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ORIGINAL RESEARCH article

Front. Microbiol.

Sec. Microbiotechnology

Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1682092

This article is part of the Research TopicInnovative Applications of Extremophilic Enzymes in Industrial BiotechnologyView all articles

Identification and characterization of a novel, low-temperature-active GH8 endo-β-1,4-glucanase exhibiting broad pH stability from Antarctic Glacieibacterium sp. PAMC 29367

Provisionally accepted
Do Young  KimDo Young Kim1*Yung Mi  LeeYung Mi Lee2Jong Suk  LeeJong Suk Lee3Hyangmi  KimHyangmi Kim4Chung-Wook  ChungChung-Wook Chung5
  • 1Microbiome Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
  • 2Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
  • 3Bio Industry Department, Gyeonggido Business & Science Accelerator, Suwon, Republic of Korea
  • 4Biological Resources Research Department, Nakdonggang National Institute of Biological Resources, Sangju, Republic of Korea
  • 5Department of Biological Sciences, Gyeongkuk National University, Andong, Republic of Korea

The final, formatted version of the article will be published soon.

Endo-β-1,4-glucanase plays an essential role in the breakdown of cellulosic substances that consist of D-glucose units linked by β-1,4-glycosidic bonds. In this work, the gene encoding a novel extracellular glycoside hydrolase (GH) family 8 endo-β-1,4-glucanase (GluS) from Glacieibacterium sp. PAMC 29367, an Antarctic lichen (Megaspora verrucosa)-associated bacterial species, was identified, cloned, and characterized. The GluS gene (1080-bp) was predicted to express a non-modular endo-β-1,4-glucanase (38,347 Da) that possesses a single catalytic GH8 domain, showing 65.5% amino acid sequence identity with an uncharacterized endoglucanase from Alphaproteobacteria bacterium (GenBank accession number: PZN92894). Recombinant endo-β-1,4-glucanase proteins (rGluS: 39.0 kDa) produced in Escherichia coli BL21 exhibited the highest carboxymethylcellulose (CMC)-degrading activity at pH 5.0 and 40°C, while maintaining over 80% of maximal endo-β-1,4-glucanase activity even at 25°C. Furthermore, the enzyme exhibited notable stability across a broad pH range from 4.5 to 10.0. rGluS activity was greatly stimulated by >1.3-fold in the presence of 1 mM Co2+, whereas it was nearly completely inhibited by 0.5% sodium dodecyl sulfate or 5 mM N-bromosuccinimide. The specific activity (31.1 U mg-1) and kcat/Km (11.02 mg-1 s-1 mL) values of rGluS for CMC were marginally greater than those for barley β-1,3-1,4-glucan, with a specific activity of 28.9 U mg-1 and kcat/Km of 8.79 mg-1 s-1 mL for barley β-1,3-1,4-glucan. The recombinant enzyme demonstrated no detectable biocatalytic activity for p-nitrophenylglucopyranoside, p-nitrophenylcellobioside, D-cellobiose, and D-cellotriose, while it could cleave D-cellotetraose to generate two molecules of D-cellobiose. Moreover, rGluS-mediated degradation of D-cellopentaose led mainly to D-cellobiose production along with D-glucose and D-cellotriose, while its hydrolysis of CMC yielded D-cellotriose as the dominant end product, accompanied by D-glucose, D-cellobiose and D-cellotetraose. The substrate preferences and degradation profiles of rGluS on cellulosic materials supported its classification as a true GH8 endo-acting β-1,4-glucanase without transglycosylation activity. The findings of this study suggest that rGluS represents a novel, highly active, cold-adapted GH8 endo-β-1,4-glucanase exhibiting broad pH stability, and may serve as an effective candidate for low-temperature processing in the food and textile industries.

Keywords: GH8, endo-β-1,4-glucanase, Cold-adapted enzyme, Broad pH stability, Antarctic, Glacieibacterium sp.

Received: 08 Aug 2025; Accepted: 29 Sep 2025.

Copyright: © 2025 Kim, Lee, Lee, Kim and Chung. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Do Young Kim, kdy119@kribb.re.kr

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