Influence of Organic Buffers on Bacteriocin Production by <Emphasis Type="Italic">Streptococcus thermophilus</Emphasis> ST110

The effect of the organic buffer salts MES, MOPS, and PIPES on the growth of S. thermophilus ST110, medium pH, and accumulation of the antipediococcal bacteriocin thermophilin 110 were evaluated in whey permeate media over a period of 24 h. In nonbuffered medium, thermophilin 110 production at 37°C paralleled the growth of S. thermophilus ST110 and reached a maximum after 8–10 h. Addition of organic buffer salts decreased the drop in medium pH and resulted in increased biomass (dry cells; μg/mL) and higher yields of thermophilin 110 (units/μg cells). The best results were obtained by the addition of 1% (w/v) MES to the medium, which reduced the pH drop to 1.8 units after 10 h of growth (compared to 2.3 pH units in the control) and resulted in a 1.5-fold increase in cell mass (495 μg/mL) and a 7-fold increase in thermophilin 110 yield (77 units/μg dry cells) over the control. The results showed that whey permeate-based media may be suitable for producing large amounts of thermophilin 110 needed for controlling spoilage pediococci in industrial wine and beer fermentations. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.