I am doing Trichoderma reesei transformation with amds seletive marker. For preparation of selective medium,10mM acetamide as the sole nitrogen source,Cscl was addded to reduce the growth of background,agarose was used to replace of agar.But however on the 3th day,the baackground still grow too fast,and it is difficult to screen transformants.I picked up some putative transformants. After several times single spore isoaltion,I still can not get transformants,except mixture of background and putative transformants.
So, I hope sb may give me some suggestion.