Bacterial synthesis and decomposition of bioplastics
Ehime university senior high school

Introduction

Two types of bioplastics

More than 10 million tons ofplastic waste are washed away
into the sea every year, andmicroplastics pollution is aproblem. We wanted to isolate
marine bacteria from sun-driedsalt and make bioplastics thatwould be degraded in the ocean.

Biomass plastics（Both properties）（Resource recycling type）
ＰＬＡ
Biopolycarbonate
ＰＨＢＨ
ＰＥＴ
ＰＴＴ
BioＰＢＳ
BioＰＥ
BioＰＰ
BioＰＥＴetc Polylactic acid, Polybutyric acidPurpose①Let marine bacteria synthesize biodegradable plastics②Are biomass plastics environmentally friendly?
Culturing marine bacteria in commercially available sun-dried
Expt.① salt

Liquid culture in marine broth medium⇒Colony on flat plate agar

12 kinds of sun-dried salt in the world ⇒ 66 strains
Origin of sun-dried salt

①China②Australia③Italy④Spain⑤Mexico⑥FranceStrain Origin of sun-dried salt Strain
19 species ⑦South Africa
6 species
6 species ⑧Argentina
2 species
14 species ⑨Australia2
2 species
4 species ⑩Southern France 5 species
4 species ⑪Japan / Okinawa 1 species
2 species ⑫Tokyo / Oshima 1 species

Expt.② Synthesize bioplastics with bacteria ①
Thought of synthesis conditions with PLA，PHB（material）○make alkaline medium →add Ｎa₂ＣＯ₃（weak alkaline）○change C/N concentration ratio of medium → add 5% ofsucrose○change into hyperosmotic medium →add 10% ofＮａＣｌ

Verify and extract bioplastic storage and secretion′ methylene blue solution○intracellular storage ：Loffleres○exocrine secretion ：ink dye⇒observe with microscope○centrifuge, NaOH dissolve precipitate, deposit ethanol
supern precipi type supern precipi
atant tation
atant tation
SA3-6 ○
○
I3-3
○
○
F3-1
×
○
I3-1
○
○
C10-4 ×
○
SA3-1
×○
type

Ocean degradability

Biomassplastics
formulation
ｃheck
Expt.③the disassembly speed of plastic
shopping bags
Fill the plastic shopping bag with biomass plastic(mixing ratio 10%, 25%, 30%, 50%) in the soil.

2 months later
Only the plastic shopping bag with acompounding ratio of 30% had several
holes of ab out 4 mm (the ot h er
compounding ratios did not change).

【Forecast】
It takes more than a year to disassemble, and it may
not be completely disassembled.

Consideration〇There are bacteria in the sun salt thatcan synthesize biodegradable plastics○ Biomass plastics shopping bags

are not environmentally friendly

Research tasks from now on① study about the decomposition
speed of the bioplastics we made② develop our study and make itpractical for the SDGs
③cooperate with partnership schools
to save ocean environment(ex.) find out where the plastic bottle flowed
from/testing different types of plastic bags
including bioplastics/participate in idea
contest about environment preservation

Harvest from the research＜Results＞◎was able to synthesize, extract bioplastics
materials from many bacteria◎was able to verify that materials aren’tneither protein, polysaccharide nor nucleic acid◎was able to disassemble extracted materials
with soil bacteria

Biodegradable plastics（Natural biodegradation type）
ＰＣＬ
ＰＢＳ etc

staining results
and extract

・we realized what we can do tosave the environment as students
・noticed what’s “good” in thesociety doesn’t always be ”good”
・learned that students like us canmake success by making effort
・we want to be a researcher anddo something useful to the society