title: Enhancement of Exopolysaccharide Production by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 with a Simplified Defined Medium.
abstract: The aim of this work was to investigate the medium requirements for growth and production of exopolysaccharides by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772. The strain was grown in batch cultures on a chemically defined medium, and the technique of single omission of medium components was applied to determine the nutritional requirements. The omission of aspartic acid, glutamic acid, or glycine affected growth only slightly, and the omission of glutamine, asparagine, or threonine resulted in a stronger reduction of the growth. All the other amino acids were essential. Multiple omissions of amino acids caused an almost complete loss of growth. L. delbrueckii subsp. bulgaricus required only riboflavin, calcium pantothenate, and nicotinic acid as individual vitamins. Surprisingly, when only these vitamins were present in the medium and other vitamins were not, less growth was observed than in the complete medium but the amount of exopolysaccharide produced was significantly greater. These observations were studied in more detail with a simplified defined medium in which L. delbrueckii subsp. bulgaricus was able to grow and produce exopolysaccharides. Although the final optical density in the simplified medium was lower, the production of exopolysaccharides was about twofold higher than in the complete medium.
authors.affiliation: Division of Industrial Microbiology, Department of Food Technology and Nutrition Sciences, Wageningen Agricultural University, 6700 EV Wageningen, Friesland Coberco Dairy Foods, 8901 MA Leeuwarden, and Netherlands Institute for Dairy Research, 6710 BA Ede, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Grobben
authors.forename: I
authors.initials: I
authors.lastname: Chin-Joe
authors.forename: V A
authors.initials: VA
authors.lastname: Kitzen
authors.forename: I C
authors.initials: IC
authors.lastname: Boels
authors.forename: F
authors.initials: F
authors.lastname: Boer
authors.forename: J
authors.initials: J
authors.lastname: Sikkema
authors.forename: M R
authors.initials: MR
authors.lastname: Smith
authors.forename: J A
authors.initials: JA
authors.lastname: de Bont