Metabolomic Study of Heterotrophically Grown Chlorella sp. Isolated from Wastewater in Northern Sweden.

Jean Claude Nzayisenga,Anita Sellstedt

doi:10.3390/molecules26092410

Jean Claude Nzayisenga, Anita Sellstedt

Open Access

https://doi.org/10.3390/molecules26092410

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Abstract

There are numerous strains of Chlorella with a corresponding variety of metabolic pathways. A strain we previously isolated from wastewater in northern Sweden can grow heterotrophically as well as autotrophically in light and has higher lipid contents under heterotrophic growth conditions. The aims of the present study were to characterize metabolic changes associated with the higher lipid contents in order to enhance our understanding of lipid production in microalgae and potentially identify new compounds with utility in sustainable development. Inter alia, the amino acids glutamine and lysine were 7-fold more abundant under heterotrophic conditions, the key metabolic intermediate alpha-ketoglutarate was more abundant under heterotrophic conditions with glucose, and maltose was more abundant under heterotrophic conditions with glycerol than under autotrophic conditions. The metabolite 3-hydroxy-butyric acid, the direct precursor of the biodegradable plastic PHB (poly-3-hydroxy-butyric acid), was also more abundant under heterotrophic conditions. Our metabolomic analysis has provided new insights into the alga’s lipid production pathways and identified metabolites with potential use in sustainable development, such as the production of renewable, biodegradable plastics, cosmetics, and nutraceuticals, with reduced pollution and improvements in both ecological and human health.

Highlights

Microalgae can play important roles in sustainable development and amelioration of climate change [1,2], both as potential sources of renewable fuel and substances such as the biodegradable plastic polyhydroxy butyric acid (PHB, from poly-3-hydroxybutyric acid)
This study provides more detailed information on the metabolic profiles, and key pathways, of the local Chlorella strain under four conditions: autotrophic, mixotrophic, and heterotrophic with glycerol or glucose as the sole carbon source
After 8 days of growth, there was no significant difference in biomass between cultures grown autotrophically, mixotrophically with glycerol, and heterotrophically with glucose (Table 1)

Summary

Introduction

Microalgae can play important roles in sustainable development and amelioration of climate change [1,2], both as potential sources of renewable fuel (biodiesel) and substances such as the biodegradable plastic polyhydroxy butyric acid (PHB, from poly-3-hydroxybutyric acid). There is a direct comparison that can be drawn between micro particles from plastic and diesel particles. Diesel engines exhaust small particles that are less than. These particles are capable of crossing cell membranes and triggering oxidative stress and inflammation that have been linked to increased risk of cardiovascular and respiratory diseases and lung cancer [4]. Taking this into account, it is urgent to decrease the use of plastics from oil-based materials by increasing the use of products from microalgae.

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