Degradation of naphthalene and pyrene by several biofilm-forming photosynthesis purple bacterial strains

Aromatic hydrocarbons such as naphthalene, pyrene are recalcitrant compounds found in oil contaminated areas including petroleum storage tanks, oil exploiting companies. These components are difficult to be degraded/transformed in the lack of oxygen conditions. Among anaerobic and micro-aerobic microorganisms, photosynthetic purple bacteria are the dominant group. Photosynthetic purple bacteria (PPB) are considered as aquatic organisms which are able to grow in anaerobic conditions by photosynthesis but without oxygen. This bacterial group has flexible metabolic types depending on living conditions, then they are widely distributed in nature. There are numerous publications on planktonic PPB which could use naphthalene and pyrene as carbon and energy sources. However, there is no publication on biofilm formed by PPB to degrade their aromatic compounds. In this research, 4 biofilm-forming PPB strains including DQ41, PY2, PY6 and DG12 were screened and estimated their pyrene and napthalene degradation capacity. These organisms demonstrated high biofilm forming ability. As biofilm types, their utilization efficiencies were upper 79% with the initial concentrations of naphthalene and pyrene of 200 and 250 ppm, respectively. These results may contribute to enlarge the number of biofilm-forming microorganisms to degrade/transform aromatic hydrocarbons in polluted area treatment in Vietnam.

Contribution of low-temperature single-molecule techniques to structural issues of pigment–protein complexes from photosynthetic purple bacteria

As the electronic energies of the chromophores in a pigment–protein complex are imposed by the geometrical structure of the protein, this allows the spectral information obtained to be compared with predictions derived from structural models. Thereby, the single-molecule approach is particularly suited for the elucidation of specific, distinctive spectral features that are key for a particular model structure, and that would not be observable in ensemble-averaged spectra due to the heterogeneity of the biological objects. In this concise review, we illustrate with the example of the light-harvesting complexes from photosynthetic purple bacteria how results from low-temperature single-molecule spectroscopy can be used to discriminate between different structural models. Thereby the low-temperature approach provides two advantages: (i) owing to the negligible photobleaching, very long observation times become possible, and more importantly, (ii) at cryogenic temperatures, vibrational degrees of freedom are frozen out, leading to sharper spectral features and in turn to better resolved spectra.

B800–B850 coherence correlates with energy transfer rates in the LH2 complex of photosynthetic purple bacteria

Delocalization of a model light-harvesting complex is investigated using multipartite measures inspired by quantum information science.