Tan , Pei Lei
(2015)
Production Of Bacteriocin Sf By Lactobacillus Gasseri Sf For Use In Dermal Bacterial Infection
And Wound Healing.
PhD thesis, Universiti Sains Malaysia.
Abstract
Enam belas strain Lactobacillus dan Bifidobacterium telah disaring berdasarkan pertumbuhan di dalam susu skim. B. longum 8643, L. plantarum 8943, L. casei 1268, L. fermentum 8312, L. fermentum 8848, dan L. gasseri SF menunjukkan kemandirian yang lebih tinggi (P< 0.05), dan ekstrak extrasel daripada enam strain ini juga mengandungi bioaktif pada konsentrasi yang mampu meningkatkan kesihatan kulit. Di samping itu, protein mentah yang diperolehi daripada ekstrak extrasel juga menunjukkan aktiviti penghambatan yang lebih tinggi (P< 0.05) terhadap pertumbuhan patogen kulit, dan mungkin disebabkan oleh sebatian antimikrob protein. Unsur seperti bakteriosin yang dihasilkan oleh L. gasseri SF menunjukkan aktiviti penghambatan yang lebih tinggi terhadap Enterococcus faecalis FM 2138, dan memenuhi ciri-ciri bakteriosin kelas II, justeru dinamakan sebagai bakteriosin SF. Bakteriosin SF juga didapati stabil haba dengan jisim molekul ketara sebanyak 3.5 kDa. Bakteriosin SF pada kepekatan 10240 AU/mL juga mengurangkan cas negatif pada permukaan sel E. faecalis FM 2138 dengan signifikan (P <0.05), dan seterusnya menyebabkan depolarisasi membran dan pembentukan liang seni, seperti yang ditunjukkan dalam mikrograf elektron.
Sixteen strains of Lactobacillus and Bifidobacterium were screened based on their growth in reconstituted skimmed milk. However, six strains (B. longum 8643, L. plantarum 8943, L. casei 1268, L. fermentum 8312, L. fermentum 8848, and L. gasseri SF) exhibited significantly higher viability (P< 0.05). Extracellular extracts of these strains contained bioactives at concentrations capable of promoting dermal health. Meanwhile, crude protein fractions fractionated from extracellular extracts of all six strains exhibited significantly higher antagonistic activity on skin pathogens, probably due to the production of putative bacteriocins. Putative bacteriocin produced from L. gasseri SF exhibited significantly higher (P< 0.05) antagonistic activity on Enterococcus faecalis FM 2138, and fitted the characteristics of class II bacteriocin and was thus renamed as bacteriocin SF. Bacteriocin SF was found to be heat-stable, with an apparent molecular mass of 3.5 kDa. Bacteriocin SF at a concentration of 10240 AU/mL significantly reduced (P< 0.05) the negative charge on the cellular surface of E. faecalis FM 2138, subsequently leading to membrane depolarization and pore formation, as visible in electron micrographs.
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