The Possible Photosynthetic Use of Sulfide by the Filamentous Phototrophic Bacteria of Hot Springs1

Abstract

Filamentousgliding bacteria containing bacteriochlorophylls a and c occur abundantly in hot springs of alkaline pH and usually arc in direct contact with blue-green photoautotrophs even though the bacteria may have a higher growth temperature limit. In contrast, hot springs with at least 0.2 mg liter-l of soluble sulfide in water of 60-70°C support orange to green mats of these bacteria upstream from and independent of the presumed organic donation of the blue-green algae. In these cases sulfide seemed the only plausible source of rcductant in phototrophism and CO, the only likely carbon source. In the field an d in culture, the stimulatory effect of sulfide on COz photoincorporation was only a small ( 1.2-3.4-fold) increase over the nonsulfide rate. Anaerobic illuminated cultures showed an increase in dry weight and pigment in basal autotrophic medium only when sulfide was added. However, small amounts of yeast extract resulted in far greater yields. The combined observations and results suggest that photoautotrophy, with sulfide as electron donor, is a possible alternative to photoheterotrophy in this newly discovered group of phototrophic bacteria.

Cyanobacteria of the thermal spring at Pancharevo, Sofia, Bulgaria

“…4) were dominated by Lyngbya thermalis and Phormidesmis molle. The data concur with CASTENHOLZ (1969CASTENHOLZ ( , 1973, who stressed that dramatic changes of temperature occurred along the gradient from the mouth of the spring, with concomitant changes in species composition.…”

Winter Planktonic Microbial Communities in Highland Aquatic Habitats

“…From representative depths, chlorophyll a (Chl a) concentration was determined spectrophotometrically after hot methanol extraction using the absorption coefficients determined by Wellburn (1994). In Lake Ursu, bacteriochlorophyll a (Bchl a) and c (Bchl c) were also determined at different depths according to Biel (1986) and Castenholz (1973), respectively. In vivo absorption spectra of the phototrophic communities were also recorded according to Castenholz et al (1973).…”

Compound-Specific Isotopic Fractionation Patterns Suggest Different Carbon Metabolisms among Chloroflexus -Like Bacteria in Hot-Spring Microbial Mats

“…(3,4,5,12,23,47). C. aurantiacus, the most studied representative of the green nonsulfur bacteria available in pure cultures, can grow heterotrophically by aerobic respiration, photoheterotrophically (using light to incorporate prereduced organic compounds), and photoautotrophically (using light to fix inorganic carbon) (26).…”