Mixed evolutionary origins of endogenous biomass-depolymerizing enzymes in animals

Area of Science:

• Genomics
• Evolutionary Biology
• Biochemistry

Background:

• The conventional understanding of lignocellulose digestion in animals relies heavily on symbiotic gut microbes, with less focus on endogenous animal systems.
• The existence of animal-encoded biomass conversion systems has not been definitively established.

Purpose of the Study:

• To conduct an exhaustive search for glycoside hydrolase (GH) genes within animal genomes across major lineages.
• To investigate the evolutionary origins and dietary influences on animal lignocellulolytic enzyme repertoires.

Main Methods:

• Genome-wide search for glycoside hydrolase (GH) genes in 21 animal genomes and a unicellular relative (Capsaspora owczarzaki).
• Comparative analysis of 126 crustacean transcriptomes.
• Phylogenetic analyses to determine gene origins (vertical inheritance vs. horizontal gene transfer).

Main Results:

• Identified 16,723 GH homologs (2373 genes from animal genomes, 14,350 from crustacean transcriptomes) across 60 GH families.
• Demonstrated that animals encode enzymatic suites for biomass decomposition, functioning as micro-scale bioreactors.
• Revealed multiple evolutionary origins for animal lignocellulolytic enzymes, including vertical inheritance and acquisition from non-animal sources.

Conclusions:

• Animal biomass decay capabilities are linked to dietary strategies; detritivores exhibit broader enzymatic functions compared to specialists.
• The identified animal GH gene candidates are valuable for future functional genomics research.
• This study provides a platform for discovering novel enzyme candidates with potential industrial applications.