In Situ Biomass Production of a Hot Spring Sulfur-Turf Microbial Mat

Sulfur-turf microbial mats develop in sulfide-containing hot spring water dominated by chemolithoautotrophic sulfur-oxidizing bacteria. The sulfur-turf mat that developed at a source of hot water (72°C, pH 6.8) exhibited a growth rate of 0.48±0.04 h−1 and biomass production of 4.6±1.0 mg of C h−1. On a per-cell basis, this biomass production was at least an order of magnitude higher than the CO2 uptake rate calculated for a photosynthetic mat dominated by thermophilic Synechococcus spp. at 70°C. The sulfur-turf-associated microbial community likely contributes to carbon fixation and primary production in this geothermal habitat.