. Author manuscript; available in PMC: 2016 Nov 18.

Published in final edited form as: J Food Prot. 2013 Nov;76(11):1854–1862. doi: 10.4315/0362-028X.JFP-13-089

TABLE 5.

Influence of initial L. monocytogenes CFSAN-82 (Lm) and L. innocua ARL-Ln-001 (Ln) spiking levels on recovery and final 48-h populations of L. monocytogenes in BLEB at 30°C

	Mean ± SD initial spiking levels (log CFU/ml)^a:

Results	Lm: 2.7 ± 0.06 Ln: 0.8 ± 0.01	Lm: 1.7 ± 0.06 Ln: 0.8 ± 0.01	Lm: 0.7 ± 0.06 Ln: 0.8 ± 0.01	Lm: 0.7 ± 0.06 Ln: 1.8 ± 0.01	Lm: 0.7 ± 0.06 Ln: 2.8 ± 0.01
48-h enrichment population (log CFU/ml)^b
L. monocytogenes	9.0 ± 0.10	8.1 ± 0.07	6.9 ± 0.13	6.1 ± 0.09	5.3 ± 0.2
Listeria spp.	9.1 ± 0.05	9.2 ± 0.03	9.1 ± 0.03	9.1 ± 0.05	9.1 ± 0.07
Streak plate recovery of L. monocytogenes^c
Oxford agar
Colonies	24/30	0/30	0/30	0/30	0/30
Replicates	3/3	0/3	0/3	0/3	0/3
Chromogenic Listeria agar
Colonies	9/30	5/30	0/30	0/30	0/30
Replicates	3/3	3/3	0/3	0/3	0/3

Spiking levels were estimated by plate count on TSAYE following serial dilution of the overnight culture in phosphate buffer.

L. monocytogenes populations were determined on TSAYE supplemented with 200 μg/ml streptomycin sulfate. Total Listeria spp. populations were determined by surface plating onto Oxford agar.

Streak plate analysis was performed using both Oxford agar and Oxoid chchromogenic Listeria agar. Results are expressed qualitatively as the number of positive colonies or replicates/number tested.