Antagonistic activity of probiotic lactobacilli and bifidobacteria against entero- and uropathogens

AIM: To develop in vitro assays for comparing the antagonistic properties and anti-oxidative activity of probiotic Lactobacillus and Bifidobacterium strains against various entero- and urinary pathogens. METHODS AND RESULTS: The antagonistic activity of five probiotic lactobacilli (Lactobacillus rhamnosus GG, Lactobacillus fermentum ME-3, Lactobacillus acidophilus La5, Lactobacillus plantarum 299v and Lactobacillus paracasei 8700:2) and two bifidobacteria (Bifidobacterium lactis Bb12, Bifidobacterium longum 46) against six target pathogens was estimated using different assays (solid and liquid media, anaerobic and microaerobic cultivation) and ranked (low, intermediate and high). Bacterial fermentation products were determined by gas chromatography, and the total anti-oxidative activity of probiotics was measured using linolenic acid test. Pyelonephritic Escherichia coli was highly suppressed by GG and both bifidobacteria strains. Lactobacilli strains 8700:2, 299v and ME-3 were the most effective against Salmonella enterica ssp. enterica in microaerobic while ME-3 and both bifidobacteria expressed high activity against Shigella sonnei in anaerobic milieu. Lact. paracasei, Lact. rhamnosus and Lact. plantarum strains showed intermediate antagonistic activity against Helicobacter pylori under microaerobic conditions on solid media. The highest anti-oxidative activity was characteristic for Lact. fermentum ME-3 (P < 0.05). No efficient antagonist against Clostridium difficile was found. The positive correlations between the pH, lactic acid production and anti-microbial activity for all tested probiotics were assessed. CONCLUSIONS: Developed experimental assays enable to compare the anti-microbial and -oxidative activity of Lactobacillus and/or Bifidobacterium probiotics, which have been claimed to possess the ability of suppressing the growth of various enteric and urinary pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: Screening Lactobacillus and Bifidobacterium sp. strains according to their activity in various environmental conditions could precede the clinical efficacy studies for adjunct treatment with probiotics in cure of different gastrointestinal and urinary tract infections.     

Enzyme production by lactobacilli and the potential link with infective endocarditis

H.J. OAKEY, D.W.S. HARTY AND K.W. KNOX. 1995. Fifty-six strains of lactobacilli were examined for the production of glycosidases and proteases (arylamidases) that could be associated with the ability to grow in vivo and/or be a factor in the pathogenesis of endocarditis. The strains were from seven species, with an emphasis on Lactobacillus rhamnosus and Lact. paracasei subsp. paracasei , both of which have been associated with endocarditis and provided 12 of the 13 strains isolated from cases of the disease. Other species were Lact. acidophilus, Lact. plantarum, Lact. salivarius, Lact. fermentum and Lact. oris.
Commonly expressed glycosidase activities were α-D-galactosidase and β- N -acetyl-D-glucosaminidase followed by β-D-glucosidase and α-L-fucosidase. The combined production of β- N -acetyl-D-glucosaminidase and α-D-galactosidase was a feature of the endocarditis isolates. In contrast, β-D-galactosidase was produced by very few of the strains within species implicated in endocarditis but most of the strains of Lact. salivarius, Lact. fermentum and Lact. oris.
The most commonly produced arylamidases active against substrates employed for testing human blood clotting cascade were activated protein C(Ca)-like, activated factor X(Xa)-like and Hageman factor-like followed by kallikrein-like and chymotrypsin-like enzymes. Kallikrein-like enzyme activity was shown more frequently by strains from species commonly isolated from cases of endocarditis ( Lact. rhamnosus and Lact. paracasei subsp. paracasei ) than from other oral species ( Lact. plantarum, Lact. salivarius, Lact. fermentum and Lact. oris ).
The data indicate that some lactobacilli can produce enzymes that would enable the breakdown of human glycoproteins and the synthesis and lysis of human fibrin clots, characteristics which aid the colonization and survival of bacteria infecting an endocarditis vegetation.     

