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Q9 - Screening Shrimp Gut Bacteria for Probiotic Potential Against Vibrio

Theoretical A Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Immune Physiology

Four different bacterial strains were isolated from the gut of a shrimp to study their probiotic potency through the decrease of their pathogenicity of Vibrio harveyi, a common bacteria infecting shrimp culture. In the first experiment, the four isolated bacteria were inoculated in cross-streak plates to observe inhibition zones against 4 bacterial strains (Fig.9A). In the second experiment, the shrimp survival rate in presence of Vibrio harveyi and each bacterial isolate after 5 days of incubation was measured (Fig.9B).

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. Candidate No.1 (P1) produced an antimicrobial compound that inhibited Gram negative and Gram positive bacteria.
B. Candidate No.2 (P2) was able to decrease Vibrio sp. pathogenicity without killing them.
C. Candidate No.3 (P3) produced an antimicrobial compound targeting the outer membrane.
D. Candidate No.4 (P4) had good effect on the shrimp survival by inhibiting Gram-negative bacteria.
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Question reproduced from IBO 2016, Theoretical Paper A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)