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Sahu N, Mahanty B, Haldar D. Challenges and opportunities in bioprocessing of gellan gum: A review. Int J Biol Macromol 2024; 276:133912. [PMID: 39025193 DOI: 10.1016/j.ijbiomac.2024.133912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/26/2024] [Accepted: 07/14/2024] [Indexed: 07/20/2024]
Abstract
Gellan gum (GG) - the microbial exopolysaccharide is increasingly being adopted into drug development, tissue engineering, and food and pharmaceutical products. In spite of the commercial importance and expanding application horizon of GG, little attention has been directed toward the exploration of novel microbial cultures, development of advanced screening protocols, strain engineering, and robust upstream or downstream processes. This comprehensive review not only attempts to summarize the existing knowledge pool on GG bioprocess but also critically assesses their inherent challenges. The process optimization design augmented with advanced machine learning modeling tools, widely adopted in other microbial bioprocesses, should be extended to GG. The unification of mechanistic insight into data-driven modeling would help to formulate optimal feeding and process control strategies.
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Affiliation(s)
- Nageswar Sahu
- Division of Biotechnology, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Coimbatore 641114, Tamil Nadu, India.
| | - Biswanath Mahanty
- Division of Biotechnology, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Coimbatore 641114, Tamil Nadu, India.
| | - Dibyajyoti Haldar
- Division of Biotechnology, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Coimbatore 641114, Tamil Nadu, India.
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2
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Dev MJ, Mahajan GB, Warke RG, Warke GM, Patil TA, Satardekar MR, Dalvi RC, Singhal RS. Mutagenesis enhances gellan gum production by a novel Sphingomonas spp.: upstream optimization, kinetic modeling, and structural and physico-functional evaluation. Int Microbiol 2024; 27:459-476. [PMID: 37495894 DOI: 10.1007/s10123-023-00399-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/11/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023]
Abstract
Gellan gum (GG) has gained tremendous attention owing to its diversified applications. However, its high production and hence market cost are still a bottleneck in its widespread utilization. In the present study, high GG producing mutant of Sphingomonas spp. was developed by random mutagenesis using ethyl methylsulphonate (EMS) for industrial fermentation and identified as Sphingomonas trueperi after 16S rRNA and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) analysis. The fermentation conditions such as pH, temperature, and inoculum ratio were optimized by one factor at a time (OFAT) followed by screening of medium components by the Plackett-Burman statistical design. The most critical nutrients were further optimized by response surface methodology for maximizing GG production. The effect of dissolved oxygen tension in bioreactor on cell growth, substrate consumption, GG production, and batch productivity was elucidated. The highest GG titer (23 ± 2.4 g/L) was attained in optimized medium at 10% inoculum (6.45 ± 0.5 log cfu/mL) under controlled fermentation conditions of pH (7), temperature (30 °C), agitation (300-600 rpm), and aeration (0.5-2.0 SLPM) at 22 ± 2% dissolved oxygen tension in a 10-L bioreactor. Kinetic modeling of optimized batch process revealed that logistic growth model could best explain biomass accumulation, while GG formation and substrate consumption were best explained by Luedeking-Piret and exponential decay model, respectively. Structural and physico-functional features of GG produced by mutant Sphingomonas spp. were characterized by HPLC, FTIR, NMR, DSC, TGA, GPC, SEM, and rheological analysis. The higher productivity (0.51 g/L/h) under optimized fermentation conditions suggests potential consideration of mutant and process for commercial utilization.
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Affiliation(s)
- Manoj J Dev
- Food Engineering and Technology Department, Institute of Chemical Technology, Mumbai, 400019, India
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Girish B Mahajan
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Rahul G Warke
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Gangadhar M Warke
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Tanuja A Patil
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Milan R Satardekar
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Rachana C Dalvi
- Department of Microbiology, HiMedia Laboratories Pvt. Ltd, Mumbai, India
| | - Rekha S Singhal
- Food Engineering and Technology Department, Institute of Chemical Technology, Mumbai, 400019, India.
