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

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. fermentumMCC 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.