Answer: Propionibacterium shermanii.
- A Penicillium roqueforti
- B Propionibacterium shermanii
- C Lactobacillus helveticus
- D Streptococcus thermophilus
Correct answer: B. Propionibacterium shermanii
Explanation: Propionibacterium shermanii produces large amounts of CO<sub>2</sub> during cheese ripening, creating the characteristic holes (eyes) 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