though both (as well as actinomycetes) are capable of spore formation.

Electron microscopy of the carboxysomes (polyhedral bodies) of Thiobacillus neapolitanus.

The carboxysomes of Thiobacillus neapolitanus are shown, by electron microscopy, to consist of a paracrystalline array of 10-nm particles surrounded by a "membrane." The 10-nm particles have a center hole or depression and have been previously identified as ribulose diphosphate carboxylase. The membrane is a monolayer approximately 3.5-nm thick.

Electron transport-linked compared with proton-induced ATP generation in Thiobacillus novellus.

The apparently soluble electron-transport system, that does not sediment when centrifuged at 144,000 x g or 300,000 x g for 3 hr, catalyzes oxidative phosphorylation with an efficiency comparable to that of an intact mitochondrial system. While the proton-induced phosphorylation occurs in whole cells, crude cell-free extracts, and supernatants from low-speed centrifugation, it does not occur in either the 144,000 or 300,000 x g supernatant fractions. The data show that oxidative energy can be conserved as ATP under conditions that are incompatible with the basic postulate of the chemiosmotic hypothesis.

Functional organelles in prokaryotes: polyhedral inclusions (carboxysomes) of Thiobacillus neapolitanus.

The polyhedral inclusions of Thiobacillus neapolitanus have been isolated; they contain ribulose diphosphate carboxylase.

Cell envelope of an iron-oxidizing bacterium: studies of lipopolysaccharide and peptidoglycan.

Further structural detail is presented of the cell envelope of the chemolithotroph Ferrobacillus ferrooxidans (Thiobacillus ferrooxidans). Thin sections of purified lipopolysaccharide (LPS) and peptidoglycan show structures comparable to those seen in the envelope of intact cells, whereas negative stains of LPS appear as sheets, or ribbons, or both. The sugars common to LPS, namely, heptose, glucose, galactose, mannose, and 2-keto-3-deoxyoctulosonate, were identified. The cations, iron, calcium, and magnesium, were associated with LPS. The purified LPS had a density of 1.28 and an uncorrected sedimentation coefficient of 99.9S.