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Hwang IC, Valeriano VD, Song JH, Pereira M, Oh JK, Han K, Engstrand L, Kang DK. Mucosal immunization with lactiplantibacillus plantarum-displaying recombinant SARS-CoV-2 epitopes on the surface induces humoral and mucosal immune responses in mice. Microb Cell Fact 2023; 22:96. [PMID: 37161468 PMCID: PMC10169176 DOI: 10.1186/s12934-023-02100-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/17/2023] [Indexed: 05/11/2023] Open
Abstract
BACKGROUND The use of probiotic lactic acid bacteria as a mucosal vaccine vector is considered a promising alternative compared to the use of other microorganisms because of its "Generally Regarded as Safe" status, its potential adjuvant properties, and its tolerogenicity to the host. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), is highly transmissible and pathogenic. This study aimed to determine the potential of Lactiplantibacillus plantarum expressing SARS-CoV-2 epitopes as a mucosal vaccine against SARS-CoV-2. RESULTS In this study, the possible antigenic determinants of the spike (S1-1, S1-2, S1-3, and S1-4), membrane (ME1 and ME2), and envelope (E) proteins of SARS-CoV-2 were predicted, and recombinant L. plantarum strains surface-displaying these epitopes were constructed. Subsequently, the immune responses induced by these recombinant strains were compared in vitro and in vivo. Most surface-displayed epitopes induced pro-inflammatory cytokines [tumor necrosis factor alpha (TNF-α and interleukin (IL)-6] and anti-inflammatory cytokines (IL-10) in lipopolysaccharide-induced RAW 264.7, with the highest anti-inflammatory to pro-inflammatory cytokine ratio in the S1-1 and S1-2 groups, followed by that in the S1-3 group. When orally administered of recombinant L. plantarum expressing SARS-CoV-2 epitopes in mice, all epitopes most increased the expression of IL-4, along with induced levels of TNF-α, interferon-gamma, and IL-10, specifically in spike protein groups. Thus, the surface expression of epitopes from the spike S1 protein in L. plantarum showed potential immunoregulatory effects, suggesting its ability to potentially circumvent hyperinflammatory states relevant to monocyte/macrophage cell activation. At 35 days post immunization (dpi), serum IgG levels showed a marked increase in the S1-1, S1-2, and S1-3 groups. Fecal IgA levels increased significantly from 21 dpi in all the antigen groups, but the boosting effect after 35 dpi was explicitly observed in the S1-1, S1-2, and S1-3 groups. Thus, the oral administration of SARS-CoV-2 antigens into mice induced significant humoral and mucosal immune responses. CONCLUSION This study suggests that L. plantarum is a potential vector that can effectively deliver SARS-CoV-2 epitopes to intestinal mucosal sites and could serve as a novel approach for SARS-CoV-2 mucosal vaccine development.
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Affiliation(s)
- In-Chan Hwang
- Department of Animal Resources Science, Dankook University, Cheonan, 31116, Republic of Korea
| | - Valerie Diane Valeriano
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Ji Hoon Song
- Department of Animal Resources Science, Dankook University, Cheonan, 31116, Republic of Korea
| | - Marcela Pereira
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Ju Kyoung Oh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Kyudong Han
- Department of Microbiology, College of Science and Technology, Dankook University, Cheonan, 31116, Republic of Korea
| | - Lars Engstrand
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Dae-Kyung Kang
- Department of Animal Resources Science, Dankook University, Cheonan, 31116, Republic of Korea.
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Wang P, Wang T, Ismael M, Wang X, Yi Y, Lü X. Development of an electroporation method and expression patterns of bacteriocin-encoding genes in Companilactobacillus crustorum MN047. FOOD BIOSCI 2021. [DOI: 10.1016/j.fbio.2021.101420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kong LH, Xiong ZQ, Xia YJ, Ai LZ. High-efficiency transformation of Streptococcus thermophilus using electroporation. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2021; 101:6578-6585. [PMID: 33937994 DOI: 10.1002/jsfa.11292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/20/2021] [Accepted: 05/03/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Streptococcus thermophilus, one of the most important lactic acid bacteria, is widely used in food fermentation, which is beneficial to improve food quality. However, the current genetic transformation systems are inefficient for S. thermophilus S-3, which hinders its further study. RESULTS We developed three electroporation transformation methods for S. thermophilus S-3, and optimized various parameters to enhance the transformation efficiency up to 1.3 × 106 CFU/μg DNA, which was 32-fold higher than that of unoptimized. Additionally, transcriptional analysis showed that a series of competence genes in S. thermophilus S-3 were remarkedly up-regulated after optimization, indicating that improvement of transformation efficiency was attributed to the expression level of competence genes. Furthermore, to prove their potential, expression of competence genes (comEA, cbpD and comX) were employed to increase transformation efficiency. The maximum transformation efficiency was obtained by overexpression of comEA, which was 14-fold higher than that of control. CONCLUSION This is the first report of competence gene expression for enhancing transformability in S. thermophilus, which exerts a positive effect on the development of desirable characteristics strains. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Ling-Hui Kong
- Shanghai Engineering Research Center of Food Microbiology, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Zhi-Qiang Xiong
- Shanghai Engineering Research Center of Food Microbiology, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Yong-Jun Xia
- Shanghai Engineering Research Center of Food Microbiology, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Lian-Zhong Ai
- Shanghai Engineering Research Center of Food Microbiology, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, China
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Li Q, Zhang J, Yang J, Jiang Y, Yang S. Recent progress on n-butanol production by lactic acid bacteria. World J Microbiol Biotechnol 2021; 37:205. [PMID: 34698975 DOI: 10.1007/s11274-021-03173-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 10/13/2021] [Indexed: 11/26/2022]
Abstract
n-Butanol is an essential chemical intermediate produced through microbial fermentation. However, its toxicity to microbial cells has limited its production to a great extent. The anaerobe lactic acid bacteria (LAB) are the most resistant to n-butanol, so it should be the first choice for improving n-butanol production. The present article aims to review the following aspects of n-butanol production by LAB: (1) the tolerance of LAB to n-butanol, including its tolerance level and potential tolerance mechanisms; (2) genome editing tools in the n-butanol-resistant LAB; (3) methods of LAB modification for n-butanol production and the production levels after modification. This review will provide a theoretical basis for further research on n-butanol production by LAB.
