Poly-γ-glutamic acid (γ-PGA) is an important multifunctional biopolymer with various applications, for which adenosine triphosphate (ATP) supply plays a vital role in biosynthesis. In this study, the enhancement of γ-PGA production was attempted through various approaches of improving ATP supply in the engineered strains of Bacillus licheniformis. The first approach is to engineer respiration chain branches of B. licheniformis, elimination of cytochrome bd oxidase branch reduced the maintenance coefficient, leading to a 19.27% increase of γ-PGA yield. The second approach is to introduce Vitreoscilla hemoglobin (VHB) into recombinant B. licheniformis, led to a 13.32% increase of γ-PGA yield. In the third approach, the genes purB and adK in ATP-biosynthetic pathway were respectively overexpressed, with the AdK overexpressed strain increased γ-PGA yield by 14.69%. Our study also confirmed that the respiratory nitrate reductase, NarGHIJ, is responsible for the conversion of nitrate to nitrite, and assimilatory nitrate reductase NasBC is for conversion of nitrite to ammonia. Both NarGHIJ and NasBC were positively regulated by the two-component system ResD-ResE, and overexpression of NarG, NasC, and ResD also improved the ATP supply and the consequent γ-PGA yield. Based on the above individual methods, a method of combining the deletion of cydBC gene and overexpression of genes vgB, adK, and resD were used to enhance ATP content of the cells to 3.53 μmol/g of DCW, the mutant WX-BCVAR with this enhancement produced 43.81 g/L of γ-PGA, a 38.64% improvement compared to wild-type strain WX-02. Collectively, our results demonstrate that improving ATP content in B. licheniformis is an efficient strategy to improve γ-PGA production.

Visible light along with 5 mol % eosin B catalyzed the first direct C-H phosphorylation of thiazole derivatives with diarylphosphine oxides by a photoredox process in the absence of an external oxidant. The scope of thiazoles and phosphine oxides was further investigated, as was functional group tolerance. The general and operational simplicity provides a novel metal and oxidant-free alternative for the formation of heteroaryl-P bonds, and only molecular hydrogen is generated as a byproduct.

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We reveal here a direct autoxidative phosphorylation of heteroarenes induced by oxygen under metal-free and solvent-free conditions. This new methodology provides an economical, operationally simple, and environmentally friendly approach toward (Het)C(sp(2))-P formation with medium to excellent yields. Heteroarenes including thiazole and quinoxaline derivatives are applicable under standard conditions, which is testified via a radical mechanism.

A palladium-catalyzed coupling of allenylphosphine oxides with N-tosylhydrazones, leading to phosphinyl [3]­dendralenes, is established. The coupling reaction can be catalyzed by bis­(triphenylphosphine)­palladium chloride with sodium pivalate as a key additive, presumably via π-allyl-Pd-carbene intermediates. This protocol provides an expedient synthesis of unprecedented multisubstituted phosphinyl [3]­dendralenes with a broad substrate diversity and dominant Z-stereoselectivity, depending on the substitution positions. X-ray crystallographic analyses confirm the relative stereochemistry of products and reveal multiple double bonds in a phosphinyl [3]­dendralenes array with a “fanlike” dimensional orientation. Further applications of phosphinyl [3]­dendralenes to intramolecular cyclization and selective oxidation demonstrate the differentiated reactivities of double bonds.