The normal Lactobacillus flora of healthy human rectal and oral mucosa

The Lactobacillus flora of the rectal and oral mucosa was sampled from 42 healthy volunteers. Species identification was carried out by numerically comparing API 50CH fermentation patterns with type strains, using an S_J-similarity cut-off level of 79%. For the largest groups, identity was further confirmed by DNA-DNA hybridizations against the type strain of the species. Seventeen lactobacilli clusters were defined, of which most were found both on rectal and oral mucosa. The largest taxa were Lactobacillus plantarum , Lact. rhamnosus and Lact. paracasei ssp. paracasei , which were isolated from 52%, 26% and 17% of the individuals, respectively. Most isolates were tested for their capacity to adhere to the human colonic cell line HT-29 in the absence and presence of methyl-α- D -mannoside. Mannose-sensitive adherence to HT-29 cells was encountered in two-thirds of the Lact. plantarum isolates, but infrequently among isolates of other taxa. The results suggest that Lact. plantarum is a major colonizer of the human gastrointestinal mucosa, and that its capacity to adhere to mannose-containing receptors may be of some ecological importance.     

Comparative study on cell envelope-associated proteinases in natural isolates of mesophilic lactobacilli

Lactobacilli isolated from different natural sources were screened for the presence of cell envelope-associated proteinases (Prt⁺ strains). Among them 17 of 75 tested isolates were Prt⁺. All Prt⁺ strains were producers of a serine-type proteinase, since their proteolytic activity was inhibited by phenylmethylsulfonyl fluoride. Most of the natural isolates of mesophilic lactobacilli degraded only β-casein such as Lactobacillus paracasei subsp. paracasei strains BGLI17 and BGLI18 and Lact. rhamnosus BGEN1. Only Lact. divergens BG742 cleaved all three, α-, β- and κ-caseins, even in the presence of Ca²⁺ ions. Total DNA isolated from Lact. paracasei subsp. paracasei strains BGLI17 and BGLI18 hybridized to the lactococcal proteinase gene probes originated from Lactococcus lactis subsp. cremoris Wg2. Hybridization could not be linked to the plasmid DNA, and pulse-field gel electrophoresis analysis suggested that the proteinase genes of these two strains are most probably chromosomally located.     

Diversity and dynamics of lactobacilli populations during ripening of RDO Camembert cheese

The diversity and dynamics of Lactobacillus populations in traditional raw milk Camembert cheese were monitored throughout the manufacturing process in 3 dairies. Culture-dependent analysis was carried out on isolates grown on acidified de Man - Rogosa - Sharpe agar and Lactobacillus anaerobic de Man Rogosa Sharpe agar supplemented with vancomycin and bromocresol green media. The isolates were identified by polymerase chain reaction - temperature gradient gel electrophoresis (PCR-TGGE) and (or) species-specific PCR and (or) sequencing, and Lactobacillus paracasei and Lactobacillus plantarum isolates were characterized by pulsed field gel electrophoresis (PFGE). Milk and cheese were subjected to culture-independent analysis by PCR-TGGE. Presumed lactobacilli were detected by plate counts throughout the ripening process. However, molecular analysis of total DNA and DNA of isolates failed to detect Lactobacillus spp. in certain cases. The dominant species in the 3 dairies was L. paracasei. PFGE analysis revealed 21 different profiles among 39 L. paracasei isolates. Lactobacillus plantarum was the second most isolated species, but it occurred nearly exclusively in one dairy. The other species isolated were Lactobacillus parabuchneri, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus helveticus, a Lactobacillus psittaci/delbrueckii subsp. bulgaricus/gallinarum/crispatus group, Lactobacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, Lactobacillus brevis, Lactobacillus kefiri, and Lactobacillus perolens. Lactobacilli diversity at the strain level was high. Dynamics varied among dairies, and each cheese exhibited a specific picture of species and strains.     