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Affiliation(s)
- Qi Li
- College of Life Sciences, Sichuan Normal University, Chengdu, 610101, China
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Jieze Zhang
- Department of Chemistry, University of Southern California, Los Angeles, CA, 90089, USA
| | - Junjie Yang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China
| | - Yu Jiang
- Huzhou Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou, 313000, China
- Shanghai Taoyusheng Biotechnology Company Ltd, Shanghai, 200032, China
| | - Sheng Yang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
- Huzhou Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou, 313000, China.
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5
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Wang C, Cui Y, Qu X. Optimization of electrotransformation (ETF) conditions in lactic acid bacteria (LAB). J Microbiol Methods 2020; 174:105944. [DOI: 10.1016/j.mimet.2020.105944] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/11/2020] [Accepted: 05/11/2020] [Indexed: 10/24/2022]
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Ozyigit II. Gene transfer to plants by electroporation: methods and applications. Mol Biol Rep 2020; 47:3195-3210. [PMID: 32242300 DOI: 10.1007/s11033-020-05343-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/22/2020] [Indexed: 01/09/2023]
Abstract
Developing gene transfer technologies enables the genetic manipulation of the living organisms more efficiently. The methods used for gene transfer fall into two main categories; natural and artificial transformation. The natural methods include the conjugation, transposition, bacterial transformation as well as phage and retroviral transductions, contain the physical methods whereas the artificial methods can physically alter and transfer genes from one to another organisms' cell using, for instance, biolistic transformation, micro- and macroinjection, and protoplast fusion etc. The artificial gene transformation can also be conducted through chemical methods which include calcium phosphate-mediated, polyethylene glycol-mediated, DEAE-Dextran, and liposome-mediated transfers. Electrical methods are also artificial ways to transfer genes that can be done by electroporation and electrofusion. Comparatively, among all the above-mentioned methods, electroporation is being widely used owing to its high efficiency and broader applicability. Electroporation is an electrical transformation method by which transient electropores are produced in the cell membranes. Based on the applications, process can be either reversible where electropores in membrane are resealable and cells preserve the vitality or irreversible where membrane is not able to reseal, and cell eventually dies. This problem can be minimized by developing numerical models to iteratively optimize the field homogeneity considering the cell size, shape, number, and electrode positions supplemented by real-time measurements. In modern biotechnology, numerical methods have been used in electrotransformation, electroporation-based inactivation, electroextraction, and electroporative biomass drying. Moreover, current applications of electroporation also point to some other uncovered potentials for various exploitations in future.
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Affiliation(s)
- Ibrahim Ilker Ozyigit
- Department of Biology, Faculty of Science and Arts, Marmara University, Goztepe, 34722, Istanbul, Turkey. .,Department of Biology, Faculty of Science, Kyrgyz-Turkish Manas University, 720038, Bishkek, Kyrgyzstan.
