Antibiotic susceptibility and heterogeneity in technological traits of lactobacilli isolated from Algerian goat's milk

Abstract

The objective of this study was to identify and study the heterogeneity of technological traits of lactobacilli from goat's milk of Algeria and to evaluate in vitro their safety aspect. Using API50 CHL system and 16S rDNA sequencing, 51 % of strains were assigned as Lactobacillus plantarum, 34 % as L. pentosus, 7 % as L. rhamnosus and 8 % as L. fermentum. A large variability was noted for the acidifying capacity in skim milk after 6, 12 and 24 h of incubation. All strains expressed aminopeptidase activity against alanine-ρ-NA and leucine-ρ-NA at different levels. All strains were resistant to vancomycin and most of strains showed more susceptibility to β-lactam antibiotic. High susceptibility toward the inhibitors of protein synthesis was also observed. Minimum inhibitory concentrations data obtained revealed that isolates were susceptible to penicillin and chloramphenicol, and resistant to gentamicin and vancomycin. Minimum inhibitory concentrations distribution of other antibiotics showed variability. The analysis of graphical representation of principal component analysis of technological properties of L. plantarum and L. pentosus strains showed diversity among the isolates. Finally, eight L. plantarum (LAM1, LAM3, LAM21, LAM25, LAM35, LF15, LAM34, and LAM35), four L. pentosus (LAM38, LAM39, LF9 and LF16) and two L. rhamnosus (LF3 and LF10) strains, could be good candidates as adjunct culture in dairy product in Algeria.

Keywords: Algeria; Antibiotic susceptibility; Goat’s milk; Heterogeneity; Lactobacilli; Technological properties.

Fig. 1

Acid production of the faster acidifying lactobacilli strains of each species

Fig. 2

Distribution of lactobacilli strains sensitivity toward different antibiotics agents tested by disc diffusion method. Penicillin (a), Ampicillin (b), Amoxicillin (c), Cefotaxime (d), Kanamycin (e), Erythomycin (f), Tetracycline (g), Chloraphenicol (h), Imipinen (i), and Fusidic acid (j)

Fig. 3

Graphical representation of the principal component analysis of the technological properties of L. plantarum strains showing axis F1 versus F2: a factor loading, b factor scor Leu-ρ-NA: L-leucine-ρ -nitroaniline; Ala-ρ-NA: L-alanine-ρ -nitroaniline; ΔpH6: pH variation after 6 h of incubation; ΔpH12: pH variation after 12 h of incubation; ΔpH24 : pH variation after 24 h of incubation; Coag 24 h: coagulation 24 h: coagulation of skim milk after 24 h ofincubation

Fig. 4

Graphical representation of the principal component analysis of the technological properties of L. pentosus strains showing axis F1 versus F2 : (a) factor loading, (b) factor scor Leu-ρ-NA : L-leucine-ρ -nitroaniline; Ala-ρ-NA : L-alanine-ρ -nitroaniline; ΔpH6 : pH variation after 6 h of incubation; ΔpH12 : pH variation after 12 h of incubation; ΔpH24 : pH variation after 24 h of incubation; Coag 24 h : coagulation 24 h : coagulation of skim milk after 24 h ofincubation