1a. Why are sulfur oxidizers obligate acidiphiles 1b. Why are Fe oxidizers obligate acidophiles 1c. What are sulfur granules and which type of respiratory bacteria accumulate them? Solution Ans1(a) Acidothiobacillus are rod shaped Gramnegative bacteria which are obligate acidophillus because they reduces sulfur for energy with pH less than 4. And its suevive at moderatetemprature (18 to 28degree c). its oxidation system reduced inorganic sulfur compounds (RISCs).so sulfur oxidisers are obligate acidiphiles..