In Vitro Culture Conditions for Maintaining a Complex Population of Human Gastrointestinal Tract Microbiota

A stable intestinal microbiota is important in maintaining human physiology and health. Although there have been a number of studies using in vitro and in vivo approaches to determine the impact of diet and xenobiotics on intestinal microbiota, there is no consensus for the best in vitro culture conditions for growth of the human gastrointestinal microbiota. To investigate the dynamics and activities of intestinal microbiota, it is important for the culture conditions to support the growth of a wide range of intestinal bacteria and maintain a complex microbial community representative of the human gastrointestinal tract. Here, we compared the bacterial community in three culture media: brain heart infusion broth and high- and low-carbohydrate medium with different growth supplements. The bacterial community was analyzed using denaturing gradient gel electrophoresis (DGGE), pyrosequencing and real-time PCR. Based on the molecular analysis, this study indicated that the 3% fecal inoculum in low-concentration carbohydrate medium with 1% autoclaved fecal supernatant provided enhanced growth conditions to conduct in vitro studies representative of the human intestinal microbiota

Inverse-photoemission measurement of iron oxides on polycrystalline Fe

We measured the inverse-photoemission spectra (IPES) of iron oxides grown on an Fe substrate and calculated the band structure of paramagnetic FeO to analyze the IPES. The band-structure calculation showed some overlap between Fe 3d states and O 2p states in the region of occupied states, and s,p-like states of Fe in the unoccupied region. Isochromatic IPES showed two structures at ∼2.5 and ∼7.5 eV above the Fermi energy. We estimated from the IPES data a full band gap of 2.5 eV for FeO

Optical Properties of Mo

The interband optical conductivity of Mo was calculated using a self-consistent relativistic band structure. Including electric dipole matrix elements, the results are in excellent quantitative agreement with experiment in the 1–6-eV region. The use of nonrelativistic bands and the neglect of the dipole matrix elements each lead to poorer agreement with experiment. The major relativistic effect is the lowering of the s-like bands, not the spin-orbit splitting. k-space searches identified the regions of the Brillouin zone contributing to the three principal structures, which were found to be large volumes of the zone consisting of general points, away from symmetry points or lines

Interpretation of the optical properties of Nb

The interband optical conductivity of Nb was calculated from a self-consistent relativistic band structure. For the optical conductivity, the major relativistic effect is the lowering of the s-like bands relative to the d-like bands, not spin-orbit splitting. k-space searches identified the regions of the Brillouin zone contributing to the principal structures of the optical conductivity. The regions were found to be large volumes of the zone that did not include symmetry points or lines. Along with previous results for Mo, the good agreement between theory and experiment suggests that the effects of the omitted self-energy are small for these two bcc metals