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Cho SW, Yim J, Seo SW. Engineering Tools for the Development of Recombinant Lactic Acid Bacteria. Biotechnol J 2020; 15:e1900344. [DOI: 10.1002/biot.201900344] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/27/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Sung Won Cho
- School of Chemical and Biological EngineeringInstitute of Chemical ProcessesSeoul National University 1 Gwanak‐ro Gwanak‐gu Seoul 08826 Republic of Korea
| | - Jaewoo Yim
- School of Chemical and Biological EngineeringInstitute of Chemical ProcessesSeoul National University 1 Gwanak‐ro Gwanak‐gu Seoul 08826 Republic of Korea
| | - Sang Woo Seo
- School of Chemical and Biological EngineeringInstitute of Chemical ProcessesSeoul National University 1 Gwanak‐ro Gwanak‐gu Seoul 08826 Republic of Korea
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Chae JP, Pajarillo EA, Hwang IC, Kang DK. Construction of a Bile-responsive Expression System in Lactobacillus plantarum. Food Sci Anim Resour 2019; 39:13-22. [PMID: 30882070 PMCID: PMC6413156 DOI: 10.5851/kosfa.2018.e58] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/14/2018] [Accepted: 11/18/2018] [Indexed: 12/16/2022] Open
Abstract
This study aimed to develop a bile-responsive expression system for lactobacilli. The promoters of four genes, encoding phosphoenolpyruvate-dependent sugar phosphotransferase (mannose-specific), L-lactate dehydrogenase (LDH), HPr kinase, and D-alanine-D-alanine ligase, respectively, which were highly expressed by bile addition in Lactobacillus johnsonii PF01, were chosen. Each promoter was amplified by polymerase chain reaction and fused upstream of the β-glucuronidase gene as a reporter, respectively. Then, these constructs were cloned into E. coli-Lactobacillus shuttle vector pULP2, which was generated by the fusion of pUC19 with the L. plantarum plasmid pLP27. Finally, the constructed vectors were introduced into L. plantarum for a promoter activity assay. The LDH promoter showed the highest activity and its activity increased 1.8-fold by bile addition. The constructed vector maintained in L. plantarum until 80 generations without selection pressure. A bile-responsive expression vector, pULP3-PLDH, for Lactobacillus spp. can be an effective tool for the bile-inducible expression of bioactive proteins in intestine after intake in the form of fermented dairy foods.
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Affiliation(s)
- Jong Pyo Chae
- Department of Animal Resources Science, Dankook University, Cheonan 31116, Korea
| | | | - In-Chan Hwang
- Department of Animal Resources Science, Dankook University, Cheonan 31116, Korea
| | - Dae-Kyung Kang
- Department of Animal Resources Science, Dankook University, Cheonan 31116, Korea
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Dafni E, Weiner I, Shahar N, Tuller T, Yacoby I. Image-Processing Software for High-Throughput Quantification of Colony Luminescence. mSphere 2019; 4:e00676-18. [PMID: 30602526 PMCID: PMC6315083 DOI: 10.1128/msphere.00676-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 12/07/2018] [Indexed: 11/20/2022] Open
Abstract
Many microbiological assays include colonies that produce a luminescent or fluorescent (here generalized as "luminescent") signal, often in the form of luminescent halos around the colonies. These signals are used as reporters for a trait of interest; therefore, exact measurements of the luminescence are often desired. However, there is currently a lack of high-throughput methods for analyzing these assays, as common automatic image analysis tools are unsuitable for identifying these halos in the presence of the inherent biological noise. In this work, we have developed CFQuant-automatic, high-throughput software for the analysis of images from colony luminescence assays. CFQuant overcomes the problems of automatic identification by relying on the luminescence halo's expected shape and provides measurements of several features of the colonies and halos. We examined the performance of CFQuant using one such colony luminescence assay, where we achieved a high correlation (R = 0.85) between the measurements of CFQuant and known protein expression levels. This demonstrates CFQuant's potential as a fast and reliable tool for analysis of colony luminescence assays.IMPORTANCE Luminescent markers are widely used as reporters for various biologically interesting traits. In colony luminescence assays, the levels of luminescence around each colony can be used to compare the levels of traits of interest for different strains, treatments, etc., using quantitative measurements of the luminescence. However, automatic methods of obtaining this data are underdeveloped, making this a laborious manual process, especially in analyzing large numbers of colonies. The significance of this work is in developing an automatic, high-throughput tool for quantitative analysis of colony luminescence assays, which will allow fast collection of qualitative data from these assays and thus increase their overall usability.
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Affiliation(s)
- Eyal Dafni
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Iddo Weiner
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Noam Shahar
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Iftach Yacoby
- School of Plant Sciences and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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Park MJ, Park MS, Ji GE. Improvement of electroporation-mediated transformation efficiency for a Bifidobacterium strain to a reproducibly high level. J Microbiol Methods 2018; 159:112-119. [PMID: 30529116 DOI: 10.1016/j.mimet.2018.11.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 02/07/2023]
Abstract
Bifidobacteria are representative probiotics which are defined as live microorganisms that confer a health benefit on the host. Because of their safety and healthfulness when applied to humans, bifidobacteria are suitable as genetically engineered bacteria for applications to benefit human physiology and pathology. However, molecular biological studies of bifidobacteria have been limited due to insufficient genetic tools including effective transformation methods. The aim of this study is to improve the electroporation-mediated transformation efficiency of bifidobacteria to a reproducibly high level. The crucial factors that determine electroporation efficiency are the restriction-modification system, together with the cell wall and cell membrane structure of the bacteria. We optimized the bifidobacterial electroporation conditions by focusing on these factors as well as the amount of plasmid DNA used, the electrical parameters and the bacterial growth phase. As a result, the electroporation efficiency of B. bifidum BGN4 drastically and consistently increased from 103 to 105 CFU / μg DNA. The most significant factor for increasing the electroporation efficiency was the cell wall weakening mediated by NaCl, which improved the electroporation frequency by 20 times. Because the optimized electrotransformation conditions reported here should be widely applicable to other Bifidobacterium species, these could promote the extensive genetic manipulation of the various Bifidobacterium species in future studies.
