Preliminary Observations on the Effect of Sodium Alginate on Selected Nonsporing Organisms.

The sodium salt of alginic acid, commonly called "algin" or "alginate," has been used as a stabilizer in foods for over a quarter of a century. In experiments conducted in this laboratory in which sodium alginate was a component part of the suspending medium for selected nonsporing organisms, under varying conditions, it appeared that there may be a difference in response to the presence of alginate among genera. This observation was incidental to the original purpose and design of most of the experiments and is reported here briefly both because the results appear to offer interesting possibilities for further studies and because there may be possible practical applications of the findings. In 1956 a series of experiments was underway which sought to investigate the relationship between viscosity of the medium in which the cells were heated and the heat resistance of Salmonella typhimurium strain no. 84 (Woodburn, 1956). Sodium alginate5 was selected as the agent by which to achieve variation in viscosity of physiological saline solution. This product formed a homogeneous suspension neither coagulated by heating nor gelled by cooling. No observable scum formed during its use as described. Preliminary experiments were conducted to determine the effect of the sodium alginate on the test organism. In so doing, a known number of cells of S. typhimurium 84 were added to 1 ml of sterile sodium alginate suspension, adjusted to pH 7. A suitable dilution was plated at once with tryptone glucose extract (TGE) agar. Following an incubation period of 1 hr at room temperature, a second plating was made, similarly. After 24 hr incubation of the plates at 37 C, colony counts were made in both cases. In the original inoculum, the average number of salmonella cells per ml of a 4 per cent sodium alginate