ANTIMICROBIAL ACTIVITIES AND BACTERIOCINS OF LACTIC ACID BACTERIA ISOLATED FROM NIGERIA INDIGENOUS FERMENTED COWMILK “NUNU”
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Date
2024
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Ceylon Journal of Science
Abstract
Nunu is a nutritious fermented yoghurt-like milk
beverage that can serve as a source of lactic acid bacteria
(LAB) with antimicrobial and bacteriocin potentials. LAB were
isolated from nunu samples using MRS agar and screened for
antimicrobial activity against test organisms. Three LAB, namely
Lactobacillus parafarraginis OCLP1, L. fermentum CSL58
and L. buchneri MZE12 out of a total of 14 isolates produced
antimicrobial activity against Bacillus anthracis CHF-2011-32b,
B. cereus DHM5-1, Providencia vermicola KSVDL-09-71600,
P. rettgeri SIRT3, P. stuartii SILT11 and other test organisms.
Antimicrobial factors were assayed in LAB cell-free extracts
(CFE), neutralized CFE, and ammonium sulphate precipitants of
the CFE, and Lactobacillus parafarraginis OCLP1 demonstrated
the highest activity with zones of inhibition of 20.33±3.51 mm ,
13.33±1.09 mm and 25.33±2.52 mm, respectively. The CFE of
the LAB especially L. parafarraginis OCLP1 demonstrated
wide activity spectra by inhibiting both the Gram-positive and
Gram-negative bacteria tested. Result of plasmid curing of the
LAB indicated that the bacteriocins of L. parafarraginis OCLP1
was plasmid-encoded while the others have their gene clusters
on the chromosome. This study concluded that bacteriocin-
producing LAB can be found in “nunu” and recommend the use
of the isolated LAB as starters in fermented food production after
ensuring their safety through toxicological studies.
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Citation
Fermented milk; Nunu; Lactobacillus; Antimicrobials; Bacteriocins