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Affiliation(s)
- Min Ju Park
- Department of Food and Nutrition, Research Institute of Human Ecology, Seoul National University, Seoul 151-742, Republic of Korea
| | - Myeong Soo Park
- Research Center, BIFIDO Co., Ltd, Hongcheon 205-804, Republic of Korea; Department of Hotel Culinary Arts, Yeonsung University, Anyang 430-749, Republic of Korea.
| | - Geun Eog Ji
- Department of Food and Nutrition, Research Institute of Human Ecology, Seoul National University, Seoul 151-742, Republic of Korea; Research Center, BIFIDO Co., Ltd, Hongcheon 205-804, Republic of Korea.
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Chahuki FF, Aminzadeh S, Jafarian V, Tabandeh F, Khodabandeh M. Hyaluronic acid production enhancement via genetically modification and culture medium optimization in Lactobacillus acidophilus. Int J Biol Macromol 2018; 121:870-881. [PMID: 30342141 DOI: 10.1016/j.ijbiomac.2018.10.112] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/17/2018] [Accepted: 10/14/2018] [Indexed: 01/16/2023]
Abstract
Hyaluronic acid (HA) is a natural polymer with various molecular weights that specify multiple biological roles. Traditionally, HA is obtained from animal waste and conventional pathogenic streptococci. However, there are challenges in these processes such as the presence of exotoxins, hyaluronidase, and viral contamination. In order to reduce these problems, this study was conducted to produce HA using recombinant bacterium that is generally recognized as safe (GRAS), and thereafter increase production through experimental design. At first, some lactic acid bacteria were screened and evaluated for HA production. Accordingly, among the selected bacteria, Lactobacillus acidophilus PTCC1643 produced about 0.25 g HA/L in the 48th hour of cultivation, and was thus selected as an alternative host for heterologous HA production. An expression vector containing HA synthase genes was transformed into L. acidophilus by electroporation. Consequently, HA production increased to 0.4 g/L. Eventually, response surface method (RSM) was used, which increased HA production to 1.7 g/L. This is approximately 7-fold higher than that produced at first. The resulting HA was characterized by FTIR spectroscopy and its molecular weight was estimated using agarose gel electrophoresis. In conclusion, L. acidophilus could be a safe, effective, and novel HA producer with industrial potential and commercial prospects.
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Affiliation(s)
- Fatemeh Fotouhi Chahuki
- National Institute for Genetic Engineering and Biotechnology (NIGEB), Institute of Industrial and Environmental Biotechnology, Bioprocess Engineering Research Group, Shahrak-e Pajoohesh km 15, Tehran-Karaj Highway, P. O. Box: 14965/161, Tehran, Iran; Department of Biology, Faculty of Sciences, University of Zanjan, Iran
| | - Saeed Aminzadeh
- National Institute for Genetic Engineering and Biotechnology (NIGEB), Institute of Industrial and Environmental Biotechnology, Bioprocess Engineering Research Group, Shahrak-e Pajoohesh km 15, Tehran-Karaj Highway, P. O. Box: 14965/161, Tehran, Iran.
| | - Vahab Jafarian
- Department of Biology, Faculty of Sciences, University of Zanjan, Iran
| | - Fatemeh Tabandeh
- National Institute for Genetic Engineering and Biotechnology (NIGEB), Institute of Industrial and Environmental Biotechnology, Bioprocess Engineering Research Group, Shahrak-e Pajoohesh km 15, Tehran-Karaj Highway, P. O. Box: 14965/161, Tehran, Iran
| | - Mahvash Khodabandeh
- National Institute for Genetic Engineering and Biotechnology (NIGEB), Institute of Industrial and Environmental Biotechnology, Bioprocess Engineering Research Group, Shahrak-e Pajoohesh km 15, Tehran-Karaj Highway, P. O. Box: 14965/161, Tehran, Iran
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12
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Arnold JW, Simpson JB, Roach J, Bruno-Barcena JM, Azcarate-Peril MA. Prebiotics for Lactose Intolerance: Variability in Galacto-Oligosaccharide Utilization by Intestinal Lactobacillus rhamnosus. Nutrients 2018; 10:E1517. [PMID: 30332787 PMCID: PMC6213946 DOI: 10.3390/nu10101517] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 10/09/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022] Open
Abstract
Lactose intolerance, characterized by a decrease in host lactase expression, affects approximately 75% of the world population. Galacto-oligosaccharides (GOS) are prebiotics that have been shown to alleviate symptoms of lactose intolerance and to modulate the intestinal microbiota, promoting the growth of beneficial microorganisms. We hypothesized that mechanisms of GOS utilization by intestinal bacteria are variable, impacting efficacy and response, with differences occurring at the strain level. This study aimed to determine the mechanisms by which human-derived Lactobacillus rhamnosus strains metabolize GOS. Genomic comparisons between strains revealed differences in carbohydrate utilization components, including transporters, enzymes for degradation, and transcriptional regulation, despite a high overall sequence identity (>95%) between strains. Physiological and transcriptomics analyses showed distinct differences in carbohydrate metabolism profiles and GOS utilization between strains. A putative operon responsible for GOS utilization was identified and characterized by genetic disruption of the 6-phospho-β-galactosidase, which had a critical role in GOS utilization. Our findings highlight the importance of strain-specific bacterial metabolism in the selection of probiotics and synbiotics to alleviate symptoms of gastrointestinal disorders including lactose intolerance.
