I use 50ug/ ml Gentamycin in my culture media already. I have to dissect the sub-ventricular zone under a microscope which takes a while to do and all the steps upto the collection of region of interest are performed outside the hood. Please suggest if I should add the antibiotic in my dissection medium as well, for extra protection from the contamination.
I suggest you to keep the microscope in a hood and do the dissection inside the hood because adding antibiotic will lead to death of cells and will also affect the health of viable cells. Therefore, you will get very less number of cells for your cultures and also you cannot negate the chances of contamination even after adding antibiotic.
Not required if you are performing it under a laminar hood and using all sterile precautions. 1X pen/strep will not do any harm. I usually add that to L15 medium, better than ca-ma free pbs.