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Chapter IV: Results
Fig. 4.9 CLUSTAL X alignment of bacteriocin from L. casei LAM-1 with Pisciocin V1b,
from Carnobacterium piscicola (1), Lactococcin MMFII from Lactococcus lactis (2),
Sakacin-A from L. sakei (3), Curvacin-A from L. curvatus (4), Enterocin P from E.
feacium (5). Asterisks below the aligned sequences indicate amino acids present in all
seven sequences. Positions with colons below contain a residue of the strongly conserved
groups in all seven sequences, and periods indicate more weakly conserved groups in all
seven sequences
The physiochemical properties of the peptide sequence the molecular weight,
theoretical isoelectric point (pI), amino acid composition, atomic composition and grand
average of hydropathicity (GRAVY) predicted by Bactibase database (Table 4.24).
4.11 Batch fermentation for bacteriocin production L. casei LAM-1
Production of bacteriocin by L. casei LAM-1 was studied under batch culture
conditions as shown in Fig. 4.10 and 4.11. Cell density of L. casei LA-1 increased from 0.1 to
3 (OD600 nm) during 48 h of growth at 37°C. The pH of the medium decreased from 6.0 to 3.5
over the same period. Bacteriocin production started at the late exponential phase and reached
its maximum at the early stationary phase suggesting that the antimicrobial peptide to be a
secondary metabolite, whereas maximum biomass occurred at 18 h. Results showed that L.
casei LAM-1 produced bacteriocin in MRS broth and exhibited higher bacteriocin activity of
2844 AU/ml at pH 6.5 and temperature around 37°C at 20 h.