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Li D, Wang X, Huo L, Zeng W, Li J, Zhou J. Computer-Aided Semi-Rational Design to Enhance the Activity of l-Sorbosone Dehydrogenase from Gluconobacter oxidans WSH-004. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:10995-11001. [PMID: 38701424 DOI: 10.1021/acs.jafc.3c08365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
The titer of the microbial fermentation products can be increased by enzyme engineering. l-Sorbosone dehydrogenase (SNDH) is a key enzyme in the production of 2-keto-l-gulonic acid (2-KLG), which is the precursor of vitamin C. Enhancing the activity of SNDH may have a positive impact on 2-KLG production. In this study, a computer-aided semirational design of SNDH was conducted. Based on the analysis of SNDH's substrate pocket and multiple sequence alignment, three modification strategies were established: (1) expanding the entrance of SNDH's substrate pocket, (2) engineering the residues within the substrate pocket, and (3) enhancing the electron transfer of SNDH. Finally, mutants S453A, L460V, and E471D were obtained, whose specific activity was increased by 20, 100, and 10%, respectively. In addition, the ability of Gluconobacter oxidans WSH-004 to synthesize 2-KLG was improved by eliminating H2O2. This study provides mutant enzymes and metabolic engineering strategies for the microbial-fermentation-based production of 2-KLG.
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Affiliation(s)
- Dong Li
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Xinglong Wang
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Lin Huo
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Weizhu Zeng
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jianghua Li
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jingwen Zhou
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
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Li D, Deng Z, Hou X, Qin Z, Wang X, Yin D, Chen Y, Rao Y, Chen J, Zhou J. Structural Insight into the Catalytic Mechanisms of an L-Sorbosone Dehydrogenase. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301955. [PMID: 37679059 PMCID: PMC10602560 DOI: 10.1002/advs.202301955] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 07/29/2023] [Indexed: 09/09/2023]
Abstract
L-Sorbosone dehydrogenase (SNDH) is a key enzyme involved in the biosynthesis of 2-keto-L-gulonic acid , which is a direct precursor for the industrial scale production of vitamin C. Elucidating the structure and the catalytic mechanism is essential for improving SNDH performance. By solving the crystal structures of SNDH from Gluconobacter oxydans WSH-004, a reversible disulfide bond between Cys295 and the catalytic Cys296 residues is discovered. It allowed SNDH to switch between oxidation and reduction states, resulting in opening or closing the substrate pocket. Moreover, the Cys296 is found to affect the NADP+ binding pose with SNDH. Combining the in vitro biochemical and site-directed mutagenesis studies, the redox-based dynamic regulation and the catalytic mechanisms of SNDH are proposed. Moreover, the mutants with enhanced activity are obtained by extending substrate channels. This study not only elucidates the physiological control mechanism of the dehydrogenase, but also provides a theoretical basis for engineering similar enzymes.
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Affiliation(s)
- Dong Li
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Zhiwei Deng
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Xiaodong Hou
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Zhijie Qin
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Xinglong Wang
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Dejing Yin
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Yue Chen
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Yijian Rao
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
| | - Jian Chen
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan UniversityWuxi214122China
| | - Jingwen Zhou
- Engineering Research Center of Ministry of Education on Food Synthetic BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Science Center for Future FoodsJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Key Laboratory of Industrial BiotechnologyMinistry of Education and School of BiotechnologyJiangnan University1800 Lihu RoadWuxiJiangsu214122China
- Jiangsu Province Engineering Research Center of Food Synthetic BiotechnologyJiangnan UniversityWuxi214122China
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Li D, Liu L, Qin Z, Yu S, Zhou J. Combined evolutionary and metabolic engineering improve 2-keto-L-gulonic acid production in Gluconobacter oxydans WSH-004. BIORESOURCE TECHNOLOGY 2022; 354:127107. [PMID: 35381333 DOI: 10.1016/j.biortech.2022.127107] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
The direct fermentation of the precursor of vitamin C, 2-keto-L-gulonic acid (2-KLG), has been a long-pursued goal. Previously, a strain of Gluconobacter oxydans WSH-004 was isolated that produced 2.5 g/L 2-KLG, and through adaptive evolution engineering, the strain G. oxydans MMC3 could tolerate 300 g/L D-sorbitol. This study verified that the sndh-sdh gene cluster encoded two key dehydrogenases for the 2-KLG biosynthesis pathway in this strain. Then G. oxydans MMC3 further evolved through adaptive evolution to G. oxydans 2-KLG5, which can tolerate high concentrations of D-sorbitol and 2-KLG. Finally, by increasing the gene expression levels of the sndh-sdh and terminal oxidase cyoBACD in G. oxydans 2-KLG5, the 2-KLG accumulation in the 5-L fermenter increased to 45.14 g/L by batch fermentation. The results showed that combined evolutionary and metabolic engineering efficiently improved the direct production of 2-KLG from D-sorbitol in G. oxydans.
