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Gloeocapsa magma

Gloeocapsa magma is a species of bacteria belonging to the gloeocapsa genus of cyanobacteria, an ancient line of photosynthesizing bacteria that photolyze water generating gaseous oxygen. Gloeocapsa magma may resemble "algae" because they are green, but in fact cyanobacteria are bacteria themselves, whereas algae are unicellular eukaryotes (cells with nuclei) closely related to plants.


Gloeocapsa magma cyanobacteria is responsible for creating black spots and streaks on roofs. Bacteria accumulates over time as it feeds on moisture and calcium carbonate. This accumulation turns into large black spots as the cyanobacteria develops their dark and hard outer UV protective coating.

Humidity and high temperatures promote the spread of more and more spores and, over time, the Gloeocapsa magma decomposes the shingles by feeding on the limestone granules embedded in the shingles. This decreases the roof's ability to reflect ultraviolet light rays and shortens the roof's useful life.

Once the bacteria have become noticeable, the stains will continue to worsen year to year. As the bacterial colony grows, gravity pulls it downward, resulting in the smear-like stain down the roof. Most experts within the subject area conclude the bacteria to be harmful -if left untreated- as the growth holds moisture within shingles causing premature aging, rotting, and/or granule loss.


The buildup of Gloeocaspa magma on residential properties has led to earlier roof replacements, lowered property resale values, insurance companies canceling policies and increased utility costs as the black stained roofing draws in more heat.

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