Aims: To investigate the effects of whey retentate from Bi®dobacteria fermented milk. Methods and Results: The simulator of the human intestinal microbial ecosystem (SHIME) was used. The composition of the microbiota and its metabolic activities were analysed. Changes in the microbial composition became apparent within 15 days of the treatment in the vessels representing the ileum and the large intestine. The whey retentate favoured the growth of endogenous bi®dobacteria and induced a decrease in Bacteroides fragilis and in sul®pho-reducing clostridia, especially Clostridium perfringens. After the administration was stopped, these populations tended to revert to their original levels, except for the streptococci and the staphylococci populations. The treatment also led to an increase in acetic acid, CH 4 and CO 2 production, suggesting overgrowth of some anaerobic bacteria. Ammonium, generally considered as undesirable, declined. Conclusions: The whey retentate clearly altered the microbial community in the SHIME. Signi®cance and Impact of the Study: Whey retentate appears to exert a bene®cial effect on the in vitro gastrointestinal system; these ®ndings warrant con®rmation by in vivo studies.

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An evaluation of the antimicrobial activity of essential oil (EO) and methanol extract (ME) from Algerian L. seeds against microbial strains isolated from the oral cavities of periodontal patients was performed. Twelve Gram-positive bacteria, eleven Gram-negative bacteria and three microscopic fungi strains were isolated and identified. The antimicrobial activities of EO and ME were tested against ,, ,, , sp., , sp., ., sp. and sp.. The total polyphenol and flavonoids contents of ME were higher than those of EO. Thin layer chromatography showed that catechin, gallic acid and quercetin were most likely present in the extracts. Fourier transform infrared spectrometry analysis (FT-IR) indicated the presence of bands from the CO groups of acids, alcohols, phenols, and ethers and the C[bond, double bond]O band of aldehydes. Analysis of the antimicrobial activity of extracts obtained by the microdilution method showed excellent bactericidal activity of the essential oil and moderate efficiency of the ME against all the microbes tested. and sp. were the most sensitive to EO (minimum bactericidal concentration (MBC): 16,500 μg/ml) at 48 h of incubation and, 125,000 μg/ml of ME was the most active against all the microbes tested. However, after18 or 24 h, this efficiency was decreased in some strains. In addition, sp. and were more sensitive to EO than ME during the incubation, while this efficiency was clearly not visible with the agar well method, and most microbes tested presented remarkable resistance to these extracts.

With the emergence of multidrug-resistant organisms, combining medicinal plants with synthetic medicines against resistant bacteria becomes necessary. In this study, Synergism between plants extracts (methanolic extract, essential oils) of Inula viscosa and Anacyclus valentinus and two commonly used antibiotics: gentamycin and oxacillin were investigated on three bacterian strains Escherichia. coli, Bacillus subtilis and Staphylococcus aureus. In the first time, the antibacterial effect of extracts alone was tested against 7 strains by disc diffusion and microdilution methods. The minimum inhibitory concentrations of methanolic extracts ranged between 6.25 and 50mg/ml while that of the essential oils varied between 12.5 and 100µL/mL. The inhibitory concentrations of antibiotics varied between 125 and 31.25 µg/ml. Interactions extracts /antibiotics and extracts/extracts were determined by disc diffusion agar and by checkboard. The results show that the synergistic effect of combinations plant extracts/antibiotics was more important than extracts/extracts.