Bacterial streamer growth in a disused pyrite mine

Hallberg

Hedrich

2014

Appl Environ Microbiol

127

135

A betaproteobacterium, shown by molecular techniques to have widespread global distribution in extremely acidic (pH 2 to 4) ferruginous mine waters and also to be a major component of "acid streamer" growths in mine-impacted water bodies, has proven to be recalcitrant to enrichment and isolation. A modified "overlay" solid medium was devised and used to isolate this bacterium from a number of mine water samples. The physiological and phylogenetic characteristics of a pure culture of an isolate from an abandoned copper mine ("Ferrovum myxofaciens" strain P3G) have been elucidated. "F. myxofaciens" is an extremely acidophilic, psychrotolerant obligate autotroph that appears to use only ferrous iron as an electron donor and oxygen as an electron acceptor. It appears to use the Calvin-Benson-Bassham pathway to fix CO 2 and is diazotrophic. It also produces copious amounts of extracellular polymeric materials that cause cells to attach to each other (and to form small streamer-like growth in vitro) and to different solid surfaces. "F. myxofaciens" can catalyze the oxidative dissolution of pyrite and, like many other acidophiles, is tolerant of many (cationic) transition metals. "F. myxofaciens" and related clone sequences form a monophyletic group within the Betaproteobacteria distantly related to classified orders, with genera of the family Nitrosomonadaceae (lithoautotrophic, ammonium-oxidizing neutrophiles) as the closest relatives. On the basis of the phylogenetic and phenotypic differences of "F. myxofaciens" and other Betaproteobacteria, a new family, "Ferrovaceae," and order, "Ferrovales," within the class Betaproteobacteria are proposed. "F. myxofaciens" is the first extreme acidophile to be described in the class Betaproteobacteria.

Section: Discussionmentioning

confidence: 99%

Uncovering a Microbial Enigma: Isolation and Characterization of the Streamer-Generating, Iron-Oxidizing, Acidophilic Bacterium “Ferrovum myxofaciens”

Hallberg

Hedrich

2014

Appl Environ Microbiol

127

135

“…Enrichment cultures for PR2 were prepared in 20 mmferrous sulphate medium, pH 2.0, using samples of coal leachate, incubated at 30 "C. The other three protozoa (PR3, PR4 and PR5) were isolated, as PR1, from Cae Coch mine. As described elsewhere (Johnson et al, 1979), the main microbiological features within this mine (a pyrite ore body that has been undisturbed for over 50 years) are the extensive growths (> 100 m3) of 'acid streamers' in its main drainage stream and on moist rock faces. In some areas, acid streamers, comprising a mixed population of acidophilic bacteria, contain protozoa which may be observed actively grazing the streamer bacteria.…”

Section: Methodsmentioning

confidence: 99%

Effects of acidophilic protozoa on populations of metal-mobilizing bacteria during the leaching of pyritic coal

Journal of General Microbiology

Rang

1993

Five acidophilic protozoa (three flagellates, one ciliate and one amoeba) were isolated from acid mine water and a coal biotreatment plant, and grown in mixed cultures with acidophilic bacteria. Cultures were routinely maintained in ferrous sulphate media: in media containing pyrite or pyritic coal, protozoa grew in cultures containing coarse-grain (61-200 pm) but not fine-grain (c 61 pm) minerals. In cultures of pyritic coal, protozoa grazed iron-oxidizing and heterotrophic bacteria, but to varying extents. One of the flagellates appeared only transiently in coal leachates, whilst the four others persisted through the 100 d incubation. A reduction of numbers of unattached iron-oxidizing acidophiles, due to protozoan grazing, did not always result in lower rates of pyrite oxidation. The presence of protozoa was noted to effect changes in acidophilic populations, in particular often causing Leptospirihm ferrooxidans to become the dominant iron-oxidizer at an earlier stage than in corresponding protozoa-free controls.

“…The oxidation of pyrite and other sulfidic minerals by acidophilic chemolithoOffprint requests to: Dr. D. B. Johnson. trophs produces AMD, which, besides having a low pH, also contains elevated concentrations of sulfate, iron (ferrous and ferric), and other heavy metals, dependent on the geochemical nature of the material being oxidized (e.g., [9]). More recently, it has been recognized that obligately acidophilic heterotrophic bacteria are also active in AMD [4]; many of these, such as Acidiphilium cryptum, are oligotrophic and may utilize, for example, the small amounts of soluble organic compounds leaked by actively growing chemolithotrophs such as T. ferrooxidans.…”

Section: Introductionmentioning

confidence: 99%

Grazing of acidophilic bacteria by a flagellated protozoan

McGinness

1992

Microb Ecol

A biflagellated protozoan was isolated from an acidic drainage stream located inside a disused pyrite mine. The stream contained copious amounts of "acid streamer" bacterial growths, and the flagellate was observed in situ apparently grazing the streamer bacteria. The protozoan was obligately acidophilic, growing between pH 1.8 and 4.5, but not at pH 1.6 or 5.0, with optimum growth between pH 3 and 4. It was highly sensitive to copper, molybdenum, silver, and uranium, but tolerated ferrous and ferric iron up to 50 and 25 mM, respectively. In the laboratory, the protozoan was found to graze a range of acidophilic bacteria, including the chemolithotrophs Thiobacillus ferrooxidans, Leptospirillum ferrooxidans, and the heterotroph Acidiphilium cryptum. Thiobacillus thiooxidans and Thiobacillus acidophilus were not grazed. Filamentous growth of certain acidophiles afforded some protection against being grazed by the flagellate. In mixed cultures of T. ferrooxidans and L. ferrooxidans, the protozoan isolate displayed preferential grazing of the former. The possibility of using acidophilic protozoa as a means of controlling bacteria responsible for the production of acid mine drainage is discussed.