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3
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Huang H, Lin J, Wang W, Li S. Biopolymers Produced by Sphingomonas Strains and Their Potential Applications in Petroleum Production. Polymers (Basel) 2022; 14:1920. [PMID: 35567089 PMCID: PMC9104527 DOI: 10.3390/polym14091920] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/02/2022] [Accepted: 05/03/2022] [Indexed: 02/04/2023] Open
Abstract
The genus Sphingomonas was established by Yabuuchi et al. in 1990, and has attracted much attention in recent years due to its unique ability to degrade environmental pollutants. Some Sphingomonas species can secrete high-molecular-weight extracellular polymers called sphingans, most of which are acidic heteropolysaccharides. Typical sphingans include welan gum, gellan gum, and diutan gum. Most sphingans have a typical, conserved main chain structure, and differences of side chain groups lead to different rheological characteristics, such as shear thinning, temperature or salt resistance, and viscoelasticity. In petroleum production applications, sphingans, and their structurally modified derivatives can replace partially hydrolyzed polyacrylamide (HPAM) for enhanced oil recovery (EOR) in high-temperature and high-salt reservoirs, while also being able to replace guar gum as a fracturing fluid thickener. This paper focuses on the applications of sphingans and their derivatives in EOR.
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Affiliation(s)
- Haolin Huang
- College of Biotechnology and Pharmaceutical Engineering, Jiangpu Campus, Nanjing Tech University, Nanjing 211816, China;
| | - Junzhang Lin
- Research Institute of Petroleum Engineering and Technology, Shengli Oilfield Company, Sinopec, Dongying 257000, China; (J.L.); (W.W.)
| | - Weidong Wang
- Research Institute of Petroleum Engineering and Technology, Shengli Oilfield Company, Sinopec, Dongying 257000, China; (J.L.); (W.W.)
| | - Shuang Li
- College of Biotechnology and Pharmaceutical Engineering, Jiangpu Campus, Nanjing Tech University, Nanjing 211816, China;
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Wang D, Kim H, Lee S, Kim DH, Joe MH. Improved gellan gum production by a newly-isolated Sphingomonas azotifigens GL-1 in a cheese whey and molasses based medium. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.02.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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5
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Liu X, Zhao M, Xu Z, Xu H, Li S. Construction of a Robust Sphingomonas sp. Strain for Welan Gum Production via the Expression of Global Transcriptional Regulator IrrE. Front Bioeng Biotechnol 2020; 8:674. [PMID: 32695762 PMCID: PMC7338795 DOI: 10.3389/fbioe.2020.00674] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/01/2020] [Indexed: 11/16/2022] Open
Abstract
Welan gum is a widely used microbial polysaccharide produced by Sphingomonas sp. However, an important factor hindering the expansion of its production is the maladaptation of strain to fermentation conditions. In this work, the global transcriptional regulator gene irre was selected as a stress-resistant element. And it was integrated into the site of the genomic carotene synthesis key enzyme gene crtB to construct a robust carotenoid-free welan gum producing strain. Fermentation with the recombinant strain effectively reduced the ethanol consumption and pigment content in the product. The tolerance temperature increased by 10°C without the need for controlling the pH. Under this fermentation condition, welan gum concentration could still reach 20.26 ± 0.25 g/L, which was 187.38% higher than that of the wild-type strain (7.05 ± 0.15 g/L). Transcriptome analysis showed that with the control of IrrE, more than 1000 genes that are involved in multiple pathways, including two-component system, bacterial chemotaxis, flagellar assembly, and cell cycle, exhibited changes at the transcriptional level and jointly allowed the strain to protect against environmental stresses.
