مشروع البحث: Effect of bacteriocin produced by lactic acid bacteria isolated from fermented milk collected in Zintan city on bacterial growth in milk
تحميل...
المساهمين
الممولين
رقم التعريف
1-2
الباحث
ريما امحمد العابد
الوصف
With the increasing global tendency towards reducing dependence on chemical preservatives in the food industry, there is a growing demand for natural and safe alternatives that ensure food safety and quality without harming consumer health. Bacteriocins, produced by lactic acid bacteria, are key biopreservation agents that inhibit harmful microorganisms and help extend food shelf life while maintaining nutritional and sensory properties.
The study analyzed traditional fermented milk from Zintan to isolate lactic acid bacteria producing bacteriocins and tested their activity against Staphylococcus aureus, a key pathogen and food contaminant.
A total of 160 microbial isolates were obtained, and after excluding those not matching lactic acid bacteria traits, 146 remained. These isolates underwent cultural, microscopic, and biochemical characterization. They were gram-positive, spherical and rod-shaped, arranged in pairs or short chains. Catalase and oxidase tests were negative, with clear ability to ferment glucose and fructose. Only three isolates inhibited Staphylococcus aureus, one weakly (<8 mm), and none affected Escherichia coli. Isolates were identified as Enterococcus faecium and Lactococcus lactis, showing inhibition zones of 12.33 mm and 13 mm, indicating effective bacteriocin production.
With the aim of evaluating the practical application of these compounds, their effect on the growth of bacteria in pasteried milk stored at 4°C for three days was studied. Untreated milk showed continuous colony increase, while bacteriocin-treated samples had significant reductions (p<0.05). The strongest effect appeared on the second and third days. Dual treatment (nisin + enterocin) was most effective, recording the lowest colony count (0.33 ± 0.33).
The study highlights locally produced bacteria improving dairy safety and enabling natural biopreservation. It also stresses exploring microbial diversity to reduce reliance on additives.
الكلمات الدالة
Effect of bacteriocin produced by lactic acid bacteria isolated from fermented milk collected in Zintan city on bacterial growth in milk