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July 19, 2021
JAMSTEC
TOYOHASHI UNIVERSITY OF TECHNOLOGY
National Institutes of Natural Sciences
National Institute for Physiological Sciences

Discovering the capability of the phytoplankton Dicrateria rotunda to synthesize hydrocarbons equivalent to petroleum

1. Key points

Phytoplankton: We discovered that Dicrateria rotunda (D. rotunda), a species of Haptophyte, can synthesize hydrocarbons equivalent to petroleum (saturated hydrocarbons with a carbon number ranging from 10 to 38). No organism capable of petroleum production has been previously reported.
All of the eleven Dicrateria strains examined in this study, including ARC1 obtained during a science cruise in the Arctic Ocean, were found to be capable of synthesizing a series of saturated hydrocarbons. This has indicated that this capability of synthesis is common to the entire Dicrateria genus.
The saturated hydrocarbon content of the D. rotunda ARC1 increased under dark and nitrogen-deficient conditions. Understanding the physiological function and synthesis pathways of these saturated hydrocarbons may contribute to the development of biofuels in the future.

2. Overview

Director-General Naomi Harada and colleagues from the Research Institute for Global Change at the Japan Agency for Marine-Earth Science and Technology, in collaboration with Assistant Professor Yuu Hirose from Toyohashi University of Technology and Specially Appointed Professor Kazuyoshi Murata from the National Institute for Physiological Sciences, discovered that the phytoplankton Dicrateria rotunda (D. rotunda) can synthesize a series of saturated hydrocarbons with a carbon number ranging from 10 to 38*.

A phytoplankton community was collected from seawater of the Chukchi Sea (Figure 1: observation point at 70° 0.06ʹ N, 168° 44.96ʹ W) during a science cruise of the research vessel “Mirai” in the Arctic Ocean in 2013, from which we isolated and cultured the Arctic strain of D. rotunda, ARC1 (Figure 2). ARC1 contained a series of saturated hydrocarbons with a carbon number ranging from 10 to 38, which are categorized as petrol (carbon number 10 to 15), diesel oils (carbon number 16 to 20), and fuel oils (carbon number 21 or higher) (Figure 3a). Moreover, we examined ten additional strains of Dicrateria stored in culture collections, all of which were found to be similarly capable of hydrocarbon synthesis, indicating that this was common to the entire Dicrateria genus (Figure 3b). This study is the first to report on an organism with the capability to synthesize hydrocarbons equivalent to petroleum.

The capability of the ARC1 strain to synthesize saturated hydrocarbons was shown to increase depending on the environmental conditions (Figure 3c), and the findings of this study are expected to contribute to the development of biofuels in the future.

This study was supported by JSPS Grants-in-Aid for Scientific Research JP22221003 and JP15H05712.

The findings of this study were published in “Scientific Reports” on July 19th (Japan time).

Title:
A novel characteristic of a phytoplankton as a potential source of straight-chain alkanes
Authors:
Naomi Harada1、Yuu Hirose2、Song Chihong3、Hirofumi Kurita2、Miyako Sato1、Jonaotaro Onodera1、Kazuyoshi Murata3、Fumihiro Itoh4
Affiliation :
1. Japan Agency for Marine-Earth Science and Technology
2. Toyohashi University of Technology
3. National Institute of Physiological Sciences
4. Phytopetrum Inc.

【Supplemental information】

*
Saturated hydrocarbons: Organic compounds composed of carbon and hydrogen. Saturated hydrocarbon with the smallest mass number is methane (CH4), which has a carbon number of one.
1

Figure 1. Sampling site of the Arctic strain ARC1 of D. rotunda in the Arctic Ocean (the Chukchi Sea) (red circle: 70° 0.06ʹ N, 168° 44.96ʹ W).

2

Figure 2. a) Photographs of the Arctic strain ARC1 of D. rotunda captured by bright field microscopy (upper left), fluorescence microscopy (lower left), and electron microscopy (right). b) A 3D structure of ARC1 cell reconstructed from multiple electron microscope images.

3

Figure 3. a) Gas chromatogram of hydrocarbons extracted from the Arctic strain ARC1 of D. rotunda. b) Amount of C10-C38 saturated hydrocarbons in 11 strains of D. rotunda. c) Amount of C10-C38 saturated hydrocarbons in the ARC1 strain cultured under different conditions. (with continuous light at 20 °C, ② dark at 20 °C, ③ continuous light at 4 °C, ④ continuous light under nitrogen-deficient conditions at 20 °C) *Error bars (standard deviation)

Contacts:

(For this study)
Naomi Harada, Principal Researcher, Research Institute for Global Change (RIGC), JAMSTEC
(For press release)
Public Relations Section, Marine Science and Technology Strategy Department, JAMSTEC
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