Entrapment of anaerobic thermophilic and hyperthermophilic marine micro-organisms in a gellan/xanthan matrix.

AIMS: The aims of this study were (i) to develop a protocol for the entrapment of anaerobic (hyper)thermophilic marine micro-organisms; (ii) to test the use of the chosen polymers in a range of physical and chemical conditions and (iii) to validate the method with batch cultures. METHODS AND RESULTS: The best conditions for immobilization were obtained at 80°C with gellan and xanthan gums. After 5-week incubation, beads showed a good resistance to all tested conditions except those simultaneously including high temperature (100°C), low NaCl (<0∙5 mol l(-1) ) and extreme pH (4/8). To confirm the method efficiency, batch cultures with immobilized Thermosipho sp. strain AT1272 and Thermococcus kodakarensis strain KOD1 showed an absence of detrimental effect on cell viability and a good growth within and outside the beads. CONCLUSION: This suggests that entrapment in a gellan-xanthan matrix could be employed for the culture of anaerobic (hyper)thermophilic marine micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: (Hyper)thermophilic marine micro-organisms possess a high biotechnological potential. Generally microbial cells are grown as free-cell cultures. The use of immobilized cells may offer several advantages such as protection against phage attack, high cell biomass and better production rate of desired metabolites.

Antifungal properties of durancins isolated from Enterococcus durans A5-11 and of its synthetic fragments.

The aim of this work was to study the antifungal properties of durancins isolated from Enterococcus durans A5-11 and of their chemically synthesized fragments. Enterococcus durans A5-11 is a lactic acid bacteria strain isolated from traditional Mongolian airag cheese. This strain inhibits the growth of several fungi including Fusarium culmorum, Penicillium roqueforti and Debaryomyces hansenii. It produces two bacteriocins: durancin A5-11a and durancin A5-11b, which have similar antimicrobial properties. The whole durancins A5-11a and A5-11b, as well as their N- and C-terminal fragments were synthesized, and their antifungal properties were studied. C-terminal fragments of both durancins showed stronger antifungal activities than other tested peptides. Treatment of D. hansenii LMSA2.11.003 strain with 2 mmol l(-1) of the synthetic peptides led to the loss of the membrane integrity and to several changes in the ultra-structure of the yeast cells. Chemically synthesized durancins and their synthetic fragments showed different antimicrobial properties from each other. N-terminal peptides show activities against both bacterial and fungal strains tested. C-terminal peptides have specific activities against tested fungal strain and do not show antibacterial activity. However, the C-terminal fragment enhances the activity of the N-terminal fragment in the whole bacteriocins against bacteria.

Comparative study of a new quantitative real-time PCR targeting the xylulose-5-phosphate/fructose-6-phosphate phosphoketolase bifidobacterial gene (xfp) in faecal samples with two fluorescence in situ hybridization methods.

AIMS: To detect and enumerate bifidobacteria in faeces with a new quantitative multiplex real-time PCR (qPCR) method and to compare the results obtained with fluorescence in situ hybridization (FISH) methods. METHODS AND RESULTS: A multiplex qPCR assay was developed, which enabled the enumeration of Bifidobacterium spp. by targeting the bifidobacterial xylulose-5-phosphate/fructose-6-phosphate phosphoketolase gene (xfp) and total bacteria using universal Eub-primers targeting 16S rRNA gene from the domain bacteria. The qPCR assay showed high sensitivity and specificity and a low detection limit of about 2.5 x 10(3) bifidobacterial cells per gram of faeces. The qPCR results were compared with FISH combined with microscopy or flow cytometry (FCM). No statistical differences among bifidobacterial counts averages measured in adult faeces with the three methods were observed. Total bacterial count averages were higher with the FISH method coupled with microscopic analyses compared to FISH with FCM, whereas total cell numbers estimated by qPCR were intermediate between the two FISH methods. CONCLUSIONS: The new qPCR assay was shown to be sensitive, rapid and accurate for enumerating bifidobacteria in faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: This method is a valuable alternative for other molecular methods for detecting faecal bifidobacteria, especially when their counts are below the detection limit of the FISH methods.

Study of the physicochemical and biological stability of pediocin PA-1 in the upper gastrointestinal tract conditions using a dynamic in vitro model.

