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Microbiology Spectrum Jul 2019is the best characterized species among the lactococci, and among the most consumed food-fermenting bacteria worldwide. Thanks to their importance in industrialized... (Review)
Review
is the best characterized species among the lactococci, and among the most consumed food-fermenting bacteria worldwide. Thanks to their importance in industrialized food production, lactococci are among the lead bacteria understood for fundamental metabolic pathways that dictate growth and survival properties. Interestingly, lactococci belong to the Streptococcaceae family, which includes food, commensal and virulent species. As basic metabolic pathways (e.g., respiration, metal homeostasis, nucleotide metabolism) are now understood to underlie virulence, processes elucidated in lactococci could be important for understanding pathogen fitness and synergy between bacteria. This chapter highlights major findings in lactococci and related bacteria, and covers five themes: distinguishing features of lactococci, metabolic capacities including the less known respiration metabolism in Streptococcaceae, factors and pathways modulating stress response and fitness, interbacterial dialogue metabolites, and novel applications in health and biotechnology.
Topics: Bacterial Proteins; Fermentation; Lactococcus lactis; Metabolic Networks and Pathways
PubMed: 31298208
DOI: 10.1128/microbiolspec.GPP3-0035-2018 -
Microbial Cell Factories Apr 2017Lactococcus lactis has progressed a long way since its discovery and initial use in dairy product fermentation, to its present biotechnological applications in genetic... (Review)
Review
Lactococcus lactis has progressed a long way since its discovery and initial use in dairy product fermentation, to its present biotechnological applications in genetic engineering for the production of various recombinant proteins and metabolites that transcends the heterologous species barrier. Key desirable features of this gram-positive lactic acid non-colonizing gut bacteria include its generally recognized as safe (GRAS) status, probiotic properties, the absence of inclusion bodies and endotoxins, surface display and extracellular secretion technology, and a diverse selection of cloning and inducible expression vectors. This have made L. lactis a desirable and promising host on par with other well established model bacterial or yeast systems such as Escherichia coli, Saccharomyces [corrected] cerevisiae and Bacillus subtilis. In this article, we review recent technological advancements, challenges, future prospects and current diversified examples on the use of L. lactis as a microbial cell factory. Additionally, we will also highlight latest medical-based applications involving whole-cell L. lactis as a live delivery vector for the administration of therapeutics against both communicable and non-communicable diseases.
Topics: Communicable Diseases; Food Microbiology; Genetic Engineering; Genetic Vectors; Lactococcus lactis; Metabolic Engineering; Probiotics; Recombinant Proteins
PubMed: 28376880
DOI: 10.1186/s12934-017-0669-x -
Biomolecules Jan 2022Membrane proteins play key roles in most crucial cellular processes, ranging from cell-to-cell communication to signaling processes. Despite recent improvements, the... (Review)
Review
Membrane proteins play key roles in most crucial cellular processes, ranging from cell-to-cell communication to signaling processes. Despite recent improvements, the expression of functionally folded membrane proteins in sufficient amounts for functional and structural characterization remains a challenge. Indeed, it is still difficult to predict whether a protein can be overproduced in a functional state in some expression system(s), though studies of high-throughput screens have been published in recent years. Prokaryotic expression systems present several advantages over eukaryotic ones. Among them, () has emerged in the last two decades as a good alternative expression system to E. coli. The purpose of this chapter is to describe and its tightly inducible system, NICE, for the effective expression of membrane proteins from both prokaryotic and eukaryotic origins.
Topics: Escherichia coli; Eukaryotic Cells; Lactococcus lactis; Membrane Proteins
PubMed: 35204681
DOI: 10.3390/biom12020180 -
FEMS Microbiology Reviews Sep 2014Lactococcus lactis is used extensively worldwide for the production of a variety of fermented dairy products. The ability of L. lactis to successfully grow and acidify... (Review)
Review
Lactococcus lactis is used extensively worldwide for the production of a variety of fermented dairy products. The ability of L. lactis to successfully grow and acidify milk has long been known to be reliant on a number of plasmid-encoded traits. The recent availability of low-cost, high-quality genome sequencing, and the quest for novel, technologically desirable characteristics, such as novel flavour development and increased stress tolerance, has led to a steady increase in the number of available lactococcal plasmid sequences. We will review both well-known and very recent discoveries regarding plasmid-encoded traits of biotechnological significance. The acquired lactococcal plasmid sequence information has in recent years progressed our understanding of the origin of lactococcal dairy starter cultures. Salient points on the acquisition and evolution of lactococcal plasmids will be discussed in this review, as well as prospects of finding novel plasmid-encoded functions.
Topics: Bacteriophages; DNA Replication; Evolution, Molecular; Food Microbiology; Lactococcus lactis; Plasmids
PubMed: 24861818
DOI: 10.1111/1574-6976.12074 -
Analytical and Bioanalytical Chemistry Jan 2018The aim of the study was to neutralize zearalenone by lactic acid bacteria (LAB) such as Lactococcus lactis and Bifidobacterium sp. and investigate the mechanism of...
