On the Origin of Heterotrophy

Area of Science:

• Origin of Life Studies
• Biochemistry
• Geochemistry

Background:

• The autotrophic theory suggests early life utilized CO2 for carbon.
• Hydrothermal vents show methane synthesis linked to geochemistry.
• The origin of early heterotrophs and their substrates remains unclear.

Purpose of the Study:

• To propose a substrate for the first chemoorganoheterotrophs.
• To identify potential early heterotrophic metabolic pathways.
• To link early heterotrophy to an autotrophic origin.

Main Methods:

• Analyzing proposed substrates for early heterotrophs.
• Investigating amino acid and purine fermentation pathways.
• Examining the role of specific biochemical processes like electron bifurcation.

Main Results:

• Cellular mass, similar to E. coli, is proposed as the initial substrate.
• Amino acid and purine fermentations are identified as early heterotrophic metabolisms.
• Ribose is suggested as an early abundant sugar, with specific pathways potentially indicating ancient heterotrophy.

Conclusions:

• Early heterotrophy likely utilized cell mass and simple fermentation pathways.
• Metabolic processes like chemiosmotic coupling and electron bifurcation support an autotrophic origin for heterotrophy.
• The study provides insights into the transition from autotrophic to heterotrophic life forms.