FORMALDEHYDE METABOLISM IN PURPLE NON SULPHUR BACTERIUM RHODOBACTER SPHAEROIDES

我们正在研究甲醛同化的途径。 紫色的非硫细菌球形红杆菌。紫色 非硫细菌以其代谢多样性而闻名， 使用各种各样的衬底来满足碳和能源需求。这个 某些底物的代谢，特别是甲基化 化合物，产生甲醛，必须进一步代谢或 会对细胞产生毒性。我们的数据表明，甲醛 球状芽孢杆菌的命运取决于细胞是否在 缺氧存在或缺乏氧气。在厌氧(光合作用)下 生长条件下，球藻能够以甲醇为底物生长。 唯一的碳源。因为甲醛是直接的产物 甲醇氧化，它必须为R. 光合作用生长条件下的球藻。在这些小路中 以前被描述为甲醛同化的 粗提物中的微生物、酶分析表明球孢杆菌 可以使用丝氨酸-异柠檬酸循环或卡尔文循环 光合作用的甲基营养生长。在好氧生长下 条件下，类似的酶分析表明甲醛是 被氧化成二氧化碳，然后释放到大气中 解毒甲醛从细胞中释放出来。通过使用13C标记的 底物的酶测定，我们希望确定的路径(S) 这些细胞中的甲醛氧化产物。通过表明 预测的产物是在特定的甲醛途径下形成的 将中间体添加到球藻提取物中，我们将提供 直接证据支持我们对甲醛的初步研究 在有氧和无氧情况下的氧化。

We are investigating the pathway of formaldehyde assimilation in the purple non-sulphur bacterium Rhodobacter sphaeroides. Purple non-sulphur bacteria are well known for their metabolic diversity, using a wide variety of substrates for carbon and energy needs. The metabolism of some of these substrates, specifically methylated compounds, generates formaldehyde that must be further metabolized or would prove toxic to the cells. Our data suggest that formaldehyde's fate in R. sphaerodies is dependent on whether cells are grown in the presence or absence of oxygen. Under anaerobic (photosynthetic) growth conditions, R. sphaeroides is able to grow using methanol as a sole carbon source. Since formaldehyde is the immediate product of methanol oxidation, it must provide all the carbon skeletons for R. sphaeroides under photosynthetic growth conditions. Of the pathways that have previously been described for formaldehyde assimilation in microbes, enzyme assays in crude extracts suggest that R. sphaerodies may use either the Serine-Isocitrate cycle or the Calvin cycle for photosynthetic methylotrophic growth. Under aerobic growth conditions, similar enzyme assays suggest that formaldehyde is oxidized to carbon dioxide and released to the atmosphere thus detoxifiying formaldehyde form the cells. By using 13C-labeled substrates in enzyme assays, we hope to confirm the path(s) of formaldehyde oxidation products in these cells. By showing that the predicted products are formed when specific formaldehyde pathway intermediates are added to R. sphaeroides extracts, we will provide direct evidence to support our tentative pathway for formaldehyde oxidation in the presence and absence of oxygen.