Abstract The aim of this work was to investigate the effect
of growth conditions on the maximum activity of bacteriocin
production by Lactobacillus acidophilus AA11. The
bacteriocin was produced at maximum activity in M17
broth supplemented with 0.5% lactose (M17L). The
maximum growth of Lactobacillus acidophilus AA11 was
obtained at 37°C, while the optimal temperature for the
bacteriocin production was 30°C. The pH of bacterial
culture also affected bacteriocin production. The optimal
pH for bacterial growth and bacteriocin production was 6.5.
Moreover, carbon and nitrogen sources significantly influenced
the production of bacteriocin. The bacteriocin yield
was at least 4-fold higher in M17 broth supplemented with
lactose compared to other carbon sources. The optimal
organic nitrogen source for bacteriocin production was
yeast extract (4%). The addition of KH2PO4, CaCl2 or
NH4PO4 into the medium resulted in significant suppression
of bacteriocin; however, incorporation of MnSO4
resulted in an impressive increase in bacteriocin production.
No increase in bacteriocin production was recorded in
medium supplemented with vitamins. The addition of
glycerol to the growth medium decreased bacteriocin
production. Consequently, maximum bacteriocin activity
was obtained in M17L medium (pH 6.5) supplemented with
4% yeast extract and MnSO4 at 30°C. This optimization of
bacteriocin production by modification of environmental
growth conditions will greatly benefit efficient commercial
application.