Answer: Lactobacillus.
- A Saccharomyces cerevisiae
- B Lactobacillus
- C Aspergillus niger
- D Penicillium notatum
Correct answer: B. Lactobacillus
Explanation: Lactobacillus is the bacterium responsible for converting milk into curd through lactic acid fermentation.
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