The aim of the research described in this thesis was to identify and characterize the genetic element carrying the information for nisin biosynthesis and sucrose proficiency, the nisin-sucrose element. The thesis has the following outline. Chapter 2 describes our current knowledge of nisin genetics and the recent advances in the protein engineering of nisin. The cloning and analysis of several parts of the nisin-sucrose element of L. lactis strain NIZO R5 are described in the next two chapters. Chapter 3 deals with the prenisin gene, nis A, and its surrounding region, which includes the insertion sequence IS 1068 . In Chapter 4, the organization and transcription of the sucrose ( sac ) operon and the characterization of the gene for sucrose-6-phosphate hydrolase are described. The different parts of the nisin-sucrose element were used as DNA probes to investigate the nature and location of this element (Chapter 5). It was shown that the nisin-sucrose element of L. lactis NIZO R5 is a large (70 kb), conjugative transposon, designated Tn 5276. Chapter 6 describes the isolation and analysis of the genes that encode the transposition functions of Tn 5276. The experiments leading to a model for excision and insertion of Tn 5276 are described in Chapter 7. Chapter 8 deals with the distribution and evolution of nisin-sucrose elements in L. lactis . The thesis is completed with the summary and concluding remarks (Chapter 9) and a Dutch summary (Chapter 10).
|Qualification||Doctor of Philosophy|
|Award date||26 May 1993|
|Place of Publication||Wageningen|
|Publication status||Published - 1993|
- lactic acid bacteria