It has now been found that certain kinds of bacteria produce
asparaginase having a strong anti-tumor activity in a high yield
when cultivated in a nutrient medium under aerobic condi
tions. This finding is both unexpected and surprising, because
while the cultivation of the known micro~organisms producing
asparaginase ‘having an anti-tumor activity under aerobic con
ditions affords good growth of the micro-organisms it sup
presses markedly the production of the desired asparaginase.
Thus, cultivation of the known micro-organisms for the
production of asparaginase has been carried out only under
anaerobic conditions.