Suppose you were interested in the effect of breastfeeding versus formula feeding on the composition of gut flora in newborns. A
s part of your experiment, stool samples from healthy babies in the study get plated on various agar media. You notice that greater numbers of colonies are recovered when samples are plated on blood agar compared to nutrient agar (NA). After some diligent subculturing, you isolate several bacterial species capable of slow growth on the blood but not on the NA. You correctly surmise that these organisms: ______________ a. are opportunistic blood pathogens.
b. have extensive and complex nutritional requirements not met by NA are inhibited by the ingredients in NA.
c. should be classified as beta-hemolytic.
d. grow because the blood agar suppresses the growth of faster-growing bacteria.
