RRC ID 56497
Author Allen JW, Tevatia R, Demirel Y, DiRusso CC, Black PN.
Title Induction of oil accumulation by heat stress is metabolically distinct from N stress in the green microalgae Coccomyxa subellipsoidea C169.
Journal PLoS One
Abstract Algae are often promoted as feedstock organisms to produce a sustainable petroleum fossil fuel alternative. However, to induce lipid accumulation most often requires a severe stress that is difficult to induce in large batch cultures. The objective of this study is to analyze and mathematically model heat stress on growth, chlorophyll content, triacylglyceride, and starch synthesis in algae. We initially screened 30 algal species for the most pronounced induction of lipid droplets from heat stress using confocal microscopy and mass spectroscopy techniques. One species, Coccomyxa subellipsoidea C169, was selected and subjected to further biochemical analyses using a jacketed bioreactor amended with 1% CO2 at 25°C, 30°C, 32°C, 33°C, 34°C, 35°C, and 36°C. Lipid and starch accumulation was less extreme than N stress. Growth was reduced above 25°C, but heat stress induced lipid droplet synthesis was negatively correlated with growth only past a demonstrated threshold temperature above 32°C. The optimal temperature for lipid accumulation was 35°C, which led to 6% of dry weight triglyceride content and a 72% reduction from optimal growth after 5 days. Fatty acid influx rates into triglycerides and 15N labeling of amino acids and proteins indicate that heat stress is mechanistically distinct from N stress. Thus, this study lends support to a novel hypothesis that lipid droplet triglycerides result from a redistribution of carbon flux as fatty acids to neutral storage lipids over membrane or other lipids.
Volume 13(9)
Pages e0204505
Published 2018-9-27
DOI 10.1371/journal.pone.0204505
PII PONE-D-18-10647
PMID 30261009
PMC PMC6160078
MeSH Biofuels* Biomass Bioreactors Chlorophyll / metabolism Chlorophyta / classification Chlorophyta / growth & development Chlorophyta / metabolism* Fatty Acids / metabolism Heat-Shock Response Lipid Droplets / metabolism Lipid Metabolism Microalgae / classification Microalgae / growth & development Microalgae / metabolism* Models, Biological Nitrogen / metabolism Phylogeny Species Specificity Starch / metabolism Temperature Triglycerides / metabolism
IF 2.776
Times Cited 4