Final answer:
b) Salmonella typhi The TSI reaction is used in microbiology to identify bacterial species by their sugar fermentation and hydrogen sulfide production.
Step-by-step explanation:
The question relates to the identification of bacterial species using various biochemical tests, including the Triple Sugar Iron (TSI) test. The TSI test is used to differentiate bacteria based on their ability to ferment sugars and produce hydrogen sulfide.
When using TSI to confirm the identity of potential foodborne pathogens, we expect certain reactions from different bacteria. For example, Escherichia coli (E. coli) is expected to ferment lactose and/or sucrose, producing acid which results in a yellow slant and yellow butt in the TSI test. Additionally, E.
coli may produce gas and is not expected to produce hydrogen sulfide. On the other hand, Salmonella species are expected to produce hydrogen sulfide, which will appear as a black precipitate in the TSI agar, and may also ferment glucose but not lactose or sucrose, leading to a red slant and yellow butt.
Proper identification also includes Gram staining and other tests such as catalase, oxidase, and coagulase depending on the species.