Search Result of "Melaku Alemu"

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Characterization of Bacteriocin-Producing Lactic Acid Bacteria Strain N1-33 Isolated from Edible Fermented Bamboo Shoot)

ผู้เขียน:ImgMelaku Alemu, ImgPanthipa Laemkom, ImgKatsumi Doi, ImgSadahiro Ohmomo, ImgMizuo Yajima, Imgดร.สุนีย์ นิธิสินประเสริฐ, รองศาสตราจารย์

สื่อสิ่งพิมพ์:pdf

Abstract

Lactic acid bacteria (LAB) strain N1-33, isolated from edible fermented bamboo shoot, displayed broad spectrum of inhibitory activity against LAB and other Gram-positive food spoilage and pathogenic bacteria. On the basis of its physiological and biochemical properties together with 16S rRNA sequence analysis, N1-33 was identified as Enterococcus faecalis. It was cultivated in MRS broth at 30?C to early stationary growth phase and the resulting cell-free culture supernatant (CS) showed a maximum inhibitory activity of 12800 AU/ml against Lactobacillus sakei subsp. sakei JCM 1157T, with bactericidal mode of action and concomitant cell lysis. The antibacterial activity of the CS was completely destroyed with proteinase K and partially inactivated with pepsin treatments. Moreover, the study on its physicochemical stability indicated that it was heat tolerant up to 121?C and remained bioactive over a pH range of 2-11. Thus, the spectrum of inhibitory activity, sensitivity to proteolytic enzymes and thermostability of the CS clearly suggested that the bioactive substances had proteinaceous structures and hence classified as bacteriocins. The fact that Enterococcus faecalis N1-33 was isolated from edible fermented bamboo shoot together with these desirable physicochemical properties of its bacteriocin-activity and its ability of metabolizing low cost carbohydrates strongly suggested its great potential for use in food biopreservation. This was known to be the first report of the production of bacteriocins from LAB of fermented bamboo shoot.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 040, Issue 2, Apr 06 - Jun 06, Page 486 - 498 |  PDF |  Page 

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ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Screening and Identification of Thermophilic Lactic Acid Bacteria Producing Antibacterial Substances Determined by OMP Analysis)

ผู้เขียน:ImgMelaku Alemu, ImgDamrussiri Kraykaw, ImgSadahiro Ohmomo, Imgดร.สุนีย์ นิธิสินประเสริฐ, รองศาสตราจารย์

สื่อสิ่งพิมพ์:pdf

Abstract

A total of forty-six lactic acid bacteria (LAB) strains were screened for production of antibacterial substances, out of which two strains, JAK-CS7-1 and JAK-M1-3, displayed broad inhibition spectra against Gram-positive and Gram-negative pathogenic bacteria. Based on physiological, biochemical and molecular methods, these two bioactive thermophilic LAB strains were identified as Pediococcus acidilactici. The amounts of lactic and acetic acids produced by these two LAB strains were determined by HPLC method and then used for preparing the organic acid model system performance (OMP). Thus, comparative evaluation of the antibacterial activities of the culture supernatants (CS) and the corresponding OMP, consisting of equivalent acids concentration and similar pH like CS, revealed that the OMP displayed lower activities than the CS. It was found that the antibacterial activities of the CS were greater than the OMP by 50% that could be attributed to the presence of additional antibacterial metabolites in the CS. The results of this study suggested that these two strains of Pediococcus acidilactici appear to contain other bioactive substances in addition to lactic and acetic acids.

Article Info
Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 037, Issue 4, Oct 03 - Dec 03, Page 493 - 505 |  PDF |  Page 

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Researcher

ดร. สุนีย์ นิธิสินประเสริฐ, รองศาสตราจารย์

ที่ทำงาน:ภาควิชาเทคโนโลยีชีวภาพ คณะอุตสาหกรรมเกษตร บางเขน

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