Characterization of BpGH16A of Bacteroides plebeius, a key enzyme initiating the depolymerization of agarose in the human gut

Na Jung Park, Sora Yu, Dong Hyun Kim, Eun Ju Yun, Kyoung Heon Kim

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Abstract: Seaweeds have received considerable attention as sources of dietary fiber and biomass for manufacturing valuable products. The major polysaccharides of red seaweeds include agar and porphyran. In a marine environment, marine bacteria utilize agar and porphyran through the agarase and porphyranase genes encoded in their genomes. Most of these enzymes identified and characterized so far originate from marine bacteria. Recently, Bacteroides plebeius, a human gut bacterium isolated from seaweed-eating Japanese individuals, was revealed to contain a polysaccharide utilization locus (PUL) targeting the porphyran and agarose of red seaweeds. For example, B. plebeius contains an endo-type β-agarase, BpGH16A, belonging to glycoside hydrolase family 16. BpGH16A cleaves the β-1,4-glycosidic linkages of agarose and produces neoagarooligosccharides from agarose. Since it is crucial to study the characteristics of BpGH16A to understand the depolymerization pathway of red seaweed polysaccharides by B. plebeius in the human gut and to industrially apply the enzyme for the depolymerization of agar, we characterized BpGH16A for the first time. According to our results, BpGH16A is an extracellular endo-type β-agarase with an optimal temperature of 40 °C and an optimal pH of 7.0, which correspond to the temperature and pH of the human colon. BpGH16A depolymerizes agarose into neoagarotetraose (as the main product) and neoagarobiose (as the minor product). Thus, BpGH16A is suggested to be an important enzyme that initiates the depolymerization of red seaweed agarose or agar in the human gut by B. plebeius. Key points: • Bacteroides plebeius is a human gut bacterium isolated from seaweed-eating humans. • BpGH16A is an extracellular endo-type β-agarase with optimal conditions of 40 °C and pH 7.0. • BpGH16A depolymerizes agarose into neoagarotetraose and neoagarobiose.

Original languageEnglish
Pages (from-to)617-625
Number of pages9
JournalApplied Microbiology and Biotechnology
Volume105
Issue number2
DOIs
Publication statusPublished - 2021 Jan

Keywords

  • Agarase
  • Agarose
  • Bacteroides plebeius
  • Gut bacterium
  • Red seaweeds

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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