Final answer:
Bacillus thuringiensis (Bt) produces a protein that kills various insect pests, and its toxin genes have been used in genetically engineered plants for pest control.
Step-by-step explanation:
The microbe that produces a protein that kills a variety of insect pests is E) Bacillus thuringiensis. Bacillus thuringiensis, often abbreviated as Bt, is a bacterium that produces protein crystals during sporulation that are toxic to many insect species that affect plants, including families such as Lepidoptera, Coleoptera, and Diptera. Once these insects ingest the Bt toxin, it becomes active within their intestines, leading to their cessation of feeding and eventual death.
Bacillus thuringiensis is not only an effective biological insecticide but also considered safe for the environment and non-toxic to humans and other mammals. Bt toxin genes have been genetically engineered into plants, providing built-in protection against pests. This application is approved for use by organic farmers and is deemed more environmentally friendly than synthetic pesticides.