| Acid camel milk (Shubat) is one of the fermented dairy products in Xinjiangand Inner Mongolia region of china, its unique flavor and nutritional value is widelyfavored by consumers. This paper selected and isolated bacteriocin producing strainfrom Xinjiang acid camel milk and on this basis, to purify the bacteriocin andstudy its characteristics, the main conclusions were as follows:1. TN-2strain was selected through agar well diffusion method;16S rDNA genesequence analysis was identified as Lactobacillus casei, the similarity of99%.2. Purification of the antimicrobial bacteriocin was done by performingammonium sulfate precipitation, gel filtration, anion exchange chromatography andreversed-phase HPLC separation. SDS-PAGE electrophoresis showed that themolecular mass of the bacteriocin was between5kDa and10kDa. According to MSresult, the molecular mass of the bacteriocin was6352Da.3. Antibacterial activity of the bacteriocin remained after heating at121℃for20min and in a wide range of pH (2.0-12.0). It was sensitive to proteases, such as papainand trypsin.4. Twenty-two indicator strains including Gram-positive and Gram-negativefood-borne pathogenic bacteria and antibiotic-resistant strains were used to determinethe antimicrobial activity of the bacteriocin. It exhibited a broad antimicrobialspectrum to indicator strains of Gram-positive and Gram-negative bacteria. Moreover,it was also found that the minimum inhibitory concentration of the bacteriocin toE.coli ATCC25922and S. aureus ATCC25923was2.5mg/mL and5mg/mL.5. Amino acid composition analysis showed that the main amino acid inCaseicinTN-2was Asp, Thr, Ser, Glu, Gly, Ala, Val, Phe, and Lys.6. Scanning electron microscopy (SEM) and transmission electron microscopy(TEM) analysis were carried out to investigate the effect of the bacteriocin on the target cells, by which it was found that pore formations and changes of cytoplasm andmembranes might be the lethal reason to the target cells. |
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