Erick Vandamme

Fermentation optimization of plantaricin 423, a bacteriocin produced by Lactobacillus plantarum 423

Abstract More than 15 bacteriocins of Lactobacillus plantarum have been described. However, little information has been published on the fermentation optimization of these peptides. Plantaricin 423, produced by L. plantarum 423, is produced during exponential growth and reaches a maximum activity [6000 activity units (AU)/ml] at the beginning of stationary growth (i.e. after 15 h). This activity level is maintained for 3 h, but declines to 2600 AU/ml towards the end of fermentation (i.e. after 31 h). The increase in plantaricin 423 activity coincided with a decrease in pH from 5.8 to 4.0 during the first 15 h of fermentation. However, when the number of cells are taken into account (ODmax-value), a higher concentration of plantaricin 423 is produced in medium with an initial pH of 4.90 (2961 AU/ml/ODmax) than at pH 5.80 (2368 AU/ml/ODmax). A much lower activity of plantaricin 423 was obtained during the same fermentation period (15 h) when cells were grown in MRS broth (Merck) with an initial pH of 6.9. The production of plantaricin 423 increased from 6000 AU/ml in MRS broth (Merck) to 9600, 12,800 and 19,200 AU/ml when the medium was supplemented with 1.9% (w/v) meat extract (Oxoid), 3.4% (w/v) casaminoacids (Oxoid) or 1.9% (w/v) tryptone (Oxoid), and 1.7% (w/v) bacteriological peptone (Oxoid), respectively. The activity of plantaricin 423 was even further increased with the addition of 1% (w/v) tween 80 to MRS broth (Merck). Low concentrations of MnSO4·H2O (0.014%, w/v) stimulated the growth of strain 423 and increased the activity of plantaricin 423. Although the addition of MgSO4·7H2O had the same stimulating effect on the growth of strain 423, the activity of plantaricin 423 was not increased.

L-fucose: occurrence, physiological role, chemical, enzymatic and microbial synthesis.

An easy source of unusual monosaccharides such as the 6-deoxyhexose, L-fucose are certain microbial extracellular polysaccharides (EPS), best known for their thickening, gelling or emulsifying properties. L-Fucose and L-fucose containing oligosaccharides have potential application in the medical field in preventing tumour cell colonisation of the lung (anticancer effect), in controlling the formation of white blood cells (anti-inflammatory effect), in the treatment of rheumatoid arthritis, in the synthesis of antigens for antibody production (rational immunisation) and in cosmeceuticals as skin moisturing agent. L-Fucose production via chemical synthesis is laborious and suffers from low yield, while direct extraction from brown algae is costly and subject to seasonal variations in supply volume and quality. Enzymatic synthesis is currently under investigation. Chemical or enzymatic hydrolysis of L-fucose-rich microbial EPS opens up a new route towards efficient L-fucose production. This review deals with the properties, occurrence, physiological roles, chemical, enzymatic and microbial production of L-fucose. © 1999 Society of Chemical Industry

Pediocin PD-1, a bactericidal antimicrobial peptide from Pediococcus damnosus NCFB 1832

Pediocin PD‐1, produced by Pediococcus damnosus NCFB 1832, is inhibitory to several food spoilage bacteria and food‐borne pathogens. However, pediocin PD‐1 is not active against other Pediococcus spp. and differs in this respect to other pediocins produced by Pediococcus acidilactici and Pediococcus pentosaceus. Production of pediocin PD‐1 starts during early growth and reaches a plateau at the end of exponential growth. Pediocin PD‐1 was partially purified and its size was determined by tricine‐SDS‐PAGE as ≈ 3·5 kDa. The isoelectric point (pI) of pediocin PD‐1 is ≈ 3·5, as determined with the Rotofor electrofocusing cell (BioRad). Pediocin PD‐1 is heat‐resistant (10 min at 121°C) and remains active after 30 min of incubation at pH 2–10. Pediocin PD‐1 is resistant to treatment with pepsin, papain, α‐chemotrypsin and trypsin, but not Proteinase K. Pediocin PD‐1 is bactericidal against sensitive cells of Oenococcus oeni (previously Leuconostoc oenos).

Growth optimization of Pediococcus damnosus NCFB 1832 and the influence of pH and nutrients on the production of pediocin PD-1.

Aims: Optimization of the growth of Pediococcus damnosus NCFB 1832 and the production of pediocin PD‐1 by traditional fermentation methods.

Optimization of exopolysaccharide production by Tremella mesenterica NRRL Y-6158 through implementation of fed-batch fermentation.

In liquid culture conditions, the yeast-like fungus Tremella mesenterica occurs in the yeast state and synthesizes an exopolysaccharide (EPS) capsule, which is eventually released into the culture fluid. It is composed of an α-1,3-D-mannan backbone, to which β-1,2 side chains are attached, consisting of D-xylose and D-glucuronic acid. Potato dextrose broth (PDB) seemed to be an excellent medium for both growth of the yeast cells and synthesis of the EPS. This medium is composed solely of an extract of potatoes to which glucose was added. Yet an important disadvantage of this production medium is the presence of starch in the potato extract, since Tremella cells are not capable of metabolizing this component; furthermore, it coprecipitates upon isolation of the polymer [3]. In this respect, it was essential to remove the starch in order to achieve high polysaccharide production and recovery. A good method was the removal of starch through ultrafiltration of the PDB medium before inoculation of the strain. This resulted in an excellent starch-free medium in which other components essential for polysaccharide production were still present [3]. Through implementation of single and cyclic fed-batch fermentations with glucose feed, 1.6- and 2.2-fold increases in EPS yield were obtained, respectively. Lowering the carbon source level by using a cyclic fed-batch technique might decrease the osmotic effect of glucose or any catabolite regulation possibly exerted by this sugar on enzymes involved in EPS synthesis. Journal of Industrial Microbiology & Biotechnology (2002) 29, 181–184 doi:10.1038/sj.jim.7000276

Extracellular Tremella polysaccharides: structure, properties and applications

Tremella sp. is a yeast-like fungus from which polysaccharides can be isolated from either the yeast or the fungus phase, depending on the species. All of the polymers synthesized by these organisms consist of a mannan backbone to which small xylose side chains and glucuronic acid are attached. The main interest in these glucuronoxylomannans is their application in medicine to enhance the immune system.

Exopolysaccharide degrading enzyme and use of the same

The present invention relates to an exopolysaccharide degrading enzyme, to enzymatic compositions capable of degrading exopolysaccharides and in particular to the reduction or removal of biofilm on surfaces and to the prevention of biofilm formation on such surfaces. More particularly, the present invention relates to the use of the enzyme and/or the enzymatic composition, comprising at least one exopolysaccharide degrading enzyme, for the reduction, removal and/or prevention of biofilm on surfaces of aqueous systems (water-bearing systems, fluid systems). The present invention further relates to a bacterial strain producing an exopolysaccharide degrading enzyme, and to the exopolysaccharide degrading enzyme prepared from a newly isolated strain of Streptomyces. Specifically, the exopolysaccharide degrading enzyme of the present invention is a colanic acid degrading enzyme.