The effectiveness of artificial microbial community selection: a conceptual framework and a meta-analysis.

The potential for artificial selection at the community level to improve ecosystem functions has received much attention in applied microbiology. However, we do not yet understand what conditions in general allow for successful artificial community selection. Here we propose six hypotheses about factors that determine the effectiveness of artificial microbial community selection, based on previous studies in this field and those on multilevel selection. In particular, we emphasize selection strategies that increase the variance among communities. We then report a meta-analysis of published artificial microbial community selection experiments. The reported responses to community selection were highly variable among experiments; and the overall effect size was not significantly different from zero. The effectiveness of artificial community selection was greater when there was no migration among communities, and when the number of replicated communities subjected to selection was larger. The meta-analysis also suggests that the success of artificial community selection may be contingent on multiple necessary conditions. We argue that artificial community selection can be a promising approach, and suggest some strategies for improving the performance of artificial community selection programs.

Modification of C-segment of Cfa DnaE split intein for improving clean-in-place in chromatography process.

This research focuses on the construction of an affinity purification system based on Cfa DnaE split intein. Cfa DnaE intein is an artificially constructed intein with the advantages of a fast cleavage reaction and good stability. In a previous study, a purification system that uses Cfa intein as a tag was constructed, the separation of the target protein and the tag during the purification process was completed, and the purity of the purified target protein reached 98.21%. Guided by molecular docking results, we identified flexible regions in the split intein and inserted several glycines into the protein to decrease the stability of the Cfa IC , thereby improving the regenerability of the IN media. Inserting 6 glycines between amino acids 14 and 15 of IC improved the regeneration rate of IC -GFP on the column to approximately 96%.

[Nonlinear optical absorption characteristics of a novel organic material ZnTBP/CA/PhR].

The measurement of optical absorption spectrum in visible light range of a novel organic material Zn-tetrabenzoporphincrotonic acid/phenoxy resin (ZnTBP/CA/PhR) is reported in this paper. The nonlinear absorption property of the sample illuminated by lasers with different wavelengths was studied. And the absorption alteration and kinetic process of the major spectrum bands were observed. The saturation absorption (SA) and reverse saturation absorption (RSA) appeared as the input fluence increased, and re-reverse saturation absorption process of the material was demonstrated in the experiment. These properties occurred in a broad range of visible spectrum. The paper qualitatively analyses the physical mechanism during the whole course. Based on the nonlinear absorption characteristics, we showed some applications in photonics field of ZnTBP/CA/PhR.