Probiotic attributes of Lactobacillus fermentum isolated from human feces and dairy products

Abstract

The objective of this study was to characterize native Lactobacillus fermentum isolates for their probiotic attributes. Accordingly, 12 L. fermentum isolates selected from indigenous fermented dairy products and infant fecal samples were evaluated for their probiotic properties by in vitro and PCR methods. The cultures exhibited high tolerance to acid and bile as well as survival in simulated transit fluids (above 70 %). Cell surface hydrophobicity was in the range of 0.55-57.69 % for xylene and 0.45-77.12 % for hexadecane, whereas auto-aggregation ranged between 9 and 62 %. Isolates exhibited efficient binding to mucin and fibronectin, bile salt hydrolase activity, cholesterol assimilation (49-76 %), and radical scavenging activity (37-77 %). The isolates demonstrated antibacterial activity against Listeria monocytogenes Scott A and Micrococcus luteus ATCC 9341. Molecular fingerprinting and identification of the isolates were achieved by PCR with GTG5 as well as 16S rRNA, phenylalanyl-tRNA synthetase alpha subunit (pheS), and RNA polymerase alpha subunit (rpoA) genes. This revealed the genomic diversity of the isolates from the two sources. Gene-specific amplification of probiotic marker genes was attained by PCR-based methods, and resultant products were sequenced. Multiple sequence alignment of the probiotic marker genes using bioinformatics revealed similarity to completely sequenced genomes of L. fermentum CECT 5716 and IFO 3956 with a few variations in mucin-binding protein gene sequences. Isolates designated as L. fermentum MCC 2759 and L. fermentum MCC 2760 showed the best probiotic attributes with high survival in simulated gastrointestinal fluids, in vitro adhesion, cholesterol reduction, and high antioxidative potential. Thus, these cultures could be potential probiotic candidates for application as functional foods.

In vitroadhesion and anti-inflammatory properties of nativeLactobacillus fermentumandLactobacillus delbrueckiispp.

“…Probiotic isolates L. fermentum MCC 2759, L. fermentum MCC 2760 and L. delbrueckii MCC 2775 obtained from infant faeces, curd and breast milk, respectively, were used for this study (Archer and Halami ; Archer et al . ).…”

“…In addition, expression of adhesion and immune markers upon coculture with Caco‐2 cells were monitored via real‐time qPCR. These isolates were previously reported for their probiotic properties in vitro and anti‐inflammatory properties in vivo (Archer and Halami ; Archer et al . ).…”

“…The human microbiome is an integral component of our system majorly colonizing the gastrointestinal tract and functions as a distinct organ influencing vital processes of the body. This discrete niche of microbes comprises largely of beneficial microbiota like lactic acid bacteria (LAB; Archer and Halami ). Shift in the healthy microbial balance due to dietary interventions and excessive use of antibiotics can lead to disease status which can be restored by application of probiotics (Duary et al .…”

“…Lactobacillus fermentum is known to possess inherent resistance to acid and bile conditions, adhesion ability to mucosa, and antibacterial activity besides promoting the immune system (Archer and Halami ). Lactobacillus delbrueckii on the other hand is a pronounced dairy starter culture recently reported for its probiotic traits and immunological effects in vivo (Dos Santos et al .…”

In vivo safety assessment of Lactobacillus fermentum strains, evaluation of their cholesterol‐lowering ability and intestinal microbial modulation

“…Strains of L. fermentum are known to exhibit higher levels of survival in the gastrointestinal tract (GIT) environment (pH tolerance), adhesion to mucosal cell surfaces, antibacterial and antioxidant properties and beneficial effects on the immune system . With all its observed beneficial attributes, L. fermentum was prompted to be a potential probiotic in food formulations …”