Dr Thirumalachar has done considerable work in the fields of medical mycology and plant disease control. Studies carried out under his guidance have led to the discovery of a new antiparasitic antibiotic, antiamoebin, which is being used by the Armed Forces for deworming military dogs.When fed with animal feed, it increases the yield of milk in cows, and enhances egg production in poultry. In the field of antibiotics, he has developed the antifungal antibiotics Hamycin, Dermostatin, Aureofungin, MYc-4 and Tetraenenin