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Affiliation(s)
- Jason W Arnold
- Center for Gastrointestinal Biology and Disease, Division of Gastroenterology and Hepatology, and UNC Microbiome Core, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Joshua B Simpson
- Center for Gastrointestinal Biology and Disease, Division of Gastroenterology and Hepatology, and UNC Microbiome Core, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Jeffery Roach
- Research Computing, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Jose M Bruno-Barcena
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27607, USA.
| | - M Andrea Azcarate-Peril
- Center for Gastrointestinal Biology and Disease, Division of Gastroenterology and Hepatology, and UNC Microbiome Core, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
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Vedantam G, Kochanowsky J, Lindsey J, Mallozzi M, Roxas JL, Adamson C, Anwar F, Clark A, Claus-Walker R, Mansoor A, McQuade R, Monasky RC, Ramamurthy S, Roxas B, Viswanathan VK. An Engineered Synthetic Biologic Protects Against Clostridium difficile Infection. Front Microbiol 2018; 9:2080. [PMID: 30233548 PMCID: PMC6134020 DOI: 10.3389/fmicb.2018.02080] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/14/2018] [Indexed: 12/18/2022] Open
Abstract
Morbidity and mortality attributed to Clostridium difficile infection (CDI) have increased over the past 20 years. Currently, antibiotics are the only US FDA-approved treatment for primary C. difficile infection, and these are, ironically, associated with disease relapse and the threat of burgeoning drug resistance. We previously showed that non-toxin virulence factors play key roles in CDI, and that colonization factors are critical for disease. Specifically, a C. difficile adhesin, Surface Layer Protein A (SlpA) is a major contributor to host cell attachment. In this work, we engineered Syn-LAB 2.0 and Syn-LAB 2.1, two synthetic biologic agents derived from lactic acid bacteria, to stably and constitutively express a host-cell binding fragment of the C. difficile adhesin SlpA on their cell-surface. Both agents harbor conditional suicide plasmids expressing a codon-optimized chimera of the lactic acid bacterium's cell-wall anchoring surface-protein domain, fused to the conserved, highly adherent, host-cell-binding domain of C. difficile SlpA. Both agents also incorporate engineered biocontrol, obviating the need for any antibiotic selection. Syn-LAB 2.0 and Syn-LAB 2.1 possess positive biophysical and in vivo properties compared with their parental antecedents in that they robustly and constitutively display the SlpA chimera on their cell surface, potentiate human intestinal epithelial barrier function in vitro, are safe, tolerable and palatable to Golden Syrian hamsters and neonatal piglets at high daily doses, and are detectable in animal feces within 24 h of dosing, confirming robust colonization. In combination, the engineered strains also delay (in fixed doses) or prevent (when continuously administered) death of infected hamsters upon challenge with high doses of virulent C. difficile. Finally, fixed-dose Syn-LAB ameliorates diarrhea in a non-lethal model of neonatal piglet enteritis. Taken together, our findings suggest that the two synthetic biologics may be effectively employed as non-antibiotic interventions for CDI.
