1) Clostridium and Streptococcus are both catalase-negative. Streptococcus grows through fermentation. describe why is Clostridium killed by oxygen, while Streptococcus is not?
2) Suppose that after washing your hands, you leave ten bacteria cells on a new bar of soap. You then decide to do a plate count of the soap after it was left in the soap dish for 24-hours. You dilute 1g of the soap 1:106 and plate it on standard plate count agar. After 24-hours of incubation, there are 168 colonies. describe how many bacteria were on the soap? describe how did they get there?