Screening of Probiotic Activities of Forty-Seven Strains of Lactobacillus spp. by In Vitro Techniques and Evaluation of the Colonization Ability of Five Selected Strains in Humans

Abstract

The probiotic potential of 47 selected strains ofLactobacillus spp. was investigated. The strains were examined for resistance to pH 2.5 and 0.3% oxgall, adhesion to Caco-2 cells, and antimicrobial activities against enteric pathogenic bacteria in model systems. From the results obtained in vitro, five strains,Lactobacillus rhamnosus 19070-2, L. reuteri DSM 12246, L. rhamnosus LGG, L. delbrueckii subsp.lactis CHCC 2329, and L. casei subsp.alactus CHCC 3137, were selected for in vivo studies. The daily consumption by 12 healthy volunteers of two doses of 1010 freeze-dried bacteria of the selected strains for 18 days was followed by a washout period of 17 days. Fecal samples were taken at days 0 and 18 and during the washout period at days 5 and 11.Lactobacillus isolates were initially identified by API 50CHL and internal transcribed spacer PCR, and their identities were confirmed by restriction enzyme analysis in combination with pulsed-field gel electrophoresis. Among the tested strains, L. rhamnosus 19070-2, L. reuteri DSM 12246, and L. rhamnosus LGG were identified most frequently in fecal samples; they were found in 10, 8, and 7 of the 12 samples tested during the intervention period, respectively, whereas reisolations were less frequent in the washout period. The bacteria were reisolated in concentrations from 105 to 108 cells/g of feces. Survival and reisolation of the bacteria in vivo appeared to be linked to pH tolerance, adhesion, and antimicrobial properties in vitro.

Vaginal Lactobacillus gasseri CMUL57 can inhibit herpes simplex type 2 but not Coxsackievirus B4E2

“…Therefore, Vero cells at 80 % of confluency were incubated with 100 µl of tenfold serial dilutions (10 8 CFU/ml to 10 4 CFU/ml) and cultured up to 48 h before measuring cell viability. In addition, the presence of bacteria was measured as previously described (Jacobsen et al 1999). Briefly, a cell suspension containing 10 5 cells in 4-ml complete DMEM medium was transferred to each well of a six-well tissue culture plate.…”

“…The plates were incubated for 2 h at 37 °C in the presence of 5 % CO 2 . The monolayer cells were washed five times with sterile PBS, and the adhesion score was determined by counting the adhered bacteria within 20 random microscopic fields after Giemsa staining (Jacobsen et al 1999). Bacteria were grouped into three categories: nonadhesive (≤40 bacteria), adhesive (41-100 bacteria) and highly adhesive (>100 bacteria).…”

“…The percentages of adhesion were determined by plating MRS agar plate followed by colony counting after 48 h of incubation. The adhered bacteria were harvested together with the eukaryotic cells by trypsination; the mixture was serially diluted and streaked onto MRS agar plates (Jacobsen et al 1999).…”

Scientific Opinion on the substantiation of health claims related toLactobacillus plantarum299 (DSM 6595, 67B) (ID 1078) and decreasing potentially pathogenic intestinal microorganisms pursuant to Article 13(1) of Regulation (EC) No 1924/2006

“…Five references were cited to substantiate the claim. These references were two human studies (Jacobsen et al, 1999;Johansson et al, 1993), two animal studies and one reference quoting an internal report that was not provided.…”

“…The study of Jacobsen et al (1999) evaluated the ability of different lactobacillus strains to survive gastrointestinal transit by detection in faeces; L. plantarum 299, however, was not included in this part of the study. The same study also assessed different properties of L. plantarum 299 in vitro, including its acid and bile resistance, adhesion ability to Caco-2 cells and antimicrobial activity.…”