Answer: Propionibacterium sharmanii.
- A Propionibacterium sharmanii
- B Lactobacillus acidophilus
- C Streptococcus lactis
- D Acetobacter aceti
Correct answer: A. Propionibacterium sharmanii
Explanation: Propionibacterium sharmanii produces large amounts of CO<sub>2</sub> during ripening, which forms the characteristic holes in Swiss cheese.
Sewage passes through physical removal (primary), then aerobic biological treatment where microbes form flocs that consume organic matter (secondary); the settled activated sludge is then digested anaerobically to produce biogas - a deliberate switch from aerobic to anaerobic conditions between stages.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers