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Effect of Potassium Cyanide

bacteria, luminous, light, dried and sea-water

EFFECT OF POTASSIUM CYANIDE..

As is the case with other luminous forms, KCN has a surprisingly small effect on the light-production of luminous bacteria as compared with its effect in supressing certain oxidations of many animals. The results are expressed in table 19.

In m/40 KCN the light disappears in 6 minutes, and if the solution is now diluted with sea-water the light returns. The effect is there fore an inhibition and reversible.

Summary OF RESULTS FROM LUMINOUS BACTERIA.

1. Luminous bacteria which have been rapidly dried over calcium chloride in a vacuum will phosphoresce if moistened with oxygen-free water. Drying does not kill all bacteria, but does kill most of them. Hence phosphorescence does not depend on the living cell.

2. Dried bacteria, if finely ground with sand, will no longer phos phoresce when moistened. None of the ground bacteria can grow. Phosphorescence does depend upon the integrity of some structure in the cell.

3. Dried bacteria extracted with ether or toluol will still phosphoresce if moistened and may develop colonies on a suitable culture medium. Consequently neither ether nor toluol destroy the photogen.

Bacteria in oxygenated sea-water to which ether or toluol is added stop phosphorescing, presumably because the photogenic substance is rapidly oxidized and used up when the bacterial cell is cytolyzed.

Bacteria in oxygen-free sea-water do not glow, but will glow if oxygen is admitted, even after a period of 24 hours. Bacteria in oxygen-free sea-water to which toluol or ether is added will not glow if oxygen is readmitted after 15 minutes. Hence the phosphorescent substance undergoes decomposition in the absence of oxygen, a decomposition not due to the toluol (compare the first statement in section 3), but probably due to the action of some other substance.

4. Moist luminous bacteria to which oxygenated distilled water is added cease glowing, presumably because the photogen is rapidly oxidized and used up when the bacterial cell is cytolyzed.

Moist bacteria to which oxygen-free distilled water is added will not glow even momentarily if oxygen be readmitted after 15 minutes, a result again pointing to instability of the photogen when the cell structure is affected by cytolysis.

5. Dried bacteria placed in oxygenated sea-water phosphoresce momentarily, but if dried bacteria stand in contact with oxygen-free seawater for 15 minutes, no phosphorescence occurs when the oxygen is admitted. Again (as in sections 3 and 4) the photogen has decom posed. It is, therefore, impossible to extract a phosphorescent sub stance from bacteria with oxygen-free aqueous solvents.

6. Fat solvents extract nothing which will phosphoresce from the dried bacteria. Some of the bacteria survive and will grow after such extraction. Boiling alcohol, cold acetone, and ethyl butyrate destroy the power to phosphoresce.

7. Dried bacteria do not lose their power to phosphoresce after 24 hours' extraction with cold absolute alcohol, but moist bacteria (centri fuged) treated with 50 volumes of absolute alcohol, and then dried rapidly, will not again phosphoresce if moistened.

8. All attempts to separate the photogenic substance of luminous bacteria into photogenin and photophelein have failed, due possibly to the small amounts of these substances present at any one time.

9. A photophelein can be prepared by absolute alcohol which will give a faint light with firefly photogenin, but attempts to obtain light with firefly photophelein and bacterial photogenin prepared in various ways have failed.

10. The upper temperature-limit for luminescence is 38°; the lower is —11.5°. Bacteria heated to 38° and cooled give only a faint light, but bacteria will glow strongly if first cooled to liquid-air temperature and then raised to room temperature.

11. Oxidases for guaiac, a-napthol, para-phenylen diamine, phenol, phenolphthalin, pyrogallol, or indo-phenol formers, if present, are present in an endoenzyme condition. Catalase exists in luminous bacteria.

12. Luminous bacteria can not live if the osmotic pressure of the medium fall below a certain value or if the salt-content of the medium fall below a certain value.

13. Luminous bacteria will live for over 24 hours in pure m/2 NaCI or any sea-water salt mixtures containing both monovalent and divalent cations. They will live for over an hour in m/2 KCI, but the light disappears instantly in m/3 or m/3 14. Luminous bacteria will just live for slightly over an hour in n/8,000 HCI, n/4,000 valerianic acid, and will live for over 24 hours in n/1000 NaOH and n/500 methyl amine. The best light is given on the alkaline side of neutrality, about the alkalinity of sea-water.

15. The homologous aliphatic monohydric alcohols produce true reversible inhibition or anesthesia of light-production. The concen trations which inhibit light-production in 10 minutes are: methyl alcohol, 2 m; ethyl, m; propyl, 0.25 m; isobutyl, 0.08 m; amyl, 0.025 m; capryl or octyl, 0.002 m.

16. KCN has very little effect on light-production. The light is only slightly affected in m/320 concentration in one hour.