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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 -
Current Biology : CB May 2019Domestication refers to artificial selection and breeding of wild species to obtain cultivated variants that thrive in man-made niches and meet human or industrial... (Review)
Review
Domestication refers to artificial selection and breeding of wild species to obtain cultivated variants that thrive in man-made niches and meet human or industrial requirements. Several genotypic and phenotypic signatures of domestication have been described in crops, livestock and pets. However, domestication is not unique to plants and animals. Microbial diversity has also been shaped by the emergence of novel and highly specific man-made environments, like food and beverage fermentations. This allowed rapid adaptation and diversification of various microbes, such as certain Lactococcus, Lactobacillus, Oenococcus, Saccharomyces and Aspergillus species. During the domestication process, microbes gained the capacity to efficiently consume particular nutrients, cope with a multitude of industry-specific stress factors and produce desirable compounds, often at the cost of a reduction in fitness in their original, natural environments. Moreover, different lineages of the same species adapted to highly diverse niches, resulting in genetically and phenotypically distinct strains. In this Review, we discuss the basic principles of microbial domestication and describe how recent research is uncovering its genetic underpinnings.
Topics: Aspergillus; Domestication; Genetic Variation; Lactobacillus; Lactococcus; Oenococcus; Phenotype; Saccharomyces
PubMed: 31112692
DOI: 10.1016/j.cub.2019.04.025 -
Journal of Dairy Science Mar 2022Traditionally, starter cultures for Cheddar cheese are combinations of Lactococcus lactis and Lactococcus cremoris. Our goal was to compare growth and survival of...
Traditionally, starter cultures for Cheddar cheese are combinations of Lactococcus lactis and Lactococcus cremoris. Our goal was to compare growth and survival of individual strains during cheesemaking, and after salting and pressing. Cultures used were 2 strains of L. lactis (SSM 7605, SSM 7436) and 2 strains of L. cremoris (SSM 7136, SSM 7661). A standardized Cheddar cheese make procedure was used that included a 38°C cook temperature and salting levels of 2.0, 2.4, 2.8, 3.2, and 3.6% from which were selected cheeses with salt-in-moisture levels of 3.5, 4.5, and 5.5%. Vats of cheese were made using each strain on its own as biological duplicates on different days. Starter culture numbers were enumerated by plate counting during cheesemaking and after 6 d storage at 6°C. Flow cytometry with fluorescent staining by SYBR Green and propidium iodide was used to determine the number of live and dead cells in cheese at the different salt levels. Differences in cheese make times were strain dependent rather than species dependent. Even with correction for average culture chain length, cheeses made using L. lactis strains contained ∼4 times (∼0.6 log) more bacterial cells than those made using L. cremoris strains. Growth of the strains used in this study was not influenced by the amount of salt added to the curd. The higher pH of cheeses with higher salting levels was attributed to those cheeses having a lower moisture content. Based on flow cytometry, ∼5% of the total starter culture cells in the cheese were dead after 6 d of storage. Another 3 to 19% of the cells were designated as being live, but semipermeable, with L. cremoris strains having the higher number of semipermeable cells.
Topics: Animals; Cheese; Lactococcus; Lactococcus lactis; Sodium Chloride; Sodium Chloride, Dietary
PubMed: 35033338
DOI: 10.3168/jds.2021-20958 -
MBio Apr 2021The broadly conserved cyclic di-AMP (c-di-AMP) is a conditionally essential bacterial second messenger. The pool of c-di-AMP is fine-tuned through diadenylate cyclase...
The broadly conserved cyclic di-AMP (c-di-AMP) is a conditionally essential bacterial second messenger. The pool of c-di-AMP is fine-tuned through diadenylate cyclase and phosphodiesterase activities, and direct binding of c-di-AMP to proteins and riboswitches allows the regulation of a broad spectrum of cellular processes. c-di-AMP has a significant impact on intrinsic β-lactam antibiotic resistance in Gram-positive bacteria; however, the reason for this is currently unclear. In this work, genetic studies revealed that suppressor mutations that decrease the activity of the potassium (K) importer KupB or the glutamine importer GlnPQ restore cefuroxime (CEF) resistance in diadenylate cyclase () mutants of Metabolite analyses showed that glutamine is imported by GlnPQ and then rapidly converted to glutamate, and GlnPQ mutations or c-di-AMP negatively affects the pools of the most abundant free amino acids (glutamate and aspartate) during growth. In a high-c-di-AMP mutant, GlnPQ activity could be increased by raising the internal K level through the overexpression of a c-di-AMP-insensitive KupB variant. These results demonstrate that c-di-AMP reduces GlnPQ activity and, therefore, the level of the major free anions in through its inhibition of K import. Excessive ion accumulation in mutants results in greater spontaneous cell lysis under hypotonic conditions, while CEF-resistant suppressors exhibit reduced cell lysis and lower osmoresistance. This work demonstrates that the overaccumulation of major counter-ion osmolyte pools in c-di-AMP-defective mutants of causes cefuroxime sensitivity. The bacterial second messenger cyclic di-AMP (c-di-AMP) is a global regulator of potassium homeostasis and compatible solute uptake in many Gram-positive bacteria, making it essential for osmoregulation. The role that c-di-AMP plays in β-lactam resistance, however, is unclear despite being first identified a decade ago. Here, we demonstrate that the overaccumulation of potassium or free amino acids leads to cefuroxime sensitivity in mutants partially defective in c-di-AMP synthesis. It was shown that c-di-AMP negatively affects the levels of the most abundant free amino acids (glutamate and aspartate) in Regulation of these major free anions was found to occur via the glutamine transporter GlnPQ, whose activity increased in response to intracellular potassium levels, which are under c-di-AMP control. Evidence is also presented showing that they are major osmolytes that enhance osmoresistance and cell lysis. The regulatory reach of c-di-AMP can be extended to include the main free anions in bacteria.
