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

Investigating the biotechnological potential of lactic acid bacteria strains isolated from different Algerian dairy and farm sources

Currently, consumption of spontaneously fermented milks is common in Algeria, making it a feasible source of diverse lactic acid bacteria (LAB) with the potential to be used as adjunct cultures to improve quality and safety of fermented dairy products. In this context, to select eligible indigenous strains which could be applied as bioprotective and/or starter cultures, the present study aimed to characterize the genomic variability, biotechnological potential, and safety of thirty-eight LAB isolated from Algerian dairy and farm sources of western Algeria. The isolates were unequivocally identified by 16S rRNA gene and fingerprint-based methods. The following species were identified: Enterococcus faecium (n = 15), Enterococcus durans (n = 2), Enterococcus hirae (n = 2), Enterococcus lactis (n = 1), Lactiplantibacillus plantarum (n = 6), Lactococcus lactis (n = 4), Levilactobacillus brevis (n = 3), Lacticaseibacillus paracasei (n = 3), Lacticaseibacillus rhamnosus (n = 1), and Pediococcus acidilactici (n = 1). Among the strains, three of them, L. lactis LGMY8, Lb. plantarum LGMY30 and Lb. paracasei LGMY31 were safe and showed some valuable biotechnological properties, such as high acidification, proteolytic activity, EPS production, and inhibition of undesirable bacteria that made them powerful candidates to be used as starter.

In Vitro Anti-staphylococcal and Anti-inflammatory Abilities of Lacticaseibacillus rhamnosus from Infant Gut Microbiota as Potential Probiotic Against Infectious Women Mastitis

Infectious mastitis is the major cause of early weaning, depriving infants of breastfeeding benefits. It is associated with an inflammatory condition of the breast and lowered resistance to infection. Drug administration during lactation often being contra-indicated, it is therefore important to consider safe therapeutic alternatives to antibiotic and anti-inflammatory therapies, such as probiotics. In this study, we investigated in vitro the probiotic potential of thirteen Lacticaseibacillus (formerly Lactobacillus) rhamnosus strains isolated from the gut microbiota of breastfed healthy infants. Strains were assessed for their β-hemolytic activity, their resistance to antibiotics, and their antimicrobial activities against strains of Staphylococcus and Streptococcus, most often involved in women mastitis. Their immunomodulating abilities were also studied using in vitro stimulation of human immune cells. None of the strains exhibited β-hemolytic activity, and all of them were sensitive to ampicillin, penicillin, tetracycline, rifampicin, erythromycin, chloramphenicol, and imipenem but showed resistance to ceftazidime, trimethoprim/sulfamethoxazole, vancomycin, and cefotaxime, reported to be chromosomally encoded and not inducible or transferable. Four L. rhamnosus strains were selected for their large anti-staphylococcal spectrum: L. rhamnosus VR1-5 and L. rhamnosus VR3-1 inhibiting S. aureus, S. epidermis, and S. warneri and L. rhamnosus CB9-2 and L. rhamnosus CB10-5 exerting antagonistic effect against S. aureus and S. epidermis strains. Antimicrobial compounds released in cell-free supernatant showed proteinaceous nature and were thermoresistant. The immune modulatory analysis of the L. rhamnosus strains revealed two strains with significant anti-inflammatory potential, highlighted by strong induction of IL-10 and a weak pro-Th1 cytokine secretion (IL-12 and IFN-γ). L. rhamnosus CB9-2 combined a large anti-staphylococcal activity spectrum and a promising anti-inflammatory profile. This strain, used individually or in a mixture, can be considered as a probiotic candidate for the management of infectious mastitis during lactation.