Heat resistance of Lactobacillus spp. isolated from Cheddar cheese

Mesophilic Lactobacillus spp. are the dominant organisms in mature Cheddar cheese. The heat resistance of broth grown cultures of Lactobacillus plantarum DPC1919 at temperatures between 50 and 57.5 degrees C, Lact. plantarum DPC2102 at temperatures between 48 and 56 degrees C and Lact. paracasei DPC2103 at temperatures between 50 and 67.5 degrees C was determined. The z-values for Lact. plantarum DPC1919, Lact. Plantarum DPC2102 and Lact. paracasei DPC2103 were 6.7 degrees C, 6.2 degrees C and 5.3 degrees C, respectively. Lactobacillus paracasei DPC2103 showed evidence of injury and recovery, especially at higher temperatures. Milk grown cultures of strains DPC2102 and DPC2103 showed greater heat resistance than broth grown cultures, tailing of the death curves and a nonlinear z-curve. Of the three strains, Lact. paracasei DPC2103 had the potential to survive pasteurization temperatures, whether grown in milk or broth.     

Temporal temperature gradient gel electrophoresis (TTGE) as a tool for identification of Lactobacillus casei, Lactobacillus paracasei, Lactobacillus zeae and Lactobacillus rhamnosus

AIMS: To develop a tool for rapid and inexpensive identification of the Lactobacillus casei complex. METHODS AND RESULTS: Lactobacillus casei, Lactobacillus paracasei, Lactobacillus zeae and Lactobacillus rhamnosus were identified by PCR-amplification of the segment between the U1 and U2 regions of 16S rDNA (position 8-357, Escherichia coli numbering) and temporal temperature gradient gel electrophoresis (TTGE). Seven tested Lact. paracasei strains were divided into three TTGE-subgroups. CONCLUSION: TTGE successfully distinguished between the closely-related target species. TTGE is also a powerful method for revealing sequence heterogeneities in the 16S rRNA genes. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to rapid and easy performance, TTGE of PCR-amplified 16S rDNA fragments will be useful for the identification of extended numbers of isolates.     

Development of a 16S rDNA-targeted PCR assay for monitoring of Lactobacillus plantarum and Lact. rhamnosus during co-cultivation for production of inoculants for silages

AIMS: This paper reports a simple, rapid approach for the parallel detection of Lactobacillus plantarum and Lact. rhamnosus in co-culture in order to produce an inoculant mixture for silage purposes. METHODS AND RESULTS: The 16S rDNA-targeted PCR primers were established for parallel detection of Lact. plantarum and Lact. rhamnosus in a single multiplex PCR. A protocol for application of these primers in direct PCR as well as colony-direct (CD) PCR was developed. These primers were also applicable for the estimation of the relative amount of each DNA type in mixed probes (semi-quantitative PCR). CONCLUSIONS: The PCR assay presented in this study is a robust, fast and semi-quantitative approach for detection of Lact. plantarum and Lact. rhamnosus in liquid cultures as well as on agar plates. SIGNIFICANCE AND IMPACT OF THE STUDY: This method provides an effective tool for the establishment of a regime for co-cultivation of Lact. plantarum and Lact. rhamnosus. This would enable faster and thus cost-reduced production of ensiling inoculants.     

Differentiation of Lactobacillus isolates from infant faeces by SDS-PAGE and rRNA-targeted oligonucleotide probes

Isolates of lactobacilli from infant faeces phenotypically characterized as Lactobacillus paracasei subsp. paracasei (six strains), Lact. rhamnosus (six strains), Lact. gasseri (three strains), Lact. acidophilus (one strain) and Lact. fermentum/reuteri (three strains) according to recent classification systems were subjected to SDS-PAGE of whole cell proteins and rRNA-targeted oligonucleotide probe hybridization, in order to confirm the phenotypic characterization and elucidate the exact taxonomic position of the three strains that had properties between fermentum and reuteri. Results suggested a good agreement between the phenotypic characterization, SDS-PAGE and rRNA-targeted oligonucleotide probe hybridization for strains of all species except for the Lact. fermentum/reuteri strains. Results obtained by rRNA probes suggested a possible phylogenetic relatedness of the strains to Lact. reuteri. Isolates from infant faeces with interesting probiotic properties could be used as components of fermented milk products.     