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Affiliation(s)
- Dong Li
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Li Liu
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Zhijie Qin
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Shiqin Yu
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jingwen Zhou
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China.
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Zheng Y, Li Y, Yang Y, Zhang Y, Wang D, Wang P, Wong ACY, Hsieh YSY, Wang D. Recent Advances in Bioutilization of Marine Macroalgae Carbohydrates: Degradation, Metabolism, and Fermentation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:1438-1453. [PMID: 35089725 DOI: 10.1021/acs.jafc.1c07267] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Marine macroalgae are considered renewable natural resources due to their high carbohydrate content, which gives better utilization value in biorefineries and higher value conversion than first- and second-generation biomass. However, due to the diverse composition, complex structure, and rare metabolic pathways of macroalgae polysaccharides, their bioavailability needs to be improved. In recent years, enzymes and pathways related to the degradation and metabolism of macroalgae polysaccharides have been continuously developed, and new microbial fermentation platforms have emerged. Aiming at the bioutilization and transformation of macroalgae resources, this review describes the latest research results from the direction of green degradation, biorefining, and metabolic pathway design, including summarizing the the latest biorefining technology and the fermentation platform design of agarose, alginate, and other polysaccharides. This information will provide new research directions and solutions for the biotransformation and utilization of marine macroalgae.
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Affiliation(s)
- Yuting Zheng
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Yanping Li
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Yuanyuan Yang
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Ye Zhang
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Di Wang
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Peiyao Wang
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Ann C Y Wong
- School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei 110301, Taiwan
| | - Yves S Y Hsieh
- School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei 110301, Taiwan
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology (KTH), AlbaNova University Centre, 11421 Stockholm, Sweden
| | - Damao Wang
- College of Food Science, Southwest University, Chongqing 400715, China
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de Oliveira BFR, Lopes IR, Canellas ALB, Muricy G, Jackson SA, Dobson ADW, Laport MS. Genomic and in silico protein structural analyses provide insights into marine polysaccharide-degrading enzymes in the sponge-derived Pseudoalteromonas sp. PA2MD11. Int J Biol Macromol 2021; 191:973-995. [PMID: 34555402 DOI: 10.1016/j.ijbiomac.2021.09.076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 09/01/2021] [Accepted: 09/11/2021] [Indexed: 10/20/2022]
Abstract
Active heterotrophic metabolism is a critical metabolic role performed by sponge-associated microorganisms, but little is known about their capacity to metabolize marine polysaccharides (MPs). Here, we investigated the genome of the sponge-derived Pseudoalteromonas sp. strain PA2MD11 focusing on its macroalgal carbohydrate-degrading potential. Carbohydrate-active enzymes (CAZymes) for the depolymerization of agar and alginate were found in PA2MD11's genome, including glycoside hydrolases (GHs) and polysaccharide lyases (PLs) belonging to families GH16, GH50 and GH117, and PL6 and PL17, respectively. A gene potentially encoding a sulfatase was also identified, which may play a role in the strain's ability to consume carrageenans. The complete metabolism of agar and alginate by PA2MD11 could also be predicted and was consistent with the results obtained in physiological assays. The polysaccharide utilization locus (PUL) potentially involved in the metabolism of agarose contained mobile genetic elements from other marine Gammaproteobacteria and its unusual larger size might be due to gene duplication events. Homology modelling and structural protein analyses of the agarases, alginate lyases and sulfatase depicted clear conservation of catalytic machinery and protein folding together with suitable industrially-relevant features. Pseudoalteromonas sp. PA2MD11 is therefore a source of potential MP-degrading biocatalysts for biorefinery applications and in the preparation of pharmacologically-active oligosaccharides.
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Affiliation(s)
- Bruno Francesco Rodrigues de Oliveira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-590 Rio de Janeiro, Brazil; School of Microbiology, University College Cork, T12 Y960 Cork, Ireland
| | - Isabelle Rodrigues Lopes
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-590 Rio de Janeiro, Brazil
| | - Anna Luiza Bauer Canellas
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-590 Rio de Janeiro, Brazil
| | - Guilherme Muricy
- Departamento de Invertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, s/n°, São Cristóvão, 20940-040 Rio de Janeiro, RJ, Brazil
| | - Stephen Anthony Jackson
- School of Microbiology, University College Cork, T12 Y960 Cork, Ireland; Environmental Research Institute, University College Cork, T23 XE10 Cork, Ireland
| | - Alan D W Dobson
- School of Microbiology, University College Cork, T12 Y960 Cork, Ireland; Environmental Research Institute, University College Cork, T23 XE10 Cork, Ireland
| | - Marinella Silva Laport
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-590 Rio de Janeiro, Brazil.
