Answer: Penicillium chrysogenum.
- A Aspergillus niger
- B Trichoderma polysporum
- C Penicillium chrysogenum
- D Monascus purpureus
Correct answer: C. Penicillium chrysogenum
Explanation: Penicillium chrysogenum is the fungus used for commercial production of penicillin in large fermenters.
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