Lactic Acid Bacteria Isolated from Fresh Vegetable Products: Potential Probiotic and Postbiotic Characteristics Including Immunomodulatory Effects

Abstract

The ability to perform effectively in the gastrointestinal tract (GIT) is one of the most significant criteria in the selection of potential probiotic bacteria. Thus, the present study aimed to investigate the potential probiotic characteristics of some selected lactic acid bacteria (LAB) isolated from vegetable products. Probiotic characteristics included tolerance to acid and bile, cholesterol-removing ability, bile salt hydrolysis, resistance against lysozyme and antibiotics, production of exopolysaccharides (EPS), antimicrobial and hemolytic activities, and cell surface characteristics (auto-aggregation, co-aggregation, and hydrophobicity). The survival rate of isolates after G120 ranged from 8.0 to 8.6 Log10 CFU/mL. After the intestinal phase (IN-120), the bacterial count ranged from 7.3 to 8.5 Log10 CFU/mL. The bile tolerance rates ranged from 17.8 to 51.1%, 33.6 to 63.9%, and 55.9 to 72.5% for cholic acid, oxgall, and taurocholic acid, respectively. Isolates F1, F8, F23, and F37 were able to reduce cholesterol (>30%) from the broth. The auto-aggregation average rate increased significantly after 24 h for all isolates, while two isolates showed the highest hydrophobicity values. Moreover, isolates had attachment capabilities comparable to those of HT-29 cells, with an average of 8.03 Log10 CFU/mL after 2 h. All isolates were resistant to lysozyme and vancomycin, and 8 out of the 17 selected isolates displayed an ability to produce exopolysaccharides (EPS). Based on 16S rRNA sequencing, LAB isolates were identified as Enterococcus faecium, E. durans, E. lactis, and Pediococcus acidilactici.

Ready-To-Eat Rocket Salads as Potential Reservoir of Bacteria for the Human Microbiome

“…In this study, we focused our attention on lactic acid bacteria (LAB) associated with rocket salad because these microorganisms have been widely demonstrated to possess a wide range of peculiar abilities that can positively impact the gastrointestinal ecosystems of numerous animals (including humans), resulting in significant health benefits to the host at both the local and systemic levels ( 12 ). The phyllosphere of numerous vegetables is a well-known source of LAB ( 27 , 28 ), which have been proposed as promising cultures to be exploited for food preservation and probiotic applications ( 29 – 32 ). In particular, more than 20% of all LAB isolates in our study belonged to Leuconostoc mesenteroides , a species that has been frequently shown to exert probiotic activities in vitro and in vivo ( 29 , 33 – 36 ) and that includes several strains already employed in commercially available probiotic products.…”

Identification of Lactobacillus strains from human mother milk and cottage cheese revealed potential probiotic properties with enzymatic activity

“…Other studies have shown that upon exposure to gastric acid with a pH of 2; a significant reduction in the number of bacteria could be recognized 31,32 . Alameri et al 33 mentioned that; probiotics should possess good resistance toward bile salts in order to survive in the human GIT. Therefore, high survival percentages indicate good bile salt tolerance.…”

In Vitro Characterization and Identification of Potential Probiotic Yeasts Isolated from Fermented Dairy and Non-Dairy Food Products

“…According to Alameri et al [ 31 ], the capability of the selected yeast isolates to remove cholesterol was measured using o -phthalaldehyde at 550 nm. The cholesterol removal (%) was expressed as follows: …”