Unique Characteristics of Deep-Sea Microbial Cellulases Unveiled
-A Step Toward Sustainable Bio-Manufacturing by Deep-Sea-Inspired Chemistry-

Key Points of the Announcement

• A novel bacterium that breaks down cellulose was isolated from the deep-sea ascidian Megalodicopia hians in Toyama Bay.

• The study revealed that deep-sea microbes use unique methods to break down plant material, unlike land-based microorganisms.

• These findings could lead to new sustainable manufacturing technologies using non-edible plant materials, contributing to carbon-neutral goals.

Overview

A research team led by Dr. Mikako Tachioka and Dr. Shigeru Deguchi at JAMSTEC uncovered how deep-sea microorganisms break down cellulose, the primary component of plant biomass. This discovery could help create eco-friendly and sustainable manufacturing technologies by utilizing enzymes derived from these microbes.

This study was supported by the International Exchange Encouragement Award from the Japan Wood Science Society, JST CREST (JPMJCR21L4), JSPS KAKENHI (JP19K15956, 23K14000), and the 2024 Nagase Science and Technology Foundation Research Grant. The findings were published in the Journal of Wood Science by Springer-Nature on November 14, 2024.

Background

Cellulose is the most abundant plant material on Earth and a vital part of the global carbon cycle, as microbes help release carbon back into the atmosphere by breaking it down. While much is known about how land-based microorganisms degrade cellulose, the deep-sea process remained mysterious.

In the ocean, plant material from land sinks as "marine snow," providing food for deep-sea ecosystems. Recent research indicates that significant amounts of this material reach the deep sea. To survive in these nutrient-poor environments, deep-sea microbes have evolved efficient ways to break down tough materials like cellulose and plastics.

Key Findings

Using advanced nano-measurement technology called “SPOT,” researchers studied the cellulase enzymes of two deep-sea bacteria:
1. Strain TOYAMA8, isolated from 800 meters deep in Toyama Bay.
2. Marinagarivorans cellulosilyticus GE09, found off the coast of Noma Misaki.

- Efficient Cellulose Breakdown: These microbes produce cellulases attached to their cell membranes, enabling efficient decomposition and uptake of nutrients. In contrast, land-based microbes release enzymes into the environment, which is less efficient.
- Unique Structures: Their cellulase enzymes have unique amino acid sequences not found in land-based equivalents, reflecting adaptations to deep-sea environments.
- Selective Degradation: They can break down plant-derived materials but not seaweed, highlighting the importance of land-based plant debris as a deep-sea energy source.

Figures

Figure 1: TOYAMA8, a newly identified deep-sea microorganism, efficiently breaks down cellulose, a key component of plant material.

Figure 2: A 3D structure of a deep-sea cellulase enzyme, modeled using AlphaFold. This visualization helps reveal how the enzyme interacts with cellulose at the molecular level.

Future Perspectives

The extreme deep-sea environments and survival strategies of deep-sea organisms offer inspiration for sustainable technological innovations. JAMSTEC’s Center for Bioscience and Nanoscience is spearheading efforts in "Deep-Sea-Inspired Chemistry" to develop novel nanomaterials and promote resource recycling. This study suggests that deep-sea enzymes could lead to eco-friendly biotechnologies, supporting carbon-neutral goals.

Future work will explore the detailed functions of these enzymes and their applications in manufacturing sustainable products.

Related Press Releases