Probiotic properties of Lactobacillus rhamnosus and Lactobacillus paracasei isolated from human faeces.
BACKGROUND
The possibility of using microbes to maintain health, and to prevent or treat disease is a topic as old as microbiology. The research of novel probiotic strains is important in order to satisfy the increasing request of the market and to obtain functional products in which the probiotic cultures are more active and with better probiotic characteristics than those already present on the market.


OBJECTIVE
In this study, the probiotic potential of Lactobacillus strains isolated from Italian elderly human faeces was investigated.


METHODS
The Lactobacillus strains were identified and examined for resistance to gastric acidity and bile toxicity, adhesion to HT-29 cells, antimicrobial activities, antibiotic susceptibility and plasmid profile. Survival of the strains through human intestine was examined in a 3 months human feeding trial.


RESULTS
Two strains, Lactobacillus rhamnosus IMC 501 and Lactobacillus paracasei IMC 502, tolerated well low pH and bile acids. In antimicrobial activity assays, both strains showed inhibitory properties towards selected potential harmful microorganisms, particularly against Candida albicans. The two selected strains expressed high in vitro adherence to HT-29 cells increasing this characteristic when they are used in combination and they were resistant to vamcomycin, colistin sulphate, gentamicin, oxolinic acid and kanamycin. Moreover, the two strains could be recovered from stools of volunteers after the feeding trials.


CONCLUSIONS
Lactobacillus rhamnosus IMC 501 and L. paracasei IMC 502 present favourable strain-specific properties for their utilisation as probiotics in functional foods and the high adhesion ability of the L. rhamnosus IMC 501 and L. paracasei IMC 502 used in combination, confirmed by both in vitro and in vivo study, indicate that the two bacterial strains could be used as health-promoting bacteria.
Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Università di Camerino, Camerino, Italy.
Maria Cristina
MC
Verdenelli
Francesca
F
Ghelfi
Stefania
S
Silvi
Carla
C
Orpianesi
Cinzia
C
Cecchini
Alberto
A
Cresci
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000898:Antibiosis; D001422:Bacterial Adhesion; D001647:Bile Acids and Salts / Q000502:physiology; D002460:Cell Line; D004847:Epithelial Cells; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa; D007778:Lactobacillus / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D052201:Lacticaseibacillus rhamnosus / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010957:Plasmids / Q000302:isolation & purification; D019936:Probiotics / Q000008:administration & dosage / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013997:Time Factors; D055815:Young Adult
D000900:Anti-Bacterial Agents; D001647:Bile Acids and Salts; D012336:RNA, Ribosomal, 16S