1
|
Tanca A, Abbondio M, Palomba A, Fraumene C, Manghina V, Cucca F, Fiorillo E, Uzzau S. Potential and active functions in the gut microbiota of a healthy human cohort. Microbiome 2017; 5:79. [PMID: 28709472 PMCID: PMC5513205 DOI: 10.1186/s40168-017-0293-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/28/2017] [Indexed: 05/20/2023]
Abstract
BACKGROUND The study of the gut microbiota (GM) is rapidly moving towards its functional characterization by means of shotgun meta-omics. In this context, there is still no consensus on which microbial functions are consistently and constitutively expressed in the human gut in physiological conditions. Here, we selected a cohort of 15 healthy subjects from a native and highly monitored Sardinian population and analyzed their GMs using shotgun metaproteomics, with the aim of investigating GM functions actually expressed in a healthy human population. In addition, shotgun metagenomics was employed to reveal GM functional potential and to compare metagenome and metaproteome profiles in a combined taxonomic and functional fashion. RESULTS Metagenomic and metaproteomic data concerning the taxonomic structure of the GM under study were globally comparable. On the contrary, a considerable divergence between genetic potential and functional activity of the human healthy GM was observed, with the metaproteome displaying a higher plasticity, compared to the lower inter-individual variability of metagenome profiles. The taxon-specific contribution to functional activities and metabolic tasks was also examined, giving insights into the peculiar role of several GM members in carbohydrate metabolism (including polysaccharide degradation, glycan transport, glycolysis, and short-chain fatty acid production). Noteworthy, Firmicutes-driven butyrogenesis (mainly due to Faecalibacterium spp.) was shown to be the metabolic activity with the highest expression rate and the lowest inter-individual variability in the study cohort, in line with the previously reported importance of the biosynthesis of this microbial product for the gut homeostasis. CONCLUSIONS Our results provide detailed and taxon-specific information regarding functions and pathways actively working in a healthy GM. The reported discrepancy between expressed functions and functional potential suggests that caution should be used before drawing functional conclusions from metagenomic data, further supporting metaproteomics as a fundamental approach to characterize the human GM metabolic functions and activities.
Collapse
Affiliation(s)
- Alessandro Tanca
- Porto Conte Ricerche, Science and Technology Park of Sardinia, S.P. 55 Porto Conte - Capo Caccia km 8,400, Località Tramariglio, 07041, Alghero, SS, Italy
| | - Marcello Abbondio
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Antonio Palomba
- Porto Conte Ricerche, Science and Technology Park of Sardinia, S.P. 55 Porto Conte - Capo Caccia km 8,400, Località Tramariglio, 07041, Alghero, SS, Italy
| | - Cristina Fraumene
- Porto Conte Ricerche, Science and Technology Park of Sardinia, S.P. 55 Porto Conte - Capo Caccia km 8,400, Località Tramariglio, 07041, Alghero, SS, Italy
| | - Valeria Manghina
- Porto Conte Ricerche, Science and Technology Park of Sardinia, S.P. 55 Porto Conte - Capo Caccia km 8,400, Località Tramariglio, 07041, Alghero, SS, Italy
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Francesco Cucca
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Monserrato, Cagliari, Italy
| | - Edoardo Fiorillo
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Monserrato, Cagliari, Italy
| | - Sergio Uzzau
- Porto Conte Ricerche, Science and Technology Park of Sardinia, S.P. 55 Porto Conte - Capo Caccia km 8,400, Località Tramariglio, 07041, Alghero, SS, Italy.
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy.
| |
Collapse
|
2
|
Tanca A, Palomba A, Fraumene C, Pagnozzi D, Manghina V, Deligios M, Muth T, Rapp E, Martens L, Addis MF, Uzzau S. The impact of sequence database choice on metaproteomic results in gut microbiota studies. Microbiome 2016; 4:51. [PMID: 27671352 PMCID: PMC5037606 DOI: 10.1186/s40168-016-0196-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/12/2016] [Indexed: 05/23/2023]
Abstract
BACKGROUND Elucidating the role of gut microbiota in physiological and pathological processes has recently emerged as a key research aim in life sciences. In this respect, metaproteomics, the study of the whole protein complement of a microbial community, can provide a unique contribution by revealing which functions are actually being expressed by specific microbial taxa. However, its wide application to gut microbiota research has been hindered by challenges in data analysis, especially related to the choice of the proper sequence databases for protein identification. RESULTS Here, we present a systematic investigation of variables concerning database construction and annotation and evaluate their impact on human and mouse gut metaproteomic results. We found that both publicly available and experimental metagenomic databases lead to the identification of unique peptide assortments, suggesting parallel database searches as a mean to gain more complete information. In particular, the contribution of experimental metagenomic databases was revealed to be mandatory when dealing with mouse samples. Moreover, the use of a "merged" database, containing all metagenomic sequences from the population under study, was found to be generally preferable over the use of sample-matched databases. We also observed that taxonomic and functional results are strongly database-dependent, in particular when analyzing the mouse gut microbiota. As a striking example, the Firmicutes/Bacteroidetes ratio varied up to tenfold depending on the database used. Finally, assembling reads into longer contigs provided significant advantages in terms of functional annotation yields. CONCLUSIONS This study contributes to identify host- and database-specific biases which need to be taken into account in a metaproteomic experiment, providing meaningful insights on how to design gut microbiota studies and to perform metaproteomic data analysis. In particular, the use of multiple databases and annotation tools has to be encouraged, even though this requires appropriate bioinformatic resources.
Collapse
Affiliation(s)
- Alessandro Tanca
- Porto Conte Ricerche, Science and Technology Park of Sardinia, Tramariglio, Alghero, Italy
| | - Antonio Palomba
- Porto Conte Ricerche, Science and Technology Park of Sardinia, Tramariglio, Alghero, Italy
| | - Cristina Fraumene
- Porto Conte Ricerche, Science and Technology Park of Sardinia, Tramariglio, Alghero, Italy
| | - Daniela Pagnozzi
- Porto Conte Ricerche, Science and Technology Park of Sardinia, Tramariglio, Alghero, Italy
| | - Valeria Manghina
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Massimo Deligios
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Thilo Muth
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- Research Group Bioinformatics (NG 4), Robert Koch Institute, Berlin, Germany
| | - Erdmann Rapp
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Lennart Martens
- Department of Biochemistry, Ghent University, Ghent, Belgium
- Medical Biotechnology Center, VIB, Ghent, Belgium
- Bioinformatics Institute Ghent, Ghent University, Zwijnaarde, Ghent, Belgium
| | - Maria Filippa Addis
- Porto Conte Ricerche, Science and Technology Park of Sardinia, Tramariglio, Alghero, Italy
| | - Sergio Uzzau
- Porto Conte Ricerche, Science and Technology Park of Sardinia, Tramariglio, Alghero, Italy
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| |
Collapse
|