CD Skripsi

Uji Aktivitas Antimikroba Dan Stabilitas Bacteriocin-Like Inhibitory Substances (Blis) Dari Lactococcus Lactis Atcc 11454-Ldhδnisrkox

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Lactic acid bacteria (LAB) are widely used in the fermentation process of various food products such as yogurt, kefir, and cheese. LAB are Gram-positive, catalase- negative, non-spore-forming bacteria that are resistant to low pH. The major end product of LAB metabolism is lactic acid, and other products include organic acids and bacteriocins (nisin), which have antimicrobial properties. Lactococcus lactis ATCC 11454 is a nisin-producing strain. To enhance nisin synthesis, this strain has been genetically engineered through knockout of the lactate dehydrogenase (ldh) gene, resulting in a lactic acid-deficient strain (L. lactis ATCC 11454-ldh∆), followed by overexpression of the nisin regulatory gene (nisRK), resulting in the double mutant strain L. lactis ATCC 11454-ldh∆nisRKox. This strain showed a much higher pH in the fermentation medium (6.0) compared to MRS broth (6.2), which is significantly different from the wild type (4.2). This study aims to identify the antimicrobial activity of nisin/BLIS from L. lactis ATCC 11454-ldh∆nisRKox and to analyze the effects of various pH (acid to base) and temperature (0°C to 121°C) on the antimicrobial activity of nisin/BLIS. The results of the study showed that in the antimicrobial test, the CFS from the double mutant strain L. lactis ATCC 11454-ldh∆nisRKox exhibited broad-spectrum antimicrobial activity, but did not show inhibition against the growth of Candida sp. At storage temperatures, the activity of BLIS was stable with low activity reduction (6%) compared to fresh CFS. Additionally, CFS retained its antimicrobial activity at high temperatures (100 and 121°C); however, the activity decreased by up to 26.3% and 34.4% compared to fresh CFS. The results of the pH stability test showed that compared to fresh CFS (pH 6), CFS from the double mutant was least affected by pH 8, followed by pH 5, 9, and 10. This finding was not in line with the antimicrobial activity of nisin, which is more stable under acidic conditions. This indicates the potential use of nisin and BLIS produced from the engineered strain in various applications, supported by its broader antimicrobial activity spectrum. Further study is needed to identify the conformation of nisin and the identification of BLIS to justify the antimicrobial activity and stability of CFS.

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

1903111011

Penerbit

Pekanbaru : Universitas Riau FMIPA Kimia., 2024

Deskripsi Fisik

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Bahasa

Indonesia

ISBN/ISSN

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Klasifikasi

1903111011

Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

KIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

mardiah

Versi lain/terkait

Lampiran Berkas

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