title: Production of nisin Z by Lactococcus lactis isolated from dahi.
abstract: Lactococcus lactis CM1, an isolate from homemade "Dahi," a traditional fermented milk from India, used maltose as carbon source to produce a high level of bacteriocin. The bacterial cell mass and the bacteriocin production correlated with the initial pH of the medium and were highest when the initial pH was 11.0. The level of bacteriocin reached its peak at the late log phase with concomitant reduction of culture pH to 4.2, regardless of the initial pH of the medium. A combination of maltose and an initial medium pH of 11 resulted in the highest bacteriocin production. The antibacterial spectrum of the bacteriocin was closely similar to that of nisin and it inhibited a number of food spoilage and pathogenic bacteria. Upon sodium dodecyl sulfate polyacrylamide gel electrophoresis, the compound migrated close to the position of nisin (3.5 kDa). However, it had higher stability than nisin at a wide range of pH and temperature. PCR amplification using nisin gene-specific primers and sequencing of the amplified DNA revealed the structural gene for the bacteriocin to be identical to that of nisZ.
authors.affiliation: Department of Botany, Visva-Bharati, Santiniketan 731235, West Bengal, India.
authors.forename: Suranjita
authors.initials: S
authors.lastname: Mitra
authors.forename: Pran Krishna
authors.initials: PK
authors.lastname: Chakrabartty
authors.forename: Swadesh Ranjan
authors.initials: SR
authors.lastname: Biswas
mesh_terms: D000818:Animals; D001409:Bacillus cereus; D001430:Bacteriocins / Q000096:biosynthesis*; D043302:Cultured Milk Products / Q000382:microbiology*; D005516:Food Microbiology; D007778:Lactobacillus; D013294:Lactococcus lactis / Q000302:isolation & purification* / Q000378:metabolism*; D008089:Listeria monocytogenes; D009561:Nisin / Q000031:analogs & derivatives* / Q000096:biosynthesis; D013211:Staphylococcus aureus
chemical_list: D001430:Bacteriocins; D009561:Nisin; C071364:nisin Z