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Affiliation(s)
- Xiaoliu Liu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China.,College of Bioscience and Engineering, Hebei University of Economics and Business, Shijiazhuang, China
| | - Ming Zhao
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China.,College of Food Science and Light Industry, Nanjing Tech University, Nanjing, China
| | - Zheng Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China.,College of Food Science and Light Industry, Nanjing Tech University, Nanjing, China
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China.,College of Food Science and Light Industry, Nanjing Tech University, Nanjing, China.,Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing, China
| | - Sha Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing, China.,College of Food Science and Light Industry, Nanjing Tech University, Nanjing, China
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6
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Li A, Hu T, Luo H, Alam NU, Xin J, Li H, Lin Y, Huang J, Huang K, Meng Y, Meng F, Hu X, Li O. A Carotenoid- and Poly-β-Hydroxybutyrate-Free Mutant Strain of Sphingomonas elodea ATCC 31461 for the Commercial Production of Gellan. mSphere 2019; 4:e00668-19. [PMID: 31619503 PMCID: PMC6796983 DOI: 10.1128/msphere.00668-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 09/25/2019] [Indexed: 12/22/2022] Open
Abstract
Gellan gum is a microbial exopolysaccharide, produced after aerobic fermentation using the Gram-negative bacterium strain Sphingomonas elodea ATCC 31461. Due to its unique structure and excellent physical characteristics, gellan gum has a broad range of applications in food, pharmaceutical, and other industries where it is used for stabilizing, emulsifying, thickening, and suspending. During the fermentative production of gellan, strain ATCC 31461 also accumulates large amounts of the metabolic by-products yellow carotenoid pigments and poly-β-hydroxybutyrate (PHB), which is decreasing the gellan production and increasing processing costs. A pigment PHB-free mutant was obtained by knocking out the phytoene desaturase gene (crtI) in the carotenoid biosynthetic pathway and the phaC gene, encoding a PHB synthase for the polymerization of PHB. Unfortunately, the double gene knockout mutant produced only 0.56 g liter-1 gellan. Furthermore, blocking PHB and carotenoid synthesis resulted in the accumulation of pyruvate, which reduced gellan production. To elevate gellan production, combined UV irradiation and ethyl methanesulfonate (EMS) mutagenesis treatment were used. A mutant strain with the same level of pyruvate as that of the wild-type strain and higher gellan production was isolated (1.35 g liter-1, 132.8% higher than the double gene knockout mutant and 14.4% higher than the wild-type strain ATCC 31461). In addition, a new gellan gum recovery method based on the new mutant strain was investigated, in which only 30% isopropanol was required, which is twice for the wild-type strains, and the performance of the final product was improved. Thus, the mutant strain could be an ideal strain for the commercial production of gellan.IMPORTANCE A carotenoid- and PHB-free double gene knockout strain mutant was constructed to simplify the purification steps normally involved in gellan production. However, the production of gellan gum was unexpectedly reduced. A mutant with 14.4% higher gellan production than that of the wild-type strain was obtained and isolated after employing UV and EMS combined mutagenesis. Based on this high-yield and low-impurity-producing mutant, a new recovery method requiring less organic solvent and fewer operating steps was developed. This method will effectively reduce the production costs and improve the economic benefits of large-scale gellan production.
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Affiliation(s)
- Ang Li
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Tingting Hu
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Hangqi Luo
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Nafee-Ul Alam
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Jiaqi Xin
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Hongwei Li
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Yinuo Lin
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Jingyu Huang
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Ke Huang
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Yuan Meng
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Fenbin Meng
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Xiufang Hu
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
| | - Ou Li
- College of Life Science and Medicine, Zhejiang Sci-Tech University, Hangzhou, China
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7
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Dai X, Gao G, Wu M, Wei W, Qu J, Li G, Ma T. Construction and application of a Xanthomonas campestris CGMCC15155 strain that produces white xanthan gum. Microbiologyopen 2018; 8:e00631. [PMID: 29656507 PMCID: PMC6391268 DOI: 10.1002/mbo3.631] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 01/19/2018] [Accepted: 02/28/2018] [Indexed: 11/14/2022] Open
Abstract
In the industrial production of xanthan gum using Xanthomonas campestris CGMCC15155, large amounts of ethanol are required to extract xanthan gum from the fermentation broth and remove xanthomonadin impurities. To reduce the amount of ethanol and the overall production cost of xanthan gum, a xanthomonadin‐deficient strain of CGMCC15155 was constructed by inserting the Vitreoscilla globin (vgb) gene, under the control of the LacZ promoter, into the region of the pigA gene, which is involved in xanthomonadin synthesis. The insertion of vgb inactivated pigA, resulting in the production of white xanthan gum. The lack of xanthomonadins resulted in a decreased yield of xanthan gum. However, the expression product of vgb gene, VHb, could increase the metabolism of X. campestris, which allowed the production of xanthan gum to reach wild‐type levels in the engineered strain. The yield, molecular weight, and rheological properties of the xanthan gum synthesized by the engineered and wild‐type bacteria were essentially the same. When the same volume of ethanol was used, the whiteness values of the xanthan gum extracted from engineered and wild‐type bacteria were 65.20 and 38.17, respectively. To extract xanthan gum with the same whiteness, three and seven times the fermentation volume of ethanol was required for the engineered and wild‐type strains, respectively. Thus, the engineered train reduced the requirement for ethanol in xanthan gum production by 133.3%. The results demonstrated that the engineered bacteria used less ethanol, thus reducing the downstream processing cost in xanthan gum production.