The aim of the study was to neutralize zearalenone by lactic acid bacteria (LAB) such as Lactococcus lactis and Bifidobacterium sp. and investigate the mechanism of zearalenone (ZEA) binding. Neutralization of ZEA by LAB was confirmed by identification of binding kinetics and spectroscopic studies such as Fourier transform infrared spectroscopy (FT-IR) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The obtained results showed that the kinetic process of zearalenone binding to L. lactis is not homogeneous but is expressed with an initial rapid stage with about 90% of ZEA biosorption and with a much slower second step. In case of Bifidobacterium sp., the neutralization process is homogeneous; the main stage can be described with about 88% of ZEA biosorption. MALDI-TOF-MS measurements and FTIR analysis confirmed the uptake of zearalenone molecules by bacterial species. Moreover, the assessment of dead and live lactic acid bacteria cells after zearalenone treatment was performed using fluorescence microscopy. Graphical abstract Microbiology neutralization of zearalenone using Lactococcus lactis and Bifidobacterium sp. was confirmed by identification of binding kinetics and spectroscopic studies such as FT-IR spectroscopy and MALDI-TOF-MS spectrometry. The mechanism of ZEA binding was also investigated.
Topics: Adsorption; Bifidobacterium; Lactococcus lactis; Microbial Viability; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectroscopy, Fourier Transform Infrared; Zearalenone
PubMed: 28852794
DOI: 10.1007/s00216-017-0555-8 -
Microbial Biotechnology Apr 2022This is a highlight on the article 'Extracellular vesicle formation in Lactococcus lactis is stimulated by prophage-encoded holin-lysin system' by Yue Liu, Eddy Smid and...
This is a highlight on the article 'Extracellular vesicle formation in Lactococcus lactis is stimulated by prophage-encoded holin-lysin system' by Yue Liu, Eddy Smid and Tjakko Abee.
Topics: Extracellular Vesicles; Gram-Positive Bacteria; Lactococcus lactis
PubMed: 34689413
DOI: 10.1111/1751-7915.13956 -
FEMS Microbiology Letters Feb 2022Lactic acid bacteria (LAB) have long been used to extend the shelf life and improve the taste and texture of fermented milk. In this study, we investigated the texturing...
Lactic acid bacteria (LAB) have long been used to extend the shelf life and improve the taste and texture of fermented milk. In this study, we investigated the texturing potential of LAB in plant-based fermentation by high-throughput screening of 1232 Lactococcus lactis strains for texture in milk and liquid soybean matrices. We found that most strains with texturing abilities in fermented milk were also capable of enhancing the texture in fermented soybean, despite the large differences in composition of the two matrices. Exocellular polysaccharide production is believed to contribute positively to fermented milk and plant-base texture. It appeared as if it was the properties of the polysaccharides rather than their protein interaction partners that were responsible for the enhanced texture in both matrices. We mined whole genome sequences of texturing strains for polysaccharide biosynthesis (eps) gene clusters. The comparative genomics approach revealed 10 texturing strains with novel eps gene clusters. Currently, the relationship between the novel genes and their functionality in milk and plant matrices is unknown.
Topics: Animals; Milk; Lactococcus lactis; Glycine max; Fermentation; Carbohydrate Metabolism
PubMed: 36455587
DOI: 10.1093/femsle/fnac117 -
Microbial Cell Factories Jul 2022Dysregulated production of interleukin (IL)-6 is implicated in the pathology of inflammatory bowel disease (IBD). Neutralization of IL-6 in the gut by safe probiotic...
BACKGROUND
Dysregulated production of interleukin (IL)-6 is implicated in the pathology of inflammatory bowel disease (IBD). Neutralization of IL-6 in the gut by safe probiotic bacteria may help alleviate intestinal inflammation. Here, we developed Lactococcus lactis with potent and selective IL-6 binding activity by displaying IL-6-specific affibody on its surface.
RESULTS
Anti-IL-6 affibody (designated as ZIL) was expressed in fusion with lactococcal secretion peptide Usp45 and anchoring protein AcmA. A high amount of ZIL fusion protein was detected on bacterial surface, and its functionality was validated by confocal microscopy and flow cytometry. Removal of IL-6 from the surrounding medium by the engineered L. lactis was evaluated using enzyme-linked immunosorbent assay. ZIL-displaying L. lactis sequestered recombinant human IL-6 from the solution in a concentration-dependent manner by up to 99% and showed no binding to other pro-inflammatory cytokines, thus proving to be highly specific for IL-6. The removal was equally efficient across different IL-6 concentrations (150-1200 pg/mL) that were found to be clinically relevant in IBD patients. The ability of engineered bacteria to capture IL-6 from cell culture supernatant was assessed using immunostimulated human monocytic cell lines (THP-1 and U-937) differentiated into macrophage-like cells. ZIL-displaying L. lactis reduced the content of IL-6 in the supernatants of both cell lines in a concentration-dependent manner by up to 94%. Dose response analysis showed that bacterial cell concentrations of 10 and 10 CFU/mL (colony forming units per mL) were required for half-maximal removal of recombinant and macrophage-derived IL-6, respectively.
