Researchers at RIKEN’s Center for Sustainable Resource Science published a genomic atlas Thursday of polyesterase and cutinase genes from microbes recovered in abyssal sediment cores, a step NEDO-funded partners hope will shorten design cycles for marine-biodegradable packaging feedstocks.

What the team measured

Scientists led by Yasumasa Takenaka’s bioplastics group sequenced metagenomes from cores taken between 2,400 and 5,100 meters in the western Pacific, complementing prior RIKEN work showing polyethylene succinate variants can biodegrade in seawater when long-chain dicarboxylic acids are embedded in the backbone.

They identified 38 high-confidence enzyme candidates associated with polyhydroxyalkanoate depolymerization and aliphatic polyester breakdown—functions also observed in coastal sediments but expressed at lower temperatures in deep samples, suggesting cold-active catalysts useful for ocean-disposal scenarios industry wants to avoid but regulators still model.

Link to prior deep-sea plastic science

The results align with a 2023 Nature Communications study documenting slower—but nonzero—biodegradation of select polyesters on the deep seafloor, and with unrelated discoveries of PET-active enzymes in deep marine metagenomes. RIKEN’s contribution is mapping which gene families appear in Japan’s archived cores rather than proving open-ocean cleanup.

Industry path with Nippon Shokubai

NEDO’s marine biodegradable plastics program, which pairs RIKEN with Nippon Shokubai, is scaling gas-barrier PES films for food packaging. Enzyme data will guide which comonomers attract microbial attack without collapsing barrier properties during shelf life.

Pilot extrusion runs in Osaka are scheduled for November; commercial timelines still hinge on composting certification and fishing-gear exemptions under the plastics resource circulation law.

Limits authors stress

Deep microbes degrade plastics far slower than soil isolates. RIKEN explicitly warns against marketing the atlas as proof that dropping bioplastics offshore is safe. The practical use is bioreactor feedstock design and enzymatic recycling, not ocean dumping.

What comes next

The team will deposit sequences in a public repository with temperature activity curves for three lead enzymes, inviting startups to license through RIKEN’s venture portal. Field trials remain limited to lab bioreactors until MLIT port authorities sign off on waste-handling protocols.

Instrumentation and reproducibility

Assays ran at 4°C and 10°C to mimic benthic temperatures, with activity compared against soil isolates RIKEN already banks in Wako. Three enzymes retained more than forty percent of peak activity at 4°C, a trait polymer chemists said could matter for cold-water compost trials in Hokkaido fishing towns.

Peer reviewers asked for replication on independent cores; the team scheduled a second cruise leg for spring 2027 but released preliminary sequences now so NEDO reviewers can score milestone payments this fiscal year.

Regulatory context

The Ministry of the Environment is drafting labeling rules for marine-biodegradable claims on food wrappers. RIKEN’s authors caution that enzyme data alone cannot justify “ocean safe” stickers; biodegradation rates at depth remain orders of magnitude slower than industrial composting targets.

For Japan’s materials makers, the abyss is a library: enzymes adapted to pressure and cold may unlock feedstocks that behave on shelves—and break down where policymakers actually intend, in controlled compost and enzymatic plants, not on the seafloor.