Final answer:
The zigzag inoculation pattern used on slants is known as the streak plate method, used to isolate single bacterial species and create a pure culture. The pattern facilitates individual bacterial growth, and any difference in colonial morphology may indicate contamination.
Step-by-step explanation:
The name describing the zigzag inoculation pattern used on slants in microbiology is the streak plate method. This method is implemented to isolate a single species of bacteria from a mixed culture to obtain a pure culture. The streak pattern allows for the dilution of the bacteria across the surface of the agar in a slant culture. When streaking, a sterilized loop is used to 'zigzag' the inoculum back and forth on the slant without crossing over the previous streaks, which facilitates the isolation of individual colonies on sections of the slant.
During the observation of the slant culture, one should look for the texture, transparency, and pigmentation of the bacterial growth. The growth should be consistent with that of the originally inoculated organism, in this case, M. luteus. If another type of bacteria or different colonial morphology appears, it could indicate contamination. Colonial morphology refers to the visual characteristics of a colony of bacteria, which could range from its shape, edge, texture, elevation, pigmentation, and size, aiding in the identification of specific bacterial species.
Analyzing the slant culture, it would be important to check if there is any visual evidence of different colonial morphologies indicating that another type of bacteria is present, which is not the originally inoculated M. luteus. Such evidence would be critical as it might point out contamination or the presence of various organisms within the culture, which is not desired in a pure culture.