[Please do not crosspost in any format!] 以下摘录自 Kathy Barker: At the Bench- A Laboratory Navigator Cold Spring Harbor Laboratory Press Chapter: "Eukaryotic Cell Culture " (p.231-233) ☆ 巨观检查：拿起你的flask or dish对准光线；check for 1.) Cloudiness: "Even in a dense culture, the medium should be clear" 2.) Medium Color Change: phenol red pH indicator in red medium will turn yellow in acidic condition; magenta in alkaline condition bacterial infection often turn medium yellow fungal contamination may turn it hot pink 3.) Smell: 某些污染会散出恶臭 ☆ 微观检查：先以10X物镜锁定范围，後以40X物镜深入检查（total 400X放大倍率）； 并需观察不同景深（depth） [这段需要参考作者画的污染图] (低倍数即可观察) fungi污染: long strand, often across the field yeast污染：visible and appear to be smooth balls, sometimes budding 被破坏的细胞： bacterial infection can kill cells. cell become more irregularly shaped, larger or smaller; with a dark granularity visible at low power. (高倍数才可被观察) bacteria： may be rods or cocci, singly or in chains or in clumps. They may be associate with cells, or within cells. May be motile. The bacteria may be so many that the cell are obscured. There may be only one contaminant every two fields, which still counts as contamination. ☆ special note for suspension cell:（原文照贴） Harder (to examine) than adherent cells, especially at high power. 1.) after you place the flask on the microscope stage, leave it for a minute to let the turbulence slow 2.) focus on the bottom of the flask, and look carefully for slightly adherent cells that may have attached microorganisms. 3.) focus up through the flask, and whenever you have cells in focus, use your fine focus knob to examine around the cells for contamination ☆ 诊断污染存在的bioassay A.) 将medium离心, recover in 50 ul buffer or medium 做methylene blue or Grant stain B.) streak some of the cell/medium on a blood agar plate and incubate at 37C for 3 days, colonies? --> contamination! C.) remove 1 ml of cells/medium to a sterile microfuge tube and incubate for 3 days in the incubator. Observe for cloudiness and make a wet mount. -- Data speaks louder than words.

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