ABSTRACT
Breast milk is well known as the abundant source of beneficial bacteria. A new alternative source of human probiotic origin from breast milk is in demand and currently of interest for both the functional food industry and biopharmaceuticals. The aim in this study was to investigate the anticancer and antioxidant efficacies of the new potential probiotics isolated from human breast milk. Three strains of lactic acid bacteria (LAB) have shown their potential probiotic criteria including antimicrobial activity, non-hemolytic property, and survival in acid and bile salt conditions. These strains showed high abilities on cell surface hydrophobicity, auto-aggregation, and co-aggregation. The genera identification by 16S rRNA sequencing and comparison revealed that they were Streptococcus salivarius BP8, S. salivarius BP156, and S. salivarius BP160. The inhibition of liver cancer cells (HepG2) and breast cancer cells (MCF-7) proliferation by these probiotic strains using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was 44.83-59.65 and 29.85-37.16%, respectively. The probiotic action mode was inducted via apoptotic mechanisms since they stimulate the liver and breast cancer cell death through DNA fragmentation and positive morphological changes by acridine orange (AO) and propidium iodide (PI) staining. The antioxidant activity of these probiotics in the form of intact cells, cell free supernatant (CFS), and heat-killed cells was evaluated by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, resulting in the scavenging activity rates of 16.93-25.43, 15.47-28.03, and 13.67-23.0%, respectively. These S. salivarius probiotic strains protected the L929 mouse fibroblasts against oxidative stress with very high survival rates at 94.04-97.77%, which was significantly higher (P < 0.05) than L-ascorbic acid at 75.89-78.67% in the control groups. The results indicated that S. salivarius BP8 and S. salivarius BP160 probiotic strains could be applied as functional foods or new alternative bioprophylactics for treating liver and breast cancers.
ABSTRACT
Fifty-four strains of lactic acid bacteria obtained from fermented dairy milks were investigated for possible use as probiotics and for colon cancer biological products. Five of these strains inhibited growth of eight food-borne pathogens including Helicobacter pylori, Escherichia coli, and Salmonella typhimurium. Three of these strains survived at pH 2.5 and in 0.3% bile salts. Additionally they produced no haemolysis, were resistant to kanamycin and adhered to Caco-2 cells. 16S rRNA gene sequences of probiotic strains indicated that RM11 and RM28 were Enterococcus faecium and Lactobacillus fermentum, respectively. Both the cultured medium and live whole cells from probiotic strains were tested for antiproliferation of colon cancer cells through MTT and Trypan Blue exclusion assays. The probiotic strains of E. faecium RM11 and L. fermentum RM28 also triggered antiproliferation of colon cancer cells at the rates of 21-29%, and 22-29%, respectively. This suggested that both strains could be used as potential probiotics in functional food or for colon cancer biological products.
Subject(s)
Colonic Neoplasms/microbiology , Enterococcus faecium/physiology , Growth Inhibitors/pharmacology , Limosilactobacillus fermentum/physiology , Milk/microbiology , Probiotics/pharmacology , Animals , Bile Acids and Salts/pharmacology , Caco-2 Cells , Cell Survival , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Enterococcus faecium/drug effects , Enterococcus faecium/isolation & purification , Escherichia coli/growth & development , Formazans/metabolism , Growth Inhibitors/toxicity , Helicobacter pylori/growth & development , Hemolysis , Humans , Hydrogen-Ion Concentration , Limosilactobacillus fermentum/drug effects , Limosilactobacillus fermentum/isolation & purification , Probiotics/toxicity , RNA, Ribosomal, 16S/genetics , Salmonella typhimurium/growth & development , Tetrazolium Salts/metabolism , Trypan Blue/metabolismABSTRACT
Five strains of thermotolerant lactic acid bacteria (G 12, G 22, G 35T, G 43 and G 44) isolated from chicken faeces were characterized taxonomically. The strains were facultatively anaerobic, Gram-positive, catalase-negative, non-motile, non-spore-forming rods. They were heterofermentative lactobacilli that produced DL-lactic acid. Growth of the strains occurred at 45 degrees C but not at 15 degrees C. The optimum temperature for growth was 42 degrees C, as determined from the specific growth rate. The highest permissive temperatures for growth were 50 degrees C for strain G35T and 48 degrees C for the other four strains. DNA G+C content of the strains was between 49 and 51 mol%. Complex fatty acid patterns of the strains showed the presence of C14:0, C16:0, sometimes C18:0, C18:1 and C19:0 cyclo in the cell walls. Phylogenetic analysis of the 16S rRNA gene sequences of the five strains placed them in the Lactobacillus caseil Pediococcus group, with Lactobacillus fermentum as their closest relative (about 95% sequence similarity). DNA-DNA hybridization data indicated that the thermotolerant strains were not L. fermentum. Taken together, the findings of this study show that the five strains isolated from chicken faeces represent a novel species within the genus Lactobacillus, for which the name Lactobacillus thermotolerans is proposed (G 35T = DSM 14792T =JCM 11425T).
