Direct Synthesis of C4-Acyl Indoles via C-H Acylation.

The direct synthesis of C4-acyl indoles deprived of C2 and C3 substituents has proven to be challenging, with scarce efficient synthetic routes being reported. Herein, we disclose a highly site-selective palladium-catalyzed C-H acylation for the construction of C4-acyl indoles via a Catellani-Lautens cyclization strategy. In addition, we systematically studied the ortho C-H acylation mechanism of iodoaniline through density functional theory (DFT) calculations and combined experimental results to elucidate the principle of high chemoselectivity brought by triazine benzoate as an acylation reagent.

Unique bacterial communities associated with components of an artificial aquarium ecosystem and their possible contributions to nutrient cycling in this microecosystem.

In order to better understand the bacterial distribution characteristics in a whole microecosystem, the bacterial communities in different components of an artificial aquarium (i.e., plants, fishes, sand and water) were characterized using high throughput sequencing of bacterial 16S rRNA genes. Across all samples, 2873 operational taxonomic units were identified and assigned to 771 genera in 36 phyla. In a principle coordinate analysis, samples clustered according to their origin, indicating that bacterial communities from the same component were most similar. Further taxonomic analysis revealed that most dominant genera, even those with the similar functions, were biased to one component: Nitrospira and Rhodobacter were mainly abundant in plant samples; Rhodococcus, Serratia, Ralstonia, Sphingobacterium and Pseudomonas were most common in sand samples; Cetobacterium and Aeromonas dominated fish samples; and Flavobacterium, Alpinimonas and Limnobacter were especially common in water samples. Functional predictions performed by PICRUSt and the dominant genera exhibited that bacteria detected in each component could participate in all nutrient cycles in the aquarium. However, those involved in carbon and nitrogen cycling were most common in plant and fish samples, while phosphate metabolism-related pathways were more abundant in sand and water samples. Moreover, the aquarium plants, in association with their bacterial communities might be the most important component in the aquarium, as indicated by their highest bacterial richness and diversity. This study adds to our understanding on the differences in the microbiome of different components and their possible contributions to nutrient cycling in a self-sustaining aquarium.

An assessment of the genomics, comparative genomics and cellulose degradation potential of Mucilaginibacter polytrichastri strain RG4-7.

In this study, whole genome sequencing and comparative genomic analyses were performed for Mucilaginibacter polytrichastri RG4-7 and its carboxymethyl cellulose degradation potential was assessed. The results showed that the genome of strain RG4-7 was 5.84 Mb and contained 5019 predicted genes, in which a high proportion of strain-specific genes were related to carbohydrate metabolism. The carboxymethyl cellulose (CMC) degradation and cellulase activity tests revealed the strong cellulose degradation ability, CMCase and ß-glucosidase activity in strain RG4-7. Real-time RT-PCR testing of most cellulose degradation related glycoside hydrolase (GH) families showed that GH9 (OKS85969), GH1 (OKS85832), GH3 (OKS89331 and OKS85615) were significantly up-regulated when strain RG4-7 was inoculated with CMC-Na, which suggested that GH9, GH1 and GH3 might determine its cellulose degradation ability. Certainly, further research need to be done to elucidate cellulose degradation mechanisms in strain RG4-7 in order to develop its industrial application value in lignocellulosic biomass degradation and waste management.

Genome mining and motif truncation of glycoside hydrolase family 5 endo-ß-1,4-mannanase encoded by Aspergillus oryzae RIB40 for potential konjac flour hydrolysis or feed additive.

Two novel glycosyl hydrolase family 5 (GH5) ß-mannanases (AoMan5A and AoMan5B) were identified from Aspergillus oryzae RIB40 by genome mining. The AoMan5A contains a predicted family 1 carbohydrate binding module (CBM-1), located at its N-terminal. The AoMan5A, AoMan5B and truncated mutant AoMan5AΔCL (truncating the N-terminal CBM and linker of AoMan5A) were expressed retaining the N-terminus of the native protein in Pichia pastoris GS115 by pPIC9KM. The specific enzyme activity of the purified reAoMan5A, reAoMan5B and reAoMan5AΔCL towards locust bean gum at pH 3.6 and 40°C for 10min, was 8.3, 104.2 and 15.8U/mg, respectively. The temperature properties of the reAoMan5AΔCL were improved by truncating CBM. They can degrade the pretreated konjac flour and produce prebiotics. In addition, they had excellent stability under simulative gastric fluid and simulative prilling process. All these properties make these recombinant ß-mannanases potential additives for use in the food and feed industries.