The purple photosynthetic sulfur bacteria of genus Chromatium, isolated from lakes Yavorivske (Lviv region) and Sakske (AR Crimea)

Lake A is a meromictic, perennially ice-covered lake located at the northern limit of North America (latitude 83°N, Ellesmere Island, Canada). In early June 1999, only 0.45% of incident photosynthetically available radiation (PAR) was transmitted through its 2-m ice and 0.5-m snow cover. Removal of snow from 12 m2 increased PAR under the ice by a factor of 13 and biologically effective ultraviolet radiation (UVR) by a factor of 16 (from 0.4% to 6.3% of incident). The diffuse attenuation coefficient (Kd) for UVR was substantially lower in the ice than in the underlying freshwater (e.g., 50% lower at 320 nm), indicating the exclusion of chromophoric dissolved organic matter (CDOM) during freeze-up or the subsequent degradation of CDOM retained in the ice. Peak phytoplankton concentrations occurred immediately under the ice, and a broad maximum of photosynthetic sulfur bacteria and associated sulfur particles was observed over the depth interval 2045 m at <0.005% of incident PAR. Climate-induced changes in the overlying snow and ice have the potential to cause major habitat disruption (UV exposure, PAR, temperature, mixing regime) for these stratified, extreme-shade communities.

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Investigations on the photosynthetic sulfur bacterium Chlorobium phaeobacteroides causing seasonal blooms in Lake Kinneret

Canadian Journal of Microbiology ◽

10.1139/m79-154 ◽

1979 ◽

Vol 25 (9) ◽

pp. 999-1007 ◽

Cited By ~ 54

Author(s):

T. Bergstein ◽

Y. Henis ◽

B. Z. Cavari

Keyword(s):

Light Intensity ◽

Photosynthetic Activity ◽

Large Population ◽

Optimal Growth ◽

Growth Conditions ◽

Organic Substrate ◽

Lake Kinneret ◽

Sulfur Bacteria ◽

Chlorobium Phaeobacteroides ◽

Photosynthetic Sulfur Bacteria

Between May and December, the annual stratification period in Lake Kinneret, sulfide is formed and accumulates in the hypolimnion. In July–August a large population (up to 106 cells/mL) of green, photosynthetic, sulfur bacteria develops at the boundary of the oxidative and reductive zones of the water column lasting for 3–8 weeks. These bacteria were isolated from the lake and identified as Chlorobium phaeobacteroides. Optimal growth conditions included 160 mg S=L−1 and light intensities of 5–0 μEinstein (μE) m−2s−1. Glucose and acetate augmented growth when added to the mineral medium. The lowest light intensity which still supported growth was 0.3 μE m−2s−1 when acetate was present and 1.0 μE m−2s−1 when no organic substrate was present. Under complete darkness, either with or without organic substrate, the bacteria die. Photosynthetic activity was higher when no organic compound was added to the medium. Uptake of acetate was light-dependant.In the lake the photosynthetic activity of the bacteria is low because of the limited light intensity (0.3 μE m−2s−1) at the bloom layer. It is suggested that the appearance and the disappearance of the bloom are caused by the influence of the daily internal seiche.

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