1
|
Sedlmayr VL, Schobesberger S, Spitz S, Ertl P, Wurm DJ, Quehenberger J, Spadiut O. Archaeal ether lipids improve internalization and transfection with mRNA lipid nanoparticles. Eur J Pharm Biopharm 2024; 197:114213. [PMID: 38346479 DOI: 10.1016/j.ejpb.2024.114213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/19/2024] [Accepted: 02/06/2024] [Indexed: 03/19/2024]
Abstract
Neutral and positively charged archaeal ether lipids (AEL) have been studied for their utilization as novel delivery systems for pDNA, showing efficient immune response with a strong memory effect while lacking noticeable toxicity. Recent technological advances placed mRNA lipid nanoparticles (LNPs) at the forefront of next-generation delivery systems; however, no study has examined AELs in mRNA delivery yet. In this study, we investigated either a crude lipid extract or the purified tetraether lipid caldarchaeol from Sulfolobus acidocaldarius as potential novel excipients for mRNA LNPs. Depending on their molar share in the respective LNP, particle uptake, and mRNA expression levels could be increased by up to 10-fold in in vitro transfection experiments using both primary cell sources (HSMM) and established cell lines (Caco-2, C2C12) compared to a well-known reference formulation. This increased efficiency might be linked to a substantial effect on endosomal escape, indicating fusogenic and lyotropic features of AELs. This study shows the high value of archaeal ether lipids for mRNA delivery and provides a solid foundation for future in vivo experiments and further research.
Collapse
Affiliation(s)
- Viktor Laurin Sedlmayr
- Research Division Integrated Bioprocess Development, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Straße 1a, Vienna 1060, Austria
| | - Silvia Schobesberger
- Research Division Organic & Biological Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, Vienna 1060, Austria
| | - Sarah Spitz
- Research Division Organic & Biological Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, Vienna 1060, Austria
| | - Peter Ertl
- Research Division Organic & Biological Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, Vienna 1060, Austria
| | | | - Julian Quehenberger
- Research Division Integrated Bioprocess Development, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Straße 1a, Vienna 1060, Austria; NovoArc GmbH, Pottendorfer Straße 23-25, Vienna 1120, Austria
| | - Oliver Spadiut
- Research Division Integrated Bioprocess Development, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Gumpendorfer Straße 1a, Vienna 1060, Austria.
| |
Collapse
|
2
|
Sedlmayr V, Horn C, Wurm DJ, Spadiut O, Quehenberger J. Archaeosomes facilitate storage and oral delivery of cannabidiol. Int J Pharm 2023; 645:123434. [PMID: 37739097 DOI: 10.1016/j.ijpharm.2023.123434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/15/2023] [Accepted: 09/19/2023] [Indexed: 09/24/2023]
Abstract
Cannabidiol (CBD) has received great scientific interest due to its numerous therapeutic applications. Degradation in the gastrointestinal (GI) tract, first-pass metabolism, and low water solubility restrain bioavailability of CBD to only 6% in current oral administration. Lipid-based nanocarriers are delivery systems that may enhance accessibility and solubility of hydrophobic payloads, such as CBD. Conventional lecithin-derived liposomes, however, have limitations regarding stability in the GI tract and long-term storage. Ether lipid-based archaeosomes may have the potential to overcome these problems due to chemical and structural uniqueness. In this study, we compared lecithin-derived liposomes with archaeosomes in their applicability as an oral delivery system of CBD. We evaluated drug load, storage stability, stability in a simulated GI tract, and in vitro particle uptake in Caco-2 cells. Loading capacity was 6-fold higher in archaeosomes than conventional liposomes while providing a stable formulation over six months after lyophilization. In a simulated GI tract, CBD recovery in archaeosomes was 57 ± 3% compared to only 34 ± 1% in conventional liposomes and particle uptake in Caco-2 cells was enhanced up to 6-fold. Our results demonstrate that archaeosomes present an interesting solution to tackle current issues of oral CBD formulations due to improved stability and endocytosis.
