Lactococcus lactis strain A5 producing nisin-like bacteriocin active against gram positive and negative bacteria
In this study, a Lactic acid bacteria (LAB) strain was isolated on MRS medium from gastrointestinal tissues of Broadhead catfish (Clarias macrocephalus). Out of 50 isolates, 25 isolates were found to be positive on lactose utilization test and was identified to be Gram positive cocci. Using disc...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English English |
| Published: |
Penerbit Universiti Sains Malaysia
2017
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/52458/ http://irep.iium.edu.my/52458/ http://irep.iium.edu.my/52458/7/52458-Lactococcus%20lactis%20strain%20A5%20producing%20nisin-like%20bacteriocin%20active%20against%20gram%20positive.pdf http://irep.iium.edu.my/52458/8/52458-Lactococcus%20lactis%20strain%20A5%20producing%20nisin-like%20bacteriocin%20active%20against%20gram%20positive_SCOPUS.pdf |
| Summary: | In this study, a Lactic acid bacteria (LAB) strain was isolated on MRS medium from gastrointestinal
tissues of Broadhead catfish (Clarias macrocephalus). Out of 50 isolates, 25 isolates were
found to be positive on lactose utilization test and was identified to be Gram positive cocci. Using disc
diffusion methods, one out of 22 isolates, i.e., a strain A5 demonstrated inhibitions against three
indicator organisms; Bacillus cereus, Staphylococcus aureus and Salmonella thyphimurium. Partial 16S
rDNA sequencing identified isolate A5 as a member of Lactococcus lactis, with 100% DNA homology.
Cell free supernatant fluid from Lactococcus lactis A5 showed inhibitory activities against both gram
positive pathogens (Bacillus cereus and Staphylococcus aureus) and gram negative pathogens
(Salmonella thyphimurium). Chloroform precipitated bacteriocin retained antagonistic activities in the
presence of catalase and lysozyme; and was completely inactivated by Proteinase K treatment. The
bacteriocin has a molecular weight of 3.4 kDa, based on SDS-PAGE analysis and the extract was heat
stable at 37°C and 65°C, for 15 minutes. The antibacterial activity was suppressed with the addition of
EDTA but was significantly increased with the addition of SDS, Triton X-100, Tween 20 and Tween 80.
This bacteriocin belongs to class 1 bacteriocin, which was shown to have a nisin-like properties. This
strain can be used as potential probiotics in animal or aquaculture feeding; and the bacteriocin it
produces will be useful in food preservative.
Dalam kajian ini, strain bakteria asid Laktik (LAB) telah dipencilkan pada medium
MRS daripada tisu gastro-intestinal ikan keli Broadhead (Clarias macrocephalus). Daripada
50 isolat, 25 isolat didapati positif pada ujian penggunaan laktosa dan dikenal pasti sebagai
cocci gram positif. Dengan menggunakan kaedah penyebaran cakera, satu daripada 22
isolat, iaitu, strain A5 menunjukkan hambatan terhadap tiga organisma penunjuk; Bacillus
cereus, Staphylococcus aureus dan Salmonella thyphimurium. Susunan seksyen 16S rDNA
dikenal pasti mengasingkan A5 sebagai ahli Lactococcus lactis, dengan 100% homologi
DNA. Cecair supernatan bebas dari Lactococcus lactis A5 menunjukkan aktiviti perencatan
terhadap kedua-dua patogen positif gram (Bacillus cereus dan Staphylococcus aureus)
dan gram negatif patogen (Salmonella thyphimurium). Chloroform precipitated bacteriocin
mengekalkan aktiviti antagonistik di hadapan katalase dan lysozyme; Dan benar-benar tidak
aktif oleh rawatan Proteinase K. Bacteriocin mempunyai berat molekul 3.4 kDa, berdasarkan
analisis SDS-PAGE dan ekstrak adalah haba stabil pada 37 °C dan 65 °C, selama 15 minit.
Aktiviti antibakteria direncat dengan penambahan EDTA tetapi meningkat dengan ketara
dengan penambahan SDS, Triton X-100, Tween 20 dan Tween 80. Bacteriosin ini tergolong
dalam kelas 1 bacteriocin, yang ditunjukkan mempunyai sifat seperti nisin. Strain ini boleh
digunakan sebagai probiotik yang berpotensi dalam pemakanan haiwan atau akuakultur;
dan bacteriosin yang dihasilkan akan berguna dalam pengawet makanan |
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