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Affiliation(s)
- Xiaohui Dai
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Ge Gao
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Mengmeng Wu
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Weiying Wei
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Jianmei Qu
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Guoqiang Li
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.,Tianjin Engineering Technology Center of Green Manufacturing Biobased Materials, Tianjin, China
| | - Ting Ma
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.,Tianjin Engineering Technology Center of Green Manufacturing Biobased Materials, Tianjin, China
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8
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Ou L, Ang L, Chujun Z, Jingyu H, Yongli M, Shenjing Y, Junhua H, Xu G, Yulong Y, Rui Y, Jinpan H, Bin D, Xiufang H. Identification and characterization of six glycosyltransferases involved in the biosynthesis of a new bacterial exopolysaccharide in Paenibacillus elgii. Appl Microbiol Biotechnol 2017; 102:1357-1366. [PMID: 29199353 DOI: 10.1007/s00253-017-8673-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 02/06/2023]
Abstract
Paenibacillus elgii B69 produces a new xylose-containing exopolysaccharide (EPS) that effectively removes the pollutants from wastewater through flocculation. However, information about the biosynthesis of this EPS is limited. In this study, sequence analysis showed six putative glycosyltransferases (GTs) genes in polysaccharide gene clusters involved in glycosidic linkages of repeating units. Each gene was deleted and phenotypes were examined to understand the functions of these genes. Two of the genes were deleted successfully to encode a priming glucose GT and a side-chain xylose GT, but other genes were unsuccessfully deleted because of the accumulation of toxic intermediate products. The six genes were cloned and expressed in Escherichia coli, and the corresponding enzymes were purified. The activity of GTs was analyzed through mass spectrometry by using the purified membrane fraction as a lipid carrier receptor after a hexasaccharide repeated unit was reconstructed in vitro. The specificities of six different GTs and the building order of the hexasaccharide were characterized. This study provided a basis for future research on the biosynthetic pathway of EPS in Paenibacillus or other genera.
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Affiliation(s)
- Li Ou
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China. .,The department of development technology of marine resources, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
| | - Li Ang
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Zhang Chujun
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Huang Jingyu
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Meng Yongli
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Yuan Shenjing
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Huang Junhua
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Gao Xu
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Yao Yulong
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Yin Rui
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Hu Jinpan
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Ding Bin
- Zhejiang Chinese Medical University, Hangzhou, 310018, China
| | - Hu Xiufang
- Zhejiang Province Key Laboratory of Plant Secondary Metabolism and Regulation, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
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Huang H, Wu M, Yang H, Li X, Ren M, Li G, Ma T. Structural and physical properties of sanxan polysaccharide from Sphingomonas sanxanigenens. Carbohydr Polym 2016; 144:410-8. [DOI: 10.1016/j.carbpol.2016.02.079] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 11/27/2022]
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Vijayendra SVN, Shamala TR. Film forming microbial biopolymers for commercial applications—A review. Crit Rev Biotechnol 2013; 34:338-57. [DOI: 10.3109/07388551.2013.798254] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Genome sequence of the welan gum-producing strain Sphingomonas sp. ATCC 31555. J Bacteriol 2013; 194:5989-90. [PMID: 23045500 DOI: 10.1128/jb.01486-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sphingomonas sp. strain ATCC 31555 can produce an anionic heteropolysaccharide, welan gum, which shows excellent stability and viscosity retention even at high temperatures. Here we present a 4.0-Mb assembly of its genome sequence. We have annotated 10 coding sequences (CDSs) responsible for the welan gum biosynthesis and 55 CDSs related to monosaccharide metabolism.
