Surface Slime Research Articles

海洋細菌に及ぼす銅の影響-II

In the previous paper, the author reported on the depressing effect of copper sulfate upon the development of marine bacterial community, and then he described the existence of the bacteria tolerated fairly well against copper. The present report gives a preliminary survey on the occurrence and distribution of the specific “copper bacteria” that have a difinite affinity for copper in the sea water. The results of the investigation are summerized as follows: (1) The specific “copper bacteria” that develop as the red-brown colonies on the WAKSMAN's copper medium, are detected always in the sea water and in the surface slime films on glass slides submerged in the sea at Aburatsubo Bay. General characteristics of the bacteria are the same as WAKSMAN's observation (1943). (2) The amounts of “copper bacteria” vary with the fluctuation of total bacterial population in sea water (Fig. 1). And the vertical distribution of the “copper bacteria” is not same in the depths or seasons (Table. 1). (3) When the glass slides are submerged in the sea for abont two weeks, so many “copper bacteria” are frequently detected in the slime films attached on the glass slides (Table. 2). (4) The relative amounts of “copper bacteria” in the sea are different from place to place: in general, they seem to distribute widely in the sea water of the oceanic region, while they scarcely distribute in the sea wafer of the coastal region where the land drainages or river stresms affect strongly (Table. 3, 4).

Vertical Distribution of Bacteria in Marine Sediments

Off the coast of Southern California bacteria are more abundant in marine sediments than in the overlying water, there being thousands to millions per gram of sediment and only a few hundred or less per milliliter of water. The distribution of bacteria in the sediment is more or less independent of the depth of the overlying water, the temperature of the ocean floor, and the distance from mainland. The bacterial population seems to be influenced more greatly by the organic content of the sediments than by other factors. Vertical sections from cores 40 to 75 cm. in length show that the number of bacteria in the sediments decreases greatly with depth in the upper 5 cm. of the core and more slowly beyond. In the surface slime, aerobes are 5 to 100 times more plentiful than a aerobes, but at depths exceeding 15 centimeters about as many anaerobes as aerobes are present. Both anaerobes and aerobes have been demonstrated at all depths analyzed. The oxidation-reduction potential (intensity factor expressed as Eh) increases with core depth, although the oxygen-absorbing capacity decreases with depth. Both properties are ascribed primarily to bacterial activity. Bacteria recovered from marine sediments exhibit many biochemical processes such as ammonification, proteolysis, nitrate reduction, nitrification, urea fermentation, chitin digestion, methane production, fat hydrolysis, cellulose decomposition, glucose, xylose, and arabinose fermentation and starch hydrolysis.