細菌培養方法

細菌培養方法

1儀器：

K罩細菌過濾效率檢測儀、高壓蒸汽滅菌器、電子天平、生化培養箱、軌道式振蕩器、超潔凈工作臺、菌落計數器

1. 試劑及材料：

蒸餾水、75%酒精、金黃色葡萄球菌ATCC 6538、胰蛋白酶大豆瓊脂（TSA)、胰蛋白胨大豆肉湯培養基（TSB）、蛋白胨水、酒精燈、90mm平皿、500ml錐形瓶

1. TSA培養基的配制：

取一個干凈的500ml的錐形瓶，稱取16g TSA,溶于400ml水中，包扎后放入高壓蒸汽滅菌器中滅菌（121℃-123℃，20min），滅菌結束后取出，待其冷卻至50℃-60℃時，將液體培養基逐個倒25ml左右入無菌培養皿中，操作應在超潔凈工作臺上進行，以酒精燈的火焰周圍作為無菌區域，避免雜菌污染。

待培養基冷卻凝固后，將其倒置放入恒溫培養箱中，37℃條件下培養24h，將有菌落生長的培養基舍棄不用，無雜菌生長的取出備用，盡量現用現做，如不能盡快使用，應密封放在4℃冰箱內冷藏，可保存3-4天。                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

1. 菌懸液的制備：

將金黃色葡萄球菌ATCC6538接種在已滅菌好的100mlTSB(胰蛋白胨大豆肉湯液體培養基）中，在37℃震蕩培養24h。

用無菌移液槍取出上述培養好的菌液1ml注入9ml一滅菌好的蛋白胨水中，混勻，一次逐級稀釋10倍，稀釋至10^-7(根據菌種實際情況來判斷需要稀釋至多少），然后分別取10^-5、10^-6、10^-7菌液各0.1ml接種到備TSA培養基上，每個稀釋稀釋倍數做少4組平行，用涂布棒沿同一方向涂抹均勻，（不要涂抹到培養皿的邊緣上），放入生化培養箱中培養，培養溫度(37±2)℃,培養時間（24±2）h。培養結束后用菌落計數器計數，根據稀釋倍數確定原始菌液的濃度。

計算公式：原始濃度=（A/V)*D

A為培養皿上的平均菌落數

V為接種液的體積

D為稀釋倍數

按照上述方法確定原始菌液的濃度后，用1.5%的蛋白胨水將上述培養物稀釋至約5*10⁵cfu/ml。

TSB的制備：稱取3gTSB, 溶于100ml水中，放入高壓蒸汽滅菌器中（121℃-123℃，20min）滅菌，冷卻后備用。

蛋白胨水的配制：稱取1.5g蛋白胨溶于100ml水中，包扎，放入高壓蒸汽滅菌器中（121℃-123℃，20min）滅菌，冷卻后備用。

實驗結束后逐級取出培養皿并蓋上皿蓋，標記后倒置放入恒溫培養箱中，37℃培養24-48h.試驗中，陽性對照組應進行至少兩次實驗，終陽性質控結果取平均值。

培養結束后，將所有培養皿取出，使用菌落計數器進行計數，并將每一級菌落數對應陽性孔轉換表進行轉換，轉換后的數值求和，即得出菌落總數，陽性質控值范圍應在（2200±500）cfu之間。

細菌過濾效率計算公式如下：

BFE=(C-T)/C*

式中：C為陽性質控平均值，T為實驗組菌落總和