The antibiotic obtained from the yeast is

The correct option is Ephedrine.

Let us break down each of the options step-by-step to understand the logical reasoning behind the correct choice:
1. Ephedrine: Ephedrine is a sympathomimetic amine. In industrial biotechnology, the yeast Saccharomyces cerevisiae is used in a fermentation process to convert benzaldehyde into L-phenylacetylcarbinol (L-PAC), which serves as the key precursor in the production of ephedrine. Thus, its manufacture is deeply associated with yeast fermentation.
2. Saccharin: This is a widely used artificial sweetener. It is synthesized chemically in laboratories from organic compounds like toluene, and is not a biological product or antibiotic derived from yeast.
3. Polymyxin: Although this is indeed an antibiotic, it is biosynthesized by the gram-positive bacterium Bacillus polymyxa (also known as Paenibacillus polymyxa), rather than a yeast species.
4. Campestrin: This is an antibiotic substance obtained from the mushroom Psalliota campestris (commonly known as the field mushroom), which is a multicellular basidiomycete fungus and not yeast.

Consequently, Ephedrine is the correct option representing the compound obtained through yeast-based industrial processes.