Though some bacteria cause disease and illness in humans, the majority are harmless. some bacteria are used to aid digestion, used in preparation of certain foods, used to battle infections or used by industry. bacteria have many important roles in nature. all but one is a role of bacteria out in the world around us.

a) some bacteria increase the soil fertility.
b) bacteria carry out 60% of total nitrogen fixation in natural ecosystems.
c) bacteria are responsible for converting sunlight into usable chemical energy.
d) bacteria decompose organic matter, by decay and putrefaction, to keep our earth clean.

Bacteria have many important roles in nature except being responsible for

converting sunlight into usable chemical energy.

Bacteria are organisms and are prokaryotes and have some beneficial

uses e.g in decomposition as well as non-beneficial uses e.g pathogens for

illnesses.

Bacteria however don't convert sunlight into usable chemical energy as this

is done by the primary producers such as plants. This process is regarded as

photosynthesis in which plants convert light energy from the sun to

chemical energy needed by the consumers.

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C) Bacteria are responsible for converting sunlight into usable chemical energy.

**This is the role of producers, mostly plants and algae, on Earth. Producers start a food chain; decomposers like bacteria complete it.

this is a good question! i'll do some research and come back when i have the answer!

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.