Lactobacilli in the intestinal microbiota of Swedish infants

Lactobacillus colonisation was examined in 112 Swedish infants. Faecal samples obtained at 1, 2, 4 and 8 weeks and at 6, 12 and 18 months of age were cultivated quantitatively on Rogosa agar. Lactobacilli were speciated by PCR and typed to the strain level by randomly amplified polymorphic DNA (RAPD). Lactobacilli reached a peak at 6 months when 45% of the infants were colonised. L. rhamnosus and L. gasseri were the most common species in this period. Colonisation by lactobacilli in general (P < 0.01) and L. rhamnosus in particular (P < 0.05) was more common in breast-fed than in weaned infants at 6 months of age. Lactobacillus isolation reached a nadir of 17% by 12 months (P < 0.0001), but increased to 31% by 18 months of age P < 0.05). The food-related species L. paracasei, L. plantarum, L. acidophilus and L. delbrueckii dominated in this second phase. A single strain persisted for at least 3 weeks in 17% of the infants during the first 6 months, most commonly L. rhamnosus. Lactobacillus population counts in colonised infants increased from 10(6.4) cfu/g at 1 week to 10(8.8) cfu/g at 6 months, and then dropped to 10(5.4) cfu/g faeces at 12 months of age. Lactobacillus colonisation was not significantly related to delivery mode, or to presence of siblings or pets in the household. Our results suggest that certain Lactobacillus species, especially L. rhamnosus, thrive in the intestinal flora of breast-fed infants. After weaning they are replaced by other Lactobacillus species of types found in food.     

Probiotic properties of Lactobacillus strains isolated from the feces of breast-fed infants and Taiwanese pickled cabbage

This study assessed potential probiotic Lactobacillus strains isolated from the feces of breast-fed infants and from Taiwanese pickled cabbage for their possible use in probiotic fermented foods by evaluating their (i) in vitro adhesive ability, resistance to biotic stress, resistance to pathogenic bacteria, and production of β-galactosidase; (ii) milk technological properties; and (iii) in vivo adhesive ability, intestinal survival and microbial changes during and after treatment. Five Lactobacillus isolates identified as Lactobacillus reuteri F03, Lactobacillus paracasei F08, Lactobacillus rhamnosus F14, Lactobacillus plantarum C06, and Lactobacillus acidophilus C11 that showed resistance to gastric juice and bile salts were selected for further evaluation of their probiotic properties. All the strains demonstrated the ability to adhere to Caco-2 cells, particularly, strain L. plantarum C06 and L. reuteri F03 showed satisfactory abilities, which were similar to that of the reference strain L. rhamnosus GG. The strains L. paracasei F08 and L. acidophilus C11 had the highest β-galactosidase activity. Most of the strains were resistant to aminoglycosides and vancomycin but sensitive to ampicillin, erythromycin, and penicillin. All the 5 strains elicited antibacterial activity against both Gram-positive (Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus) and -negative (Escherichia coli and Salmonella enterica) pathogens. Moreover, the strains L. reuteri F03, L. paracasei F08, and L. plantarum C06 could grow rapidly in milk without nutrient supplementation and reached 10? cfu/mL after 24 h of fermentation at 37 °C. The viable cell counts of the 3 strains remained above 10? cfu/mL after 21 d of storage at 4 °C. In the animal feeding trial, the number of intestinal lactobacilli increased significantly after administration of milk fermented with the 3 strains, and the counts of fecal coliforms and Clostridium perfringens were markedly reduced. Lactobacillus strains could also survive in the ileal intestinal tissue of the treated rats. Technologically interesting Lactobacillus isolates may be used in the future as probiotic starter cultures for manufacturing novel fermented foods.     

