Biological Sciences, School of


Date of this Version

Fall 10-8-2010

Document Type



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Biological Sciences, Under the Supervision of Professor Robert W. Hutkins. Lincoln, NE: October 2010
Copyright 2010 Caitlin D. Goin.


Lactic acid bacteria are a vital part of the fermented food industry and are the subject of much interest and research. Industry is especially interested in using modern molecular approaches to maintain and improve selected strains; several industrial uses could be improved by closer investigation, namely the protocooperation of S. thermophilus and L. bulgaricus, the role of CRISPRs in phage resistance, and the utilization of prebiotic carbohydrates. Questions such as what genes and pathways are shared during milk fermentation between S. thermophilus and L. bulgaricus, when and what genes are active during bacteriophage infection, and how and where does prebiotic carbohydrate utilization occur can be answered. By using microarrays, complete snapshot of gene expression during each of these conditions are generated and detailed expression profiles can be produced. By devising a screening system, the distribution of the phenotype of GOS fermentation over a wide array of lactic acid bacteria from Bifidobacterium, Lactobacillus, Lactococcus, Leuconostoc, and S. thermophilus can be explored. Once this phenotypic distribution is generated, selected strains that are able to utilize GOS can be studied in detail to determine the mechanics of GOS fermentation. Answering these questions will add to the understanding of what factors are involved in successful fermentation and eventually be able to improve strain selection methods.