Encapsulation of bacteria

S. Fennouh, S. Guyon, C. Jourdant, J. Livage, and C. Roux, eds, Encapsulation of bacteria, in Silica Gels, Vol. 2 (Translated). Comptes Rendus Academy of Sciences, Paris, p. 625 (1999). 

Coiffier A., Coradin T., Roux C., Bouvet O.M.M., Livage J. Sol-gel encapsulation of bacteria a comparison between aUtoxide and aqueous routes. J. Mater. Chem, 2001 11 2039-2044... 

Figure 12.29 Scheme for the (a) one-step and (b) two-step encapsulation of bacteria by electrodeposited sol-gel films, (c) Viable bacteria cells (BacLight analysis) as a function of storage time for the two-step deposited... 

Platinum—polyethyleneimine complexes prevent the division of bacteria, and are being tested as carriers in the treatment of cancer and vimses (445—447). Encapsulated PEIs containing nucleic acid bases activate the neutrophils in human blood (448). 

Ferrer, M.L., Yuste, L., Rojo, F. and Del Monte, F. (2003) Biocompatible sol-gel route for encapsulation of living bacteria in organically modified silica matrixes. Chemistry of Materials 15, 3614-3618. 

The resident microbes within the mouth readily form biofilms on teeth. A biofilm consists of a population of bacteria coexisting in an orderly structure at the interface of a solid and a liquid [14] and, within a biofilm, bacteria living in colonies encapsulated in a matrix of extracellular polymer. Oral biofilms are known to vary extensively in structure throughout the colony, with regions of densely packed microorganisms surrounded by open water channels. Each type of bacteria exists in reasonably defined environments which are influenced by surrounding cells, distance from the outer surface and local structure, all of which influence availability of nutrients and ambient pH. 

The presence of edema and increased skin fragility (often the site of entrance of bacteria) are among the causes of increased risk of infections in nephrotic syndrome. Losses of immunoglobulin G and factor B (from the alternative pathway of the activation of complement) into the urine weaken the ability of the defense system to respond mainly to encapsulated microbes like pneumococci. The function of lymphocytes can be further weakened as a consequence of losses of zinc and transferrin into the urine. Weakening of the phagocytic function of macrophages has been described as well. 

A novel all-aqueous-based system that relies on the thermodynamic incompatibility of biopolymers has been described for the encapsulation of probiotics. A two-phase system comprising of polyvinyl pyrolidone and dextran was used as the carrier material for a probiotic bacterium in the preparation of spray dried preparations of probiotics. The survival of the bacteria Enterococcus faecium E74) was dependent on the composition of the system. Although the survival rate during drying was better when only dextran was used, there were better survival rates of the bacteria during storage with the two-phase carrier system (Millqvist-Fureby et al. 2000). 

Iyer, C., and Kailasapathy, K. (2005). Effect of co-encapsulation of probiotics with prebiotics on increasing the viability of encapsulated bacteria under in vitro acidic and bile salt conditions and in yogurt. J. FoodSci. 70, M18-M23. 

Sultana, K., Godward, G., Reynolds, N., Animugaswamy, R., Peiris, P., and Kailasapathy, K. (2000). Encapsulation of probiotic bacteria with alginate-starch and evaluation of survival in simulated gastrointestinal conditions and in yoghurt. Int. J. Food Microbiol. 62,47 55. 

Insect cellular defense reactions involve phagocytosis of bacteria or fungi (2,3) and encapsulation of foreign objects by a layer of blood cells to seal the invader from the hemolymph (4,5). Humoral immunity in some Diptera involves a phenoloxidase-based humoral encapsulation reaction (6,7), and in many types of... 

Then freshly obtained encapsulated lactobacilli bacteria are added to achieve a final concentration of at least 1 million viable bacteria per suppository. (Inasmuch as the goal is to achieve a final concentration of at least 1 million viable bacteria per suppository, a four- to sixfold excess of bacteria are usually added because some loss of the viability occurs during the various mixing processes. This means that about 500 mg of the encapsulated bacteria are usually added.) It is important to mix these organisms not only thoroughly to ensure uniformity but also quickly because moisture adversely affects the viability of the organisms. 

Avery wanted to be certain that the active agent was the DNA and not a small amount of protein contamination. To verify the result, a quantity of DNase, an enzyme that would destroy the DNA without affecting the protein, was prepared and added to the sample. When a portion of bacteria was tested, it could no longer transform the unencapsulated bacteria into encapsulated bacteria. Avery and his co-workers had conclusively proven that DNA was the transforming principle responsible for the development of polysaccharide capsules in the tmencapsulated bacteria. 

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