Bifidobacterium longum BB‐79 produced an acidic extracellular polysaccharide (EPS), especially when grown on solid medium. The EPS was isolated by ethanol precipitation followed by dialysis and lyophilization. Anion exchange and gel‐filtration chromatography were used to further purify and characterize the EPS. The average molecular weight was greater than 200 kDa as estimated by chromatography. Based on gas‐liquid chromatography (GLC) and GLC‐mass spectrometry analyses, the EPS appears to be composed of galactose and an unidentified hexose (possibly glucose) with a carboxyethyl (lactic acid) substituent. Lactose, when used as the primary carbon source in liquid media, gave the highest yield of EPS. Incubation times longer than 24 h and the initial culture pH (pH 6·0–9·0) had little effect on the amount of EPS produced.
W e investigated the combined effects of pressure, temperature, pH, initial spore concentration and the presence of nisin on the survival of spores of Bacillus coagiilrins. Spores were more sensitive to pressure both at lower p H and at higher treatment temperatures. An additional 1.5-logl,, reduction in cfu ml I was observcd when pH was lowered from 7.0 to 4.0 during pressurization at 400 M p a and 45°C. A 4-logl(, cfu ml ' reduction was observed when the temperature was increased from 25°C to 70°C during pressurization at 400 Mpa. T h e spores were sensitive to nisin at concentrations as low as 0.2 IU m1-I. At least a 6-logl, reduction was generally achieved with pressurization at 400 M p a in pH 4.0 buffer at 70°C for 30 min when plated in nutrient agar containing 0.8 IU mi-' nisin.
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