7803
Saturable spermidine transport in stk2 : : lacZ mutants had an approximately fivefold - lower affinity and twofold - lower Vmax than in the parental strain .
 stk2, lacZ mutants
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 stk2, lacZ mutants