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Dry or does powder food: Takes the 25g sample by the asepticoperation, puts in is loaded with the 225ml diluent and right amount玻璃珠 500ml 稀释瓶 center. Rapidly inspires broadcasts, mixesuniform the sample, makes 1: 10 samples uniform fluids. Inspires thetime transmission, the scope is in 30cm,7s inspires broadcasts 25times, also may use the mechanical oscillator to vibrate 15s toreplace hand operated.
Separately adds the 12-15ml plate to count the agar-agar (to put in4,5+1 ℃ water baths constant temperature) to each even dish in, willput down in the dish the sample fluid and the agar-agar culture mediumintensive mixing, the mix method will be immediately puts down thedish to incline and to revolve, will have to prevent will splash themixture to the even dish wall on and covers. Meanwhile counts theagar-agar the plate to plunge Canada to have the 1ml diluent anotherantiseptic even dish to do the blank comparison. Joins the even dishafter the sample fluid to be supposed to pour into the agar-agarculture medium immediately, each sample from starts to dilute to poursinto the time which last the even dish uses not to have to surpass20min.
After will wait the agar-agar to coagulate puts down the dish to turnover, will admit immediately 36±1 ℃ in the constant temperatureraise box will raise 48±2h, will raise the box to be supposed tomaintain the certain humidity, will not have to surpass 15% after the48h raise agar-agar culture medium and weightlessness.
Usually has three kind of different types the spread growth colonies.The first kind of type is the chain shape colony, between the colonynot the obvious demarcation line. These colonies are work as whenagar-agar and experiment mix, 细菌块 is dispersed is the result of;The second kind of type is the water film type colony which formsbetween the agar-agar peaceful dish bottom; The third kind is thewater film type colony which forms in the even dish edge or theagar-agar surface. If chooses the plate appears the excessive spreadcolony to grow, so that a. Spreads the place which the colony covers,including because the spread colony creates the suppression growtharea area surpasses the dull area 50%, or b. Because the spread colonycreates the suppression growth area area surpasses the dull area 25%,such plate report is "the spread colony", does not give counts. Countson other plate colony number, these values arithmetic mean valuereports for dull colony number (next table, sample 10)
When has the essential technology except above a. With b. Whenoutside spread growth colony, separately counts three kind ofdifferent types spread colonies. Regarding first kind of type, if onlyhas a chain, takes it a colony idea. If has the origin differentseveral chains, each chain took a colony idea, does not want eachcolony which on the chain grows to separate counts. Second kind of andthe third kind of type spread growth forms the colony which easy todistinguish, namely counts according to the general colony, puts orbring together the technical spread growth colony number identicalcolony number, computation dull colony number.
The operator reexamines to the identical plate own counts the result,its difference should in 5%, but other people count to this platerepetition, its difference should in 10%. Otherwise, should discoverthe reason, performs to adjust.
Is suitable 稀释度 two dull colonies numbers mean value or two稀释度 dull colonies numbers mean value while figure out each gramby the corresponding dilution multiple idea (milliliter) in the samplethe dull colony number.
Adjusts pH with probably the 175ml 1mol/L caustic soda solution to7.2, dilutes with the distilled water after 1000ml stores to therefrigerator.
Diluent: Dilutes the 1.25ml storing fluid with the distilled water to1000ml, loads separately to the appropriate vessel, 121 ℃high-pressured antiseptic 15min.
This standard mainly referred to American food and the medicineadministrative bureau (FDA)"Bacterium Study Analysis Handbook" the 6thedition 4th chapter (in 1984
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