Planta

, Volume 238, Issue 5, pp 895–906

Conversion of membrane lipid acyl groups to triacylglycerol and formation of lipid bodies upon nitrogen starvation in biofuel green algae Chlorella UTEX29

  • Elton C. Goncalves
  • Jodie V. Johnson
  • Bala Rathinasabapathi
Original Article

DOI: 10.1007/s00425-013-1946-5

Cite this article as:
Goncalves, E.C., Johnson, J.V. & Rathinasabapathi, B. Planta (2013) 238: 895. doi:10.1007/s00425-013-1946-5

Abstract

Algal lipids are ideal biofuel sources. Our objective was to determine the contributors to triacylglycerol (TAG) accumulation and lipid body formation in Chlorella UTEX29 under nitrogen (N) deprivation. A fivefold increase in intracellular lipids following N starvation for 24 h confirmed the oleaginous characteristics of UTEX29. Ultrastructural studies revealed increased number of lipid bodies and decreased starch granules in N-starved cells compared to N-replete cells. Lipid bodies were observed as early as 3 h after N removal and plastids collapsed after 48 h of stress. Moreover, the identification of intracellular pyrenoids and differences in the expected nutritional requirements for Chlorella protothecoides (as UTEX29 is currently classified) led us to conduct a phylogenetic study using 18S and actin cDNA sequences. This indicated UTEX29 to be more phylogenetically related to Chlorella vulgaris. To investigate the fate of different lipids after N starvation, radiolabeling using 14C-acetate was used. A significant decrease in 14C-galactolipids and phospholipids matched the increase in 14C-TAG starting at 3 h of N starvation, consistent with acyl groups from structural lipids as sources for TAG under N starvation. These results have important implications for the identification of key steps controlling oil accumulation in N-starved biofuel algae and demonstrate membrane recycling during lipid body formation.

Keywords

BiofuelChlorellaGalactolipidRadiolabelingTriacylglycerolUltrastructure

Supplementary material

425_2013_1946_MOESM1_ESM.docx (69 kb)
Supplementary material (DOCX 69 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Elton C. Goncalves
    • 1
  • Jodie V. Johnson
    • 2
  • Bala Rathinasabapathi
    • 1
  1. 1.Plant Molecular and Cellular Biology Program, Horticultural Sciences DepartmentUniversity of FloridaGainesvilleUSA
  2. 2.Chemistry DepartmentUniversity of FloridaGainesvilleUSA