AIMS: To evaluate the survival of Pediococcus acidilactici UL5 and its ability to produce pediocin PA-1 during transit in an artificial gastrointestinal tract (GIT). To investigate the physicochemical and biological stability of purified pediocin PA-1 under GIT conditions. METHODS AND RESULTS: Skim milk culture of Ped. acidilactici UL5 was fed to a dynamic gastrointestinal (GI) model known as TIM-1, comprising four compartments connected by computer-controlled peristaltic valves and simulating the human stomach, duodenum, jejunum and ileum. This strain tolerated a pH of 2·7 in the gastric compartment, while lower pH reduced its viability. Bile salts in the duodenal compartment brought a further 4-log reduction after 180 min of digestion, while high viable counts (up to 5 × 10(7) CFU ml(-1) fermented milk) of Ped. acidilactici were found in both the jejunal and ileal compartments. Pediococcus acidilactici recovered from all four compartments was able to produce pediocin at the same level as unstressed cells. The activity of the purified pediocin in the gastric compartment was slightly reduced after 90 min of gastric digestion, while no detectable activity was found in the duodenal, jejunal and ileal compartments during 5 h of digestion. HPLC analysis showed partial degradation of the pediocin peptide in the duodenal compartment and massive breakdown in the jejunal and ileal compartments. CONCLUSIONS: Pediococcus acidilactici UL5 showed high resistance to GIT conditions, and its ability to produce pediocin was not affected, suggesting its potential as a probiotic candidate. The physicochemical and biological stability of pediocin was significantly poor under GIT conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Pediococcus acidilactici UL5 appears to be a potential probiotic candidate because its capacity to produce pediocin PA-1 is not affected by the GI conditions as well as the strain shows an acceptable survival rate. Meanwhile, purified pediocin PA-1 losses activity during GIT transit; microcapsules could be used to deliver it to the target site.

Application of denaturing high-performance liquid chromatography (DHPLC) for yeasts identification in red smear cheese surfaces.

AIMS: To evaluate and optimize the use of denaturing high-performance liquid chromatography (DHPLC) for yeasts identification in red smear cheese surfaces. METHODS AND RESULTS: The resolution of DHPLC was first evaluated and optimized using a mixture of PCR amplicons of the internal transcribed spacer 2 (ITS2) region of 19 yeast reference strains representing 18 species that are common in the cheese microbiota. Sixteen of the 18 yeast species could be resolved by combining runs at temperatures of 57.5 and 59 degrees C. Then, DHPLC was used to investigate the yeast microbiota of pasteurized Maroilles, Munster and Livarot cheese surfaces by comparing their peak profiles with our reference yeast database and by collecting/sequencing of peak fractions. Debaryomyces hansenii and Geotrichum candidum for Munster and Maroilles cheeses, and Candida catenulata, Candida intermedia and G. candidum for Livarot cheese were identified using the reference database and collecting/sequencing of peak fractions. CONCLUSIONS: DHPLC technique was found to have good resolution properties and to be useful for investigating the yeast microbiota of red smear cheese surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that DHPLC is applied to study the yeast microbiota of red smear cheese surfaces.

In vitro inhibition activity of different bacteriocin-producing Escherichia coli against Salmonella strains isolated from clinical cases.

AIMS: To compare in vitro the inhibitory activity of four bacteriocin-producing Escherichia coli to a well-characterized panel of Salmonella strains, recently isolated from clinical cases in Switzerland. METHODS AND RESULTS: A panel of 68 nontyphoidal Salmonella strains was characterized by pulsed-field gel electrophoresis analysis and susceptibility to antibiotics. The majority of tested strains were genetically different, with 40% resistant to at least one antibiotic. E. coli Mcc24 showed highest in vitro activity against Salmonella (100%, microcin 24), followed by E. coli L1000 (94%, microcin B17), E. coli 53 (49%, colicin H) and E. coli 52 (21%, colicin G) as revealed using a cross-streak activity assay. CONCLUSIONS: Escherichia coli Mcc24, a genetically modified organism producing microcin 24, and E. coli L1000, a natural strain isolated from human faeces carrying the mcb-operon for microcin B17-production, were the most effective strains in inhibiting in vitro both antibiotic resistant and sensitive Salmonella isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to an increasing prevalence of antibiotic resistant Salmonella strains, alternative strategies to fight these foodborne pathogens are needed. E. coli L1000 appears to be a promising candidate in view of developing biotechnological alternatives to antibiotics against Salmonella infections.

Lactobacilli intra-tracheal administration protects from Pseudomonas aeruginosa pulmonary infection in mice - a proof of concept.

