title: Lipid storage in high-altitude Andean Lakes extremophiles and its mobilization under stress conditions in Rhodococcus sp. A5, a UV-resistant actinobacterium.
abstract: The production of triacylglycerols (TAG) or wax esters (WS) seems to be a widespread feature among extremophile bacteria living in high-altitude Andean Lakes (HAAL), Argentina. Twelve out of twenty bacterial strains isolated from HAAL were able to produce TAG or WS (between 2 and 17 % of cellular dry weight) under nitrogen-limiting culture conditions. Among these strains, the extremophile Rhodococcus sp. A5 accumulated significant amounts of TAG during growth on glucose (17 %, CDW) and hexadecane (32 %, CDW) as sole carbon sources. The role of accumulated TAG in the response to carbon starvation, osmotic stress, UV-radiation and desiccation was investigated in Rhodococcus sp. A5 using an inhibitor of TAG degradation. Cells degraded TAG during these stresses in the absence of the inhibitor. The inhibition of TAG mobilization affected cell survival during osmotic stress only during the initial growth stage. Little or no surviving cells were observed after carbon starvation, UV-treatment and desiccation, when TAG mobilization was inhibited. These results suggested that TAG metabolism is relevant for the adaptation and survival of A5 cells under carbon starvation, osmotic stress and UV irradiation, and essential under desiccation conditions, which prevail in HAAL environments.
authors.affiliation: Facultad de Ciencias Naturales, Centro Regional de Investigación Y Desarrollo Científico Tecnológico (CRIDECIT), Universidad Nacional de la Patagonia San Juan Bosco, Km 4-Ciudad Universitaria, Comodoro Rivadavia, Chubut, Argentina.
authors.forename: Susana
authors.initials: S
authors.lastname: Bequer Urbano
authors.forename: Virginia H
authors.initials: VH
authors.lastname: Albarracín
authors.forename: Omar F
authors.initials: OF
authors.lastname: Ordoñez
authors.forename: María E
authors.initials: ME
authors.lastname: Farías
authors.forename: Héctor M
authors.initials: HM
authors.lastname: Alvarez
mesh_terms: D000473:Alkanes / Q000378:metabolism; D000531:Altitude; D001118:Argentina; D002244:Carbon / Q000378:metabolism; D049109:Cell Proliferation; D003890:Desiccation; D005947:Glucose / Q000378:metabolism; D060106:Lakes / Q000382:microbiology; D009154:Mutation; D009997:Osmotic Pressure; D010802:Phylogeny; D012240:Rhodococcus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism* / Q000528:radiation effects; D013217:Starvation; D013312:Stress, Physiological; D014280:Triglycerides / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D000473:Alkanes; D014280:Triglycerides; D002244:Carbon; C007932:n-hexadecane; D005947:Glucose