Title

Community genomic analysis of an extremely acidophilic sulfur-oxidizing biofilm

Files

Link to Full Text

Download Full Text

Publication Date

January 2012

Abstract

Highly acidic (pH 0–1) biofilms, known as ‘snottites’, form on the walls and ceilings of hydrogen sulfide-rich caves. We investigated the population structure, physiology and biogeochemistry of these biofilms using metagenomics, rRNA methods and lipid geochemistry. Snottites from the Frasassi cave system (Italy) are dominated (>70% of cells) by Acidithiobacillus thiooxidans, with smaller populations including an archaeon in the uncultivated ‘G-plasma’ clade of Thermoplasmatales (>15%) and a bacterium in the Acidimicrobiaceae family (>5%). Based on metagenomic evidence, the Acidithiobacillus population is autotrophic (ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), carboxysomes) and oxidizes sulfur by the sulfide–quinone reductase and sox pathways. No reads matching nitrogen fixation genes were detected in the metagenome, whereas multiple matches to nitrogen assimilation functions are present, consistent with geochemical evidence, that fixed nitrogen is available in the snottite environment to support autotrophic growth. Evidence for adaptations to extreme acidity include Acidithiobacillus sequences for cation transporters and hopanoid synthesis, and direct measurements of hopanoid membrane lipids. Based on combined metagenomic, molecular and geochemical evidence, we suggest that Acidithiobacillus is the snottite architect and main primary producer, and that snottite morphology and distributions in the cave environment are directly related to the supply of C, N and energy substrates from the cave atmosphere.

Notes

The ISME Journal, Vol. 6 (2012).

Keywords

Acidimicrobium, Acidophile, Acidithiobacillus, Metagenomics, Pyrosequencing, Thermoplasmatales

Description

RDA

Subject: topical

Acidimicrobium; Acidophile; Acidithiobacillus; Metagenomics; Pyrosequencing; Thermoplasmatales

Type

Article

Genre

serial

Identifier

SFS0072804_00001

Share

COinS