Bioengineering of the Enterobacter aerogenes strain for biohydrogen production

Enterobacter aerogenes is one of the most widely-studied model strains for fermentative hydrogen production. To improve the hydrogen yield of E. aerogenes, the bioengineering on a biomolecular level and metabolic network level is of importance. In this review, the fermentative technology of E. aerogenes for hydrogen production will be first briefly summarized. And then the bioengineering of E. aerogenes for the improvement of hydrogen yield will be thoroughly reviewed, including the anaerobic metabolic networks for hydrogen evolution in E. aerogenes, metabolic engineering for improving hydrogen production in E. aerogenes and mixed culture of E. aerogenes with other hydrogen-producing bacteria to enhance the overall yield in anaerobic cultivation. Finally, a perspective on E. aerogenes as a hydrogen producer including systems bioengineering approach for improving the hydrogen yield and application of the engineered E. aerogenes in mixed culture will be presented.     

Synthesis and acrosin inhibitory activities of substituted ethyl 5-(4-aminophenyl)-1H-pyrazole-3-carboxylate derivatives

A series of novel ethyl 5-(4-aminophenyl)-1H-pyrazole-3-carboxylate derivatives were designed and synthesized and their in vitro acrosin inhibitory activities were evaluated. Most of the compounds exhibited acrosin inhibitory activities. Among them, three compounds (5l, 5n, and 5v) were more potent than that of the control TLCK. These provide a new structural type for the development of novel contraceptive acrosin inhibitory agents.     

Genome sequence of Corynebacterium glutamicum S9114, a strain for industrial production of glutamate

Here we report the genome sequence of Corynebacterium glutamicum S9114, an industrial producer widely used in production of glutamate in China. Preliminary comparison with the sequences of the Corynebacterium glutamicum strains ATCC 13032 and R revealed some notable mutagenesis that might be related to the high yield of glutamate.     

Antiasthmatic drugs targeting the cysteinyl leukotriene receptor 1 alleviate central nervous system inflammatory cell infiltration and pathogenesis of experimental autoimmune encephalomyelitis

Cysteinyl leukotrienes (CysLTs) are potent proinflammatory mediators and are considered to play a key role in inflammatory diseases such as asthma. Antagonists targeting the receptor of CysLTs (CysLT1) are currently used as antiasthmatic drugs. CysLTs have also been implicated in other inflammatory reactions. In this study, we report that in experimental autoimmune encephalomyelitis animals, CysLT1 is upregulated in immune tissue and the spinal cord, and CysLT levels in the blood and cerebrospinal fluid are also higher than in normal mice. Two clinically used antiasthma drugs, montelukast and zafirlukast, both targeting CysLT1, effectively block the CNS infiltration of inflammatory cells and thus reduce the incidence, peak severity, and cumulative clinical scores. Further study indicated that CysLT1 signaling does not affect the differentiation of pathogenic T helper cells. It might affect the pathogenesis of experimental autoimmune encephalomyelitis by increasing the secretion of IL-17 from myelin oligodendrocyte glycoprotein-specific T cells, increasing the permeability of the blood-brain barrier and inducing chemotaxis of T cells. These effects can be blocked by CysLT1 antagonists. Our findings indicate that the antiasthmatic drugs against CysLT1 can also be used to treat multiple sclerosis.     