Collapse
Affiliation(s)
- Viktor Sedlmayr
- TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Vienna, Austria
| | | | | | - Oliver Spadiut
- TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Vienna, Austria
| | - Julian Quehenberger
- TU Wien, Institute of Chemical, Environmental and Bioscience Engineering, Vienna, Austria; NovoArc GmbH, Vienna, Austria.
| |
Collapse
|
3
|
Rastädter K, Wurm DJ, Spadiut O, Quehenberger J. k La based scale-up cultivation of the extremophilic archaeon Sulfolobus acidocaldarius: from benchtop to pilot scale. Front Bioeng Biotechnol 2023; 11:1160012. [PMID: 37609112 PMCID: PMC10441222 DOI: 10.3389/fbioe.2023.1160012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 07/24/2023] [Indexed: 08/24/2023] Open
Abstract
The two major scale-up criteria in continuously stirred bioreactors are 1) constant aerated power input per volume (Pg/Vl), and 2) the volumetric O2 mass transfer coefficient (kla). However, Pg/Vl is only influenced by the stirrer geometry, stirrer speed, aeration and working volume, while the kla is additionally affected by physiochemical properties of the medium (temperature, pH, salt content, etc.), sparging of gas and also by the bioreactor design. The extremophilic archaeon Sulfolobus acidocaldarius, thriving at 75°C and pH 3.0, has the potential for many biotechnological applications. However, previous studies imply that the family Sulfolobaceae might be affected by higher oxygen concentration in the headspace (>26%). Hence, adequate oxygen supply without being toxic has to be ensured throughout the different scales. In this study, the scale-up criteria Pg/Vl and kla were analyzed and compared in a 2 L chemostat cultivation of S. acidocaldarius on a defined growth medium at 75°C and a pH value of 3.0, using two different types of spargers at the same aerated power input. The scale-up criterion kLa, ensuring a high specific growth rate as well as viability, was then used for scaleup to 20 L and 200 L. By maintaining a constant kla comparable dry cell weight, specific growth rate, specific substrate uptake rates and viability were observed between all investigated scales. This procedure harbors the potential for further scale-up to industrial size bioreactors.
Collapse
Affiliation(s)
- Kerstin Rastädter
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | | | - Oliver Spadiut
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Julian Quehenberger
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
- NovoArc GmbH, Vienna, Austria
| |
Collapse
|
4
|
Rastädter K, Tramontano A, Wurm DJ, Spadiut O, Quehenberger J. Flow cytometry-based viability staining: an at-line tool for bioprocess monitoring of Sulfolobus acidocaldarius. AMB Express 2022; 12:107. [PMID: 35947320 PMCID: PMC9365904 DOI: 10.1186/s13568-022-01447-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
Determination of the viability, ratio of dead and live cell populations, of Sulfolobus acidocaldarius is still being done by tedious and material-intensive plating assays that can only provide time-lagged results. Although S. acidocaldarius, an extremophilic Archaeon thriving at 75 °C and pH 3.0, and related species harbor great potential for the exploitation as production hosts and biocatalysts in biotechnological applications, no industrial processes have been established yet. One hindrance is that during development and scaling of industrial bioprocesses timely monitoring of the impact of process parameters on the cultivated organism is crucial—a task that cannot be fulfilled by traditional plating assays. As alternative, flow cytometry (FCM) promises a fast and reliable method for viability assessment via the use of fluorescent dyes. In this study, commercially available fluorescent dyes applicable in S. acidocaldarius were identified. The dyes, fluorescein diacetate and concanavalin A conjugated with rhodamine, were discovered to be suitable for viability determination via FCM. For showing the applicability of the developed at-line tool for bioprocess monitoring, a chemostat cultivation on a defined growth medium at 75 °C, pH 3.0 was conducted. Over the timeframe of 800 h, this developed FCM method was compared to the plating assay by monitoring the change in viability upon controlled pH shifts. Both methods detected an impact on the viability at pH values of 2.0 and 1.5 when compared to pH 3.0. A logarithmic relationship between the viability observed via plating assay and via FCM was observed. Development of a flow cytometry (FCM) method for viability determination of S. acidocaldarius using the fluorescent dyes fluorescein diacetate and concanavalin A conjugated with rhodamine. Applicability of the developed method was shown via viability monitoring during a continuous cultivation with triggered pH shifts. A logarithmic trend was observed between the developed FCM method and the state-of-the-art method, plating assay.
