A. thiooxidans is a Gram-negative, rod-shaped bacterium with rounded ends that occurs in nature either as singlecells, as is the most common case, or sometimes in pairs, but rarely in triplets.
[2] Anything with the tendency to change the medium to an alkaline state would be considered harmful to the uniform growth of A. thiooxidans, but if it is left unharmed by an excess of acid or alkali, numerous consecutive generations may be kept alive on the liquid media.
[2] A general lack of knowledge exists for acidophilic microorganisms in terms of the oxidation systems of reduced inorganic sulfur compounds (RISCs).
[3] Fazzini et al.. (2013) presented the first experimentally validated stoichiometric model that was able to quantitatively assess the RISCs oxidation in A. thiooxidans (strain DSM 17318), the sulfur-oxidizing acidophilic chemolithotrophic archetype.
[2] Bicarbonate, however, is unnecessary because the CO2 from the atmosphere appears to be sufficient to support growth of A. thiooxidans, and would actually have an injurious effect in that it would tend to make the medium less acidic.
[2] In addition to sulfur, A. thiooxidans can use thiosulfate or tetrathionate as sources of energy, but growth in a liquid medium on thiosulfate is slow, generally taking about 10 to 12 days under favorable conditions as opposed to only 4 to 5 days for growth on elemental sulfur, as demonstrated by the change in pH and turbidity.
[2] Because A. thiooxidans derives its energy from inorganic elemental sulfur, carbon directly from the atmosphere, and nitrogen from ammonium sulfate and other inorganic salts, and also because of its small mineral requirements, this autotrophic microorganism was likely among the first aerobes contributing to weathering through the formation of sulfuric acid, which interacted with insoluble phosphates, carbonates, and silicates.
The complete draft genome sequence of A. thiooxidans ATCC 19377 was determined using a whole-genome shotgun strategy and was revealed to contain a total of 3,019,868 base pairs in 164 contigs.
[4] Acidithiobacillus thiooxidans strains have been differentiated from other related Acidithiobacilli, including A. ferrooxidans and A. caldus, by sequence analyses of the PCR-amplified 16S-23S rDNA intergenic spacer (ITS) and restriction fragment length polymorphism (RFLP).
[5] Bergamo et al.. (2004) concluded that the 16S-23S rDNA spacer region is a useful target for developing molecular methods that focus on the detection, rapid differentiation and identification of Acidithiobacillus species.
[6] Microcrystalline gypsum precipitates as a corrosion residue that eventually limits pH buffering by the underlying limestone and enables the development of extremely acidic wall surfaces.
[6] Snottite formations are generally milky in color, suspended vertically from cave ceilings and walls, and have a phlegm-like consistency (hence the name).
Compared to traditional smelting and extracting procedures, bioleaching is much less expensive and does not release as many environmental toxicants, but it does require a greater amount of time.
Bioleaching involves at least three important subprocesses, viz., attack of the sulfide mineral, microbial oxidation of ferrous iron, and some sulfur moiety.