Difference Between Phototrophs and Chemotrophs


Main Difference

The main difference between phototrophs and chemotrophs is that phototrophs are the group of organisms that use energy from sunlight to produce ATP to bring out cellular functions whereas chemotrophs are organisms that acquire energy from chemical oxidation or the chemosynthesis.

Phototrophs vs. Chemotrophs

Phototrophs are the organisms that consume sunlight as their energy source to bring out their cellular functions whereas chemotrophs are the creatures that depend on energy producing by the oxidation of inorganic or organic molecules. There are two types of phototrophs as photoautotrophs and photoheterotrophs whereas chemotrophs contain two main types namely chemoautotrophs and chemoheterotrophs. The prefix “Photo” denotes to the light, and the word “trophy” denotes to the way of obtaining food or the nutrition whereas the prefix “chemo” refers to the chemical. The energy source of phototrophs is mainly sunlight, but the energy source of the chemotrophs is the oxidizing energy of chemical compounds. Phototrophs are not capable of performing chemosynthesis whereas chemotrophs are competent in doing chemosynthesis. Examples of phototrophs are algae, cyanobacteria, green plants, purple non-sulfur bacteria, green non-sulfur bacteria whereas chemotrophs are nitrifiers, thermoacidophiles, methanogens, halophiles, sulfur oxidizers, animals, etc.


Comparison Chart

Phototrophs rely on sunlight to obtain energy.Chemotrophs rely on chemicals for energy production.
Photoautotrophs or photoheterotrophsChemoorganotrophs or chemolithotrophs
Energy Source
SunlightOxidizing energy of chemical compounds
Energy Production Process
Carry out photosynthesisPerform chemosynthesis
Use of Sunlight
Use sunlightCannot use sunlight
Unable to perform chemosynthesisAble to do chemosynthesis
Plants, algae, cyanobacteria, green non-sulfur bacteria, purple non-sulfur bacteria, and heliobacteriaAcidithiobacillus, Nitrosomonas, Nitrobacter, ferrooxidans, and Algae, are chemolithotrophs

What are Phototrophs?

Phototrophs use the energy from light to yield food in the form of organic compounds. In additional words, phototrophs are the organisms that depend on sunlight to produce their particular foods or oxidize organic molecules to provide energy for cellular functions. The prefix “Photo” denotes to the light, and the word “trophy” refers to the mode of obtaining food or the nourishment. Complex organic compounds are eventually used to strengthen cellular metabolic procedures. Photosynthesis is the primary process of taking protons. During photosynthesis, carbon dioxide is anabolically converted into organic material. Glucose is the original form of the organic compound produced in the photosynthesis. Phototrophs use electron transport chain or direct proton pumping to build the electrochemical gradient use in the ATP synthase. ATP provides the chemical energy for cellular functions. Phototrophs are either photoautotrophs or photoheterotrophs. Photoautotrophs convert carbon into simple sugars with light as the energy source. Examples for photoautotrophs are green plants, algae, and cyanobacteria. Photoheterotrophs are carbon fixing organisms from carbon dioxide. Phototrophs which use chlorophyll to capture the light energy, splitting water to yield oxygen are oxygenic photosynthetic organisms. Photoautotrophs are very important for the reliable functioning of most of the ecosystems and the existence of the heterotrophs. Phototrophs are essential as they can eliminate carbon dioxide from the atmosphere and release oxygen in the atmosphere for animal respiration.


What are Chemotrophs?

The organisms which attain their energy by oxidizing electron donors are known as chemotrophs — their carbon source either inorganic carbon or organic carbon. Chemosynthesis is the prime production metabolism in chemotrophs. The prefix “chemo” denotes to the chemical and the word “trophy” states to the nourishment. These organisms are dependent on the chemicals for the energy source. During chemosynthesis, carbon-containing molecules are kept to produce organic compounds as nutrients by dissolving hydrogen gas or hydrogen sulfide. Chemotrophs consist of biogeochemically important taxa like neutrophilic, sulfur-oxidizing proteobacteria, iron-oxidizing bacteria, and methanogenic archaea. Organisms that exit in the dark like oceans use chemosynthesis to produce their food. Chemosynthetic bacteria are consuming by organisms in the sea to carry out a symbiotic relationship. Secondary producers in hydrothermal vents, methane clathrates, cold seeps, and isolating cave water are benefiting by chemotrophs. Two types of chemotrophs can identify as Chemolithotrophs, which oxidize inorganic compounds for energy. Chemoorganotrophs which oxidize organic compounds for strength and Chemolithotrophs use electrons from inorganic chemical sources like ammonium ions, hydrogen sulfide, ferrous ions, and elemental sulfur. Chemotrophs also can either autotrophs or heterotrophs. Chemoautotrophs can produce their foods through chemosynthesis. Chemoautotrophs can identify in ocean floors like underwater volcanos, liberating from sunlight.

Key Differences

  1. The organisms which capture proton to attain energy are known as phototrophs whereas the organisms which accomplish their strength by oxidizing electron donors are known as chemotrophs.
  2. The energy source of phototrophs is primarily sunlight, but the energy source of the chemotrophs is the oxidizing energy of chemical compounds.
  3. Phototrophs are either photoautotrophs or photoheterotrophs while Chemotrophs are either chemoorganotrophs or chemolithotrophs.
  4. Most of the phototrophs bring out photosynthesis oppositely chemotrophs cannot bring out photosynthesis.
  5. Phototrophs can use sunlight on the other hand chemotrophs cannot use sunlight.
  6. Phototrophs are unable to do chemosynthesis on the flip side chemotrophs can do chemosynthesis.
  7. Examples of phototrophs are green algae, cyanobacteria plants, purple non-sulfur bacteria, green non-sulfur bacteria conversely chemotrophs are nitrifiers, thermoacidophiles, methanogens, halophiles, sulfur oxidizers, animals, etc.


Phototrophs and chemotrophs are two leading groups of organisms that are classified based on the type of nutrition. Phototrophs create energy for their cellular processes using sunlight. Chemotrophs are incapable of using solar energy, but they depend on the energy-producing by the chemosynthesis.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White