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Applied Microbiology and Biotechnology

, Volume 98, Issue 11, pp 4839–4851 | Cite as

The prominent role of fungi and fungal enzymes in the ant–fungus biomass conversion symbiosis

  • L. Lange
  • M. N. Grell
Mini-Review

Abstract

Molecular studies have added significantly to understanding of the role of fungi and fungal enzymes in the efficient biomass conversion, which takes place in the fungus garden of leaf-cutting ants. It is now clear that the fungal symbiont expresses the full spectrum of genes for degrading cellulose and other plant cell wall polysaccharides. Since the start of the genomics era, numerous interesting studies have especially focused on evolutionary, molecular, and organismal aspects of the biological and biochemical functions of the symbiosis between leaf-cutting ants (Atta spp. and Acromyrmex spp.) and their fungal symbiont Leucoagaricus gongylophorus. Macroscopic observations of the fungus-farming ant colony inherently depict the ants as the leading part of the symbiosis (the myrmicocentric approach, overshadowing the mycocentric aspects). However, at the molecular level, it is fungal enzymes that enable the ants to access the nutrition embedded in recalcitrant plant biomass. Our hypothesis is that the evolutionary events that established fungus-farming practice were predisposed by a fascinating fungal evolution toward increasing attractiveness to ants. This resulted in the ants allowing the fungus to grow in the nests and began to supply plant materials for more fungal growth. Molecular studies also confirm that specialized fungal structures, the gongylidia, with high levels of proteins and rich blend of enzymes, are essential for symbiosis. Harvested and used as ant feed, the gongylidia are the key factor for sustaining the highly complex leaf-cutting ant colony. This microbial upgrade of fresh leaves to protein-enriched animal feed can serve as inspiration for modern biorefinery technology.

Keywords

Leucoagaricus Leaf-cutting ants Fungus garden Fungal enzymes Expressed enzyme profiles Biomass conversion 

Notes

Acknowledgments

We would like to thank Jacobus J. Boomsma for his critical reading of a previous version of this manuscript and for constructive comments and suggestions and Pepijn Kooij for sharing unpublished observations and for providing colony material for photographs (Leucoagaricus gongylophorus, AC-2009-47, leg. et det. Pepijn Kooij, Gamboa, Panama). The authors further wish to thank David Nash and Henrik H. De Fine Licht, University of Copenhagen, and Ib Søndergaard for the fungus garden photographs. The authors were partially funded by the Danish Strategic Research Foundation, grant no. 2101-07-0099.

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© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Department of Biotechnology, Chemistry and Environmental EngineeringAalborg UniversityCopenhagenDenmark

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