by Cliff Bueno de Mesquita
In our recent and ongoing experiments on the effects of herbicides on soil microbes, we found one species of fungus, Mortierella elongata, that was not negatively affected by the herbicide Glyphosate (ingredient in Roundup), and actually responded positively to the surfactant it is usually spread with, Agridex. Soils collected from the nearby Chatfield Farm outside of Denver had received treatments of Glyphosate, Agridex, Promax (another surfactant), Agridex and Glyphosate combined, and controls with no chemical additions.
M. elongata is a fungus in the Mucoromycota phylum. Mortierella species are typically saprotrophs but also grow on the surface of roots. They are capable of degrading complex carbon compounds such as chitin and hemicellulose. They reproduce via formation of thick-walled spores called zygospores, which are produced by many other species of fungi as well as algae (Gams, Chien, and Domsch 2009). Typically, they are not pathogenic.
Figure 1. Morphology of Mortierella elongata CNUFC-YR329-1. A, D colony on potato dextrose agar; B, E colony on oatmeal agar; C, F colony on water agar; (A-C: observed view, D-F: reverse view). G-I young sporangia on sporangiophores; J the collar at the top of the sporangiophore (white arrow). K sporangiosphores (scale bars: G-K ¼ 20 lm). From Nguyen et al. 2019.
M. elongata has been isolated and cultured. It produces Arachidonic acid (an omega-6 fatty acid also found in red meat), as well as Eicosapentaenoic acid (also known as EPA omega-3 fatty acid), both of which people take as supplements (Bajpai, Bajpai, and Ward 1991; Yamada, Shimizu, and Shinmen 1987). However, it appears that there was never large-scale commercial production of M. elongata for those purposes. Another interesting thing about this fungus is it contains a bacterium inside of it, called an endobacterium, which was identified as Mycoavidus cysteinexigens (Ohshima et al. 2016). Researchers suggested that this endobacterium was responsible for the production of nitrous oxide (Sato et al. 2010), a greenhouse gas, and there has been considerable interest in the bacterium, as its whole genome has been sequenced and assembled (Fujimura et al. 2014).
Our result with M. elongata highlights the importance of studying chemicals used to help spread herbicides, in addition to the herbicide itself. Stay tuned in future months for more results from our herbicide experiment!
Bajpai, P., P. K. Bajpai, and O. P. Ward. 1991. “Eicosapentaenoic Acid (EPA) Formation: Comparative Studies with Mortierella Strains and Production by Mortierella Elongata.” Mycological Research 95(11): 1294–98. http://dx.doi.org/10.1016/S0953-7562(09)80577-7.
Fujimura, R. et al. 2014. “Draft Genome Sequence of the Betaproteobacterial Endosymbiont Associated with the Fungus Mortierella Elongata FMR23-6.” Genome Announcements 2(6): 2010–11.
Gams, W., Chiu-Yuan Chien, and K.H. Domsch. 2009. “Zygospore Formation by the Heterothallic Mortierella Elongata and a Related Homothallic Species, M. Epigama Sp.Nov.” Transactions of the British Mycological Society 58(1): 5–13. http://dx.doi.org/10.1016/S0007-1536(72)80065-2.
Nguyễn, Thưởng & Won Park, Se & Pangging, Monmi & Lee, Hyang. (2019). Molecular and Morphological Confirmation of Three Undescribed Species of Mortierella from Korea. Mycobiology. 47. 31-39. 10.1080/12298093.2018.1551854.
Ohshima, Shoko et al. 2016. “Mycoavidus Cysteinexigens Gen. Nov., Sp. Nov., an Endohyphal Bacterium Isolated from a Soil Isolate of the Fungus Mortierella Elongata.” International Journal of Systematic and Evolutionary Microbiology 66(5): 2052–57.
Sato, Yoshinori et al. 2010. “Detection of Betaproteobacteria inside the Mycelium of the Fungus Mortierella Elongata.” Microbes and Environments 25(4): 321–24. http://joi.jlc.jst.go.jp/JST.JSTAGE/jsme2/ME10134?from=CrossRef.
Yamada, Hideaki, Sakayu Shimizu, and Yoshifumi Shinmen. 1987. “Production of Arachidonic Acid by Mortierella 1S-5.” Agricultural and Biological Chemistry 51(3): 5–10.
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