CONCLUSION
The ability of ZIL-displaying L. lactis to bind pathological concentrations of IL-6 at common bacterial doses suggests physiological significance.
Topics: Humans; Inflammatory Bowel Diseases; Interleukin-6; Lactococcus lactis; Protein Binding; Recombinant Proteins
PubMed: 35842694
DOI: 10.1186/s12934-022-01873-7 -
Applied and Environmental Microbiology Nov 2021Acetoin, 3-hydroxyl,2-butanone, is extensively used as a flavor additive in food products. This volatile compound is produced by the dairy bacterium Lactococcus lactis...
Acetoin, 3-hydroxyl,2-butanone, is extensively used as a flavor additive in food products. This volatile compound is produced by the dairy bacterium Lactococcus lactis when aerobic respiration is activated by haem addition, and comprises ∼70% of carbohydrate degradation products. Here we investigate the targets of acetoin toxicity, and determine how acetoin impacts L. lactis physiology and survival. Acetoin caused damage to DNA and proteins, which related to reactivity of its keto group. Acetoin stress was reflected in proteome profiles, which revealed changes in lipid metabolic proteins. Acetoin provoked marked changes in fatty acid composition, with massive accumulation of cycC19:0 cyclopropane fatty acid at the expense of its unsaturated C18:1 fatty acid precursor. Deletion of the gene, encoding the cycC19:0 synthase, sensitized cells to acetoin stress. Acetoin-resistant transposon mutagenesis revealed a hot spot in the high affinity phosphate transporter operon , which is known to increase resistance to multiple stresses. This work reveals the causes and consequences of acetoin stress on L. lactis, and may facilitate control of lactic acid bacteria production in technological processes. Acetoin, 3-hydroxyl,2-butanone, has diverse uses in chemical industry, agriculture, and dairy industries as a volatile compound that generates aromas. In bacteria, it can be produced in high amount by Lactococcus lactis when it grows under aerobic respiration. However, acetoin production can be toxic and detrimental for growth and/or survival. Our results showed that it damages DNA and proteins via its keto group. We also showed that acetoin modifies membrane fatty acid composition with the production of cyclopropane C19:0 fatty acid at the expense of an unsaturated C18:1. We isolated mutants more resistant to acetoin than the wild-type strain. All of them mapped to a single locus operon, suggesting a simple means to limit acetoin toxicity in dairy bacteria and to improve its production.
Topics: Acetoin; Fatty Acids; Flavoring Agents; Industrial Microbiology; Lactococcus lactis
PubMed: 34613757
DOI: 10.1128/AEM.01079-21 -
Journal of Bacteriology Jan 2015Lactic acid bacteria have been isolated from living, harvested, and fermented plant materials; however, the adaptations these bacteria possess for growth on plant...
Lactic acid bacteria have been isolated from living, harvested, and fermented plant materials; however, the adaptations these bacteria possess for growth on plant tissues are largely unknown. In this study, we investigated plant habitat-specific traits of Lactococcus lactis during growth in an Arabidopsis thaliana leaf tissue lysate (ATL). L. lactis KF147, a strain originally isolated from plants, exhibited a higher growth rate and reached 7.9-fold-greater cell densities during growth in ATL than the dairy-associated strain L. lactis IL1403. Transcriptome profiling (RNA-seq) of KF147 identified 853 induced and 264 repressed genes during growth in ATL compared to that in GM17 laboratory culture medium. Genes induced in ATL included those involved in the arginine deiminase pathway and a total of 140 carbohydrate transport and metabolism genes, many of which are involved in xylose, arabinose, cellobiose, and hemicellulose metabolism. The induction of those genes corresponded with L. lactis KF147 nutrient consumption and production of metabolic end products in ATL as measured by gas chromatography-time of flight mass spectrometry (GC-TOF/MS) untargeted metabolomic profiling. To assess the importance of specific plant-inducible genes for L. lactis growth in ATL, xylose metabolism was targeted for gene knockout mutagenesis. Wild-type L. lactis strain KF147 but not an xylA deletion mutant was able to grow using xylose as the sole carbon source. However, both strains grew to similarly high levels in ATL, indicating redundancy in L. lactis carbohydrate metabolism on plant tissues. These findings show that certain strains of L. lactis are well adapted for growth on plants and possess specific traits relevant for plant-based food, fuel, and feed fermentations.
Topics: Bacterial Proteins; Gas Chromatography-Mass Spectrometry; Lactococcus lactis; Plants
PubMed: 25384484
DOI: 10.1128/JB.02193-14