title: Production of nisin by Lactococcus lactis in media with skimmed milk.
abstract: Nisin is a bacteriocin that inhibits the germination and growth of Gram-positive bacteria. With nisin expression related to growth conditions of Lactococcus lactis subsp. lactis, the effects of growth parameters, media components, and incubation time were studied to optimize expression. L. lactis ATCC 11454 was grown (100 rpm at 30 degrees C for 36 h) in both M17 and MRS standard broth media (pH 6.0-7.0) supplemented with sucrose (1.0-12.5 g/L), potassium phosphate (0.13 g/L), asparagine (0.5 g/L), and sucrose (0.24 g/L), and diluted 1:1 with liquid nonfat milk. Liquid nonfat milk, undiluted, was also used as another medium (9% total solids, pH 6.5). Nisin production was assayed by agar diffusion using Lactobacillus sake ATCC 15521 (30 degrees C for 24 h) as the sensitive test organism. The titers of nisin expressed and released in culture media were quantified and expressed in arbitrary units (AU/L of medium) and converted into known concentrations of "standard nisin" (Nisaplin, g/L). The detection of nisin activity was <0.01 AU/L in M17 and MRS broths, and 7.5 AU/L in M17 with 0.14% sucrose or 0.13% other supplements, and the activity increased to 142.5 AU/L in M17 diluted with liquid nonfat milk (1:1). The 25% milk added to either 25% M17 or 25% MRS provided the highest levels of nisin assayed.
authors.affiliation: Department of Biochemical and Pharmaceutical Technology, School of Pharmaceutical Science, University of São Paulo, Rua Antonio de Macedo Soares, 452, São Paulo, SP, Brazil 04607-000. tcvpenna@usp.br
authors.forename: Thereza Christina Vessoni
authors.initials: TC
authors.lastname: Penna
authors.forename: Angela Faustino
authors.initials: AF
authors.lastname: Jozala
authors.forename: Letícia Célia
authors.initials: LC
authors.lastname: De Lencastre Novaes
authors.forename: Adalberto
authors.initials: A
authors.lastname: Pessoa
authors.forename: Olivia
authors.initials: O
authors.lastname: Cholewa
mesh_terms: D000818:Animals; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D003470:Culture Media / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000254:growth & development* / Q000378:metabolism*; D008892:Milk / Q000145:classification / Q000382:microbiology*; D009561:Nisin / Q000096:biosynthesis*; D013395:Sucrose / Q000378:metabolism*
chemical_list: D003470:Culture Media; D009561:Nisin; D013395:Sucrose