No abstract

-Strains of lactic acid bacteria (LAB) and propionic acid bacteria (PAB) were screened as biopreservatives against food spoilage yeasts, molds and Bacillus spp. singly and in combination. A combination of Lactobacillus rhamnosus strain LC705 and Propionibacterium freudenreichii ssp. shermanii strain JS was found to be the most active against yeasts, molds and Bacillus spp. The combination was tested for its activity against yeasts and molds in different food applications and the best results were obtained in fermented milks and in bakery products. An initiallevel of 10 7 cells.g " fermented milk product and a level of 1as cells.g " sour dough were found to be effective' against yeasts and Bacillus spp. Technology for the use of the combination in different applications was developed. © Inra/Elsevier, Paris.propionic acid bacteria / lactic acid bacteria / protective culture / antimicrobial activity

The adhesion of various lactobacilli and streptococci to columnar epithelial cells of pigs and calves were studied, by in vitro methods. The porcine strains isolated most frequently were Lactobacillus delbrueckii, Lact, acidophilus and Lact. fermentum. Thirteen of the 22 lactobacilli were adhesive. All the streptococci isolated belonged to Lancefield's D-group; none of them adhered to pig epithelial cells. The adhesive strains (9 of 22) of calves were identified as Lact. fermentum. Adherence was variable even between strains of the same species. Isolates from plant material, cultured milk and cheese did not adhere to the columnar epithelial cells in vitro. The adhesive porcine strains tolerated low pH and bile acids, which is important for their survival under conditions in the stomach and intestine.

Thirteen Lactobacillus and five Pediococcus strains were shown to produce an antimicrobial agent, 2-pyrrolidone-5-carboxylic acid (PCA). PCA inhibited many spoilage bacteria, particularly Enterobacter cloacae 1575, Pseudomonas fluorescens KJLG, and P. putida 1560-2. The antimicrobial activity of PCA did not change at higher temperatures. However, the activity was destroyed rapidly by neutralization with ammonium hydroxide. PCA showed slightly lower antimicrobial activity than lactic acid.