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对陕西段家坡黄土剖面61个样品(所在层位以S0和S1为主,其次为与它相邻的L1和L2层段)进行了磁场下的富集和移接培养等生物和地球化学综合分析。结果表明黄土剖面中存在向磁南极泳动的趋磁细菌,它在黄土层中分布少(<25个/格),呈弧形或厚壁形,单个菌体仅载有2～4个磁小体,在古土壤层中数量多(>125个/格),多呈杆状,单个菌体载有8～26个磁小体,磁小体近圆形,其线状排列不够规则,主要金属元素为Fe和Co.趋磁细菌中可检测到C_(14:0)-C_(28:0)系列的正构脂肪酸,不饱和脂肪酸甚微。磁小体形成最佳生长需氧量为10％,需铁量为0.02mmol/L(以0.01mol/L奎尼酸铁为铁源)。研究表明,趋磁细菌在古土壤时期最发育,磁小体大量形成是在古土壤层向黄土层转变的气候变化时期。
Sixty-one samples of the Loess section of Duanjiapo, Shaanxi province, which are dominated by S0 and S1, followed by L1 and L2 intervals adjacent to it, were subjected to bio-and geochemistry Comprehensive analysis. The results show that there are magnetotactic bacteria that migrate toward the magnetic south pole in the loess section, which are less distributed in the loess layer (<25 pieces / grid), arc-shaped or thick-walled. The single cell contains only 2-4 magnetic Small bodies, in ancient soil layer in the number of more (> 125 / grid), mostly rod-shaped, single bacteria carrying 8 to 26 magnetosomes, magnetosomes nearly circular, the linear arrangement of rules, The main metal elements are Fe and Co. Magnesium-forcing bacteria can detect C_ (14: 0) -C_ (28: 0) series of n-type fatty acids, unsaturated fatty acids is very small. Optimum growth of magnetosome formation of oxygen was 10%, the required iron content of 0.02mmol / L (0.01mol / L iron as the source of quinic acid). Studies have shown that magnetotactic bacteria are the most developed in the paleosol period, and the formation of large numbers of magnetosomes is a period of climate change that changes from the paleosol layer to the loess layer.