The source of microbiological contamination of whey protein concentrate (WPC), a quality problem for the dairy industry, has not been thoroughly investigated. The objectives of this study were to identify the bacteria isolated from whey protein concentrate containing 80% protein (WPC 80) and determine their ability to form biofilms as a potential source of contamination in a whey processing line. Six Bacillus species including (percentage of isolates in brackets) Bacillus licheniformis (67%), Bacillus cereus (19%), Bacillus thuringensis (4%), Bacillus subtilis (4%), Bacillus pumilus (4%) and Paenibacillus glucanolyticus (2%) were identified based on BLAST databases in six different WPC80 batches. B. licheniformis was the predominant isolate. B. licheniformis are thermo-tolerant bacteria with the ability to form biofilm. This biofilm is a potential source of microbial contamination of product, resulting in microbial specification limits being exceeded. Spoilage of product may result from the metabolic products, such as enzymes, produced by these biofilms.
When low-CO 2 grown Chlorellapyrenoidosa (YSK strain) cells were exposed to high CO 2 partial pressures (pCO 2 ), the specific growth rate () declined exponentially reaching a steady state value in about 20 h. A short interruption (up to 1 h) by temporarily lowering the pCO 2 did not prevent the continuous decline in y when high pCO 2 was restored. In chemostate studies, light-limited cultures were supplied with 2 to 90 kPa of CO 2 . The steady state biomass production rate and bioenergetic growth yield were related inversely to pCO 2 and the average energy uptake rate. The maintenance energy coefficient was, however, independent of dissolved pCO 2 in the pCO 2 range studied.
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