Apart from plants and animals, microbes form a permanent biotic component in an ecosystem. While plants are referred to as autotrophs and animals as heterotrophs, what are microbes referred to as? How do microbes fulfill their energy requirements?

(N/A) Microbes, specifically bacteria and fungi, are primarily referred to as $saprotrophs$ or $decomposers$ in an ecosystem.
They fulfill their energy requirements by breaking down complex organic matter from dead and decaying plants and animals into simpler substances.
This process is known as $extracellular$ $digestion$, where microbes secrete digestive enzymes onto the organic matter, absorb the resulting nutrients, and release inorganic minerals back into the soil, thereby playing a crucial role in nutrient cycling.