Hello Skyland

I think you have problem with the dilutions and the stock preparations. Prepare stock solutions of your glycine, and xylitol powders. Suppose dissolve 1000 mg of powder in 10 ml of sterile water/solvent, and pass through 0.22 micron syringe filters. You have now a stock solution of 100 mg/ml (0.1g/ml ).

Dear

1.5 % of powder concentration in agar media means 100 ml media contain 1.5 g of powder. In order to achieve homogeneous mixture of growth media, you need to think in term of liquid (if agar in picture, think about molten agar media)

Suppose you want to prepare your 100 ml mueller hinton agar media supplemented with 1.5 % glycine . It means you need 15 ml of your stock solution.

1.5 % glycine = 1.5 g in 100 ml

0.1 g = 1 ml powder stock

1 g = 1/0.1 ml

1.5 g = (1*1.5)/0.1 ml

= 15 ml

Suppose you need to dissolve X g of media in 100 ml (according to formulation guideline). Dissolve it in (100-15) 85 ml and sterile it through autoclave. After this wait to reach the temperature about 40-45 degree Centigrade (I think your powder component is heat sensitive). Mix 15 ml of your glycine stock solution to get a desired concentration of 1.5 %.

I just showed you how to go for one component (glycine). If you have more than one component you can still follow the same processor.

Please keep in mind if the powder is heat sensitive (can be degraded during media sterilization through autoclaving) follow this, if the component is heat labile directly add the powder in the media according to (volume to weight).

All the best !!