2×10⁹ → 2×10³ CFU/mL → 6 管,每管 100 µL + 900 µL 过夜肉汤培养物浓度为 2×10⁹ CFU/mL,需要降到约 2×10³ 才能直接涂布。log₁₀(10⁶) = 6 步整,第 6 管恰为 2×10³ CFU/mL。每管配方:从上一管取 100 µL + 900 µL 稀释液(1 mL 管),每次转移换新枪头。{"result":"6 × 10-fold steps: 2e9 → 2e3 (tube-by-tube table included); per tube 100 µL sample + 900 µL diluent.","metadata":{"result":{"steps":6,"finalConcentration":2000,"sampleVolumeUl":100,"diluentVolumeUl":900}}}
你的 SOP 固定做 4 个 10 倍稀释管。从 5×10⁶ 菌液出发,规划器确认末管浓度为 5×10⁶ ÷ 10⁴ = 500,并列出途中 5×10⁵、5×10⁴、5×10³ 各管浓度,方便挑选最合适的管用于测定。{"result":"4 × 10-fold steps: 5e6 → 500 (500000, 50000, 5000, 500); per tube 100 µL sample + 900 µL diluent.","metadata":{"result":{"steps":4,"finalConcentration":500}}}