Posted 06 August 2012 - 08:00 PM
Recently I conducted experiment on growing bacteria on MSM agar plate with various C-source (using the spot test). To my surprise, I found bacteria grew on the control plate without C-source. It only happened to two bacteria genus (I tested six).
Is it really possible for certain bacteria to eat the agar as their carbon source? (I used agar noble)
Posted 20 August 2012 - 04:41 PM
Minimal salts medium for studies of hydrocarbon degradation in soil contained 4 g of NaNO3, 1.5 g of KH2PO4, 0.5 g of Na2HPO4, 0.0011 g of FeSO4 · 7H2O, 0.2 g of MgSO4 · 7H2O, and 0.01 g of CaCl2 per liter of water at pH 7.0
Yes, there are microorganisms capable of using agar as C-source. Also could be some C-fixation if there is a suitable E-source.
Do you wash your inocula? Residual media may be present. In this case, colonies are usually punctiform.