Researchers at the University of Mississippi are looking to imported fire ants (IFA) (Solenopsis sp.) as a source for oleaginous microorganisms or enzymes supporting the digestion of raw sugars for the production of oil to be used as feedstock for biodiesel.
In a paper in the journal Fuel, they note that the yield of ant oil is 16% dry weight and contains most of the fatty acids also found in other biomass resources. Thus, the unusual amount of oil extracted from the imported fire ant (Solenopsis sp.) may be an indication of the presence of oleaginous microorganisms, they suggested.
Black (Solenopsis richteri) and red (Solenopsis invicta, Buren) imported fire ants (IFA) were introduced to the United States form South America by the early 1930s and now represent a considerable nuisance to humans in both rural and urban settings. Various chemical and biological methods for IFA control were developed, but few attempts have been made to utilize the ants or their associated chemistry and microbiology for practical applications.
One study of the lipid composition of IFA determined that 65-75% was composed of hydrocarbons. In these studies, only the cuticular lipids were extracted by dipping the insects briefly into hexane. This dipping method effectively enriches the extract with non-oxygenated hydrocarbons and piperidine venom alkaloids, but leaves behind more polar fatty acids and mono-, di-, and tri-glycerides. In contrast, exhaustive extraction of the IFA produces an unprecedented large amount of oil which contains significant amounts of fatty acid related components commonly used in the production of biodiesel.
… Very little information concerning the internal microbial flora of IFA is available; it is possible that symbiotic microorganisms reside in association with the IFS providing digestion support for a variety of materials including processing raw saccharide into lipid. Such a symbiotic relationship between microbes and ants has already been observed in the case of the fungus growing attine ants which cultivate a fungal crop to provide food for its colony.—Bowling et al.
After collecting ants from several IFA colonies, preparing them and extracting the lipids, the researchers found that purification of the crude lipid extract produced an amber oil of 16% overall dry weight. This is slightly lower than the yield reported for soybeans (18%), but the amount could reasonably increase or decrease, the researchers suggested.
Heat of combustion for the ant oil was 133,000 BTU/gal—comparable to typical soybean oil and soybean biodiesel.
Our investigation highlights a potential route for the development of a more affordable fuel. The development of a high capacity method for production of oils from lignocellulosic material or even simpler carbohydrates could reduce the materials cost of producing biodiesel. Investigation of a microbial source for thie extraordinary amount of oil production in IFA or insects that digest plant matter (i.e., termites, carpenter ants) could lead to improvements in bioenergy production.—Bowling et al.
John J. Bowling, James B. Anderson, Kevin L. Armbrust, Mark T. Hamann (2014) “Evaluation of potential biodiesel feedstock production from oleaginous insect Solenopsis sp.,” Fuel, Volume 117, Part A, Pages 5-7 doi: 10.1016/j.fuel.2013.08.058