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Brandsma JB, Brinkman J, Wolkers-Rooijackers JCM, van Swam I, van Uitert K, Zwietering MH, Smid EJ. Pyruvate stimulates transamination of leucine into α-ketoisocaproic acid and supports 3-methylbutanal production by Lactococcus lactis. J Appl Microbiol 2024; 135:lxae257. [PMID: 39380147 DOI: 10.1093/jambio/lxae257] [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: 06/17/2024] [Revised: 09/25/2024] [Accepted: 10/07/2024] [Indexed: 10/10/2024]
Abstract
AIM To investigate the effect of pyruvate and glucose on leucine transamination and 3-methylbutanal production by Lactococcus lactis, including the comparison with cells possessing glutamate dehydrogenase (GDH) activity. METHODS AND RESULTS Lactococcus lactis cells were incubated in chemically defined medium (CDM) with the pH controlled at 5.2 to mimic cheese conditions. Pyruvate supplementation stimulated the production of the key flavour compound 3-methylbutanal by 3-4 times after 72 h of incubation. Concurrently, alanine production increased, demonstrating the involvement of pyruvate in transamination reactions. Glucose-metabolizing cells excreted α-ketoisocaproic acid and produced even 3 times more 3-methylbutanal after 24 h than pyruvate-supplemented cells. Conjugal transfer technique was used to transfer the plasmid pGdh442 carrying the gdh gene encoding for GDH to L. lactis. Introducing GDH did not stimulate the excretion of α-ketoisocaproic acid and the production of 3-methylbutanal. CONCLUSIONS These results demonstrate that Lactococcus uses pyruvate to transaminate leucine into α-ketoisocaproic acid which supports 3-methylbutanal production. Surprisingly, GDH activity did not stimulate leucine transamination and 3-methylbutanal production.
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Affiliation(s)
- Johannes B Brandsma
- dsm-firmenich, Taste, Texture & Health, Center for Food Innovation, Wageningen, 6708 WH, The Netherlands
| | - Judith Brinkman
- dsm-firmenich, Taste, Texture & Health, Center for Food Innovation, Wageningen, 6708 WH, The Netherlands
| | | | - Iris van Swam
- dsm-firmenich, Taste, Texture & Health, Center for Food Innovation, Wageningen, 6708 WH, The Netherlands
| | - Kim van Uitert
- dsm-firmenich, Taste, Texture & Health, Center for Food Innovation, Wageningen, 6708 WH, The Netherlands
| | - Marcel H Zwietering
- Wageningen University & Research, Food Microbiology, Wageningen, 6708 WG, The Netherlands
| | - Eddy J Smid
- Wageningen University & Research, Food Microbiology, Wageningen, 6708 WG, The Netherlands
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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: 8] [Impact Index Per Article: 4.0] [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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