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Distinguish the appearance of selected gram-negative bacterial colonies growing on EMB Agar, representing strong, moderate and non- lactose fermenters

User Yamachan
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Final answer:

On EMB Agar, strong lactose fermenters show metallic green or deep purple colonies, moderate fermenters display pink or dark purple colonies, and non-fermenters produce colorless colonies.

Step-by-step explanation:

The distinction in the appearance of gram-negative bacterial colonies on EMB Agar is based on their ability to ferment lactose. Strong lactose fermenters will display colonies with a distinctive metallic green sheen or deep purple color. Moderate lactose fermenters produce pink or dark purple colonies without the metallic sheen, while non-lactose fermenters form colorless or transparent colonies due to the lack of lactose fermentation.

On EMB Agar, strong, moderate, and non-lactose fermenters can be distinguished by their colony appearance. Lactose fermenters will form metallic green or deep purple colonies on EMB Agar. These colonies have a distinctive color due to the fermentation of lactose, which produces acid that reacts with the eosin and methylene blue dyes in the agar. Non-lactose fermenters, on the other hand, will form colonies that are completely colorless on EMB Agar.

User MiStr
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