Magnetotactic bacteria (MB) have been isolated from 61 samples which have been collected from S0, L1, S1 and L2 layers in the Duanjiapo loess section. A few MB (<25 cell counts per sieve mesh) have been found in lo...Magnetotactic bacteria (MB) have been isolated from 61 samples which have been collected from S0, L1, S1 and L2 layers in the Duanjiapo loess section. A few MB (<25 cell counts per sieve mesh) have been found in loess layers (L1, L2), bow-shaped, each cell containing only two magnetosomes. while much more MB (>125 cells counts per sieve mesh) have been found from paleosol layers (S0, S1), rod-shaped, each cell containing 8-26 magnetosomes arranged in irregular chains. Magnetosomes with Fe and Co as the main metallic elements are spheroid-shaped, and mainly round in cross-section. Normal saturated fatty acids in MB ranged from C14 to C28; almost no monounsaturated fatty acids have been identified. Most suitable oxygen content for MB growing is 10%, and low concentration of organic salt (0.02mmol/L qumsic iron) is beneficial to the forming of magnetosomes. Results suggest that the paleosol development stage is suitable for the growing of MB and the climate fluctuation periods for magnetosomes formation.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Magnetotactic bacteria (MB) have been isolated from 61 samples which have been collected from S0, L1, S1 and L2 layers in the Duanjiapo loess section. A few MB (<25 cell counts per sieve mesh) have been found in loess layers (L1, L2), bow-shaped, each cell containing only two magnetosomes. while much more MB (>125 cells counts per sieve mesh) have been found from paleosol layers (S0, S1), rod-shaped, each cell containing 8-26 magnetosomes arranged in irregular chains. Magnetosomes with Fe and Co as the main metallic elements are spheroid-shaped, and mainly round in cross-section. Normal saturated fatty acids in MB ranged from C14 to C28; almost no monounsaturated fatty acids have been identified. Most suitable oxygen content for MB growing is 10%, and low concentration of organic salt (0.02mmol/L qumsic iron) is beneficial to the forming of magnetosomes. Results suggest that the paleosol development stage is suitable for the growing of MB and the climate fluctuation periods for magnetosomes formation.
