Lactococcus lactis: A non-pathogenic species of LACTOCOCCUS found in DAIRY PRODUCTS and responsible for the souring of MILK and the production of LACTIC ACID.Lactococcus: A genus of gram-positive, coccoid bacteria mainly isolated from milk and milk products. These bacteria are also found in plants and nonsterile frozen and dry foods. Previously thought to be a member of the genus STREPTOCOCCUS (group N), it is now recognized as a separate genus.Nisin: A 34-amino acid polypeptide antibiotic produced by Streptococcus lactis. It has been used as a food preservative in canned fruits and vegetables, and cheese.Cheese: A nutritious food consisting primarily of the curd or the semisolid substance formed when milk coagulates.Bacterial Proteins: Proteins found in any species of bacterium.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Bacteriophages: Viruses whose hosts are bacterial cells.Bacteriocins: Substances elaborated by specific strains of bacteria that are lethal against other strains of the same or related species. They are protein or lipopolysaccharide-protein complexes used in taxonomy studies of bacteria.Genes, Bacterial: The functional hereditary units of BACTERIA.Siphoviridae: A family of BACTERIOPHAGES and ARCHAEAL VIRUSES which are characterized by long, non-contractile tails.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Leuconostoc: A genus of gram-positive, facultatively anaerobic bacteria whose growth is dependent on the presence of a fermentable carbohydrate. It is nonpathogenic to plants and animals, including humans.Lactobacillus: A genus of gram-positive, microaerophilic, rod-shaped bacteria occurring widely in nature. Its species are also part of the many normal flora of the mouth, intestinal tract, and vagina of many mammals, including humans. Pathogenicity from this genus is rare.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Fermentation: Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Kluyveromyces: An ascomycetous yeast of the fungal family Saccharomycetaceae, order SACCHAROMYCETALES.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Milk: The white liquid secreted by the mammary glands. It contains proteins, sugar, lipids, vitamins, and minerals.Operon: In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Lactose: A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry.Cultured Milk Products: Milk modified with controlled FERMENTATION. This should not be confused with KAFFIR LIME or with KAFFIR CORN.Acetoin: A product of fermentation. It is a component of the butanediol cycle in microorganisms. In mammals it is oxidized to carbon dioxide.Conjugation, Genetic: A parasexual process in BACTERIA; ALGAE; FUNGI; and ciliate EUKARYOTA for achieving exchange of chromosome material during fusion of two cells. In bacteria, this is a uni-directional transfer of genetic material; in protozoa it is a bi-directional exchange. In algae and fungi, it is a form of sexual reproduction, with the union of male and female gametes.Diacetyl: Carrier of aroma of butter, vinegar, coffee, and other foods.Open Reading Frames: A sequence of successive nucleotide triplets that are read as CODONS specifying AMINO ACIDS and begin with an INITIATOR CODON and end with a stop codon (CODON, TERMINATOR).Streptococcus thermophilus: A species of thermophilic, gram-positive bacteria found in MILK and milk products.Food Microbiology: The presence of bacteria, viruses, and fungi in food and food products. This term is not restricted to pathogenic organisms: the presence of various non-pathogenic bacteria and fungi in cheeses and wines, for example, is included in this concept.Food Industry: The industry concerned with processing, preparing, preserving, distributing, and serving of foods and beverages.Streptococcus Phages: Viruses whose host is Streptococcus.Genetic Engineering: Directed modification of the gene complement of a living organism by such techniques as altering the DNA, substituting genetic material by means of a virus, transplanting whole nuclei, transplanting cell hybrids, etc.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Pediococcus: A genus of gram-positive, facultatively anaerobic bacteria whose growth is dependent on the presence of a fermentable carbohydrate. No endospores are produced. Its organisms are found in fermenting plant products and are nonpathogenic to plants and animals, including humans.Chromosomes, Bacterial: Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.Dairy Products: Raw and processed or manufactured milk and milk-derived products. These are usually from cows (bovine) but are also from goats, sheep, reindeer, and water buffalo.Phosphofructokinases: Allosteric enzymes that regulate glycolysis and gluconeogenesis. These enzymes catalyze phosphorylation of fructose-6-phosphate to either fructose-1,6-bisphosphate (PHOSPHOFRUCTOKINASE-1 reaction), or to fructose-2,6-bisphosphate (PHOSPHOFRUCTOKINASE-2 reaction).Restriction Mapping: Use of restriction endonucleases to analyze and generate a physical map of genomes, genes, or other segments of DNA.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Industrial Microbiology: The study, utilization, and manipulation of those microorganisms capable of economically producing desirable substances or changes in substances, and the control of undesirable microorganisms.Cholates: Salts and esters of CHOLIC ACID.Bacteriolysis: Rupture of bacterial cells due to mechanical force, chemical action, or the lytic growth of BACTERIOPHAGES.Aminopeptidases: A subclass of EXOPEPTIDASES that act on the free N terminus end of a polypeptide liberating a single amino acid residue. EC 3.4.11.Lactobacillus plantarum: A species of rod-shaped, LACTIC ACID bacteria used in PROBIOTICS and SILAGE production.Caseins: A mixture of related phosphoproteins occurring in milk and cheese. The group is characterized as one of the most nutritive milk proteins, containing all of the common amino acids and rich in the essential ones.DNA Transposable Elements: Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.Transformation, Bacterial: The heritable modification of the properties of a competent bacterium by naked DNA from another source. The uptake of naked DNA is a naturally occuring phenomenon in some bacteria. It is often used as a GENE TRANSFER TECHNIQUE.Lactic Acid: A normal intermediate in the fermentation (oxidation, metabolism) of sugar. The concentrated form is used internally to prevent gastrointestinal fermentation. (From Stedman, 26th ed)Cell Wall: The outermost layer of a cell in most PLANTS; BACTERIA; FUNGI; and ALGAE. The cell wall is usually a rigid structure that lies external to the CELL MEMBRANE, and provides a protective barrier against physical or chemical agents.Food Technology: The application of knowledge to the food industry.Streptococcus: A genus of gram-positive, coccoid bacteria whose organisms occur in pairs or chains. No endospores are produced. Many species exist as commensals or parasites on man or animals with some being highly pathogenic. A few species are saprophytes and occur in the natural environment.Phosphoglucomutase: An enzyme that catalyzes the conversion of alpha D-glucose 1-phosphate to alpha D-glucose 6-phosphate. EC 5.4.2.2.Bifidobacterium: A rod-shaped, gram-positive, non-acid-fast, non-spore-forming, non-motile bacterium that is a genus of the family Bifidobacteriaceae, order Bifidobacteriales, class ACTINOBACTERIA. It inhabits the intestines and feces of humans as well as the human vagina.Micrococcal Nuclease: An enzyme that catalyzes the endonucleolytic cleavage to 3'-phosphomononucleotide and 3'-phospholigonucleotide end-products. It can cause hydrolysis of double- or single-stranded DNA or RNA. (From Enzyme Nomenclature, 1992) EC 3.1.31.1.L-Lactate Dehydrogenase: A tetrameric enzyme that, along with the coenzyme NAD+, catalyzes the interconversion of LACTATE and PYRUVATE. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist.Lactobacillaceae: A family of gram-positive bacteria found regularly in the mouth and intestinal tract of man and other animals, in food and dairy products, and in fermenting vegetable juices. A few species are highly pathogenic.