• 作者： 林仁混；賴陳欽
• 作者服務機構： 國立臺灣大學醫學院生化學科
• 中文摘要： 亞硝基化合物包括一大類的物質，在動物實驗方面已被證明它們可在胃、肝、腸、腦、咽、鼻等器官引起種種癌症。而 且若將亞硝酸鹽（甚至硝酸鹽）與二級胺或三級胺同時投與?物，可在其體中檢?到亞硝基化合物之存在。長期投與之後可 引起癌症。由此看來，食物中亞硝基化合物之前驅物質如亞硝酸鹽、硝酸鹽、二級胺及三級胺也應加以重視，以維國民的健 康。 本研究注意另一方面的因素。硝酸鹽還原?可將硝酸鹽轉變成亞硝酸鹽。在前報中已指出腸胃管中多種微生物具有該? 之活性。在本報告中提出數?陳明市面上一些乳酸菌類成品中也有硝酸鹽還原?之活性。這些成品含此?之活性略有高低， 但若將其菌種分出再加培養所得之菌體，其所含該?之活性非常相近。再進一步觀察此?之動力學性質，發現它在37℃與 pH7.0狀?下作用最?。 依數據推算乳酸菌製劑一天劑量在腸管中?小時可產生約0.06mg亞硝酸鹽，但若該菌株繼續生長繁殖，即其產量可 能增加。另一方面吾人體中已有自然存在之乳酸菌，估計每公斤腸內含物所棲息的乳酸菌在10小時內可?生約200mg的 亞硝酸鹽。 投與之乳酸菌能否在健康的胃中、缺乏胃酸的胃中，或服用抗酸?的胃中寄生繁殖亦加討論。此可能性可能牽涉到胃癌 問題，本研究室正進一步在探索之中。
• 英文摘要： The activity of nitrate reductase in the commercial Lactobacillus preparations such as fermented milks and Lactobacillus powders was estimated and compared. The enzyme activity was somewhat different among the various samples tested. But it was relatively constant when the activity was estimated from the microbes of Lactobacillus species isolated from these commercial products. This indicated that the microorganisms contained in these samples were quite similar in origin. The effects of temperature, pH value, nitrate concentration and incubation time on the specific activity of nitrate reductase in the commercial Lactobacillus powders were studied. It is apparent that the optimum temperature is 37蚓 and the optimum pH is around 7.0. The amounts of nitrite that might be produced by a single dose of Lactobacillus powder was found to be 0.06 mg per hr, if the microbes keep growing in the gastrointestinal tract, the amounts of nitrite produced should be higher. It was also estimated that the naturally occurring Lactobacilli in the colon of man would produce 200 mg nitrite per Kg contents in 10 hr if nitrate is fully supplied from the ingested foods. The possible effects of achlorohydria and antacid medication on the growth of ingested Lactobacillus species in stomach were discussed. Further studies on the effects of medicated Lactobacillus preparations on the activity of nitrate reductase in gastrointestinal tract is now in progress.
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