Collapse
Affiliation(s)
- Kerstin Rastädter
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, 1060, Vienna, Austria
| | - Andrea Tramontano
- Department of Functional and Evolutionary Ecology, Archaea Biology and Ecogenomics Unit, University of Vienna, 1030, Vienna, Austria
| | | | - Oliver Spadiut
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, 1060, Vienna, Austria
| | - Julian Quehenberger
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, 1060, Vienna, Austria.
| |
Collapse
|
5
|
Quehenberger J, Pittenauer E, Allmaier G, Spadiut O. The influence of the specific growth rate on the lipid composition of Sulfolobus acidocaldarius. Extremophiles 2020; 24:413-420. [PMID: 32200441 PMCID: PMC7174258 DOI: 10.1007/s00792-020-01165-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/09/2020] [Indexed: 12/22/2022]
Abstract
Archaeal lipids are constituted of two isoprenoid chains connected via ether bonds to glycerol in the sn-2, 3 position. Due to these unique properties archaeal lipids are significantly more stable against high temperature, low pH, oxidation and enzymatic degradation than conventional lipids. Additionally, in members of the phylum Crenarchaeota condensation of two (monopolar) archaeal diether lipids to a single (bipolar) tetraether lipid as well as formation of cyclopentane rings in the isoprenoid core strongly reduce permeability of the crenarchaeal membranes. In this work we show that the Crenarchaeum Sulfolobus acidocaldarius changes its lipid composition as reaction to a shift in growth rate caused by nutrient limitation. We thereby identified a novel influencing factor for the lipid composition of S. acidocaldarius and were able to determine the effect of this factor on the lipid composition by using MALDI-MS for the semi-quantification of an archaeal lipidome: a shift in the specific growth rate during a controlled continuous cultivation of S. acidocaldarius from 0.011 to 0.035 h−1 led to a change in the ratio of diether to tetraether lipids from 1:3 to 1:5 and a decrease of the average number of cyclopentane rings from 5.1 to 4.6.
Collapse
Affiliation(s)
- Julian Quehenberger
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Ernst Pittenauer
- Research Group for Mass Spectrometric Bio and Polymer Analytics, Faculty of Technical Chemistry, Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Günter Allmaier
- Research Group for Mass Spectrometric Bio and Polymer Analytics, Faculty of Technical Chemistry, Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Oliver Spadiut
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria.
