PURIFICATION AND SPECIFICATION OF BACTERIOCIN PRODUCED BY SOME Lactobacillus SPP. ISOLATED FROM FOOD

Abstract

A total of 20 isolates of lactic acid bacteria (LAB) were isolated anaerobically from different food sources (Domiati cheese; raw milk and mixed pickles). Three out of 20 isolates showed high inhibition of growth pathogenic bacteria by well diffusion assay method and therefore they were chosen for bacteriocin production and further studies. The selected isolates were identified based on morphological, biochemical and MALDI-TOF mass spectrometry. All of the tested species gave a score value between 2.116 to 2.165 (100%) were correctly identified by MALDI-TOF-MS to the genus and species levels. They were identified as L. brevis, L. plantarum and L. fermentum. The bacteriocin was purified by salt precipitation and gel chromatography methods. The molecular weight was determined by SDS-PAGE and amino acid composition was also analysed. The purified bacteriocin was characterized and found to be thermostable at temperatures up to 90°C for 30min, pH from 3 to 11 and its activity improved in the presence of Tween 80, SDS and EDTA. The contents of bacteriocin from the acidic amino acid residues aspartic + glutamic (asp+glu) were 0.74% for all tested samples. The contents of the basic amino acids argnine + lysine + hisitidine (arg + lys + his) were 0.23% for all the tested samples.

In vitro application of bacteriocin produced by Lactiplantibacillus plantarum for the biopreservation of meat at refrigeration temperature

“…These polar amino acids are responsible for the overall structure and solubility of the proteins in aqueous solution however nonpolar amino acids contain R group that usually folds and buried inside during 3D structure formation of proteins (Dyson et al., 2006; Xiong et al., 1995). One of the studies also stated the presence of polar and non‐polar amino acids in bacteriocins produced from L. plantarum , L. brevis and L. fermentum (Mostafa et al., 2019).…”