Genus VI Lamprocystis Schroeter 1886 151AL Johannes F Imhoff

Lam'pro.cys'tis. Gr. adj. lampros bright, brilliant; Gr. n. cystis the bladder, abag; M.L. fem. n. Lamprocystis brilliant bag.

Cells spherical to ovoid, 1.9-3.8 |im in diameter, diplococcus-shaped before cell division and may occur in irregular aggregates, multiply by binary fission, nonmotile or motile by means of a single flagellum, form gas vesicles in central part. Gram negative and belong to the Gammaproteobacteria. At high sulfide concentration (4-6 mM) and light intensity (1000-2000 lux), cells may grow as long, branching cell aggregates embedded in slime. Under favorable growth conditions, cell aggregates may break up into smaller clusters and spheroidal microcolonies, which become motile by flagella; finally, individual motile cells are liberated. Internal photosynthetic membranes are of vesicular type and contain the photosynthetic pigments bacteriochlorophyll a and carotenoids.

Photolithoautotrophic growth under anoxic conditions in the light with reduced sulfur compounds such as sulfide and S0 as electron donors. During oxidation of sulfide, S0 is transiently stored in the peripheral part of the cells that is free of gas vesicles. Final oxidation product is sulfate. In the presence of sulfide and bicarbonate, simple organic substrates are photoassimilated. Ob-ligately phototrophic or facultatively chemotrophic under mi-crooxic to oxic conditions in the dark.

Type species: Lamprocystis roseopersicina (Kiitzing 1849) Schroeter 1886,151 (Protococcus roseopersicinus Kiitzing 1849,196.)

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