Table 2.

MPN and MPN-MCR test results

Strain (flask no.)DayCFU/ml on HI-80 platesbNo. of positive tubes at dilutiona:MPN estimate of viable cells/ml
10010−110−210−310−4
C1784-opaque (1)25480101060079
10c 1040049
2780940003
10c 20003
33<100000<1
0c 0000<1
2400-112 (1)2665010520086
10c 6300120
29100101010028
10c 900017
36<100000<1
0c 0000<1
MLT403 (2)12510101041056
1490900002
16<100000<1
MLT367 (1)26460101040049
289000000<1
35<100000<1
VV1009 (1)28900101040049
349200000<1
42<100000<1
  • a There were 10 tubes at each dilution.

  • b HI-80 plate counts in the ASW microcosms are shown. The HI plate counts were <1 CFU/ml at all of these time points.

  • c MPN-MCR test; scored as positive if they contained both Lac+ and Lac colonies (see the text).