BS EN ISO 20743:2021 pdf download – Textiles — Determination of antibacterial activity of textile products Add 10 ml of cryoprotective solution (6.13) to the surface of the TSA plate culture and resuspend the cells in the solution using a sterile glass spreader. Sample the suspended cells from the surface of the agar, dilute them in 100 ml of cryoprotective solution and incubate for 30 min at 20 °C. Using a pipette (5.15), sample 1 ml of the suspension and transfer it to a cryogenic vial (5.16) containing the beads (5.19). Shake the vial in order to spread the suspended cells around the beads. — Where a cryoprotective solution containing dimethylsulfoxide is used, do not let it stand longer than 1 min at ambient temperature. — Where a cryoprotective solution containing glycerol is used, let it stand for 30 min at 20 °C. — Withdraw the excess cryoprotective solution with a sterile pipette. Place the cryogenic vials in a freezer (5.12) set at −70 °C or lower. Prepare 10 −6 and 10 −7 dilutions of the suspension using the serial dilution method. Take a 1,0 ml sample of each dilution and transfer it to separate Petri dishes. Add 12 ml to 15 ml of nutritive solution, cooled down to 45 °C ± 1 °C. Incubate for 18 h to 24 h under the conditions specified for the strain. Enumerate the plate cultures and confirm that the suspension contains less than 5 × 10 8 CFU/ml. Store the cryogenic vials in a freezer at a temperature below −70 °C. 7.2.3 Glycerol suspension method Inoculate a 15 ml culture tube containing 5 ml of appropriate medium with a freshly grown isolated colony. Incubate, usually, for 5 h to overnight at 37 °C until the bacteria culture seems to reach the late logarithm or stationary phase in the growth curve. For each strain to be stored below −70 °C, for the archives, prepare a sterile, labelled cryogenic vial. Place 225 μl of sterile 80 % glycerol in a cryogenic vial. Add 1,0 ml of the bacterial culture (frozen stock shall be 15 % glycerol). Mix well using the vortex mixer (5.4) and store in a tube at −70 °C or lower. For each strain to be stored at −20 °C, as liquid glycerol working stock, pipette equal volumes of 80 % glycerol and bacterial culture into a labelled polypropylene tube. Mix the contents...
Download Address
Download