[Analysis of the probiotic Bifidobacterium and Lactobacillus community in child intestinal flora].

To investigate the distribution of child intestinal flora and the composition of its key probiotics community, study on intestinal flora of 21 Chinese children (age 2 - 5) was conducted, which included bacteria isolation and counting, 16S rDNA sequencing and homology analysis. For identification of the key probiotics such as Bifidobacterium and Lactobacillus in children feces at the species level, the specific primers Im26/Im3 and L159/L677 for PCR amplification of partial 16S rDNA were used. The results show that the composition of child intestinal flora is was relatively stable and almost same to the intestinal flora of the youth (age 20 - 25). Culture-based approaches show that the key probiotic community in feces at the species level was highly different in composition and numbers from individual to individual. B. longum and B. pseudocatenulatum, which are detected at levels of 10(7) CFU/g (wet) in samples and the detection rates are 90.48% and 85.71% respectively, are believed to be major bifidobacterial species in child intestinal microbiota. In addition, B. adolescentis, B. bifidum, B. infantis and B. thermacidophium have also been found. L. mucosae, L. fermentum, L. salivarius, L. ruminis, L. gasseri and L. plantarum are isolated from the stools. L. mucosae (3.68 log10 CFU/g (wet), detection rate 71.43%) and L. fermentum (3.97 log10 CFU/g (wet), detection rate 52.38%) are two dominant species of Lactobacillus. Study on Chinese child intestinal flora, especially on the compositions and numbers of key probiotics in the feces will be very helpful to the development of effective probiotics in future.

Comparison of Different Effects of Chloroacetates on Electron Transports in PS II and in the Reaction Center of Rb. sphaeroides 601.

Chloroacetates displayed different effects on electron transports in the photosynthetic reaction center of purple bacteria (Rb.sphaeroides 601) and in the photosystem II (PS II) of higher plants. Decays of chlorophyII a fluorescence measured after actinic flashes show that chloroacetates inhibit the electron transport from Q(A)(-) to Q(B) (Q(B)(-)) and the equilibrium between Q(A)(-)Q(B) (Q(B)(-)) and Q(A)Q(B)(-) (Q(B)(2-)), acting on electron transport as well as proton transduction. The study on PSII electron transport indicates another inhibition site of chloroacetate at the oxidation side of PSII. Chloroacetates up to 500 mM have no inhibition on the DCPIPH(2) right curved arrow MV electron transport in the RS601's chromatophores. Dissociation constants of OP and trichloroacetates from RS601 reaction center were assessed to be 1.1x10(-3) M and from Dixon curve respectively. The differences on aspects of structures and functions between RS601 reaction center and PS II were discussed.