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Tsevelkhorloo M, Kim SH, Kang DK, Lee CR, Hong SK. NADP +-Dependent Dehydrogenase SCO3486 and Cycloisomerase SCO3480: Key Enzymes for 3,6-Anhydro-L-Galactose Catabolism in Streptomyces coelicolor A3(2). J Microbiol Biotechnol 2021; 31:756-763. [PMID: 33820885 PMCID: PMC9706016 DOI: 10.4014/jmb.2103.03030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/30/2021] [Accepted: 04/05/2021] [Indexed: 12/15/2022]
Abstract
Agarose is a linear polysaccharide composed of D-galactose and 3,6-anhydro-L-galactose (AHG). It is a major component of the red algal cell wall and is gaining attention as an abundant marine biomass. However, the inability to ferment AHG is considered an obstacle in the large-scale use of agarose and could be addressed by understanding AHG catabolism in agarolytic microorganisms. Since AHG catabolism was uniquely confirmed in Vibrio sp. EJY3, a gram-negative marine bacterial species, we investigated AHG metabolism in Streptomyces coelicolor A3(2), an agarolytic gram-positive soil bacterium. Based on genomic data, the SCO3486 protein (492 amino acids) and the SCO3480 protein (361 amino acids) of S. coelicolor A3(2) showed identity with H2IFE7.1 (40% identity) encoding AHG dehydrogenase and H2IFX0.1 (42% identity) encoding 3,6-anhydro-L-galactonate cycloisomerase, respectively, which are involved in the initial catabolism of AHG in Vibrio sp. EJY3. Thin layer chromatography and mass spectrometry of the bioconversion products catalyzed by recombinant SCO3486 and SCO3480 proteins, revealed that SCO3486 is an AHG dehydrogenase that oxidizes AHG to 3,6-anhydro-L-galactonate, and SCO3480 is a 3,6-anhydro-L-galactonate cycloisomerase that converts 3,6-anhydro-L-galactonate to 2-keto-3-deoxygalactonate. SCO3486 showed maximum activity at pH 6.0 at 50°C, increased activity in the presence of iron ions, and activity against various aldehyde substrates, which is quite distinct from AHG-specific H2IFE7.1 in Vibrio sp. EJY3. Therefore, the catabolic pathway of AHG seems to be similar in most agar-degrading microorganisms, but the enzymes involved appear to be very diverse.
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Affiliation(s)
- Maral Tsevelkhorloo
- Department of Biosciences and Bioinformatics, Myongji University, Yongin 17058, Republic of Korea
| | - Sang Hoon Kim
- Department of Animal Resources Science, Dankook University, Cheonan 31116, Republic of Korea
| | - Dae-Kyung Kang
- Department of Animal Resources Science, Dankook University, Cheonan 31116, Republic of Korea
| | - Chang-Ro Lee
- Department of Biosciences and Bioinformatics, Myongji University, Yongin 17058, Republic of Korea
| | - Soon-Kwang Hong
- Department of Biosciences and Bioinformatics, Myongji University, Yongin 17058, Republic of Korea,Corresponding author Phone: 82-31-330-6198 Fax: 82-31-335-8249 E-mail:
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Agarose degradation for utilization: Enzymes, pathways, metabolic engineering methods and products. Biotechnol Adv 2020; 45:107641. [PMID: 33035614 DOI: 10.1016/j.biotechadv.2020.107641] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 09/27/2020] [Accepted: 10/03/2020] [Indexed: 12/14/2022]
Abstract
Red algae are important renewable bioresources with very large annual outputs. Agarose is the major carbohydrate component of many red algae and has potential to be of value in the production of agaro-oligosaccharides, biofuels and other chemicals. In this review, we summarize the degradation pathway of agarose, which includes an upstream part involving transformation of agarose into its two monomers, D-galactose (D-Gal) and 3,6-anhydro-α-L-galactose (L-AHG), and a downstream part involving monosaccharide degradation pathways. The upstream part involves agarolytic enzymes such as α-agarase, β-agarase, α-neoagarobiose hydrolase, and agarolytic β-galactosidase. The downstream part includes the degradation pathways of D-Gal and L-AHG. In addition, the production of functional agaro-oligosaccharides such as neoagarobiose and monosaccharides such as L-AHG with different agarolytic enzymes is reviewed. Third, techniques for the setup, regulation and optimization of agarose degradation to increase utilization efficiency of agarose are summarized. Although heterologous construction of the whole agarose degradation pathway in an engineered strain has not been reported, biotechnologies applied to improve D-Gal utilization efficiency and construct L-AHG catalytic routes are reviewed. Finally, critical aspects that may aid in the construction of engineered microorganisms that can fully utilize agarose to produce agaro-oligosaccharides or as carbon sources for production of biofuels or other value-adding chemicals are discussed.
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