Nitrogen Availability Affects the Metabolic Profile in Cyanobacteria.

Kosuke Inabe,Yuichi Kato,Tomohisa Hasunuma,Akihiko Kondo,Ryota Hidese,Mami Matsuda,Takanobu Yoshida,Ayaka Miichi

doi:10.3390/metabo11120867

Abstract

Nitrogen is essential for the biosynthesis of various molecules in cells, such as amino acids and nucleotides, as well as several types of lipids and sugars. Cyanobacteria can assimilate several forms of nitrogen, including nitrate, ammonium, and urea, and the physiological and genetic responses to these nitrogen sources have been studied previously. However, the metabolic changes in cyanobacteria caused by different nitrogen sources have not yet been characterized. This study aimed to elucidate the influence of nitrate and ammonium on the metabolic profiles of the cyanobacterium Synechocystis sp. strain PCC 6803. When supplemented with NaNO3 or NH4Cl as the nitrogen source, Synechocystis sp. PCC 6803 grew faster in NH4Cl medium than in NaNO3 medium. Metabolome analysis indicated that some metabolites in the CBB cycle, glycolysis, and TCA cycle, and amino acids were more abundant when grown in NH4Cl medium than NaNO3 medium. 15N turnover rate analysis revealed that the nitrogen assimilation rate in NH4Cl medium was higher than in NaNO3 medium. These results indicate that the mechanism of nitrogen assimilation in the GS-GOGAT cycle differs between NaNO3 and NH4Cl. We conclude that the amounts and biosynthetic rate of cyanobacterial metabolites varies depending on the type of nitrogen.

Highlights

Nitrogen is an important element for living things, being used in amino acids, nucleotides, lipids, and sugars, which are building blocks of all forms of life
In our previous report, we revealed that the different metabolic profiles produced during dark anoxic cultivation after a transfer from phototrophic cultivation with different nitrogen sources enhanced the production of succinate
The growth rate of Synechocystis was calculated based on the growth data by 48 h when there are the residual nitrogen sources

Summary

Introduction

Nitrogen is an important element for living things, being used in amino acids, nucleotides, lipids, and sugars, which are building blocks of all forms of life. Cyanobacteria are Gram-negative bacteria and are known to be oxygenic photosynthetic microorganisms that utilize solar energy to generate chemical energy (ATP and NADPH). Such chemical energy is used in the Calvin–Benson–Bassham cycle (CBB cycle), glycolysis, and tricarboxylic acid (TCA cycle). PCC 6803 can take up nitrogen as NO3 − , NO2 − , NH4 + , CO(NH2 ).

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