Phylogenetic Diversity in the Macromolecular Composition of Microalgae

Abstract

The elemental stoichiometry of microalgae reflects their underlying macromolecular composition and influences competitive interactions among species and their role in the food web and biogeochemistry. Here we provide a new estimate of the macromolecular composition of microalgae using a hierarchical Bayesian analysis of data compiled from the literature. The median macromolecular composition of nutrient-sufficient exponentially growing microalgae is 32.2% protein, 17.3% lipid, 15.0% carbohydrate, 17.3% ash, 5.7% RNA, 1.1% chlorophyll-a and 1.0% DNA as percent dry weight. Our analysis identifies significant phylogenetic differences in macromolecular composition undetected by previous studies due to small sample sizes and the large inherent variability in macromolecular pools. The phylogenetic differences in macromolecular composition lead to variations in carbon-to-nitrogen ratios that are consistent with independent observations. These phylogenetic differences in macromolecular and elemental composition reflect adaptations in cellular architecture and biochemistry; specifically in the cell wall, the light harvesting apparatus, and storage pools.

Production of chemicals from microalgae lipids – status and perspectives

“…Cyanobacteria usually have the lowest cellular lipid content due to their high protein demand for the phycobilisomes. In contrast, heterokonts and haptophytes exhibit the highest relative lipid content, as revealed in a recent analysis which was based on more than hundred published studies about the macromolecular composition of microalgae .…”

“…The values are compiled from different studies under different culture conditions and harvesting points and represent maximum values reported . Hence, they are not directly comparable, but serve as indicators for high lipid producing algae species.…”

Metabolism and foraging strategies of mid‐latitude mesozooplankton during cyanobacterial blooms as revealed by fatty acids, amino acids, and their stable carbon isotopes

“…In waters off southwest Norway, the diet for copepods consists usually of diatoms and dinoflagellates, while cyanobacteria are absent (Erga & Skjoldal, 1990;Peters, Dutz, & Hagen, 2007). Cyanobacteria typically are assumed to be lipid reduced relative to other microalgae groups (Finkel et al, 2016;Jónasdóttir, 2019), yet filamentous Nodularia spumigena and Aphanizomenon spp. made up the majority (43%-67%) of the total phytoplankton cell-carbon at our EGB station during both summers .…”

Stability of Marine Organic Matter Respiration Stoichiometry

“…Respiratory quotient (RQ) estimated from laboratory‐based measurements of phytoplankton macromolecule content. (a) Grey dots = N:C and RQ calculated from 420 observations of marine and freshwater microalgae macromolecular content (Finkel et al, ). Blue dots = Macromolecule endmembers.…”

“…In calculating the elemental composition of bulk phytoplankton biomass, we assume fixed elemental compositions for protein, lipid, carbohydrate, and chlorophyll in terms of C, H, O, N, P (Table S1). Lipid is further split into two pools, two thirds to the P‐free lipid pool and one third to phospholipid (Finkel et al, ). We calculate C, H, O, N, and P content of the bulk organic matter (sum of all the macromolecules) and then compute RQ assuming complete aerobic oxidation of organic matter coupled with nitrification of ammonia to nitrate (Anderson, ): …”