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Affiliation(s)
- Gayatri Vedantam
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
- Department of Immunobiology, The University of Arizona, Tucson, AZ, United States
- Bio5 Institute for Collaborative Research, The University of Arizona, Tucson, AZ, United States
- Southern Arizona VA Health Care System, Tucson, AZ, United States
| | - Joshua Kochanowsky
- Department of Immunobiology, The University of Arizona, Tucson, AZ, United States
| | - Jason Lindsey
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Michael Mallozzi
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Jennifer Lising Roxas
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Chelsea Adamson
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Farhan Anwar
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Andrew Clark
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Rachel Claus-Walker
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Asad Mansoor
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Rebecca McQuade
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Ross Calvin Monasky
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Shylaja Ramamurthy
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Bryan Roxas
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - V. K. Viswanathan
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
- Department of Immunobiology, The University of Arizona, Tucson, AZ, United States
- Bio5 Institute for Collaborative Research, The University of Arizona, Tucson, AZ, United States
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Ortiz-Velez L, Ortiz-Villalobos J, Schulman A, Oh JH, van Pijkeren JP, Britton RA. Genome alterations associated with improved transformation efficiency in Lactobacillus reuteri. Microb Cell Fact 2018; 17:138. [PMID: 30176942 PMCID: PMC6122466 DOI: 10.1186/s12934-018-0986-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 08/24/2018] [Indexed: 12/30/2022] Open
Abstract
Background Lactic acid bacteria (LAB) are one of the microorganisms of choice for the development of protein delivery systems for therapeutic purposes. Although there are numerous tools to facilitate genome engineering of lactobacilli; transformation efficiency still limits the ability to engineer their genomes. While genetically manipulating Lactobacillus reuteri ATCC PTA 6475 (LR 6475), we noticed that after an initial transformation, several LR 6475 strains significantly improved their ability to take up plasmid DNA via electroporation. Our goal was to understand the molecular basis for how these strains acquired the ability to increase transformation efficiency. Results Strains generated after transformation of plasmids pJP067 and pJP042 increased their ability to transform plasmid DNA about one million fold for pJP067, 100-fold for pSIP411 and tenfold for pNZ8048. Upon sequencing of the whole genome from these strains, we identified several genomic mutations and rearrangements, with all strains containing mutations in the transformation related gene A (trgA). To evaluate the role of trgA in transformation of DNA, we generated a trgA null that improved the transformation efficiency of LR 6475 to transform pSIP411 and pJP067 by at least 100-fold, demonstrating that trgA significantly impairs the ability of LR 6475 to take-up plasmid DNA. We also identified genomic rearrangements located in and around two prophages inserted in the LR 6475 genome that included deletions, insertions and an inversion of 336 Kb. A second group of rearrangements was observed in a Type I restriction modification system, in which the specificity subunits underwent several rearrangements in the target recognition domain. Despite the magnitude of these rearrangements in the prophage genomes and restriction modification systems, none of these genomic changes impacted transformation efficiency to the level induced by trgA. Conclusions Our findings demonstrate how genetic manipulation of LR 6475 with plasmid DNA leads to genomic changes that improve their ability to transform plasmid DNA; highlighting trgA as the primary driver of this phenotype. Additionally, this study also underlines the importance of characterizing genetic changes that take place after genome engineering of strains for therapeutic purposes. Electronic supplementary material The online version of this article (10.1186/s12934-018-0986-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laura Ortiz-Velez
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA
| | | | - Abby Schulman
- Department of Cognitive Sciences, Rice University, Houston, TX, USA
| | - Jee-Hwan Oh
- Department of Food Science, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Robert A Britton
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA.
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15
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Arnold JW, Simpson JB, Roach J, Kwintkiewicz J, Azcarate-Peril MA. Intra-species Genomic and Physiological Variability Impact Stress Resistance in Strains of Probiotic Potential. Front Microbiol 2018; 9:242. [PMID: 29515537 PMCID: PMC5826259 DOI: 10.3389/fmicb.2018.00242] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/31/2018] [Indexed: 12/28/2022] Open
Abstract
Large-scale microbiome studies have established that most of the diversity contained in the gastrointestinal tract is represented at the strain level; however, exhaustive genomic and physiological characterization of human isolates is still lacking. With increased use of probiotics as interventions for gastrointestinal disorders, genomic and functional characterization of novel microorganisms becomes essential. In this study, we explored the impact of strain-level genomic variability on bacterial physiology of two novel human Lactobacillus rhamnosus strains (AMC143 and AMC010) of probiotic potential in relation to stress resistance. The strains showed differences with known probiotic strains (L. rhamnosus GG, Lc705, and HN001) at the genomic level, including nucleotide polymorphisms, mutations in non-coding regulatory regions, and rearrangements of genomic architecture. Transcriptomics analysis revealed that gene expression profiles differed between strains when exposed to simulated gastrointestinal stresses, suggesting the presence of unique regulatory systems in each strain. In vitro physiological assays to test resistance to conditions mimicking the gut environment (acid, alkali, and bile stress) showed that growth of L. rhamnosus AMC143 was inhibited upon exposure to alkaline pH, while AMC010 and control strain LGG were unaffected. AMC143 also showed a significant survival advantage compared to the other strains upon bile exposure. Reverse transcription qPCR targeting the bile salt hydrolase gene (bsh) revealed that AMC143 expressed bsh poorly (a consequence of a deletion in the bsh promoter and truncation of bsh gene in AMC143), while AMC010 had significantly higher expression levels than AMC143 or LGG. Insertional inactivation of the bsh gene in AMC010 suggested that bsh could be detrimental to bacterial survival during bile stress. Together, these findings show that coupling of classical microbiology with functional genomics methods for the characterization of bacterial strains is critical for the development of novel probiotics, as variability between strains can dramatically alter bacterial physiology and functionality.
