Relevance of in situ penicillin production by P. nalgiovense
in meat products. Results of bioassays of solvent-extracted
antibiotic production by P. nalgiovense growing in situ on the
cured and semicured sausages are shown in Fig. 5. As shown in
panel 1 of Fig. 5, there was moderate penicillin production in
solvent extracts of the casing and in the lipidic interface from
semicured salami. No detectable levels of penicillin were found
either in the casing or in the meat of cured salami. Similarly,
using direct bioassays of penicillin production in the casing or
the salami meat, we found significant levels of penicillin in the
soft salami, namely, 1.25 mg/cm2 of casing, 0.66 mg/g of meat in
the outer surface layer, and 0.08 mg/g of meat in the inner
surface layer. The antibiotic produced was completely degraded
by penicillinase and was extracted with ethyl acetate,
indicating that the side chain in the penicillin molecules was
not polar.