A lesson from polybutylene succinate plastisphere to the discovery of novel plastic degrading enzyme genes in marine vibrios

• Published in: Environmental microbiology 2023-12, Vol.25 (12), p.2834-2850
• Main Authors: Kimura, Yutaro, Fukuda, Yutaka, Otsu, Rumi, Yu, Juwanen, Mino, Sayaka, Misawa, Satoru, Maruyama, Satoshi, Ikeda, Yuta, Miyamachi, Remi, Noguchi, Hiroshi, Kato, Satoshi, Yamamoto, Yasuhito, Sawabe, Tomoo
• Format: Article
• Language: English
• Subjects: Bacteria; Biodegradation; Butylene Glycols - metabolism; Degradation; Enzymes; Genes; Marine environment; Microorganisms; Oxygen consumption; Oxygen enrichment; Plastics; Plastics recycling; Polybutylenes; Polymers - metabolism; Recombinants; Seawater; Sodium chloride; Substrates; Vibrio; Vibrio - metabolism
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.16512

Polybutylene succinate (PBS) is an eco‐friendly green plastic. However, PBS was shown as being non‐biodegradable in marine environments, and up until now, only a limited number of PBS‐degrading marine microbes have been discovered. We first set up in vitro PBS‐ and PBSA (polybutylene succinate adipate)‐plastispheres to characterize novel PBS‐degrading marine microbes. Microbial growth and oxygen consumption were observed in both PBS‐ and PBSA‐plastispheres enriched with natural seawater collected from Usujiri, Hokkaido, Japan, and Vibrionaceae and Pseudoalteromonadaceae were significantly enriched on these films. Further gene identification indicated that vibrios belonging to the Gazogenes clade possess genes related to a PBS degrading enzyme (PBSase). The PBS degradation assay for six Gazogenes clade vibrios identified Vibrio ruber, Vibrio rhizosphaerae, and Vibrio spartinae as being capable of degrading PBS. We further identified the gene responsible for PBSase from the type strain of V. ruber, and the purified recombinant vibrio PBSase was found to have low‐temperature adaptation and was active under high NaCl concentrations. We also provided docking models between the vibrio PBSase and PBS and PBSA units to show how vibrio PBSase interacts with each substrate compared to the Acidovorax PBSase. These results could contribute to a more sustainable society through further utilization of PBS in marine environments and plastic recycling. We first set up an in vitro PBS‐plastisphere, and Vibrionaceae was significantly enriched on the film. Further gene mining successfully identified a gene responsible for PBSase in Vibrio ruber, and the recombinant PBSase showed low‐temperature adaptations and lower but still significant activity under high NaCl concentrations. The 3D structure model of vibrio PBSase was similar to that of the Acidovorax PBSase, and more interestingly, it is similar to the structure of PET6 from Vibrio gazogenes.