VANCOMYCIN SUSCEPTIBILITY AS AN AID TO THE IDENTIFICATION OF LACTOBACILLI

Forty strains of lactobacilli isolated from probiotic supplements or functional foods, and two clinical isolates, have been identified by API 50 CHL and tested for susceptibility to vancomycin. All the Lactobacillus acidophilus (16) and Lact. delbreuckii (two) strains were sensitive to vancomycin, while all the other strains (mainly Lact. rhamnosus, 15) were resistant. Susceptibility to other antibiotics was not species-specific. Differential susceptibility to vancomycin may be helpful in speciation of lactobacilli.     

Succinate production and citrate catabolism by Cheddar cheese nonstarter lactobacilli

AIMS: To identify strains of Cheddar cheese nonstarter lactobacilli that synthesize succinate from common precursors and characterize the biochemical pathways utilized. METHODS AND RESULTS: Whole cell incubations of Lactobacillus plantarum, Lactobacillus casei, Lactobacillus zeae and Lactobacillus rhamnosus, were used to identify strains that accumulated succinate from citrate, l-lactate, aspartic acid or isocitrate. In vivo 13C-nuclear magnetic resonance spectroscopy (13C-NMR) identified the biochemical pathway involved at pH 7.0, and under conditions more representative of the cheese ripening environment (pH 5.1/4% NaCl/13 degrees C). Enzyme assays on cell-free extracts were used to support the pathway suggested by 13C-NMR. CONCLUSIONS: The Lact. plantarum strains studied synthesize succinate from citrate by the reductive tricarboxylic acid (TCA) cycle at either pH 7.0 or pH 5.1/4% NaCl/13 degrees C. Lactobacillus casei, Lact. zeae and Lact. rhamnosus strains lack one or more enzymatic activities present in this pathway, and do not accumulate succinate from any of the four precursors studied. SIGNIFICANCE AND IMPACT OF THE STUDY: The addition of Lact. plantarum strains to milk during cheese manufacture may increase the accumulation of the flavour enhancer succinate.     

Differentiation of Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus by polymerase chain reaction

Lactobacillus casei, Lact. paracasei and Lact. rhamnosus form a closely related taxonomic group within the heterofermentative lactobacilli. These three species are difficult to differentiate using traditional fermentation profiles. We have developed polymerase chain reaction primers which are specific for each of these species based on differences in the V1 region of the 16S rRNA gene. Sixty-three Lactobacillus isolates from cheese were identified using these primers. The 12 Lact. rhamnosus and 51 Lact. paracasei identified in this way were also differentiated using a randomly amplified polymorphic DNA (RAPD) primer.     

Conjugated linoleic acid conversion by dairy bacteria cultured in MRS broth and buffalo milk

AIMS: To evaluate strains of Lactobacilli, Bifidobacteria and Streptococci for their ability to produce conjugated linoleic acid (CLA) from free linoleic acid (LA). METHODS AND RESULTS: Eight dairy bacteria tolerant to LA were grown in MRS broth containing LA (200 microg ml(-1)) and CLA was assessed. Seven bacteria were able to form CLA after 24 h of incubation, varying percentage conversion between 17% and 36%. Lactobacillus casei, Lactobacillus rhamnosus, Bifidobacterium bifidum and Streptococcus thermophilus showed the highest LA conversion and were inoculated into buffalo milk supplemented with different concentration of LA. The production of CLA at 200 microg ml(-1) of LA was two- or threefold in milk than MRS broth. All evaluated strains were able to produce CLA from high LA levels (1000 microg ml(-1)). CONCLUSIONS: The most tolerant strain to LA was Lact. casei. Lacttobacillus rhamnosus produced the maximum level of CLA at high LA concentrations (800 microg ml(-1)). The selected bacteria may be considered as adjunct cultures to be included on dairy fermented products manufacture. Low concentration of LA must be added to the medium to enhance CLA formation. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of CLA by strains using milks from regional farms as medium offer a possible mechanism to enhance this beneficial compound in dairy products and those the possibility to develop functional foods.     

