An organic-solvent-tolerant bacterium strain YP1 producing organic-solvent-stable protease was isolated from crude oil contaminant soil. Strain YP1 was strictly aerobic, motile, gram positive, spore-forming, and rod shaped. The YP1 strain was identified as Bacillus licheniformis using culture system BIOLOG analysis (SIM = 0.62, 16-24h). The 16S rDNA sequence analysis (GenBank accession number EF105377) suggested that strain YP1 was clustered together with B. licheniformis in phylogenetic tree. Based on all the taxonomy,strain YP1 was identified as B. licheniformis. YP1 strain could tolerant organic solvents at different levels, especially it can grow well in the presence of water-miscible solvents dimethylformamide (DMF, logP = -1.0) and dimethylsulphoxide (DMSO, logP = -1.35) at a concentration of 10% [V/V]. Strain YP1 can also tolerant middle concentrations of NaCl and extra alkaline conditions (pHl2). More than 80% of the biomass remained at pH range 10.5-12. However strain YP1 was sensitive to antibiotics such as ampicillin, tetracycline, kanamycin and chloromycetin. The protease production could be enhanced by acetone and repressed by alkanols such as dodecylalcohol and octanol during the fermentation. Compared to trypsin, the YP1 protease had a wider tolerance for organic solvents. YP1 protease tolerated up to at least 11 organic solvents with logP ranging from -1.35 to 5.6 including benzene, toluene, DMSO and DMF etc at 50% (V/V) concentration. Moreover, when solvents such as decane and dodecyl alcohol with log P values above 4.0 were added to the crude protease, the enzyme activity levels were 1.08 and 1.21 times higher than the control respectively. Its high tolerance for water-miscible solvents DMF and DMSO makes it an ideal catalyst for kinetic- and equilibrium-controlled synthesis. This organic solvent stable protease could be used as a biocatalyst for enzymatic synthesis in the presence of organic solvents.
Efficient utilization of lignocellulose is pivotal for economically converting renewable feedstocks into value-added products. Xylose is the second most abundant sugar in lignocellulose, but it is quite challenging to ferment xylose as efficiently as glucose by microorganisms. Here, we investigated the metabolic potential of three xylose catabolic pathways (isomerase, Weimberg, and Dahms pathways) and illustrated the synergetic effect between the isomerase pathway and Weimberg pathway for the synthesis of chemicals derived from 2-ketoglutarate and acetyl-CoA. When using glutaric acid as the target product, employment of such synergetic pathways in combination resulted in an increased glutaric acid titer (602 mg/L) compared with using each pathway alone (104 or 209 mg/L), and this titer even outcompetes that obtained from the glucose catabolic pathway for glutaric acid synthesis (420 mg/L). This work validates a novel and powerful strategy for xylose metabolic utilization to overcome the inefficiency of using a single xylose metabolic pathway for the synthesis of TCA cycle derived chemicals.
Abstract Selective ring opening of the cyclopropyl moiety of binor‐S was accomplished by several methods including acidic hydrolysis, bromination, and bydrobromination. The crystal structure of dibromide adduct 3 was solved by X‐ray diffraction analysis. Debrominations of 3 yielded either 1 or 4a , whereas dehydrobromination yielded a 3‐substituted monobromide 6a . The mechanism of conversion of 3 to 6a is depicted as involving intermediate 7 ; the existence of 7 is supported by the isolation of olefin 8 . Oxidation of alcohol 4c produced ketone 11a which was either oxidized to lactone 12 or transformed to a methylene derivative 11b . Hydroboration of 11b followed by quenching with hydrogen peroxide produced a hydroxymethyl derivative 14 .
