Hagen C A, Hawrylewicz E J, Anderson B T, Tolkacz V K, Cephus M L
Appl Microbiol. 1968 Jun;16(6):932-4. doi: 10.1128/am.16.6.932-934.1968.
Scanning electron microscopy was used for viewing Bacillus cereus and Staphylococcus aureus in three different soils. Both organisms were detected in the test soils at an approximate concentration of 10(7) cells per gram of soil; theoretically, the minimal number of microorganisms required for detection with the scanning electron microscope technique was between 10(7) and 10(10) cells per gram of soil. Because the concentration of cells was critical, the use of scanning electron microscopy as an extraterrestrial life detection instrument would be limited with soils containing more than 10(7) bacteria per gram of soil.
利用扫描电子显微镜观察了三种不同土壤中的蜡样芽孢杆菌和金黄色葡萄球菌。在测试土壤中均检测到了这两种微生物，其浓度约为每克土壤10⁷个细胞；从理论上讲，使用扫描电子显微镜技术进行检测所需的微生物最小数量为每克土壤10⁷至10¹⁰个细胞。由于细胞浓度至关重要，因此对于每克土壤中细菌含量超过10⁷个的土壤而言，将扫描电子显微镜用作外星生命检测仪器会受到限制。