Growth studies of potentially probiotic lactic acid bacteria in cereal-based substrates

AIMS: The overall growth kinetics of four potentially probiotic strains (Lactobacillus fermentum, Lact. reuteri, Lact. acidophilus and Lact. plantarum) cultured in malt, barley and wheat media were investigated. The objectives were to identify the main factors influencing the growth and metabolic activity of each strain in association with the cereal substrate. METHODS AND RESULTS: All fermentations were performed without pH control. A logistic-type equation, which included a growth inhibition term, was used to describe the experimental data. In the malt medium, all strains attained high maximum cell populations (8.10-10.11 log10 cfu ml(-1), depending on the strain), probably due to the availability of maltose, sucrose, glucose, fructose (approx. 15 g l(-1) total fermentable sugars) and free amino nitrogen (approx. 80 mg l(-1)). The consumption of sugars during the exponential phase (10-12 h) resulted in the accumulation of lactic acid (1.06-1.99 g l(-1)) and acetic acid (0.29-0.59 g l(-1)), which progressively decreased the pH of the medium. Each strain demonstrated a specific preference for one or more sugars. Since small amounts of sugars were consumed by the end of the exponential phase (17-43%), the decisive growth-limiting factor was probably the pH, which at that time ranged between 3.40 and 3.77 for all of the strains. Analysis of the metabolic products confirmed the heterofermentative or homofermentative nature of the strains used, except in the case of Lact. acidophilus which demonstrated a shift towards the heterofermentative pathway. All strains produced acetic acid during the exponential phase, which could be attributed to the presence of oxygen. Lactobacillus plantarum, Lact. reuteri and Lact. fermentum continued to consume the remaining sugars and accumulate metabolic products in the medium, probably due to energy requirements for cell viability, while Lact. acidophilus entered directly into the decline phase. In the barley and wheat media all strains, especially Lact. acidophilus and Lact. reuteri, attained lower maximum cell populations (7.20-9.43 log10 cfu ml(-1)) than in the malt medium. This could be attributed to the low sugar content (3-4 g l(-1) total fermentable sugar for each medium) and the low free amino nitrogen concentration (15.3-26.6 mg l(-1)). In all fermentations, the microbial growth ceased at pH values (3.73-4.88, depending on the strain) lower than those observed for malt fermentations, which suggests that substrate deficiency in sugars and free amino nitrogen contributed to growth limitation. CONCLUSIONS: The malt medium supported the growth of all strains more than barley and wheat media due to its chemical composition, while Lact. plantarum and Lact. fermentum appeared to be less fastidious and more resistant to acidic conditions than Lact. acidophilus and Lact. reuteri. SIGNIFICANCE AND IMPACT OF THE STUDY: Cereals are suitable substrates for the growth of potentially probiotic lactic acid bacteria.     

Antiobesity effect of trans-10,cis-12-conjugated linoleic acid-producing Lactobacillus plantarum PL62 on diet-induced obese mice

AIMS: To observe the antiobesity activity of trans-10,cis-12-conjugated linoleic acid (CLA)-producing lactobacillus in mice. METHODS AND RESULTS: Lactobacillus plantarum PL62, which can grow in the presence of linoleic acid, was selected and studied. The culture supernatant of Lact. plantarum PL62 contained trans-10,cis-12-conjugated linoleic acid (6.4 microg ml(-1)), and the crude enzyme prepared from washed cells produced trans-10,cis-12 CLA (1395 microg mg(-1) protein). Lact. plantarum PL62 reduced the weights of epididymal, inguinal, mesenteric, and perirenal white adipose tissues and significantly reduced the blood levels of total glucose and body weights of mice (P<0.01). CONCLUSIONS: trans-10,cis-12-CLA-producing Lact. plantarum PL62 can exert the same antiobesity activity as trans-10,cis-12-CLA in mice. SIGNIFICANCE AND IMPACT OF THE STUDY: trans-10,cis-12-CLA-producing Lactobacillus can be a replacement for CLA for obesity treatment via the continuous production of trans-10,cis-12-CLA. The results provide a novel opportunity to develop foods with antiobesity activity.     

