Download Centennial Honors College Western Illinois University Undergraduate Research Day 2014

Centennial Honors College
Western Illinois University
Undergraduate Research Day 2014
Poster Presentation
Detection of Carbon Catabolite Repression in Leuconostoc
Kara Chicoine, Eliese Potocek and Darrah Dunlap
Faculty Mentor: Scott Holt
Biology
Leuconostoc is a gram-positive, lactic acid-producing bacterial genus that plays a large
role in food and industrial fermentation. A defining feature of Leuconostoc is its’ ability to
produce α-glucans (dextran), which are complex exopolysaccharides composed of
glucose units. Leuconostoc makes the enzyme glucansucrase which catalyzes the
production of α-glucans via catabolizing the sugar sucrose. The goal of this study was to
determine if glucansucrase production by Leuconostoc is controlled by carbon
catabolite repression (CCR). CCR is a global regulatory mechanism used by most
bacteria to ensure that bacteria will preferentially consume simple sugars first (glucose)
followed by more complex sugars (sucrose) when both are present in a culture medium.
In this study, Leuconostoc strains (L. mesenteroides B-512F, B-1118, and L. citreum B1355, B-742) were cultivated for 3-h or 6-h at 30°C in media containing either glucose
(G), sucrose (S), a mixture of glucose and sucrose (G/S), or a mixture of glucose and
sucralose (G/Su). Glucansucrase activity patterns were determined for each sample (0h & 3-h or 6-h) using SDS-PAGE and in-situ detection of enzyme activity in the gels.
Glucansucrase production for L. mesenteroides B-1118 was not significantly altered by
any carbohydrate tested. The L. citreum strains and L. mesenteroides B-512F showed
that glucansucrase production was not inhibited when the strains were grown in the
(G/S) media, indicating that these strains are not controlled by CCR. Lack of a
catabolite repression mechanism for Leuconostoc may indicate that metabolism of
sucrose for energy and carbon is not the primary function of glucansucrase.