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Melkonian C, Zorrilla F, Kjærbølling I, Blasche S, Machado D, Junge M, Sørensen KI, Andersen LT, Patil KR, Zeidan AA. Microbial interactions shape cheese flavour formation. Nat Commun 2023; 14:8348. [PMID: 38129392 PMCID: PMC10739706 DOI: 10.1038/s41467-023-41059-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 08/15/2023] [Indexed: 12/23/2023] Open
Abstract
Cheese fermentation and flavour formation are the result of complex biochemical reactions driven by the activity of multiple microorganisms. Here, we studied the roles of microbial interactions in flavour formation in a year-long Cheddar cheese making process, using a commercial starter culture containing Streptococcus thermophilus and Lactococcus strains. By using an experimental strategy whereby certain strains were left out from the starter culture, we show that S. thermophilus has a crucial role in boosting Lactococcus growth and shaping flavour compound profile. Controlled milk fermentations with systematic exclusion of single Lactococcus strains, combined with genomics, genome-scale metabolic modelling, and metatranscriptomics, indicated that S. thermophilus proteolytic activity relieves nitrogen limitation for Lactococcus and boosts de novo nucleotide biosynthesis. While S. thermophilus had large contribution to the flavour profile, Lactococcus cremoris also played a role by limiting diacetyl and acetoin formation, which otherwise results in an off-flavour when in excess. This off-flavour control could be attributed to the metabolic re-routing of citrate by L. cremoris from diacetyl and acetoin towards α-ketoglutarate. Further, closely related Lactococcus lactis strains exhibited different interaction patterns with S. thermophilus, highlighting the significance of strain specificity in cheese making. Our results highlight the crucial roles of competitive and cooperative microbial interactions in shaping cheese flavour profile.
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Affiliation(s)
- Chrats Melkonian
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, 2970, Hørsholm, Denmark.
- Theoretical Biology and Bioinformatics, Science for Life, Utrecht University, Utrecht, the Netherlands.
- Bioinformatics Group, Wageningen University and Research, Wageningen, the Netherlands.
| | - Francisco Zorrilla
- Medical Research Council Toxicology Unit, University of Cambridge, Cambridge, UK
| | - Inge Kjærbølling
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, 2970, Hørsholm, Denmark
| | - Sonja Blasche
- Medical Research Council Toxicology Unit, University of Cambridge, Cambridge, UK
- European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Daniel Machado
- European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, 7491, Norway
| | - Mette Junge
- Strain Improvement, R&D Food Microbiology, Chr. Hansen A/S, 2970, Hørsholm, Denmark
| | - Kim Ib Sørensen
- Strain Improvement, R&D Food Microbiology, Chr. Hansen A/S, 2970, Hørsholm, Denmark
| | | | - Kiran R Patil
- Medical Research Council Toxicology Unit, University of Cambridge, Cambridge, UK
- European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Ahmad A Zeidan
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, 2970, Hørsholm, Denmark.
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Karlsen ST, Rau MH, Sánchez BJ, Jensen K, Zeidan AA. From genotype to phenotype: computational approaches for inferring microbial traits relevant to the food industry. FEMS Microbiol Rev 2023; 47:fuad030. [PMID: 37286882 PMCID: PMC10337747 DOI: 10.1093/femsre/fuad030] [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: 02/28/2023] [Revised: 05/31/2023] [Accepted: 06/06/2023] [Indexed: 06/09/2023] Open
Abstract
When selecting microbial strains for the production of fermented foods, various microbial phenotypes need to be taken into account to achieve target product characteristics, such as biosafety, flavor, texture, and health-promoting effects. Through continuous advances in sequencing technologies, microbial whole-genome sequences of increasing quality can now be obtained both cheaper and faster, which increases the relevance of genome-based characterization of microbial phenotypes. Prediction of microbial phenotypes from genome sequences makes it possible to quickly screen large strain collections in silico to identify candidates with desirable traits. Several microbial phenotypes relevant to the production of fermented foods can be predicted using knowledge-based approaches, leveraging our existing understanding of the genetic and molecular mechanisms underlying those phenotypes. In the absence of this knowledge, data-driven approaches can be applied to estimate genotype-phenotype relationships based on large experimental datasets. Here, we review computational methods that implement knowledge- and data-driven approaches for phenotype prediction, as well as methods that combine elements from both approaches. Furthermore, we provide examples of how these methods have been applied in industrial biotechnology, with special focus on the fermented food industry.