Around the world, pansies are one of the most popular garden flowers, but they are generally sensitive to high temperatures, and this limits the practicality of planting them during the warmest days of the year. However, a few pansy germplasms with improved heat tolerance have been discovered or bred, but the mechanisms of their heat resistance are not understood. In this study, we investigated the transcript profiles of a heat-tolerant pansy inbred line, DFM16, in response to high temperatures using RNAseq. Approximately 55.48 Gb of nucleotide data were obtained and assembled into 167,576 unigenes with an average length of 959 bp, of which, 5,708 genes were found to be differentially expressed after heat treatments. Real-time qPCR was performed to validate the expression profiles of the selected genes. Nine metabolic pathways were found to be significantly enriched, in the analysis of the differentially expressed genes. Several potentially interesting genes that encoded putative transcription regulators or key components involving heat shock protein (HSP), heat shock transcription factors (HSF), and antioxidants biosynthesis, were identified. These genes were highlighted to indicate their significance in response to heat stress and will be used as candidate genes to improve pansy heat-tolerance in the future.
The present study aimed to enhance the specific anti-caries immunity induced by DNA prime-protein boost strategy for an A-P fragment of a cell-surface protein antigen of Streptococcus mutans (PAc).BALB/c mice were immunized with DNA prime-protein boost, DNA-DNA or protein-protein regimens by the intranasal route, using combinations of plasmid vector (pCIA-P) that express PAc protein and a pure secretec recombinant PAc protein (rPAc). Then, a gnotobiotic mouse model was constructed 2 weeks after the last immunization, and specific immune responses in vivo and their protection against dental caries were observed.The present study revealed stronger antibody responses in the DNA prime-protein boost group compared to those elicited by either DNA-DNA vaccination or protein-protein vaccination. In particular, PAc-specific antibody concentrations were improved significantly after boosting the pCIA-P DNA-primed mice with rPAc. Moreover, protection against S. mutans challenge was obtained in the mice treated with the DNA prime-protein boost vaccination, as demonstrated by a significant reduction in S. mutans colonization compared to control mice and animals immunized with the DNA-DNA vaccination or protein-protein vaccination.The results obtained in the present study suggest that the intranasal DNA prime-protein boost vaccination regimen is a novel strategy for the practical application of DNA vaccine against dental caries.
Abstract Background: An unexpected dengue outbreak occurred in the Hunan Province in 2018. This is the first dengue outbreak in this area of inland China, and 172 cases were reported. Methods: To verify the causative agent of this outbreak and investigate gene characterization, the structural protein C/prM/E genes of viruses isolated from local residents were sequenced followed by mutation and phylogenetic analysis. The recombination, selection pressure, potential secondary structure and three-dimensional structure analysis were also performed. Results: Phylogenetic analysis revealed that all epidemic strains were classified as the cosmopolitan DENV-2 genotype, closest to the Zhejiang strain (MH010629, 2017) and then Malaysia strain (KJ806803, 2013). Compared with the DENV-2SS, 151 base substitutions were found in 89 sequences of isolates, which resulted in 20 non-synonymous mutations, of which 17 mutations existed among all samples (two in capsid protein, six in prM/M, and nine in envelope proteins). Moreover, amino acid substitutions at 602 th (E322:Q→H) and 670 th (E390: N→S) may enhance virulence of the epidemic strains. One new DNA-binding site and five new protein binding sites were observed. Two polynucleotide-binding sites and seven protein binding sites were lost compared with DENV-2SS. Meanwhile, five changes were found in helix regions. Minor changes were observed in helical transmembrane and disordered regions. The 429 th amino acid of E proteins was switch from histamine (positively charged) to asparagines (neutral) in all 89 isolate strains. No recombination events or positive selection pressure sites were observed. To our knowledge, this study is the first one to analyze the genetic characteristics of epidemic strain in the first dengue outbreak in Hunan Province, inland China. Conclusions: The causative agent is likely to come from Zhejiang Province, a neighbouring Province where dengue fever broke out in 2017. This study may help to understand the intrinsic geographical relatedness of DENV-2 and contributes to further research on pathogenicity and vaccine development.
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