How do bacteria that live in a hot spring control the fluidity of their plasma membrane?

Thermophilic bacteria adjust the fluidity of their plasma membrane by increasing the distinct fatty acids and polar carotenoid content.

Explanation:

Thermophilic bacteria adjust fluidity of their plasma membrane by increasing the following content in it;

Branched iso-fatty acids Long-chain fatty acids Saturated fatty acids Polar carotenoid content

Interestingly, the thermophilic bacteria that grow above 70°C possess lipid species such as diether, tetraethers, and tetra esters.