Pseudallescheria boydii. This is the name of a microbe which grows inside a termite from French Guiana, in a mutualism process. Three members of the CEBA have isolated this microbial symbiont and discovered that it produces two antifungal compounds in great quantity. One of these two compounds is new for science.
The results of these works were published in April 29th, 2013, in Journal of Natural Products and could have applications to combat certain mycoses present in human beings.
Social insect colonies may host large numbers of individuals in a constrained environment. Promiscuity, frequent interactions, and genetic homogeneity are factors that in principle favor the transmission of infectious pathogens. The literature demonstrates that social insects have evolved behavioral and physiological defense systems to prevent colonies from spreading infectious pathogens and have also developed mutually beneficial associations with microbes that provide colonies with antimicrobial agents. Owing to the extreme diversity of insects and microbes, insect colonies represent an alternative and attractive natural source of bioactive compounds.
On this basis, a team composed of a doctoral fellow and two researchers of the CEBA, who work at Ecofog and at the ICSN, had the idea to study the symbiont of an Amazonian termite species. The team thus discovered an antifungal activity potentially interesting for the treatment of fungal infections.
A Nasutitermes sp. termite worker was collected from a termite mound situated in a tree in Rémire-Montjoly, French Guiana, and was then surface sterilized. A strain which grows inside this termite, Pseudallescheria boydii, was isolated by the scientists, who then identified two antifungal metabolites thanks to a bioguided fractionation.
One of the compounds, N -methyltyroscherine, is described in the scientific literature for the first time through this publication. Besides, hemisynthesis has confirmed the chemical structure from the other compound, tyroscherin.
Termite mound situated in Rémire-Montjoly, French Guiana, on which the termite worker from the species Nasutitermes sp. was collected © Charlotte Nirma
After the study of the antibacterial activities of these two molecules, the researchers found that they are effective antifungal agents against Candida albicans, a yeast species which causes fungal infections called candidiasis. Moreover, they possess an interesting activity against Tricophyton rubrum, a fungus that causes skin and nail mycoses, such as the ‘athlete’s foot’.
The microbe P. boydii probably provides its host termite with an effective antifungal therapy. These findings illustrate how termite symbionts may inspire the discovery of antifungal agents.
Whether this strain is shared by the whole colony is a question that remains to be addressed.
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References of the publication:
Antifungal Agents from Pseudallescheria boydii SNB-CN73 Isolated from a Nasutitermes sp. Termite
Nirma C, Eparvier V, Stien D
Revue Journal of Natural Products, 2013, 76 (5), pages 988−991
Publication dates : April 29th, 2013
To view the publication: http://pubs.acs.org/doi/abs/10.1021/np4001703
Contact communication :
Claire Lafleur, CEBA, claire.lafleur@labex-ceba.fr, tel : +594 (0)5 94 38 87 58
