Japan discovers bacteria that can quickly decompose biodegradable plastics in the ocean
Recently, Gunma University in Japan announced that a bacterium (Halopseudomonas sp. MFKK-1 strain) was found in coastal seawater that can accelerate the decomposition of biodegradable plastics that decompose slowly in the ocean, poly(butylene succinate-co-butylene adipate, PBSA). This strain can not only degrade PBSA, but also other polyesters such as PCL and PBAT in seawater environments. In addition, the plastic degrading enzyme produced by this strain can also degrade amorphous PET. These results may greatly promote the use of biodegradable plastics in the ocean.
In this study, the researchers focused on PBSA, a plastic that decomposes at different rates due to different environmental conditions in actual marine use. The research team isolated the MFKK-1 strain that can decompose PBSA from coastal seawater and analyzed it in detail.
The results showed that the MFKK-1 strain belongs to the genus Halopseudomonas in the ocean, can adapt to environments with salt concentrations of 0.0 to 0.8M, and can decompose PBSA.
The MFKK-1 strain is able to utilize the decomposition products 1,4-butanediol and adipic acid as nutrient sources, and therefore may use the decomposition products as an energy source in the marine environment. The MFKK-1 strain and its enzyme also have the ability to decompose aliphatic and aliphatic-aromatic polyesters such as poly(ε-caprolactone, PCL) and poly(butylene adipate-co-butylene terephthalate, PBAT). Therefore, the bacterium is believed to be able to cope with a variety of plastics.
In addition, the recombinant enzyme (APHHsp) derived from the MFKK-1 strain is a plastic degrading enzyme with three catalytic residues of serine, aspartic acid, and histidine, and can decompose PBSA, PCL, and PBAT in a 0.5M NaCl environment close to the salt concentration of the ocean. The enzyme was also found to have decomposition activity against amorphous PET.
