| Effects of pH profiles on nisin production in biofilm reactor. | |
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MedLine Citation:
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PMID: 16331455 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Apart from its widely accepted commercial applications as a food preservative, nisin emerges as a promising alternative in medical applications for bacterial infection in both humans and livestock. Improving nisin production through optimization of fermentation parameters would make nisin more cost-effective for various applications. Since nisin production by Lactococcus lactis NIZO 22186 was highly influenced by the pH profile employed during fermentation, three different pH profiles were evaluated in this study: (1) a constant pH profile at 6.8 (profile 1), (2) a constant pH profile with autoacidification at 4 h (profile 2), and (3) a stepwise pH profile with pH adjustment every 2 h (profile 3). The results demonstrated that the low-pH stress exerted during the first 4 h of fermentation in profile 3 detrimentally affected nisin production, resulting in a very low maximum nisin concentration (593 IU ml(-1)). On the other hand, growth and lactic acid production were only slightly delayed, indicating that the loss in nisin production was not a result of lower growth or shifting of metabolic activity toward lactic acid production. Profile 2, in which pH was allowed to drop freely via autoacidification after 4 h of fermentation, was found to yield almost 1.9 times higher nisin (3,553 IU ml(-1)) than profile 1 (1,898 IU ml(-1)), possibly as a result of less adsorption of nisin onto producer cells. Therefore, a combination of constant pH and autoacidification period (profile 2) was recommended as the pH profile during nisin production in a biofilm reactor. |
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Authors:
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Thunyarat Pongtharangkul; Ali Demirci |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2005-12-06 |
Journal Detail:
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Title: Applied microbiology and biotechnology Volume: 71 ISSN: 0175-7598 ISO Abbreviation: Appl. Microbiol. Biotechnol. Publication Date: 2006 Aug |
Date Detail:
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Created Date: 2006-08-09 Completed Date: 2006-10-10 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8406612 Medline TA: Appl Microbiol Biotechnol Country: Germany |
Other Details:
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Languages: eng Pagination: 804-11 Citation Subset: IM |
Affiliation:
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Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, PA 16802, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Biofilms
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growth & development* Bioreactors / microbiology* Fermentation Hydrogen-Ion Concentration Lactic Acid / metabolism Lactococcus lactis / growth & development, metabolism* Nisin / biosynthesis* Sucrose / metabolism Time Factors |
| Chemical | |
Reg. No./Substance:
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1414-45-5/Nisin; 50-21-5/Lactic Acid; 57-50-1/Sucrose |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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