The spreading of antibiotic resistance is a major public health issue, which requires alternative treatments to antibiotics. Lactobacilli have shown abilities to prevent pneumonia in clinical studies when given by oral route, certainly through the gut-lung axis involvement. Rationally, respiratory administration of lactobacilli has been developed and studied in murine model, to prevent from respiratory pathogens. It allows a direct effect of probiotics into the respiratory system. To our knowledge, no study has ever focused on the effect of probiotic intra-respiratory administration to prevent from Pseudomonas aeruginosa (PA) pneumonia, a major respiratory pathogen associated with high morbidity rates. In this study, we evaluated the beneficial activity of three Lactobacillus strains (Lactobacillus fermentum K.C6.3.1E, Lactobacillus zeae Od.76, Lactobacillus paracasei ES.D.88) previously screened by ourselves and known to be particularly efficient in vitro in inhibiting PAO1 virulence factors. Cytotoxic assays in alveolar epithelial cell line A549 were performed, followed by the comparison of two lactobacilli prophylactic protocols (one or two administrations) by intra-tracheal administration in a C57BL/6 murine model of PA pneumonia. A549 cells viability was improved from 23 to 75% when lactobacilli were administered before PAO1 incubation, demonstrating a protective effect (P<0.001). A significant decrease of 2 log of PAO1 was observed 4 h after PAO1 instillation (3×106 cfu/mouse) in both groups receiving lactobacilli (9×106 cfu/mouse) compared to PAO1 group (P<0.05). One single prophylactic administration of lactobacilli significantly decreased the secretion by 50% in bronchoalveolar lavages of interleukin (IL)-6 and tumour necrosis factor-α compared to PAO1. No difference of secretion was observed for the IL-10 secretion, whatever the prophylactic study design. This is the first study highlighting that direct lung administration of Lactobacillus strains protect against PA pneumonia. Next step will be to decipher the mechanisms involved before developing this novel approach for human applications.

Cultivation of an immobilized (hyper)thermophilic marine microbial community in a bioreactor.

Cultivation in a bioreactor of immobilized deep-sea hydrothermal microbial community was tested in order to assess the stability and reactivity of this new system. A community composed of eight hydrothermal strains was entrapped in a polymer matrix that was used to inoculate a continuous culture in a gas-lift bioreactor. The continuous culture was performed for 41 days at successively 60°C, 55°C, 60°C, 85°C and 60°C, at pH 6.5, in anaerobic condition and constant dilution rate. Oxic stress and pH variations were tested at the beginning of the incubation. Despite these detrimental conditions, three strains including two strict anaerobes were maintained in the bioreactor. High cell concentrations (3 × 10(8) cells mL(-1)) and high ATP contents were measured in both liquid fractions and beads. Cloning-sequencing and qPCR revealed that Bacillus sp. dominated at the early stage, and was later replaced by Thermotoga maritima and Thermococcus sp. Acetate, formate and propionate concentrations varied simultaneously in the liquid fractions. These results demonstrate that these immobilized cells were reactive to culture conditions. They were protected inside the beads during the stress period and released in the liquid fraction when conditions were more favorable. This confirms the advantage of immobilization that highlights the resilience capacity of certain hydrothermal microorganisms after a stress period.

Alkane oxidation by a carboxylate-bridged dimanganese(III) complex.

A new manganese(II) oxamato dimer possesing an unprecedented Mn2(mu-O2CR)(mu-OH2...O2CR) core has been synthesised, structurally and magnetically characterised, and used as a catalyst for the oxidation of alkanes to alcohols and ketones by ButO2H and O2 in CH2Cl2 at rt.

Stereoselective synthesis of 4 alpha-hydroxy-8,12-guaianolides from santonin

Hydroxyester 2, easily obtained from santonin (1), has been transformed into 10 alpha-hydroxyguai-3-en-8,12-olide 6, a good intermediate for the synthesis of natural 8,12-guaianolides. Compound 6 was obtained from 2 by photochemical rearrangement of its acetyl derivative 7, stereoselective hydrogenation on Pd/C, reduction, regioselective elimination, hydrolysis, and lactonization. The synthesis of the natural guaianolides 3-5 was carried out in two sequences in which the regioselective elimination of a hydroxyl group at C10 with triflic anhydride or SOCl2 to afford, respectively, the endo or exo double bond on C10 and the regioselective opening of the C3-C4 alpha-epoxide were the key steps.

Isokinetic trunk muscle performance in pre-teens and teens with and without back pain.