Topics: Amino Acids; Anti-Bacterial Agents; Bacterial Proteins; Biological Transport; Cefuroxime; Cyclic AMP; Gene Expression Regulation, Bacterial; Lactococcus lactis; Potassium; Second Messenger Systems
PubMed: 33832972
DOI: 10.1128/mBio.00324-21 -
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 -
Microbial Genomics Feb 2022is a well-known pathogen of fish, but is rarely involved in infections in humans and other mammals. In humans, the main clinical manifestation of infections is...
is a well-known pathogen of fish, but is rarely involved in infections in humans and other mammals. In humans, the main clinical manifestation of infections is endocarditis usually related to the ingestion of contaminated food, such as undercooked fish and shellfish. This study presents the first complete genomic sequence of a clinical strain isolated from a patient with endocarditis and its comparative analysis with other genomes. This human isolate contains a circular chromosome of 2 099 060 bp and one plasmid of 50 557 bp. In comparison with other fully sequenced strains, the chromosomal DNA of Lg-Granada carries a low proportion of insertion sequence elements and a higher number of putative prophages. Our results show that, in general, is a highly recombinogenic species with an open pangenome in which almost 30 % of its genome has undergone horizontal transfers. Within the genus is the main donor of genetic components to but, taking Lg-Granada as a representative, this bacterium tends to import more genes from taxa than from other species.
Topics: Animals; Biological Evolution; Endocarditis; Genomics; Humans; Lactococcus; Mammals
PubMed: 35196218
DOI: 10.1099/mgen.0.000771 -
Probiotics and Antimicrobial Proteins Dec 2021In this study, we expressed rAvBD1-2-6-13 protein through Lactococcus lactis NZ3900, and the effects of the recombinant L. lactis NZ3900 as an immune enhancer and immune...
In this study, we expressed rAvBD1-2-6-13 protein through Lactococcus lactis NZ3900, and the effects of the recombinant L. lactis NZ3900 as an immune enhancer and immune adjuvant were verified using in vivo and in vitro tests. In vitro tests revealed that recombinant L. lactis NZ3900 significantly activated the NF-κB signaling pathway and IRF signaling pathway in J774-Dual™ report cells and significantly increased the transcript levels of IL-10, IL-12p70, CD80, and CD86 in chicken PBMCs and chicken HD11 cells. In vivo experiments revealed that the immunized group supplemented with recombinant L. lactis NZ3900 as an adjuvant had significantly higher serum antibody titers and higher proliferative activity of PBMCs in the blood of the chickens immunized with NDV live and inactivated vaccines. Our study shows that the recombinant L. lactis NZ3900 has strong immunomodulatory activity both in vivo and in vitro and is a potential immune enhancer. Our work lays the foundation for the research and development of new animal immune enhancers for application in the poultry industry.
Topics: Adjuvants, Immunologic; Animals; Chickens; Lactococcus; Vaccines; beta-Defensins
PubMed: 34595668
DOI: 10.1007/s12602-021-09847-8 -
Journal of Dairy Science Jul 2016Several enzymes are involved in the process of converting milk to lactic acid and coagulated milk to curd and, therefore, are important in dairy fermented products....
