Which type of bacteria can survive in extreme environments?

Archaea are a unique group of microorganisms that are well known for their ability to survive in extreme environments, often referred to as extremophiles. These environments can include extreme temperatures (such as hot springs and hydrothermal vents), high salinity (like salt lakes), extreme pH levels (acidic or alkaline conditions), and even anaerobic conditions (lacking oxygen). The cell membranes and metabolic processes of Archaea are specially adapted to function under these harsh conditions, unlike most other bacteria.

In contrast, Gram-positive bacteria, Proteobacteria, and Firmicutes do not generally thrive in such extreme conditions. While some species within these groups may exhibit a degree of resilience, they do not encompass the broad and specialized adaptations that Archaea possess to inhabit extreme environments. Consequently, Archaea are distinctly recognized for their extremophilic characteristics, making them the correct answer to this question.