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Aqueous Two-Phase Micellar System for Nisin Extraction in the Presence of Electrolytes

Jozala, Angela Faustino, Lopes, André Moreni, de Lencastre Novaes, Letícia Celia, Mazzola, Priscila Gava, Penna, Thereza Christina Vessoni, Júnior, Adalberto Pessoa
Food and bioprocess technology 2013 v.6 no.12 pp. 3456-3461
Gram-positive bacteria, Lactococcus lactis, culture media, electrolytes, fermentation, nisin, nonionic surfactants, pathogens, salts
Liquid-liquid extraction for aqueous two-phase micellar systems (ATPMS) is a promising technique that can either replace or be used as a complementary process to more typical chromatographic operations in order to reduce the costs of downstream processing of many biological products. This method offers attractive conditions when exploited in the extraction/purification of a target protein directly on the culture medium. Nisin, an extracellular antimicrobial peptide, is produced by Lactococcus lactis and is effective at controlling a wide range of Gram-positive bacteria, including multidrug-resistant pathogens. This study evaluates ATPMS composed by a nonionic surfactant, Triton X-114, in the presence or absence of electrolytes, to improve the extraction of nisin. The partitioning behavior of nisin showed that it can be directly extracted from the fermentation media. The partitioning coefficient (K nis) of the commercial nisin in the presence of electrolytes showed K nis values of 5.6 and 5.4 for MgSO4 and (NH4)2SO4, respectively. Similar behavior was observed for the produced nisin where K nis values were 4.1 and 5.1 for MgSO4 and (NH4)2SO4. After partition, the commercial nisin activity in the micelle-rich phase, in the absence of electrolytes, was 3.3 logAU/mL, and in the presence of MgSO4 and (NH4)2SO4, the activity was 5.0 logAU/mL. The produced nisin activity with and without MgSO4 was around 3.5 logAU/mL; however, in the presence of (NH4)2SO4, nisin activity was 4.5 logAU/mL. The increase in nisin activity after partitioning with salts encourages further researches for the optimization of nisin extraction. ©Springer Science+Business Media New York 2012.