Isolation and identification of lactic acid bacteria with antimicrobial properties from fermented food products

Goh Hweh Fen, . and Koshy Philip, . (2011) Isolation and identification of lactic acid bacteria with antimicrobial properties from fermented food products. [Proceedings Paper]

Lactic acid bacteria LAB are Generally Recognized as Safe GRAS microorganisms that play an important role in the fermentation of animal and vegetable substrates. They may produce antimicrobial peptides that have high and promising potential to inhibit the growth of spoilage pathogenic bacteria. The objectives of this study were to isolate and identify LAB from Yakult Vitagen yoghurt tempeh and chili paste and determine the antimicrobial properties of the LAB. De Man Rogosa and Sharpe MRS agar was used for its isolation. The isolated bacteria were picked and cultured to obtain pure colonies. The colonies were identified using Gram stain spore stain catalase oxidase and triple sugar iron tests. All the bacteria isolated were Gram positive catalase and oxidase negative. Nineteen isolates showed the same results for triple sugar iron test. The isolates were then tested using antimicrobial assays namely well diffusion minimal inhibitory concentration MIC and minimal bactericidal concentration MBC. From the 23 isolates 6 isolates displayed antibacterial activity against Staphylococcus aureus Escherichia coli Bacillus cereus and Pseudomonas sp. The lowest MIC obtained was 8.2 log CFU mr. Inhibitions obtained in all six isolates were bacteriostatic. These six isolates were assayed for antibacterial compounds synthesized against test microorganisms by extracting the peptides from the supernatant and then checked with reverse-phase high-performance liquid chromatography RP-HPLC. Peaks obtained showed that there were peptides present in the cell-free supernatant. Rep-PCR divided the isolates with antimicrobial properties into 2 groups and 16S rRNA gene sequencing identified them as Staphylococcus warneri and Lactobacillus paracasei.

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Abstract

Lactic acid bacteria LAB are Generally Recognized as Safe GRAS microorganisms that play an important role in the fermentation of animal and vegetable substrates. They may produce antimicrobial peptides that have high and promising potential to inhibit the growth of spoilage pathogenic bacteria. The objectives of this study were to isolate and identify LAB from Yakult Vitagen yoghurt tempeh and chili paste and determine the antimicrobial properties of the LAB. De Man Rogosa and Sharpe MRS agar was used for its isolation. The isolated bacteria were picked and cultured to obtain pure colonies. The colonies were identified using Gram stain spore stain catalase oxidase and triple sugar iron tests. All the bacteria isolated were Gram positive catalase and oxidase negative. Nineteen isolates showed the same results for triple sugar iron test. The isolates were then tested using antimicrobial assays namely well diffusion minimal inhibitory concentration MIC and minimal bactericidal concentration MBC. From the 23 isolates 6 isolates displayed antibacterial activity against Staphylococcus aureus Escherichia coli Bacillus cereus and Pseudomonas sp. The lowest MIC obtained was 8.2 log CFU mr. Inhibitions obtained in all six isolates were bacteriostatic. These six isolates were assayed for antibacterial compounds synthesized against test microorganisms by extracting the peptides from the supernatant and then checked with reverse-phase high-performance liquid chromatography RP-HPLC. Peaks obtained showed that there were peptides present in the cell-free supernatant. Rep-PCR divided the isolates with antimicrobial properties into 2 groups and 16S rRNA gene sequencing identified them as Staphylococcus warneri and Lactobacillus paracasei.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad Universiti Putra Malaysia 43400 UPM Serdang Selangor Malaysia. QR22 M3I61 2011 vol. 1 Call Number.
AGROVOC Term:	Lactic acid bacteria
AGROVOC Term:	Fermented foods
AGROVOC Term:	Isolation
AGROVOC Term:	Identification
AGROVOC Term:	Capsicum annuum
AGROVOC Term:	Tempeh
AGROVOC Term:	Yoghurt
AGROVOC Term:	Staphylococcus aureus
AGROVOC Term:	Escherichia coli
AGROVOC Term:	Bacillus cereus
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:15
URI:	http://webagris.upm.edu.my/id/eprint/13048

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