海洋性硫酸塩還元細菌に関する研究-IV : 海洋性硫酸塩還元細菌の榮養について(その1)

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In the previous paper, it has been reported that the population of sulfate-reducing bacieria in the bottom mud and the sulfides content of the bottom mud were directly correlated with the concentration of utilizable organic matter in the mud. In the present study, the authors attempted the experiments concerning the nitrogen requirement of marine sulfate reducers, with the aim of elucidating the relation between the organic matter and the bacterial production of sulfides in the mud. 1) In order to determine the source of nitrogen available to these organisms, various organic and inonganic nitrogenous compounds were tested using the basal medium (Medium 3). The results obtained are given in Tables 1 and 2 and may be summarized as follows: (a) In the case of the pure cultule, these organisms could grow Well in the medium containing the complex organic nitrogenous compounds such as pcptone, but could not in the medium containing a kind of simple nitrogenous compounds, such as inorganic salts or amino acids, as a sole source of nitrogen. (b) In the case of the crude culture, these organisms could grow in the medium containing a variety of organic and inorganic nitrogenous compounds tested, excepting KNO3, KNO2, L-aspartic acid, and L-cystcinc. From these results, the marine sulfate-reducing bacteria seem to require necessarily the complex organic nitrogenous compounds such as peptone for the growth. In the case of crude culture, it must be considered that the complex nitrogenous compounds produced by the action of the coexistent bacteria were utilized for the growth of the marine sulfate-reducing bacteria. 2) The growth response of marine sulfate-reducing bacteria to varying concentrations of peptone which was added, as a sole source of nitrogen, to the basal medium (Medium 3) was studied. The results obtained are as shown in Tables 3 and 4. These results indicate that in the case of the pure culture, the marine sulfate-reducing bacteria could develop in the presence of very minute quantities of peptone (about 1×10-8g./L.) and that although the peptone was the essential nutriment for the growth, it could be replaced by the small amount of the preculture of these organisms (about 2 loops per 7 cc.). These results probably suggest that the peptone and the preculture may be utilized for the growth of these organisms as the source of the accessory growth factors rather than as the nitrogen source. 3) When peptone was provided for the growth of marine sulfate-reducing bacteria as sources of both nitrogen and carbon, these organisms could not grow when the concentrations of pep-tone were lower than 0.1g. per litter (Table 5). This result suggests that the marine sulfate-reducing bacteria must require extraordanarily higher concentrations in carbon source than in nitrogen source for the growth. From the above mentioned facts, it is considered that in the bottom mud of the sea an important factor limitting the multiplcation and the activity of sulfate-reducing bacteria is the concentration of the organic matter which can be utilized as the carbon source for the growth of these bacteria, but not the concentration of the organic matter as the source of nitrogen.

海洋性硫酸塩還元細菌に関する研究-IV : 海洋性硫酸塩還元細菌の榮養について(その1)

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