Antimicrobial activity of bacteriocinogenic lactic acid bacteria and the effectiveness of essential oils of Artemisia herba and Ruta montana against ESBL producing Enterobacteriaceae (resistant to antibiotics)

Abstract

Lactic acid bacteria produce a variety of compounds with antimicrobial action, such as organic acids, hydrogen peroxide, diacetyl, and bacteriocins. These molecules play a key role in the bio-preservation of food. This study focuses on the investigation of the antagonistic activity of bacteriocin-producing lactic acid bacteria (LAB) isolated from various types of artisanal cheese (Lactobacillus paracasei, Enterococcus durans, Pediococcus pentosaceus, Enterococcus faecium, Lactococcus lactis subsp. lactis, and Enterococcus durans) against a wide range of Gram-positive and Gram-negative human pathogens, including antibiotic-resistant strains (ESBL) such as E. coli1 (S8E14 Merg), Klebsiella pneumoniae ssp ozaneae (S19 E21 Merg), Raoultella terrigena (S15 E23 milk), Serracia odorefira1 (S43 E9 AS). The results of in vitro antimicrobial assays especially the agar overlay method, has revealed a broad-spectrum of antimicrobial activity produced by the selected strains where the zone of inhibition (ZOI) varied between 10mm and 23mm against Gram positive strains, whereas Gram negative ones varied between 8mm and 36mm.

On the other hand,Artemisia herba and Ruta montana essential oils were obtained by hydro-distillation of aerial parts (leaves) harvested from El Ogla region (Tebessa, Algeria) .Further to our analytic study, a biological trial was carried out with the purpose of assessing the antibacterial properties of both EOs against four Gram-negative bacterial strains using disk diffusion method. The results obtained revealed that the Artemisia herba essential oil exerts a better antimicrobial activity against all tested pathogenic bacteria with a yield of 1.67 %. However, Ruta montana, displayed a weaker yield of 0.8% hence a minimal activity was recorded against the same strains. Consequently, this activity may vary depending on the tested strain along with the applied volatile extract