Assessment of cell surface properties and adhesion potential of selected probiotic strains

Aim:  To evaluate the physicochemical cell surface and adhesive properties of selected probiotic strains for human use.
Methods and Results:  Probiotic strains, Bifidobacterium longum B6, Lactobacillus acidophilus ADH, Lactobacillus paracasei , Lactobacillus rhamnosus GG, Lactobacillus brevis , Lactobacillus casei , Leuconostoc mesenteroides and Pediococcus acidilactici were tested for the physicochemical properties of cell surfaces and the adhesion abilities against foodborne pathogens. Bif .  longum B6 (53·6%) and Lact .  rhamnosus GG (46·5%) showed the highest hydrophobicity, while the least affinity to xylene was observed in Ped .  acidilactici (10·4%). Bifidobacterium longum B6 showed the strongest coaggregation phenotype with Listeria monocytogenes (53·0%), Shigella boydii (42·0%) and Staphylococcus aureus (45·9%). Lactobacillus rhamnosus GG had the strong binding ability to Caco-2 cells and effectively inhibited the adhesion of L .  monocytogenes , Salmonella Typhimurium, Sh .  boydii and Staph .  aureus to Caco-2 cells. The hydrophobicity was highly correlated with coaggregative abilities and competitive inhibition, suggesting a good relationship between in vitro adhesion and in vivo colonization.
Conclusion:  The results suggest that Bif .  longum B6 and Lact .  rhamnosus GG can be candidate probiotics available for human consumption.
Significance and Impact of the Study:  Because the use of probiotic strains has been more concerned with their beneficial effects in the GI tract, it is essential to examine the potential of probiotic strains based on the physicochemical properties in terms of bacterial-binding and adhesion capabilities.     

Evaluation of numerical analyses of RAPD and API 50 CH patterns to differentiate Lactobacillus plantarum, Lact. fermentum, Lact. rhamnosus, Lact. sake, Lact. parabuchneri, Lact. gallinarum, Lact. casei, Weissella minor and related taxa isolated from kocho and tef

AIM: The study was carried out to assess the agreement of API 50 CH fermentation data of food lactobacilli with their RAPD profiles to determine whether the system could be used alone as a reliable taxonomic tool for this genus. METHODS AND RESULTS: API 50 CH, RAPD and DNA:DNA reassociation data for 42 lactobacilli from tef and kocho were compared with 30 type strains. Discrepancies were observed between the three methods in assigning strains of Lactobacillus plantarum, Lact. fermentum, Weissella minor and Lact. gallinarum, and Lact. fermentum, Lact. amylophilus, Lact. casei subsp. pseudoplantarum and Lact. rhamnosus. DNA reassociation data agreed well with RAPD results. CONCLUSIONS: API 50 CH profiles should be complemented with molecular genetic results for effective identification in Lactobacillus. SIGNIFICANCE AND IMPACT OF THE STUDY: The study suggested less dependability of metabolic data alone as an identification tool.     

Fermentation of fructans by epiphytic lactic acid bacteria

A total of 712 strains of lactic acid bacteria isolated from forage grasses were studied for their ability to ferment fructans of phlein- as well as inulin-type. Only 16 strains utilized phlein and eight of these also fermented inulin. They were identified as Lactobacillus paracasei subsp. paracasei, Lact. plantarum, Lact. brevis and Pediococcus pentosaceus . In the species Lact. paracasei subsp. paracasei , all strains gave positive results, whereas the other positive strains possessed unique properties within their own species. In all but two cases (strains of the species Lact. plantarum ), the phlein was more intensively fermented than the inulin, as indicated by a lower pH and a higher lactic acid concentration. On the basis of the outcome of this study it seems worthwhile to inoculate grasses of low sugar content before ensiling with an active strain that can ferment fructans.