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12
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Liu X, Gai Z, Tao F, Tang H, Xu P. Carotenoids play a positive role in the degradation of heterocycles by Sphingobium yanoikuyae. PLoS One 2012; 7:e39522. [PMID: 22745775 PMCID: PMC3380023 DOI: 10.1371/journal.pone.0039522] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/22/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Microbial oxidative degradation is a potential way of removing pollutants such as heterocycles from the environment. During this process, reactive oxygen species or other oxidants are inevitably produced, and may cause damage to DNA, proteins, and membranes, thereby decreasing the degradation rate. Carotenoids can serve as membrane-integrated antioxidants, protecting cells from oxidative stress. FINDINGS Several genes involved in the carotenoid biosynthetic pathway were cloned and characterized from a carbazole-degrading bacterium Sphingobium yanoikuyae XLDN2-5. In addition, a yellow-pigmented carotenoid synthesized by strain XLDN2-5 was identified as zeaxanthin that was synthesized from β-carotene through β-cryptoxanthin. The amounts of zeaxanthin and hydrogen peroxide produced were significantly and simultaneously enhanced during the biodegradation of heterocycles (carbazole < carbazole + benzothiophene < carbazole + dibenzothiophene). These higher production levels were consistent with the transcriptional increase of the gene encoding phytoene desaturase, one of the key enzymes for carotenoid biosynthesis. CONCLUSIONS/SIGNIFICANCE Sphingobium yanoikuyae XLDN2-5 can enhance the synthesis of zeaxanthin, one of the carotenoids, which may modulate membrane fluidity and defense against intracellular oxidative stress. To our knowledge, this is the first report on the positive role of carotenoids in the biodegradation of heterocycles, while elucidating the carotenoid biosynthetic pathway in the Sphingobium genus.
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Affiliation(s)
- Xiaorui Liu
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People′s Republic of China
| | - Zhonghui Gai
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People′s Republic of China
| | - Fei Tao
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People′s Republic of China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People′s Republic of China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism & School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People′s Republic of China
- * E-mail:
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Cloning and characterization of genes involved in nostoxanthin biosynthesis of Sphingomonas elodea ATCC 31461. PLoS One 2012; 7:e35099. [PMID: 22509387 PMCID: PMC3324416 DOI: 10.1371/journal.pone.0035099] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 03/08/2012] [Indexed: 01/29/2023] Open
Abstract
Most Sphingomonas species synthesize the yellow carotenoid nostoxanthin. However, the carotenoid biosynthetic pathway of these species remains unclear. In this study, we cloned and characterized a carotenoid biosynthesis gene cluster containing four carotenogenic genes (crtG, crtY, crtI and crtB) and a β-carotene hydroxylase gene (crtZ) located outside the cluster, from the gellan-gum producing bacterium Sphingomonas elodea ATCC 31461. Each of these genes was inactivated, and the biochemical function of each gene was confirmed based on chromatographic and spectroscopic analysis of the intermediates accumulated in the knockout mutants. Moreover, the crtG gene encoding the 2,2′-β-hydroxylase and the crtZ gene encoding the β-carotene hydroxylase, both responsible for hydroxylation of β-carotene, were confirmed by complementation studies using Escherichia coli producing different carotenoids. Expression of crtG in zeaxanthin and β-carotene accumulating E. coli cells resulted in the formation of nostoxanthin and 2,2′-dihydroxy-β-carotene, respectively. Based on these results, a biochemical pathway for synthesis of nostoxanthin in S. elodea ATCC 31461 is proposed.
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