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Abstract

Title

Identification of Antimicrobial Substance Producing Lactic Acid Bacteria Presenting in Human Milk and its Antimicrobial Substance Characters
Type
Poster Presentation
Theme
Probiotics and Prebiotics: Excellence in Science and Clinical Translation
Topic
Probiotic and Prebiotic Clinical Research, From Newborns to Elderly

Authors

Main Author
Nhung Nguyen1
Presenting Author
Nhung Nguyen1
Co-Author
Massalin Nakphaichit1
Sunee Nitisinprasert1

Authors' Institution

Department / Institution / Country
Biotechnology / Kasetsart University / Thailand (ไทย)1
Content
Background and Rationale
The discovery of new group of antibiotics slowly increase while the number of bacteria resistant to the antibiotics is increasing.  Vancomycin resistant Enterococci (VRE) is a strain of Enterococci "superbugs" that have become to be difficult to treat and, occasionally, may be life threatening. Bacteriocin from lactic acid bacteria (LAB) was proposed as an interesting source to control those multiple drug resistance bacteria. Its production has been considered an important trait in the selection of probiotic strains. 
Objectives: Indicates the purpose of the study

The objective of this study was to identify bacteriocin producing LAB strain isolated from human milk and to characterize its bacteriocin.
Methodology: Describe pertinent experimental procedures

Antimicrobial activity was determined by spot on lawn method using VRE as indicator strain. Morphology, biochemical characters, peptide profile by MALDI TOF Mass  and 16S rRNA gene of the strain was determined. The bacteriocin was purified to homogeneity by Amberlite XAD-16 resin , ion exchange, reverse-phase chromatography and further analysed by MALDI-TOF mass spectrometry for molecular weight determination. Characteristics of bacteriocin were evaluated  for the sensitivities to hydrolytic enzymes, the stabilities to temperature and pH including inhibition spectrum. 
Results: Summarize the results of the research
Based on the characters of morphology, carbohydrate fermentation, peptide profile and 16S rDNA sequence, the effective LAB strain HM02-04 belonged to Enterococcus hirae. Mass spectrometry analyses revealed a molecular mass of bacterocin was 2.605 kDa. This antimicrobial substance was sensitive to proteases demonstrating its proteinaceous nature namely enterocin HM02-04. It was heat stable up to 121°C and displayed at wide pH range of 3.0 to 9.0. Enterocin HM02-04 displayed a narrow inhibitory spectrum limited to genus Enterococcus and some LAB species of Lactobacillus plantarum,  Lb. corynifomis and Lactococcus lactis.
Conclusions: State the main conclusions
E. hirae HM02-04 isolated from breast milk produced a thermostable and pH-tolerant bacteriocin including narrow inhibition spectrum, especially, Enterococcus sp. and those VRE strains. 
Keywords: Lactic acid bacteria; bacteriocin; Vancomycin resistant Enterococci.
Requires Audio or Video system for Presentation?: No