Umbelopsis (Mucoromycota) from Patagonia, Argentina: identification, phylogenetic analysis, and expression profiling of lipase activity and lipid accumulation in selected isolates

Abstract

Umbelopsis Amos & H.L. Barnett (Umbelopsidales, Mucoromycota) is a fungal genus reported as a producer of lipases and lipids. In the Southern Cone of America, there are a few records of Umbelopsis species. In this work, isolates from Nothofagus forests grown in Patagonia (Argentina) were identified using morphological and molecular criteria and characterized by their lipolytic enzyme production on Tween 20, Tween 80, olive oil, Nothofagus sawdust, and forest soil. Liquid and solid cultures and two different measurement methods were also tested. Furthermore, lipid composition in selected isolates was analyzed. Our results showed that Patagonian isolates belong to U. changbaiensis, U. nana, U. ramanniana, and U. vinacea. LPSc 520 and 521, isolated from forest soils in Tierra del Fuego and previously reported as Mortierella vinacea, were clustered in the U. ramanniana clade. A spectrophotometric method using 1,2-O-dilaurylrac-glycerol-3-glutaric acid-(6′-methylresorufin) ester as enzyme substrate was useful in detecting lipase activity in Umbelopsis isolates grown in liquid cultures; the results were compared with titrimetric analysis using NaOH. The U. ramanniana clade included isolates that showed their highest levels of lipase activity and lipid production in liquid cultures containing olive oil, Nothofagus sawdust, or forest soil. LPSc 521 showed the highest production of triacylglycerides and free fatty acids, such as palmitic acid, and unsaturated acids such as oleic, linoleic, and γ-linolenic. Since this lipid profile might be related to the habitat the fungus was isolated from, LPSc 521 may constitute an outstanding isolate for the synthesis of lipases and/or lipids adapted to cold conditions.