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Affiliation(s)
- Jason W. Arnold
- Division of Gastroenterology and Hepatology, Department of Medicine, Microbiome Core Facility, Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
| | - Joshua B. Simpson
- Department of Chemistry, College of Arts and Sciences, University of North Carolina, Chapel Hill, NC, United States
| | - Jeffrey Roach
- Research Computing, University of North Carolina, Chapel Hill, NC, United States
| | - Jakub Kwintkiewicz
- Division of Gastroenterology and Hepatology, Department of Medicine, Microbiome Core Facility, Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
| | - M. Andrea Azcarate-Peril
- Division of Gastroenterology and Hepatology, Department of Medicine, Microbiome Core Facility, Center for Gastrointestinal Biology and Disease, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
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16
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Correlation of Lactobacillus rhamnosus Genotypes and Carbohydrate Utilization Signatures Determined by Phenotype Profiling. Appl Environ Microbiol 2015; 81:5458-70. [PMID: 26048937 DOI: 10.1128/aem.00851-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 05/28/2015] [Indexed: 12/17/2022] Open
Abstract
Lactobacillus rhamnosus is a bacterial species commonly colonizing the gastrointestinal (GI) tract of humans and also frequently used in food products. While some strains have been studied extensively, physiological variability among isolates of the species found in healthy humans or their diet is largely unexplored. The aim of this study was to characterize the diversity of carbohydrate utilization capabilities of human isolates and food-derived strains of L. rhamnosus in relation to their niche of isolation and genotype. We investigated the genotypic and phenotypic diversity of 25 out of 65 L. rhamnosus strains from various niches, mainly human feces and fermented dairy products. Genetic fingerprinting of the strains by amplified fragment length polymorphism (AFLP) identified 11 distinct subgroups at 70% similarity and suggested niche enrichment within particular genetic clades. High-resolution carbohydrate utilization profiling (OmniLog) identified 14 carbon sources that could be used by all of the strains tested for growth, while the utilization of 58 carbon sources differed significantly between strains, enabling the stratification of L. rhamnosus strains into three metabolic clusters that partially correlate with the genotypic clades but appear uncorrelated with the strain's origin of isolation. Draft genome sequences of 8 strains were generated and employed in a gene-trait matching (GTM) analysis together with the publicly available genomes of L. rhamnosus GG (ATCC 53103) and HN001 for several carbohydrates that were distinct for the different metabolic clusters: l-rhamnose, cellobiose, l-sorbose, and α-methyl-d-glucoside. From the analysis, candidate genes were identified that correlate with l-sorbose and α-methyl-d-glucoside utilization, and the proposed function of these genes could be confirmed by heterologous expression in a strain lacking the genes. This study expands our insight into the phenotypic and genotypic diversity of the species L. rhamnosus and explores the relationships between specific carbohydrate utilization capacities and genotype and/or niche adaptation of this species.
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17
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Abstract
Propionicin PLG-1 is a bacteriocin produced by Propionibacterium thoenii P127. Such bacteriocin inhibits wide range of food-borne pathogens such as pathogenic Escherichia coli, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Yersinia enterocolitica and a strain of Corynebacterium sp. In the present study, plg-1 gene expressing propionicin PLG-1 was isolated, sequenced for the first time and the resulting sequence was analysed using several web-based bioinformatics programs. The PCR product containing plg-1 gene was transferred to different lactic acid bacterial (LAB) strains using pLEB590 as a cloning vector to give the modified vector pLEBPLG-1. LAB transformants showed an antimicrobial activity against Esch. coli DH5α (most affected strain), Listeria monocytogenes 18116, and Salmonella enterica 25566 as model pathogenic strains. Such LAB transformants can be used in dairy industry to control the food-borne pathogens that are largely distributed worldwide and to feed schoolchildren in the poor countries where dangerous epidemic diseases and diarrhoea prevail.
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18
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Pflügl S, Marx H, Mattanovich D, Sauer M. Genetic engineering ofLactobacillus diolivorans. FEMS Microbiol Lett 2013; 344:152-8. [DOI: 10.1111/1574-6968.12168] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 04/22/2013] [Accepted: 04/27/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
| | - Hans Marx
- Department of Biotechnology; BOKU - VIBT University of Natural Resources and Life Sciences; Vienna; Austria
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Inhibition of Staphylococcus aureus by lysostaphin-expressing Lactobacillus plantarum WCFS1 in a modified genital tract secretion medium. Appl Environ Microbiol 2011; 77:8500-8. [PMID: 21984245 DOI: 10.1128/aem.06755-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus species are a predominant member of the vaginal microflora and are critical in maintaining an acidic vaginal environment thought to contribute to the prevention of a number of urogenital diseases. However, during menstruation the pH of the vaginal environment increases to neutrality, a pH conducive for Staphylococcus aureus proliferation and the production of toxic shock syndrome toxin 1 (TSST-1) in susceptible women. In order to generate Lactobacillus species capable of expressing lysostaphin (an endopeptidase that cleaves the cell wall of S. aureus) in a modified genital tract secretion medium (mGTS) under neutral-pH conditions, six prominent proteins from Lactobacillus plantarum WCFS1 spent medium were identified by mass spectrometry. Sequences for promoters, signal peptides, and mature lysostaphin were used to construct plasmids that were subsequently transformed into L. plantarum WCFS1. The promoter and signal sequences of Lp_3014 (putatively identified as a transglycosylase) or the promoter sequence of Lp_0789 (putatively identified as glyceraldehyde 3-phosphate dehydrogenase) with the signal sequence of Lp_3014 exhibited lysostaphin activity on buffered medium containing heat-killed S. aureus. The cassettes were integrated into the chromosome of L. plantarum WCFS1, but only the cassette containing the promoter and signal sequence from Lp_3014 had integrated into the appropriate site. Coculture assays using buffered mGTS showed that lysostaphin expressed from L. plantarum WCFS1 reduced the growth of TSST-1-producing strains of S. aureus under neutral-pH conditions. This study provides the basis for determining whether lysostaphin-producing Lactobacillus strains could potentially be used as a means to inhibit the growth of S. aureus during menstruation.