| |
Collapse
|
6
|
Walter I, Landers S, Quehenberger J, Carlson E, Brisch KH. *The efficacy of the attachment-based SAFE® prevention program: a randomized control trial including mothers and fathers. Attach Hum Dev 2019; 21:510-531. [DOI: 10.1080/14616734.2019.1582599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- I. Walter
- Department of Pediatric Psychosomatic Medicine and Psychotherapy, Dr. von Hauner Children‘s Hospital, University Hospital LMU Munich, Munich, Germany
| | - S. Landers
- Department of Pediatric Psychosomatic Medicine and Psychotherapy, Dr. von Hauner Children‘s Hospital, University Hospital LMU Munich, Munich, Germany
| | - J. Quehenberger
- Department of Pediatric Psychosomatic Medicine and Psychotherapy, Dr. von Hauner Children‘s Hospital, University Hospital LMU Munich, Munich, Germany
| | - E. Carlson
- Department of Psychiatry, University of Minnesota, Minneapolis, MN, USA
| | - K. H. Brisch
- Department of Pediatric Psychosomatic Medicine and Psychotherapy, Dr. von Hauner Children‘s Hospital, University Hospital LMU Munich, Munich, Germany
| |
Collapse
|
7
|
Quehenberger J, Reichenbach T, Baumann N, Rettenbacher L, Divne C, Spadiut O. Kinetics and Predicted Structure of a Novel Xylose Reductase from Chaetomium thermophilum. Int J Mol Sci 2019; 20:ijms20010185. [PMID: 30621365 PMCID: PMC6337131 DOI: 10.3390/ijms20010185] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 12/29/2018] [Accepted: 01/01/2019] [Indexed: 11/16/2022] Open
Abstract
While in search of an enzyme for the conversion of xylose to xylitol at elevated temperatures, a xylose reductase (XR) gene was identified in the genome of the thermophilic fungus Chaetomium thermophilum. The gene was heterologously expressed in Escherichia coli as a His6-tagged fusion protein and characterized for function and structure. The enzyme exhibits dual cofactor specificity for NADPH and NADH and prefers D-xylose over other pentoses and investigated hexoses. A homology model based on a XR from Candida tenuis was generated and the architecture of the cofactor binding site was investigated in detail. Despite the outstanding thermophilicity of its host the enzyme is, however, not thermostable.
Collapse
Affiliation(s)
- Julian Quehenberger
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Faculty of Technical Chemistry, TU Wien, 1060 Vienna, Austria.
| | - Tom Reichenbach
- KTH School of Engineering Sciences in Chemistry, Biotechnology and Health, SE-100 44 Stockholm, Sweden.
| | - Niklas Baumann
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Faculty of Technical Chemistry, TU Wien, 1060 Vienna, Austria.
| | - Lukas Rettenbacher
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Faculty of Technical Chemistry, TU Wien, 1060 Vienna, Austria.
| | - Christina Divne
- KTH School of Engineering Sciences in Chemistry, Biotechnology and Health, SE-100 44 Stockholm, Sweden.
| | - Oliver Spadiut
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Bioscience Engineering, Faculty of Technical Chemistry, TU Wien, 1060 Vienna, Austria.
| |
Collapse
|
8
|
Quehenberger J, Shen L, Albers SV, Siebers B, Spadiut O. Sulfolobus - A Potential Key Organism in Future Biotechnology. Front Microbiol 2017; 8:2474. [PMID: 29312184 PMCID: PMC5733018 DOI: 10.3389/fmicb.2017.02474] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/28/2017] [Indexed: 11/13/2022] Open
Abstract
Extremophilic organisms represent a potentially valuable resource for the development of novel bioprocesses. They can act as a source for stable enzymes and unique biomaterials. Extremophiles are capable of carrying out microbial processes and biotransformations under extremely hostile conditions. Extreme thermoacidophilic members of the well-characterized genus Sulfolobus are outstanding in their ability to thrive at both high temperatures and low pH. This review gives an overview of the biological system Sulfolobus including its central carbon metabolism and the development of tools for its genetic manipulation. We highlight findings of commercial relevance and focus on potential industrial applications. Finally, the current state of bioreactor cultivations is summarized and we discuss the use of Sulfolobus species in biorefinery applications.