OBJECTIVE: To assess with an isokinetic dynamometer the force and endurance of the spinal flexor and extensor muscles in pre-teens or teens aged 11 to 13 and 14 to 16 years with and without low back pain (LBP). METHOD: The control group and the LBP group were homogeneous in terms of age, weight, height and Body Mass Index (BMI). Assessment was carried out with the isokinetic dynamometer Cybex Norm®. The spinal flexors and extensors were explored concentrically at speeds of 60°, 90° and 120°/sec. The parameters chosen were: maximal moment of force (MMF), mean power (MP), total work (TW), F/E ratios (between the flexors and the extensors for the aforesaid parameters). In the LBP groups, clinical information (pain, extensibility of the spinal and sub-pelvic muscles, sports practice) and sagittal radiological data were all measured. RESULTS: While no significant difference in isokinetic performance was found between asymptomatic and LBP children in the 11-to-13-year-old group, the isokinetic performances of the LBP children were influenced positively by BMI value, number of hours of physical activity and radiologic value of the lumbar lordosis. As regards these pre-teens, assessment with an isokinetic dynamometer does not highlight muscle characteristics that might explain LBP occurrence. As regards the 14-to-16-year-old group, muscle strength has been found to be correlated with age. LBP teens were showed to have weaker extensors and stronger flexors than the healthy teens. It is with regard to this age group that assessment with an isokinetic dynamometer clearly yields interesting results. Since we have yet to standardize our evaluation criteria (working speed, number of trials…), it is difficult to compare our results with those reported in the literature. CONCLUSION: This is a preliminary study involving a relatively low number of patients. That said, given the fact that numerous parameters are connected with the age and height of the subjects, assessment with an isokinetic dynamometer can be constructively carried out from the age of 14. In order to further enhance understanding of this phenomenon, a longitudinal and comparative study of a larger group is needed.

Probiotics: a new way to fight bacterial pulmonary infections?

Antibiotics, of which Fleming has identified the first representative, penicillin, in 1928, allowed dramatical improvement of the treatment of patients presenting with infectious diseases. However, once an antibiotic is used, resistance may develop more or less rapidly in some bacteria. It is thus necessary to develop therapeutic alternatives, such as the use of probiotics, defined by the World Health Organization (WHO) as "micro-organisms which, administered live and in adequate amounts, confer a benefit to the health of the host". The scope of these micro-organisms is broad, concerning many areas including that of infectious diseases, especially respiratory infections. We describe the rational use of probiotics in respiratory tract infections and detail the results of various clinical studies describing the use of probiotics in the management of respiratory infections such as nosocomial or community acquired pneumonia, or on specific grounds such as cystic fibrosis. The results are sometimes contradictory, but the therapeutic potential of probiotics seems promising. Implementing research to understand their mechanisms of action is critical to conduct therapeutic tests based on a specific rational for the strains to be used, the dose, as well as the chosen mode and rhythm of administration.

Biodiversity of antifungal lactic acid bacteria isolated from raw milk samples from cow, ewe and goat over one-year period.

Antifungal lactic acid bacteria (ALAB) biodiversity was evaluated in raw milk from ewe, cow and goat over one year period. Lactic acid bacteria were enumerated using 8 semi-selective media, and systematically screened for their antifungal activity against 4 spoilage fungi commonly encountered in dairy products. Depending on the selective medium, between 0.05% (Elliker agar) and 5.5% (LAMVAB agar) screened colonies showed an antifungal activity. The great majority of these active colonies originated from cow (49%) and goat (43%) milks, whereas only 8% were isolated from ewe milk. Penicillium expansum was the most frequently inhibited fungus with 48.5% of colonies active against P. expansum among the 1235 isolated, followed by Mucor plumbeus with 30.6% of active colonies, Kluyveromyces lactis with only 12.1% of active colonies and Pichia anomala with 8.7% of active colonies. In the tested conditions, 94% of the sequenced active colonies belonged to Lactobacillus. Among them, targeted fungal species differed according to the Lactobacillus group, whose presence largely depended on year period and milk origin. The Lb. casei and Lb. reuteri groups, predominantly recovered in summer/fall, were overrepresented in the population targeting M. plumbeus, whereas isolates from the Lb. plantarum group, predominantly recovered in spring, were overrepresented in the population targeting K. lactis, the ones belonging to the Lb. buchneri group, predominantly recovered in spring, were overrepresented in the population targeting P. anomala. Raw milk, especially cow and goat milks from the summer/fall period appeared to be a productive reservoir for antifungal lactobacilli.

