Answer: Trichoderma.
- A Bacillus thuringiensis
- B Trichoderma
- C Pseudomonas
- D Azotobacter
Correct answer: B. Trichoderma
Explanation: Trichoderma species are free-living fungi that act as biocontrol agents against plant pathogens by competing for nutrients and space and producing antifungal metabolites.
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