Collapse
Affiliation(s)
- Julian Quehenberger
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Biological Engineering, Vienna University of Technology, Vienna, Austria
| | - Lu Shen
- Department of Molecular Enzyme Technology and Biochemistry, Faculty of Chemistry – Biofilm Centre, University of Duisburg-Essen, Essen, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II-Microbiology, Faculty of Biology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Bettina Siebers
- Department of Molecular Enzyme Technology and Biochemistry, Faculty of Chemistry – Biofilm Centre, University of Duisburg-Essen, Essen, Germany
| | - Oliver Spadiut
- Research Division Biochemical Engineering, Faculty of Technical Chemistry, Institute of Chemical, Environmental and Biological Engineering, Vienna University of Technology, Vienna, Austria
| |
Collapse
|
9
|
Wurm DJ, Quehenberger J, Mildner J, Eggenreich B, Slouka C, Schwaighofer A, Wieland K, Lendl B, Rajamanickam V, Herwig C, Spadiut O. Teaching an old pET new tricks: tuning of inclusion body formation and properties by a mixed feed system in E. coli. Appl Microbiol Biotechnol 2017; 102:667-676. [PMID: 29159587 PMCID: PMC5756567 DOI: 10.1007/s00253-017-8641-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022]
Abstract
Against the outdated belief that inclusion bodies (IBs) in Escherichia coli are only inactive aggregates of misfolded protein, and thus should be avoided during recombinant protein production, numerous biopharmaceutically important proteins are currently produced as IBs. To obtain correctly folded, soluble product, IBs have to be processed, namely, harvested, solubilized, and refolded. Several years ago, it was discovered that, depending on cultivation conditions and protein properties, IBs contain partially correctly folded protein structures, which makes IB processing more efficient. Here, we present a method of tailored induction of recombinant protein production in E. coli by a mixed feed system using glucose and lactose and its impact on IB formation. Our method allows tuning of IB amount, IB size, size distribution, and purity, which does not only facilitate IB processing, but is also crucial for potential direct applications of IBs as nanomaterials and biomaterials in regenerative medicine.
Collapse
Affiliation(s)
- David J Wurm
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | - Julian Quehenberger
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | - Julia Mildner
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | - Britta Eggenreich
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | - Christoph Slouka
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria.,Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | | | - Karin Wieland
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Bernhard Lendl
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria
| | - Vignesh Rajamanickam
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria.,Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | - Christoph Herwig
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria.,Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria
| | - Oliver Spadiut
- Research Division Biochemical Engineering, Institute of Chemical, Environmental and Biological Engineering, TU Wien, Vienna, Austria.
| |
Collapse
|
10
|
Cardinale M, Grube M, Erlacher A, Quehenberger J, Berg G. Bacterial networks and co-occurrence relationships in the lettuce root microbiota. Environ Microbiol 2015; 17:239-52. [PMID: 25367329 DOI: 10.1111/1462-2920.12686] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 10/14/2014] [Accepted: 10/18/2014] [Indexed: 11/29/2022]
Abstract
Lettuce is one of the most common raw foods worldwide, but occasionally also involved in pathogen outbreaks. To understand the correlative structure of the bacterial community as a network, we studied root microbiota of eight ancient and modern Lactuca sativa cultivars and the wild ancestor Lactuca serriola by pyrosequencing of 16S rRNA gene amplicon libraries. The lettuce microbiota was dominated by Proteobacteria and Bacteriodetes, as well as abundant Chloroflexi and Actinobacteria. Cultivar specificity comprised 12.5% of the species. Diversity indices were not different between lettuce cultivar groups but higher than in L. serriola, suggesting that domestication lead to bacterial diversification in lettuce root system. Spearman correlations between operational taxonomic units (OTUs) showed that co-occurrence prevailed over co-exclusion, and complementary fluorescence in situ hybridization-confocal laser scanning microscopy (FISH-CLSM) analyses revealed that this pattern results from both potential interactions and habitat sharing. Predominant taxa, such as Pseudomonas, Flavobacterium and Sphingomonadaceae rather suggested interactions, even though these are not necessarily part of significant modules in the co-occurrence networks. Without any need for complex interactions, single organisms are able to invade into this microbial network and to colonize lettuce plants, a fact that can influence the susceptibility to pathogens. The approach to combine co-occurrence analysis and FISH-CLSM allows reliably reconstructing and interpreting microbial interaction networks.
Collapse
Affiliation(s)
- Massimiliano Cardinale
- Institute of Plant Sciences, University of Graz, Graz, Austria; Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
| | | | | | | | | |
Collapse
|