AGFD 103 |
| A classical chemical mutagenesis protocol was used to develop food grade b-galactosidase overproducing mutants of Lactobacillus reuteri. Six strains of L. reuteri ( MM 7, SD 2112, CF 2F, MM 2-3, DSM 2016 and MF 14) were tested by a single exposure to two chemical mutagens, ethyl methanesulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). To screen for b-galactosidase (b-gal) overproducing mutants, optimized EMS and MNNG mutant pots for each strain were plated on BHI agar containing 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal). Colonies that exhibited a blue color were selected for quantitative b-gal activities using the o-nitrophenyl-b-galactoside (ONPG) assay. Three mutants were obtained out of more than 1 million colonies screened and showed increased b-galactosidase activities compared with the wild-type strains. EMS gave a higher frequency of b-gal overproducing mutants than MNNG for one of the three b-gal mutants. When mutants were grown in lactose broth,the highest b-gal activity was obtained(54%). This food-grade classical approach has the ability to increase b-gal concentrations in lactobacillus cultures and improve the potential application for treating the symptoms of lactose malabsorption in humans. |
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General Posters
1:00 PM-3:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Poster
Division of Agricultural & Food Chemistry |