Lifestyle, metabolism and environmental adaptation inLactococcus lactis

Abstract

Lactococcus lactis serves as a paradigm organism for the lactic acid bacteria (LAB). Extensive research into the molecular biology, metabolism and physiology of several model strains of this species has been fundamental for our understanding of the LAB. Genomic studies have provided new insights in the species L. lactis, including the resolution of the genetic basis of its subspecies division, as well as the control mechanisms involved in the fine-tuning of growth-rate and energy metabolism. In addition, it has enabled novel approaches to study lactococcal lifestyle adaptations to the dairy application environment, including its adjustment to near-zero growth rates that are particularly relevant in the context of cheese ripening. This review highlights various insights in these areas and exemplifies the strength of combining experimental evolution with functional genomics and bacterial physiology research to expand our fundamental understanding of the L. lactis lifestyle under different environmental conditions.

The growth‐survival trade‐off is hard‐wired in the Lactococcus lactis gene regulation network

“…Resident microbes have evolved a variety of strategies to maintain proliferative capacity under nutrient‐poor conditions for long periods (Egli, 2010; Hoehler and Jorgensen, 2013; Hallsworth, 2021). They adapt to such conditions by minimizing their energy expenditure and metabolic activity, ultimately resulting in a slow‐ or non‐growing state (Lennon and Jones, 2011; Boutte and Crosson, 2013; Ercan et al ., 2013; Hoehler and Jorgensen, 2013; Kleerebezem et al ., 2020). Distinct non‐growing phenotypes have been described, including spores, akinetes, biofilms and viable but non‐culturable states (Harrison et al ., 2007; Navarro Llorens et al ., 2010; Lennon and Jones, 2011; Boutte and Crosson, 2013; van Mastrigt et al ., 2018; van Tatenhove‐Pel et al ., 2019).…”

Spontaneous Riboflavin-Overproducing Limosilactobacillus reuteri for Biofortification of Fermented Foods

“…Lactic acid bacteria also significantly add to the flavor and texture profiles of the fermentation end-products resulting from animal milk and plant-based substrates. Moreover, the acidification capacity of these bacteria can inhibit pathogenic growth, typically resulting in longer shelf life ( 20 ). In addition to the ability of the lactobacilli to produce riboflavin in a range of food matrices, it can be beneficial if the selected strains survive the gastrointestinal tract, so that the vitamins can be produced in situ at the target site to further enhance delivery and maximize the chance of reaching required daily intake levels ( 16 , 21 ).…”

Trade-Offs Predicted by Metabolic Network Structure Give Rise to Evolutionary Specialization and Phenotypic Diversification

“…The central carbon metabolism of the model organism used in our experiment, L. cremoris MG1363 (formerly called Lactococcus lactis ssp cremoris ), has been resolved in detail, owing to its importance in milk product fermentation ( Neves et al 2005 ; Teusink and Molenaar 2017 ). Over the course of its domestication to the dairy habitat, L. cremoris has been adapted for fast ‘batch mode’ growth on the glucose moiety of lactose (milk sugar) ( Bachmann et al 2012 ; Kok et al 2017 ; Kleerebezem et al 2020 ). Dairy strains of L. cremoris achieve maximal growth rate on glucose and, when excess glucose is available, catabolite repression downregulates other metabolic pathways in order to maximize growth rate ( Zomer et al 2007 ).…”