Salmonella typhimurium is a food-borne bacterial pathogen that can cause severe

Question

Salmonella typhimurium is a food-borne bacterial pathogen that can cause severe gastrointestinal disease. Salmonella is often phagocytosed by macrophages that normally destroy bacterial pathogens, but this bacterium is somehow able to prevent the complete maturation of phagolysosomes. Salmonella is able to tolerate the low pH of phagolysosomes, and in fact responds to the drop in pH by secreting toxins that interfere with other cellular responses. Which of the following differences would you expect contribute to the survival of a bacterium within an Salmonella-containing phagosome, compared to a healthy phagolysosome?

decreased activity of acid hydrolases

increased activity of acid hydrolases

decreased import of H+ ions

increased import of H+ ions

Explanation / Answer

Phagolysosomes contain acid hydrolases, which work under low pH. Salmonella-containing phagosomes have decreased activity of acid hydrolysis, and increased import of H+ ions, which decreases the pH. Both contribute to the survival of the bacterium.

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