Sweet Moulds

For reasons that shouldn't be too hard to work out, much of microbial diversity has only been identified within the last few decades. In 1985, researchers identified a distinctive new species of mycelium-forming bacterium from soil in China that they dubbed Glycomyces harbinensis. This was the first known species of the actinobacterial family Glycomycetaceae which have since been isolated from a wide range of soil microbiomes.

Agar culture of Stackebrandtia nassauensis (scanning electron micrograph), from Goodfellow et al. (2012).

Glycomycetes form pale (white to tan-coloured) branching mycelium a bit less than half a micron in diameter. Under certain conditions, they will form aerial mycelia comprising long chains of spores but these seem to only ever be sparse. The name of the family (which could be translated as 'sweet moulds') refers to the presence of the amino-acid glycine as a significant component of the cell wall. Other diagnostic components of the cell include the sugar ribose and the phospholipid phosphatidylglycerol (Goodfellow et al. 2012).

Since the original description of Glycomyces, half a dozen genera and numerous species have been recognised among the Glycomycetaceae. Some, such as Haloglycomyces and Natronoglycomyces, were described from high salinity soils (Sorokin et al. 2021). Other glycomycetes, such as Glycomyces sambucus, are endophytic, living inside the roots of plants. Doubtless (as always) many more remain to be discovered.

I haven't found any references to direct usage of glycomycetes by humans as yet. It has been suggested that endophytic bacteria may play a role in their hosts' uptake of nutrients from the soil. And I wonder if those species found in salty soils may have a contribution to make to the rehabilitation of such environments. In parts of the world such as here in southern Western Australia, where rising soil salinity is a concerning issue, any help would be more than welcome!

REFERENCES

Goodfellow, M., P. Kämpfer, H.-J. Busse, M. E. Trujillo, K. Suzuki, W. Ludwig & W. B. Whitman (eds) 2012. Bergey's Manual of Systematic Bacteriology 2^nd ed. vol. 5. The Actinobacteria, Part A and B. Springer.

Sorokin, D. Y., T. V. Khijniak, A. P. Zakharycheva, A. G. Elcheninov, R. L. Hahnke, O. V. Boueva, E. V. Ariskina, B. Bunk, I. V. Kublanov & L. I. Evtushenko. 2021. Natronoglycomyces albus gen. nov., sp. nov., a haloalkaliphilic actinobacterium from a soda solonchak soil. International Journal of Systematic and Evolutionary Microbiology 71: 004804.