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Affiliation(s)
- Signe T Karlsen
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, Bøge Allé 10-12, 2970 Hørsholm, Denmark
| | - Martin H Rau
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, Bøge Allé 10-12, 2970 Hørsholm, Denmark
| | - Benjamín J Sánchez
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, Bøge Allé 10-12, 2970 Hørsholm, Denmark
| | - Kristian Jensen
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, Bøge Allé 10-12, 2970 Hørsholm, Denmark
| | - Ahmad A Zeidan
- Bioinformatics & Modeling, R&D Digital Innovation, Chr. Hansen A/S, Bøge Allé 10-12, 2970 Hørsholm, Denmark
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Ulmer A, Veit S, Erdemann F, Freund A, Loesch M, Teleki A, Zeidan AA, Takors R. A Two-Compartment Fermentation System to Quantify Strain-Specific Interactions in Microbial Co-Cultures. BIOENGINEERING (BASEL, SWITZERLAND) 2023; 10:bioengineering10010103. [PMID: 36671675 PMCID: PMC9854596 DOI: 10.3390/bioengineering10010103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 01/14/2023]
Abstract
To fulfil the growing interest in investigating microbial interactions in co-cultures, a novel two-compartment bioreactor system was developed, characterised, and implemented. The system allowed for the exchange of amino acids and peptides via a polyethersulfone membrane that retained biomass. Further system characterisation revealed a Bodenstein number of 18, which hints at backmixing. Together with other physical settings, the existence of unwanted inner-compartment substrate gradients could be ruled out. Furthermore, the study of Damkoehler numbers indicated that a proper metabolite supply between compartments was enabled. Implementing the two-compartment system (2cs) for growing Streptococcus thermophilus and Lactobacillus delbrueckii subs. bulgaricus, which are microorganisms commonly used in yogurt starter cultures, revealed only a small variance between the one-compartment and two-compartment approaches. The 2cs enabled the quantification of the strain-specific production and consumption rates of amino acids in an interacting S. thermophilus-L. bulgaricus co-culture. Therefore, comparisons between mono- and co-culture performance could be achieved. Both species produce and release amino acids. Only alanine was produced de novo from glucose through potential transaminase activity by L. bulgaricus and consumed by S. thermophilus. Arginine availability in peptides was limited to S. thermophilus' growth, indicating active biosynthesis and dependency on the proteolytic activity of L. bulgaricus. The application of the 2cs not only opens the door for the quantification of exchange fluxes between microbes but also enables continuous production modes, for example, for targeted evolution studies.
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Affiliation(s)
- Andreas Ulmer
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Stefan Veit
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Florian Erdemann
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Andreas Freund
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Maren Loesch
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Attila Teleki
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Ahmad A. Zeidan
- Systems Biology, R&D Discovery, Chr. Hansen A/S, 2970 Hørsholm, Denmark
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
- Correspondence:
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Ulmer A, Erdemann F, Mueller S, Loesch M, Wildt S, Jensen ML, Gaspar P, Zeidan AA, Takors R. Differential Amino Acid Uptake and Depletion in Mono-Cultures and Co-Cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in a Novel Semi-Synthetic Medium. Microorganisms 2022; 10:microorganisms10091771. [PMID: 36144373 PMCID: PMC9505316 DOI: 10.3390/microorganisms10091771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 11/22/2022] Open
Abstract
The mechanistic understanding of the physiology and interactions of microorganisms in starter cultures is critical for the targeted improvement of fermented milk products, such as yogurt, which is produced by Streptococcus thermophilus in co-culture with Lactobacillus delbrueckii subsp. bulgaricus. However, the use of complex growth media or milk is a major challenge for quantifying metabolite production, consumption, and exchange in co-cultures. This study developed a synthetic medium that enables the establishment of defined culturing conditions and the application of flow cytometry for measuring species-specific biomass values. Time courses of amino acid concentrations in mono-cultures and co-cultures of L. bulgaricus ATCC BAA-365 with the proteinase-deficient S. thermophilus LMG 18311 and with a proteinase-positive S. thermophilus strain were determined. The analysis revealed that amino acid release rates in co-culture were not equivalent to the sum of amino acid release rates in mono-cultures. Data-driven and pH-dependent amino acid release models were developed and applied for comparison. Histidine displayed higher concentrations in co-cultures, whereas isoleucine and arginine were depleted. Amino acid measurements in co-cultures also confirmed that some amino acids, such as lysine, are produced and then consumed, thus being suitable candidates to investigate the inter-species interactions in the co-culture and contribute to the required knowledge for targeted shaping of yogurt qualities.
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Affiliation(s)
- Andreas Ulmer
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Florian Erdemann
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Susanne Mueller
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Maren Loesch
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Sandy Wildt
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | | | - Paula Gaspar
- Systems Biology, R&D Discovery, Chr. Hansen A/S, 2970 Hørsholm, Denmark
| | - Ahmad A. Zeidan
- Systems Biology, R&D Discovery, Chr. Hansen A/S, 2970 Hørsholm, Denmark
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
- Correspondence:
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