Page:Bergey's manual of determinative bacteriology.djvu/66

 when free are motile by means of polar fiagella. In pure culture also this type rarely, if ever, produces large aggregates with the development here mentioned as characteristic for the genus (Bavendamm, Die farblosen und roten Schwefelbakterien, Pflanzenforschung, Heft 2, 1924, 76). This, along with the other similarities, makes it doubtful whether future studies will result in the retention of the genera Lamprocystis and Thiocystis side by side. Produce bacteriochlorophyll and carotenoid pigments, coloring the cell masses purplish pink to red. Capable of photosynthesis in the presence of hydrogen sulfide, storing elemental sulfur as globules inside the cells.

The type species is Lamprocystis roseopersicina (Kützing) Schroeter.

1. Lamprocystis roseopersicina (Kützing, 1849) Schroeter, 1886. (Protococcus roseopersicinus Kützing, Species Algarum, Leipzig, 1849, 196; Schroeter, in Cohn, Kryptogamen-Flora von Schlesien, 3, 1, 1886, 151.)

ro.se.o.per.si.ci′na. L. adj. roseus rosy; Gr. noun persicus the peach (Persian apple); M.L. adj. roseopersicinus rosy peach (-colored).

Cells spherical to ovoid, 2 to 2.5 microns in diameter, up to 5 microns long before cell division. Motile by means of polar flagella.

Winogradsky reports that the cells frequently contain pseudovacuoles.

Habitat: Mud and stagnant water containing hydrogen sulfide and exposed to light; sulfur springs.

Illustrations: Warming, Videnskab. Meddel. naturhistor. Foren., Kjöbenhavn, 1876, Pl. VIII, fig. 3 g; Zopf, Z. Morphol. d. Spaltpflanzen, Leipzig, 1882, Pl. V, fig. 8, 13; Winogradsky, Schwefelbacterien, Leipzig, 1888, Pl. II, fig. 9-15; Bavendamm, Die farblosen und roten Schwefelbakterien, Jena, 1924, Pl. II, fig. 3.

A.moe.bo.bac′ter. M.L. noun Amoeba a protozoan genus; Gr. noun amoebe change, transformation; M.L. noun bacter a rod; M.L. mas.n. Amoebobacter changeable rod.

Sulfur purple bacteria, usually occurring in aggregates composed of many individuals without a characteristic common capsule. Slime formation can, nevertheless, be observed with very small colonies. With growth of the individual cells, the capsule bursts and the cell mass slowly moves out while the bacteria remain united. The colonies change their shape during growth and in response to environmental influences; the individual cells appear motile and cause the movements of the entire colony. Winogradsky ascribes the coherence of the cell masses to the existence of interconnecting protoplasmic filaments between cells, but these have never been observed, and their occurrence is extremely doubtful. It is much more probable that the bacteria are held together by mucus, though not so much of the latter is produced as to form a clearly discernible capsule. Produce bacteriochlorophyll and carotenoid pigments. Capable of photosynthesis in the presence of hydrogen sulfide, then storing sulfur as droplets inside the cells.

The type species is Amoebobacter roseus Winogradsky.

The characterizations of the genera Amoebobacter, Lamprocystis, Thiocystis, Thiocapsa and Thiothece are based upon the arrangement of individual bacteria in a common capsule. However, from Winogradsky's descriptions of Amoebobacter and from pure-culture studies with Thiocystis and Lamprocystis, the capsules have been shown to vary considerably, depending upon developmental stages and environmental conditions. Therefore it is quite possible that future investigations will show the desirability of restricting the number of genera.

I. Cells spherical to ovoid, abut 2.5 to 3.5 microns in diameter and up to 6 microns in length prior to cell division.