Optimization and some characteristics of bacteriocin produced by Enterococcus sp. CM9 collected from Mauritanian Camel milk

Abstract

The use of bacteriocin as a bioconservation is very promising in the agri-food industry to substitute the chemical preservatives. The production of bacteriocin by lactic acid bacteria (LAB) depending on various conditions, the purpose of the present work was to assess the effect of some ingredients of medium on the bacteriocin production. Twenty-four strains of LAB of the genera Leuconostoc, Lactobacillus, and Enterococcus, isolated from camel milk, were tested for antibacterial activity and bacteriocin production. Among these strains, three isolates showed bacteriocinogenic activity, two Enterococcus strains (bacteriocin CM9, bacteriocin CM18), and one Leuconostoc strain (bacteriocin CHBK310). The bacteriocin produced by Enterococcus sp CM9 was subject of optimisation study. The modified MRS with nitrogen sources in media containing tryptone, meat extract and yeast extract and with potassium sources in media containing 2% of K2HPO4 allowed higher activity with inhibition zone of 10 mm and this production remained stable at incubation temperatures from 25 to 40°C with an inhibition zone which reached 12 mm at 25°C. The diffusion of this bacteriocin in the neutrality condition, allowed a better evaluation of its inhibitory effect. The activity of the bacteriocin was not affected, neither by acidic or basic pH nor by heat treatments, its activity remaining stable even after 2 weeks at -20 and 4°C. The bacteriocin CM9 belonged to class II, had a molecular weight of 7.6 kDa. These results indicated that the growth and diffusion conditions have a role in the bacteriocin production and its activity.

Growth Ability of Bacteriocinogenic Strains in Milk and Their Bacteriocin Activity Against Cheese Starter Cultures

“…lactis ATCC 11454 was produced more nisin and reached the maximum level (3.6 g/L) when low fat milk was added to MRS and M17 medium at the rate of 25%. Benmouna et al (2018) achieved similar results. While no antimicrobial activity was detected in MRS medium, a clear inhibitory activity was observed after adding milk (25%) and yeast extract (%2.5) in MRS medium for three LAB strains.…”

“…were indicated that L. lactis subsp. lactis ATCC 11454 was produced more nisin and reached the maximum level (3.6 g/L) when low fat milk was added to MRS and M17 medium at the rate of 25% Benmouna et al (2018). achieved similar results.…”

Probiotic potential of Enterococcus strains with multiple enterocin-encoding genes

“…In addition, our previous studies have shown that the inhibitory activity of three strains CM9, CM18, and H3 was due to the production of bacteriocins. This was confirmed using buffered medium and catalase to overcome the inhibitory effects of organic acids and hydrogen peroxide, respectively, and using proteases also completely abolished the activity (Benmouna et al, 2018(Benmouna et al, , 2020.…”

“…The bacterial strains used in this study were Enterococcus sp CM9, Enterococcus sp CM18 and Enterococcus sp H3, and were provided from the Laboratory of Micro-organisms Biology and Biotechnology, University of Oran, Algeria. These strains were previously isolated from camel milk originated from Mauritania and fermented wheat originated from Algeria, and produced bacteriocins (Benmouna et al, 2018(Benmouna et al, , 2020.…”

“…Antibacterial activity of the cell free supernatant (CFS) of Enterococcus strains To prepare CFS, the strains were grown overnight in buffered MRS broth at 30 °C (Benmouna et al, 2018). CFS were collected by centrifugation at 6000 × g for 20 min at 4 °C in a Thermo-Scientific centrifuge and filtered through a sterile 0.22-mm filter (Millipore Corp., Bedford, MA, USA).…”