Mold or mildew spots under laminate floor. Concerns?

[Jay C.]

Hi all,

Just got a house with in the Dallas/Fort Worth area this last week. After removing the laminate floors, and the laminate padding that looks like carpet padding called 'quiet walk', the concrete has black spots that look like mold or mildew throughout the concrete.

Is this something that can be treated with bleach and water solution? Is this a normal thing with moisture trapped under the laminate padding?

How can I see if it's mold or mildew?

Thank you