Isolation of probiotic lactobacilli strains harboring l-asparaginase and arginine deiminase genes from human infant feces for their potential application in cancer prevention

The aim of this work was to isolate novel lactobacilli probiotic strains from human feces and screen them for the presence of two valuable antitumor genes—the arginine deiminase-encoding gene arcA and l-asparaginase-encoding gene ansA—for future potential therapeutic application in cancer prevention. Feces samples were collected from Egyptian infants. Forty-two isolates were determined as Lactobacillus sp. and selected for further characterization. Only 20 isolates exhibited good tolerance to pH 1.5, 0.3 % bile salts and moderate tolerance to pancreatic enzymes in addition to antagonistic action. These isolates were screened by PCR for the presence of the arcA and ansA genes. Three strains were selected and identified to subspecies levels by amplification and sequencing of 16S rRNA genes as Lactobacillus gasseri NM112 containing the ansA gene; Lactobacillus fermentum NM212; and Lactobacillus casei NM312 containing the arcA gene, and confirmed by determining enzyme activity. We conclude that these three strains can be suggested as probiotics with potential therapeutic effect against cancer.