ahlou

hello to everyone i need some help about my research i have been trying to obtain triple mutant in saccharomyces cerevisiae lacking all three pyruvate decarboxylase genes but i cannot get colonies incomplex media having glucose as carbon source..i am using the LiAc/PEG/SS DNA protocol ...till now i am successful to obtain double mutant but not triple mutan...i need really your help because my work depends on that triple mutant..Thanks for your help