15A-3 |
Use of monosodium glutamate in inhibition of bacteriophage (Lactococcus lactis ssp. lactis c2) proliferation |
I. SURJAWAN and C. L. Hicks. University of Kentucky, Lexington, KY 40546-0215 Many lactococcal bacteriophage require calcium (Ca2+) for efficient adsorption to the host and for replication. Glutamic acid (0.5% L-, D-, DL-Glu or 2% Monosodium Glutamate (MSG)) were added to M17 medium with added Ca2+ (10mM). Culture growth was monitored by recording absorbances (l600nm) every 10 min. The L-, D-, and DL-Glu inhibited C2 growth greater than 50%. C2 culture grown in M17 containing L-Glu was most inhibited with little growth after160 min incubation. However, C2 grown in M17 with MSG was only slightly inhibited (within 10 min of the control). All additional experiments were conducted with MSG. Phage inhibition tests were conducted by growing L lactis ssp. lactis C2 in M17 (10mM Ca2+) containing 1.5% or 2% MSG with and without f c2 (105 pfu/ml infections after 15 min incubation). C2 grown in 1.5% MSG medium started to clear 70 min after the C2 grown in only M17, whereas the C2 grown in the M17 containing 2% MSG reached the stationary phase and no lysis was observed. MSG at 2% was a potent inhibitor of f c2 proliferation. In a similar experiment, where C2 was grown in M17 containing 2% MSG but infected with 105 and 108 pfu/ml f c2, the MSG provided full protection to the C2 infected with 105 pfu/ml. C2 infected with 108 pfu/ml cleared after 210 min incubation (or 40 min after the control). Additional experiments were conducted where the Ca2+ was increased to 40 mM. When C2 were infected with f c2 (105 pfu/ml) the growth cleared 15 min after the control lysed. These experiments showed that MSG is an excellent chelator of Ca2+, resulted in the inhibition of phage proliferation similar to that reported for phosphate containing media. However, media prepared with MSG would not decrease cheese yield as media containing phosphate do.
Session 15A, Dairy Foods
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