Harnessing cross-resistance – sustainable nisin production from low-value food side streams using a Lactococcus lactis mutant with higher nisin-resistance obtained after prolonged chlorhexidine exposure

Ge Zhao, Paul J. Kempen, Radhakrishna Shetty, Liuyan Gu, Shuangqing Zhao, Peter Ruhdal Jensen*, Christian Solem

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Nisin has a tendency to associate with the cell wall of the producing strain, which inhibits growth and lowers the ceiling for nisin production. With the premise that resistance to the cationic chlorhexidine could reduce nisin binding, variants with higher tolerance to this compound were isolated. One of the resistant isolates, AT0606, had doubled its resistance to nisin, and produced three times more free nisin, when cultured in shake flasks. Characterization revealed that AT0606 had an overall less negatively charged and thicker cell wall, and these changes appeared to be linked to a defect high-affinity phosphate uptake system, and a mutation inactivating the oleate hydratase. Subsequently, the potential of using AT0606 for cost efficient production of nisin was explored, and were able to attain a high titer of 13181 IU/mL using a fermentation substrate based on molasses and a by-product from whey protein hydrolysate production.
Original languageEnglish
Article number126776
JournalBioresource Technology
Volume348
Number of pages10
ISSN0960-8524
DOIs
Publication statusPublished - 2022

Keywords

  • Nisin production
  • Chlorhexidine
  • Adaptive laboratory evolution
  • Molasses
  • Dairy waste

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