7th SOSORT consensus paper: conservative treatment of idiopathic & Scheuermann's kyphosis.

UNLABELLED: : Thoracic hyperkyphosis is a frequent problem and can impact greatly on patient's quality of life during adolescence. This condition can be idiopathic or secondary to Scheuermann disease, a disease disturbing vertebral growth. To date, there is no sound scientific data available on the management of this condition. Some studies discuss the effects of bracing, however no guidelines, protocols or indication's of treatment for this condition were found. The aim of this paper was to develop and verify the consensus on managing thoracic hyperkyphosis patients treated with braces and/or physiotherapy. METHODS: The Delphi process was utilised in four steps gradually modified according to the results of a set of recommendations: we involved the SOSORT Board twice, then all SOSORT members twice, with a Pre-Meeting Questionnaire (PMQ), and during a Consensus Session at the SOSORT Lyon Meeting with a Meeting Questionnaire (MQ). RESULTS: There was an unanimous agreement on the general efficacy of bracing and physiotherapy for this condition. Most experts suggested the use of 4-5 point bracing systems, however there was some controversy with regards to physiotherapeutic aims and modalities. CONCLUSION: The SOSORT panel of experts suggest the use of rigid braces and physiotherapy to correct thoracic hyperkyphosis during adolescence. The evaluation of specific braces and physiotherapy techniques has been recommended.

Extracurricular physical activity participation modifies the association between high TV watching and low bone mass.

OBJECTIVES: To examine whether different sedentary behaviours are associated with the risk of low bone mineral content in adolescents, and if so, whether extracurricular physical-sporting activity influences this association. MATERIALS AND METHODS: A total of 277 adolescents from Zaragoza (168 females and 109 males) aged 13.0-18.5 yr within frame work of the multicentre AVENA study participated in this study. Bone mineral content (BMC), lean mass, and fat mass were measured with DXA. Physical activity and sedentary independent variables: participation in extracurricular physical-sporting activity (PA), h/d of television watching, playing video/computer games during school days and on weekend days and doing homework/studying. They all were assessed by questionnaire. The main outcome was low BMC, as defined by BMC Z-score for age and sex < percentile 10. Logistic regression was used to test the interaction and association of PA and sedentary variables with low BMC, after controlling for confounders like height, maturational status or lean mass. RESULTS: Among the sedentary variables studied, only television watching > or =3 h/d was associated with an increased risk for low BMC in males (OR, 95% CI: 7.01, 1.73 to 28.40), after controlling for sexual maturation. When PA was in the models, television watching was not any longer associated with low BMC, while PA was so (OR, 95% CI: 0.23, 0.09 to 0.55). Involvement in such activity reduced the risk of low bone mass by 76% (P<0.01) independently of body mass, height and fat mass, but not of the lean mass. CONCLUSION: Watching television for 3 or more h/d seems to be associated with an increased risk for low BMC in male adolescents. However, this association is mediated by participation in PA, suggesting that negative consequences of excessive television watching on adolescent bone health could be counteracted by sport participation. Longitudinal data and randomized controlled trials will confirm or contrast our findings.

In vitro inhibition activity of nisin A, nisin Z, pediocin PA-1 and antibiotics against common intestinal bacteria.

AIMS: To evaluate the sensitivity of 21 common intestinal bacteria to six antibiotics and three broad-spectrum bacteriocins (nisins Z and A and pediocin PA-1). METHODS AND RESULTS: Neutralized cell-free culture supernatants containing active bacteriocins, and antibiotics were tested with the agar diffusion test and the disc-diffusion method, respectively. The tested intestinal strains showed high sensitivity to most antibiotics except for streptomycin and oxacillin. Nisins A and Z (8 mug per well) had similar activity spectra and inhibited all Gram-positive intestinal bacteria at different levels (except Streptococcus salivarius), with bifidobacteria (except Bifidobacterium breve and Bif. catenulatum), Collinsella aerofaciens and Eubacterium biforme being the most sensitive strains, but they were not active against Gram-negative bacteria. Surprisingly, none of the tested strains were inhibited by pediocin PA-1 (16 mug per well). CONCLUSION: Pediocin PA-1 which is very active against Listeria spp. and other food pathogens did not inhibit major intestinal species in the human intestine in contrast to both nisins A and Z. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data suggest that pediocin PA-1 has potential to inhibit Listeria within the intestinal microbiota without altering commensal bacteria.

