act ose ▁star v ation ▁The ▁E . ▁col i ▁stra in ▁FC 4 0 ▁has ▁a ▁high ▁rate ▁of ▁mut ation , ▁and ▁so ▁is ▁useful ▁for ▁studies , ▁such ▁as ▁for ▁adapt ive ▁mut ation . ▁Due ▁to ▁a ▁frames h ift ▁mut ation , ▁a ▁change ▁in ▁the ▁sequence ▁that ▁causes ▁the ▁DNA ▁to ▁code ▁for ▁something ▁different , ▁FC 4 0 ▁is ▁unable ▁to ▁process ▁la ct ose . ▁When ▁placed ▁in ▁a ▁la ct ose - rich ▁medium , ▁it ▁has ▁been ▁found ▁that ▁ 2 0 % ▁of ▁the ▁cells ▁mut ated ▁from ▁Lac - ▁( could ▁not ▁process ▁la ct ose ) ▁to ▁Lac + , ▁meaning ▁they ▁could ▁now ▁util ize ▁the ▁la ct ose ▁in ▁their ▁environment . ▁The ▁responses ▁to ▁stress ▁are ▁not ▁in ▁current ▁DNA , ▁but ▁the ▁change ▁is ▁made ▁during ▁DNA ▁rep lication ▁through ▁recom bin ation ▁and ▁the ▁rep lication ▁process ▁itself , ▁meaning ▁that ▁the ▁adapt ive ▁mut ation ▁occurs ▁in ▁the ▁current ▁b acter ia ▁and ▁will ▁be ▁inherited ▁by ▁the ▁next ▁gener ations ▁because ▁the ▁mut ation ▁becomes ▁part ▁of ▁the ▁gen etic ▁code ▁in ▁the ▁b acter ia . ▁This ▁is ▁particularly ▁obvious ▁in ▁a ▁study ▁by ▁C air ns , ▁which ▁demonstrated ▁that ▁even ▁after ▁moving ▁E . ▁col i ▁back ▁to ▁a ▁medium ▁with ▁minimal ▁levels ▁of ▁la ct ose , ▁Lac + ▁mut ants ▁continued ▁to ▁be ▁produced ▁as ▁a ▁response ▁to ▁the ▁previous ▁environment . ▁This ▁would ▁not ▁be ▁possible ▁if