XL2-Blue MRF´ ultracompetent cells are high-efficiency derivatives of our XL1-Blue MRF´ supercompetent cells. Using ultracompetent cell technology, we have achieved transformation efficiencies of greater than 5 × 109 transformants/µg of pUC18 DNA, making these ultracompetent cells an ideal choice for high-efficiency cloning. The XL2-Blue MRF´ (Minus Restriction) strain is deficient in all known restriction systems (McrA–, McrCB–, McrF–, Mrr–, HsdR–), preventing cleavage of cloned DNA that carries cytosine and/or adenine methylation, which is often present in eukaryotic DNA and cDNA. XL2-Blue MRF´ cells are restriction minus. The strain is endonuclease deficient (endA), greatly improving the quality of miniprep DNA, and recombination deficient (recA), helping to ensure insert stability. These cells allow blue-white screening for recombinant plasmids. 菌种培养及打管说明: 1、安瓿瓶开封:用浸过75%酒精的脱脂棉擦净安瓿管,用火焰加热其顶端,滴少量无菌水至加热顶端使之破裂,用锉刀或者镊子敲下已破裂的安瓿管顶端。 2、菌株恢复培养:用无菌吸管吸取0.3--0.5ml适宜的液体培养基,滴入安瓿管内,轻轻振荡,使冻干菌体溶解呈悬浮状。吸取全部菌体悬浮液,移植于1-2支建议的培养基试管中,并在建议的条件下培养。 3、注意事项:菌种活化前,请将安瓿管保存在6-10℃的环境下,某些菌种经过冷冻干燥保存后,延迟期较长,需要连续两次继代培养才能正常生长 4、复苏后的菌种在传1-2代后使用。 5、暂不启开的安瓿及复苏后需保藏的斜面应于4℃中保藏。 特别注意事项: l、微生物菌种应保藏于低温、清洁和干燥的地方,室温放置时问过长会导致菌种衰退; 2、菌种操作应在无菌条件下进行,防止杂菌污染: 3、斜面菌种保藏时间通常为1-2个月,应根据菌种状况及时转接;冻干菌种保藏时间通常为5~10年; 4、菌种使用过程中如出现杂菌污染或菌种生产性能下降,应及时与我司销售联系或更换新的菌种。