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- Title
Growth of <italic>Leptospirillum ferriphilum</italic> in sulfur medium in co-culture with <italic>Acidithiobacillus caldus</italic>.
- Authors
Smith, Sarah L.; Johnson, D. Barrie
- Abstract
<italic>Leptospirillum ferriphilum</italic> and <italic>Acidithiobacillus caldus</italic> are both thermotolerant acidophilic bacteria that frequently co-exist in natural and man-made environments, such as biomining sites. Both are aerobic chemolithotrophs; <italic>L. ferriphilum</italic> is known only to use ferrous iron as electron donor, while <italic>A. caldus</italic> can use zero-valent and reduced sulfur, and also hydrogen, as electron donors. It has recently been demonstrated that <italic>A. caldus</italic> reduces ferric iron to ferrous when grown aerobically on sulfur. Experiments were carried out which demonstrated that this allowed <italic>L. ferriphilum</italic> to be sustained for protracted periods in media containing very little soluble iron, implying that dynamic cycling of iron occurred in aerobic mixed cultures of these two bacteria. In contrast, numbers of viable <italic>L. ferriphilum</italic> rapidly declined in mixed cultures that did not contain sulfur. Data also indicated that growth of <italic>A. caldus</italic> was partially inhibited in the presence of <italic>L. ferriphilum</italic>. This was shown to be due to greater sensitivity of the sulfur-oxidizer to ferric than to ferrous iron, and to highly positive redox potentials, which are characteristic of cultures containing <italic>Leptospirillum</italic> spp. The implications of these results in the microbial ecology of extremely acidic environments and in commercial bioprocessing applications are discussed.
- Subjects
ACIDITHIOBACILLUS caldus; ELECTRON donors; IRON ions; BACTERIAL cultures; BACTERIAL growth regulators
- Publication
Extremophiles, 2018, Vol 22, Issue 2, p327
- ISSN
1431-0651
- Publication type
Article
- DOI
10.1007/s00792-018-1001-3