Final answer:
Based on the growth results on various agar plates, the bacteria did not grow on Nutrient Agar, produced a yellow color on MacConkey Agar, and displayed clear colonies on EMB and XLD Agars, suggesting it is likely a non-lactose fermenting enteric bacterium.
Step-by-step explanation:
The student is asking about the identification of a bacteria based on growth results from various agar plates. The information given describes how the bacteria did not grow on Nutrient Agar, produced a yellow color on MacConkey Agar, and formed clear colonies on both EMB Agar and XLD Agar. According to these results, the bacteria is likely a non-lactose fermenter since it did not produce colored colonies on EMB, which differentiates between lactose fermenters (colored colonies) and non-lactose fermenters (colorless colonies).
Additionally, the yellow coloration on MacConkey Agar can indicate the presence of bile pigments that are typically produced by enteric bacteria that can ferment lactose, which is somewhat contradictory unless the pH indicator reacts differently with this particular strain. The lack of growth on Nutrient Agar suggests it does not grow well on non-selective media, while clear colonies on XLD Agar rule out common food-borne pathogens like Salmonella and Shigella.