Fervidicoccus fontis Strain 3639Fd, the First Crenarchaeon Capable of Growth on Lipids

Up to now, ability of prokaryotes to grow on lipids has been shown only for bacteria. Thermococcus sibiricus, member of the phylum Euryarchaeota isolated from a high-temperature oil well and capable of growth on olive oil, is the only exception. The present work reports isolation of a pure culture of a strictly anaerobic archaeon, strain 3639Fd (=VKM B-3509, =KCTC 25228) from a Kamchatka thermal spring, capable of growth on various lipids (tributyrin, triolein, and sesame, cottonseed, and sunflower oil) at 70°C and pH 5.5–6.0. Growth on tributyrin resulted in formation of butyrate, CO2, and hydrogen. According to the results of the 16S rRNA gene sequence analysis and in silico DNA–DNA hybridization, the isolate was classified as a strain of Fervidicoccus fontis, an archaeon of the phylum Crenarchaeota. The closest characterized homologs of the α/β-hydrolases, encoded in the genomes of F. fontis 3639Fd and of the type strain of this species, Kam940T, were various carboxyl esterases (EC 3.1.1), the enzymes responsible for lipid hydrolysis. Thus, F. fontis is the first crenarchaeon able to obtain energy by hydrolysis of lipid substrates.