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Palomino MM, Allievi MC, Prado-Acosta M, Sanchez-Rivas C, Ruzal SM. New method for electroporation of Lactobacillus species grown in high salt. J Microbiol Methods 2010; 83:164-7. [DOI: 10.1016/j.mimet.2010.08.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 08/16/2010] [Accepted: 08/17/2010] [Indexed: 11/30/2022]
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Genetic and proteomic analysis of factors affecting serum cholesterol reduction by Lactobacillus acidophilus A4. Appl Environ Microbiol 2010; 76:4829-35. [PMID: 20495044 DOI: 10.1128/aem.02892-09] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
This article identifies novel factors involved in cholesterol reduction by probiotic bacteria, which were identified using genetic and proteomic approaches. Approximately 600 Lactobacillus acidophilus A4 mutants were created by random mutagenesis. The cholesterol-reducing ability of each mutant was determined and verified using two different methods: the o-phthalaldehyde assay and gas chromatographic analysis (GC). Among screened mutants, strain BA9 showed a dramatically diminished ability to reduce cholesterol, as demonstrated by a 7.7% reduction rate, while the parent strain had a more than 50% reduction rate. The transposon insertion site was mapped using inverse PCR (I-PCR), and it was determined using bioinformatic methods that the deleted region contained the Streptococcus thermophilus catabolite control protein A gene (ccpA). In addition, we have shown using two-dimensional gel electrophoresis (2-DE) that several proteins, including a transcription regulator, FMN-binding protein, major facilitator superfamily permease, glycogen phosphorylase, the YknV protein, and fructose/tagatose bisphosphate aldolase, were strongly regulated by the ccpA gene. In addition, in vivo experiments investigating ccpA function were conducted with rats. Rats fed wild-type L. acidophilus A4 showed a greater than 20% reduction in total serum cholesterol, but rats fed BA9 mutant L. acidophilus showed only an approximately 10% reduction in cholesterol. These results provide important insights into the mechanism by which these lactic acid bacteria reduce cholesterol.
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22
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Methodologies to increase the transformation efficiencies and the range of bacteria that can be transformed. Appl Microbiol Biotechnol 2009; 85:1301-13. [DOI: 10.1007/s00253-009-2349-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 11/06/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
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23
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Electroporation in Biological Cell and Tissue: An Overview. ELECTROTECHNOLOGIES FOR EXTRACTION FROM FOOD PLANTS AND BIOMATERIALS 2009. [DOI: 10.1007/978-0-387-79374-0_1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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De Keersmaecker SCJ, Braeken K, Verhoeven TLA, Perea Vélez M, Lebeer S, Vanderleyden J, Hols P. Flow cytometric testing of green fluorescent protein-tagged Lactobacillus rhamnosus GG for response to defensins. Appl Environ Microbiol 2006; 72:4923-30. [PMID: 16820489 PMCID: PMC1489346 DOI: 10.1128/aem.02605-05] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Accepted: 04/15/2006] [Indexed: 01/01/2023] Open
Abstract
Lactobacillus rhamnosus GG is of general interest as a probiotic. Although L. rhamnosus GG is often used in clinical trials, there are few genetic tools to further determine its mode of action or to develop it as a vehicle for heterologous gene expression in therapy. Therefore, we developed a reproducible, efficient electroporation procedure for L. rhamnosus GG. The best transformation efficiency obtained was 10(4) transformants per microg of DNA. We validated this protocol by tagging L. rhamnosus GG with green fluorescent protein (GFP) using the nisin-controlled expression (NICE) system. Parameters for overexpression were optimized, which allowed expression of gfp in L. rhamnosus GG upon induction with nisin. The GFP+ strain can be used to monitor the survival and behavior of L. rhamnosus GG in vivo. Moreover, implementation of the NICE system as a gene expression switch in L. rhamnosus GG opens up possibilities for improving and expanding the performance of this strain. The GFP-labeled strain was used to demonstrate that L. rhamnosus GG is sensitive to human beta-defensin-2 but not to human beta-defensin-1.
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