peptide inoculated with P. viridiflava I1A, P. chicorii I3C and P. putida I1B
caused a significant (P b 0.001) reduction in spoilage, under cold storage,
by a mean of 27.4, 37.3 and 42.3%, respectively. In the case of lettuce
wounds inoculated with I1A and I1B, a significant (P b 0.05) reduction in
the efficacy of LfcinB was found from day 5 of cold storage; however,
wounds inoculated with these strains and not supplemented with
LfcinB displayed higher and significant (P b 0.05) differences in percentage
of spoiled wounds compared with inoculated and treated ones
(Table 5).
In order to verify whether the reduction in spoilage percentage was
related to viable cell concentrations, an additional in vivo assay was carried
out with P. putida I1B. Even though LfcinB controlled the spoilage
produced by P. putida I1B and P. cichorii I3C to the same degree, the I1B
strain was chosen because this bacteria caused high spoilage rates on different
vegetables (Tables 2 & 3) and, at the same time, was the most sensitive
strain (Table 4) to pepsin-LFH peptides in the in vitro assay.
The Pseudomonas spp. population, evaluated by using whole leaf
samples, carried out immediately after the beginning of cold storage,
was found to be ca. 1 log CFU/g higher in the inoculated leaves than in
the uninoculated ones; this difference disappeared within three days
of cold storage (data not shown). Based on some preliminary calculations,
the cell recovery rate of the wound-washing method was estimated
to be close to 80% (data not shown). In contrast to the whole leaf
sample method, the wound-washing method was able to distinguish
n