Most Probable Number (MPN) Counts of Cyanophages
Label the dilution preparation plate using example in guidelines.  
Label the sample plates with the date, host, phage name, and any other applicable information (e.g. the light level).  
Using a 8x1500 µL multi-channel pipettor, put 270 µL of Pro99 or SN medium in all wells of dilution plate. 
Using a 100 µL pipettor, dispense 30 µL of virus sample into row H of the dilution plate.  
Repeat this for each of the virus samples. 
Using a 12x300 µL multi-channel pipettor set at 30 µL with 12 tips attached, pipette row H up and down to mix the dilution. 
Replace the tips and pipette 30 µL from row H into row A (the 10-2 row). 
Pipette up and down several times to mix. 
Replace the tips and transfer 30 µL into row B (10-3 row). 
Repeat this mixing, replacing tips and transferring 4 more times until you are at row F (10-7 row).   
Using a 12x300 µL multi-channel pipettor set to 30 µL with 8 tips attached, pipet 30 µL host cells into all appropriate wells of the sample plate.  
Reset the pipettor to dispense 20 µL, put on 8 fresh tips and transfer 20 µL from the virus dilution plate to the same corresponding column in the sample test plate. 	
Put the lids on the sample test plates and place in incubator under appropriate light and temperature conditions for each host, and let the virus adsorb to the host for 1 hr. 
Using the 8x1500 µL multi-channel pipettor set to step 6x200 µL, add 200 µL of Pro99 or SN medium to all wells in all sample plates.  
Seal each plate with parafilm and return plates to the incubator