Immobilization of infant fecal microbiota and utilization in an in vitro colonic fermentation model.

Bacteria isolated from infant feces were immobilized in polysaccharide gel beads (2.5% gellan gum, 0.25% xanthan gum) using a two-phase dispersion process. A 52-day continuous culture was carried out in a single-stage chemostat containing precolonized beads and fed with a medium formulated to approximate the composition of infant chyme. Different dilution rates and pH conditions were tested to simulate the proximal (PCS), transverse (TCS), and distal (DCS) colons. Immobilization preserved all nine bacterial groups tested with survival rates between 3 and 56%. After 1 week fermentation, beads were highly colonized with all populations tested (excepted Staphylococcus spp. present in low numbers), which remained stable throughout the 7.5 weeks of fermentation, with variations below 1 log unit. However, free-cell populations in the circulating liquid medium, produced by immobilized cell growth, cell-release activity from gel beads, and free-cell growth, were altered considerably by culture conditions. Compared to the stabilization period, PCS was characterized by a considerable and rapid increase in Bifidobacterium spp. concentrations (7.4 to 9.6 log CFU/mL), whereas Bifidobacterium spp., Lactobacillus spp., and Clostridium spp. concentrations decreased and Staphylococcus spp. and coliforms increased during TCS and DCS. Under pseudo-steady-state conditions, the community structure developed in the chemostat reflected the relative proportions of viable bacterial numbers and metabolites generally encountered in infant feces. This work showed that a complex microbiota such as infant fecal bacteria can be immobilized and used in a continuous in vitro intestinal fermentation model to reproduce the high bacterial concentration and bacterial diversity of the feces inoculum, at least at the genera level, with a high stability during long-term experiment.

Quantification of different Eubacterium spp. in human fecal samples with species-specific 16S rRNA-targeted oligonucleotide probes.

Species-specific 16S rRNA-targeted, Cy3 (indocarbocyanine)-labeled oligonucleotide probes were designed and validated to quantify different Eubacterium species in human fecal samples. Probes were directed at Eubacterium barkeri, E. biforme, E. contortum, E. cylindroides (two probes), E. dolichum, E. hadrum, E. lentum, E. limosum, E. moniliforme, and E. ventriosum. The specificity of the probes was tested with the type strains and a range of common intestinal bacteria. With one exception, none of the probes showed cross-hybridization under stringent conditions. The species-specific probes were applied to fecal samples obtained from 12 healthy volunteers. E. biforme, E. cylindroides, E. hadrum, E. lentum, and E. ventriosum could be determined. All other Eubacterium species for which probes had been designed were under the detection limit of 10(7) cells g (dry weight) of feces(-1). The cell counts obtained are essentially in accordance with the literature data, which are based on colony counts. This shows that whole-cell in situ hybridization with species-specific probes is a valuable tool for the enumeration of Eubacterium species in feces.

Raw potato starch and short-chain fructo-oligosaccharides affect the composition and metabolic activity of rat intestinal microbiota differently depending on the caecocolonic segment involved.

AIMS: In vitro studies have suggested that fructo-oligosaccharides (FOS) and resistant starch (two fermentable non-digestible carbohydrates) display different fermentation kinetics. This study investigated whether these substrates affect the metabolic activity and bacterial composition of the intestinal microflora differently depending on the caecocolonic segment involved. METHODS AND RESULTS: Eighteen rats were fed a low-fibre diet (Basal) or the same diet containing raw potato starch (RPS) (9%) or short-chain FOS (9%) for 14 days. Changes in wet-content weights, bacterial populations and metabolites were investigated in the caecum, proximal and distal colon and faeces. Both substrates exerted a prebiotic effect compared with the Basal diet. However, FOS increased lactic acid-producing bacteria (LAPB) throughout the caecocolon and in faeces, whereas the effect of RPS was limited to the caecum and proximal colon. As compared with RPS, FOS doubled the pool of caecal fermentation products, while the situation was just the opposite distally. This difference was mainly because of the anatomical distribution of lactate, which accumulated in the caecum with FOS and in the distal colon with RPS. Faeces reflected these impacts only partly, showing the prebiotic effect of FOS and the metabolite increase induced by RPS. CONCLUSIONS: This study demonstrates that FOS and RPS exert complementary caecocolonic effects. SIGNIFICANCE AND IMPACT OF THE STUDY: The RPS and FOS combined ingestion could be beneficial by providing health-promoting effects throughout the caecocolon.