Which of the following microbes is NOT involved in the preparation of household products?

A. Aspergillus niger

B. Lactobacillus

C. Trichoderma polysporum

D. Saccharomyces cerevisiae

E. Propionibacterium sharmanii

Choose the correct answer from the options given below:

To determine which of the microbes are NOT involved in the preparation of household products, let us analyze the role of each microbe listed:

1. Aspergillus niger (A): This is a fungus used for the industrial-scale production of citric acid, which is an organic chemical rather than a household product.
2. Lactobacillus (B): These bacteria, also known as lactic acid bacteria (LAB), are widely used in households to ferment milk and convert it into curd.
3. Trichoderma polysporum (C): This fungus is used to produce Cyclosporin A, an immunosuppressive bioactive molecule used in medicine for organ-transplant patients. Thus, it is a medical/industrial product, not a household product.
4. Saccharomyces cerevisiae (D): Commonly known as baker's yeast, it is used in households and bakeries for fermenting dough to make bread and other baked items.
5. Propionibacterium sharmanii (E): This bacterium is responsible for the fermentation and ripening of Swiss cheese, a household food product characterized by large holes due to the production of carbon dioxide gas.

Based on this analysis, the microbes not involved in the preparation of household products are Aspergillus niger (A) and Trichoderma polysporum (C).

Therefore, the correct option is A and C only.