Proline accumulation is inhibitory to Arabidopsis seedlings during heat stress

The effect of proline (Pro) accumulation on heat sensitivity was investigated using transgenic Arabidopsis (Arabidopsis thaliana) plants ectopically expressing the Δ(1)-pyrroline-5-carboxylate synthetase 1 gene (AtP5CS1) under the control of a heat shock protein 17.6II gene promoter. During heat stress, the heat-inducible expression of the AtP5CS1 transgene was capable of enhancing Pro biosynthesis. Twelve-day-old seedlings were first treated with heat at 37 °C for 24 h to induce Pro and then were stressed at 50 °C for 4 h. After recovery at 22 °C for 96 h, the growth of Pro-overproducing plants was significantly more inhibited than that of control plants that do not accumulate Pro, manifested by lower survival rate, higher ion leakage, higher reactive oxygen species (ROS) and malondialdehyde levels, and increased activity of the Pro/P5C cycle. The activities of antioxidant enzymes superoxide dismutase, guaiacol peroxidase, and catalase, but not those of glutathione reductase and ascorbate peroxidase, increased in all lines after heat treatment, but the increase was more significant in Pro-overproducing seedlings. Staining with MitoSox-Red, reported for being able to specifically detect superoxide formed in mitochondria, showed that Pro accumulation during heat stress resulted in elevated levels of ROS in mitochondria. Interestingly, exogenous abscisic acid (ABA) and ethylene were found to partially rescue the heat-sensitive phenotype of Pro-overproducing seedlings. Measurement of ethylene and ABA levels further confirmed that these two hormones are negatively affected in Pro-overproducing seedlings during heat stress. Our results indicated that Pro accumulation under heat stress decreases the thermotolerance, probably by increased ROS production via the Pro/P5C cycle and inhibition of ABA and ethylene biosynthesis.     

Biological activity exhibited by secondary metabolites of the Albizia julibrissin Durazz. pod

In present work, the chemical composition of the petroleum ether extract (PE) and the ethyl ether extract (ETE) of Albizia julibrissin Durazz Pod and their biological activity were investigated, and the biodegradation relationship between with these chemical composition were discussed. The components of the two extracts were identified by GC and by GC-MS. ETE showed a higher level of antimicrobial activity than PE, which were judged by the disc diffusion method of determination of the minimal inhibitory concentration and the minimal bactericidal concentration. The antioxidant properties of the extracts were evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the auto-oxidation of pyrogallol test, and compared with those of the butylated hydroxytoluene (BHT). The results showed that the antioxidant activity of ETE was higher than that of PE (p < 0.01) and lower than that of BHT (p > 0.01) in the DPPH radical scavenging assay. However, in the auto-oxidation of pyrogallol test, the antioxidant activity of PE was higher than that of ETE (p < 0.01) and lower than that of BHT (p < 0.01). Because components of the A. julibrissin pod were found to have biological activity, the pod has a potential use against industrially troublesome microorganisms as a natural source of raw material for the preparation of an antioxidant and a biocide.     

Post-conditioning protects rat cardiomyocytes via PKCepsilon-mediated calcium-sensing receptors

Protein kinase C (PKC) plays a role in cardioprotection through reduction of intracellular Ca(2+) concentration [Ca(2+)](i) during ischemic preconditioning (IPC). Cardioprotection against ischemic post-conditioning (PC) could be associated with reduced [Ca(2+)](i) through PKC. The calcium-sensing receptor (CaR), G protein-coupled receptor, causes accumulation of inositol phosphate (IP) to increase the release of intracellular Ca(2+). However, this phenomenon can be negatively regulated by PKC through phosphorylation of Thr-888 of the CaR. This study tested the hypothesis that the prevention of cardiomyocyte damage by PC is associated with [Ca(2+)](i) reduction through an interaction of PKC with the CaR. Isolated rat hearts were subjected to 40min of ischemia followed by 90min of reperfusion. The hearts were post-conditioned after the 40min of ischemia by three cycles of 30s of reperfusion and 30s of re-ischemia applied before the 90min of reperfusion. Immunolocalization of PKCepsilon in the cell membrane was observed with IPC and PC, and in hearts exposed to GdCl(3) during PC. CaR was expressed in cardiac cell membrane and interacted with PKC in IPC, PC, and exposure to GdCl(3) during PC groups. On laser confocal microscopy, intracellular Ca(2+) was significantly decreased with IPC, PC, and exposure to GdCl(3) during PC compared with the I/R and PKC inhibitor groups, and cell structure was better preserved and promoted the recovery of cardiac function after reperfusion in the same groups. These results suggested that PKC is involved in cardioprotection against PC through negative feedback of a CaR-mediated reduction in [Ca(2+)](i).