Several enzymes are involved in the process of converting milk to lactic acid and coagulated milk to curd and, therefore, are important in dairy fermented products. Amylase, proteinase, and lipase are enzymes that play an important role in degrading milk into monomeric molecules such as oligosaccharides, amino acids, and fatty acids, which are the main molecules responsible for flavors in cheese. In the current study, we determined the amylase, proteinase, and lipase activities of Lactococcus chungangensis CAU 28(T), a bacterial strain of nondairy origin, and compared them with those of the reference strain, Lactococcus lactis ssp. lactis KCTC 3769(T), which is commonly used in the dairy industry. Lactococcus chungangensis CAU 28(T) and L. lactis ssp. lactis KCTC 3769(T) were both found to have amylase, proteinase, and lipase activities in broth culture, cream cheese, and yogurt. Notably, the proteinase and lipase activities of L. chungangensis CAU 28(T) were higher than those of L. lactis ssp. lactis KCTC 3769(T), with proteinase activity of 10.50 U/mL in tryptic soy broth and 8.64 U/mL in cream cheese, and lipase activity of 100 U/mL of tryptic soy broth, and 100 U/mL of cream cheese. In contrast, the amylase activity was low, with 5.28 U/mL in tryptic soy broth and 8.86 U/mL in cream cheese. These enzyme activities in L. chungangensis CAU 28(T) suggest that this strain has potential to be used for manufacturing dairy fermented products, even though the strain is of nondairy origin.
Topics: Amylases; Bacterial Proteins; Cheese; Fermentation; Lactococcus; Lactococcus lactis; Lipase; Peptide Hydrolases; Yogurt
PubMed: 27108177
DOI: 10.3168/jds.2016-11002 -
Journal of Dairy Science Apr 2018The widespread dissemination of species of the lactic acid bacteria (LAB) group in different environments testifies to their extraordinary niche adaptability. Members of... (Review)
Review
The widespread dissemination of species of the lactic acid bacteria (LAB) group in different environments testifies to their extraordinary niche adaptability. Members of the LAB are present on grass and other plant material, in dairy products, on human skin, and in the gastrointestinal and reproductive tracts. The selective pressure imparted by these specific environments is a key driver in the genomic diversity observed between strains of the same species deriving from distinct habitats. Strains that are exploited in the dairy industry for the production of fermented dairy products are often referred to as "domesticated" strains. These strains, which initially may have occupied a nondairy niche, have become specialized for growth in the milk environment. In fact, comparative genome analysis of multiple LAB species and strains has revealed a central trend in LAB evolution: the loss of ancestral genes and metabolic simplification toward adaptation to nutritionally rich environments. In contrast, "environmental" strains, or those from raw milk, plants, and animals, exhibit diverse metabolic capabilities and lifestyle characteristics compared with their domesticated counterparts. Because of the limited number of established dairy strains used in fermented food production today, demand is increasing for novel strains, with concerted efforts to mine the microbiota of natural environments for strains of technological interest. Many studies have concentrated on uncovering the genomic and metabolic potential of these organisms, facilitating comparative genome analysis of strains from diverse environments and providing insight into the natural diversity of the LAB, a group of organisms that is at the core of the dairy industry. The natural biodiversity that exists in these environments may be exploited in dairy fermentations to expand flavor profiles, to produce natural "clean label" ingredients, or to develop safer products.
Topics: Animals; Biodiversity; Cheese; Humans; Lactococcus lactis; Milk
PubMed: 29395148
DOI: 10.3168/jds.2017-13331 -
Frontiers in Bioscience (Landmark... Jun 2009The taxonomically diverse lactic acid bacteria (LAB) are unified by their capability to produce lactic acid from carbohydrates by fermentation. The LAB Lactococcus (L.)... (Review)
Review
The taxonomically diverse lactic acid bacteria (LAB) are unified by their capability to produce lactic acid from carbohydrates by fermentation. The LAB Lactococcus (L.) lactis has been characterized into great detail and is increasingly used as a production host for heterologous proteins. L. lactis is a non-pathogenic and non-colonizing LAB species and can be efficiently engineered to produce proteins of viral, bacterial or eukaryotic origin, both intra- or extracellularly. Importantly, orally formulated L. lactis strains (ActoBiotics), engineered to synthesize and secrete therapeutic peptides and proteins in the gastrointestinal tract, are already in advanced stages of preclinical and clinical development. This review focuses on the genetic engineering of LAB in general and L. lactis in specific to secrete high-quality, correctly processed, bioactive molecules derived from a eukaryotic background. The therapeutic applications of these genetically modified strains are discussed, as well as the need for a sound environmental containment strategy, and a detailed review is presented on Lactococcus strains engineered to produce specific antigens, antibodies, cytokines and trefoil factors, with special regards to immunomodulation.
Topics: Animals; Antibodies; Antibody Formation; Bacterial Vaccines; Containment of Biohazards; Humans; Immunologic Factors; Inflammatory Bowel Diseases; Lactococcus; Lactococcus lactis; Probiotics; Protein Engineering; Recombinant Proteins; Th1 Cells; Vaccines, Synthetic
PubMed: 19482589
DOI: 10.2741/3571