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Title: Investigation of gene expression in Lactobacillus thermotolerans associated with attachment to intestinal mucus
Author: McGreeghan-Crosby, Keith
ISNI:       0000 0001 3624 4953
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2007
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It is possible that probiotic lactic acid bacteria may be a suitable alternative to the use of the recently banned (within the European Union) antibiotic growth promoters in poultry production. Gastrointestinal tract attachment is an important property of effective probiotic organisms. In a previous study Lactobacillus thermotolerans isolated from the poultry crop attached to intestinal cells lines and differential display reverse transcription (DDRT) PCR indicated that a cell wall synthesis gene, murC, was up-regulated in the presence of mucin (Mason,2003). It was not possible to confirm Mason's observations in the present study as the earlier DDRT-PCR experiments could not be replicated. However, using Northern blot analysis, competitive PCR and Real-Time PCR to study expression of specific genes, it was found that the expression ofmurC was unaffected by mucin.. Thus it was hypothesised that a mucus adhesion gene (mub) gene may be cotranscribed with 11lurC. A 3kb region of the Lb. thermotolerans chromosome was cloned and sequenced which confirmed that 11lurC was transcribed as part of a polycistron. However, a mub gene was not identified. During this study several putative mub genes were identified and their expression in the presence of mucin investigated using Real-Time PCR. However, the expression of the putative mub genes was not found to alter in the presence of mucin. Several models were used to investigate the ability ofLb. thermotolerans to adhere to mucin which showed that Lb. thermotolerans did adhere to passively immobilised mucus and to poultry intestinal sections. The potential for future genetic analysis and modification of Lb. thermotolerans was realised as an improved electrotransformation protocol was devised providing 104 transformants/Jlg DNA. This study suggests that Lb. thermotolerans may have potential as a poultry probiotic and shows the need for detailed well controlled experiments in the study of bacterial attachment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available