Antimicrobial efficacy of aloe-emodin mediated photodynamic therapy against antibiotic-resistant Pseudomonas aeruginosa in vitro.

Multidrug-resistant Pseudomonas aeruginosa is a common pathogen that causes topical infections following burn injuries. Antimicrobial photodynamic therapy (aPDT) has emerged as a promising approach for treating antibiotic-resistant bacterial infections. The objective of this study was to evaluate the aPDT efficacy of aloe-emodin (AE), which is a photosensitizer extracted from traditional Chinese herbs, on antibiotic-sensitive and antibiotic-resistant P. aeruginosa in vitro. In this study, we confirmed the effectiveness of AE-mediated aPDT against both standard and MDR P. aeruginosa, explored the effects of irradiation time and AE concentration on bacterial survival in AE-mediated aPDT, and observed the structural damage of P. aeruginosa by using transmission electron microscope. Our results showed that neither AE nor light irradiation alone caused cytotoxic effects on P. aeruginosa. However, AE-mediated aPDT effectively inactivated both antibiotic-sensitive and antibiotic-resistant P. aeruginosa. The transmission electron microscope investigation showed that aPDT mediated by AE primarily caused damage to the cytoplasm and cell membrane. Our findings suggest that AE is a photosensitizer in the aPDT of MDR P. aeruginosa-caused topical infections following burn injuries. Future investigations will concentrate on the safety and efficacy of AE-mediated aPDT in animal models and clinical trials.

Efficient production of a novel alkaline cold-active phospholipase C from Aspergillus oryzae by molecular chaperon co-expression for crude oil degumming.

A novel alkaline cold-active phospholipase C (PLC) gene (AoPC) from Aspergillus oryzae was cloned. AoPC exhibited the highest sequence similarity of 32.5% with that of a PLC from Arabidopsis thaliana. The gene was co-expressed in Pichia pastoris with molecular chaperone PDI (protein disulfide isomerases), and the highest PLC activity of 82, 782 U mL-1 was achieved in a 5-L fermentor. The recombinant enzyme (AoPC) was most active at pH 8.0 and 25 °C, respectively, and it was stable over a broad pH range of 4.5-9.0 and up to 40 °C. It is the first fungal alkaline PLC. The application of AoPC (with 25% citric acid, w/w) in oil degumming process significantly reduced the phosphorus of crude soybean oil by 93.3% to a commercially acceptable level (<10 mg kg-1). Therefore, the relatively high yield and excellent properties of AoPC may possess it great potential in crude oil refining industry.

Biochemical characterization of a novel L-asparaginase from Paenibacillus barengoltzii being suitable for acrylamide reduction in potato chips and mooncakes.

A novel L-asparaginase gene (PbAsnase) from Paenibaeillus barengoltzii CAU904 was cloned and expressed in Escherichia coli. The L-asparaginase gene was 1011bp encoding 336 amino acids. Multiple sequence alignment of PbAsnase with other known L-asparaginases revealed that the enzyme showed high similarities with some Rhizobial-type L-asparaginases, sharing the highest identity of 32% with a characterized L-asparaginase from Rhizobium etli CFN 42, suggesting that it should be a novel L-asparaginase. The recombinant L-asparaginase (PbAsnase) was purified to homogeneity and biochemically characterized. The purified enzyme was optimally active at pH 8.5 and 45°C, respectively. It was stable within pH 5.5-10.0 and at temperatures below 55°C. PbAsnase exhibited strict substrate specificity towards L-asparagine (35.2U/mg), with Km and Vmax values of 3.6mM and 162.2µmol/min/mg, respectively, but displayed trace activity towards L-glutamine. Moreover, the application potential of PbAsnase on acrylamide migration in potato chips and mooncakes was evaluated. The pretreatment by PbAsnase significantly decreased the acrylamide contents in potato chips and mooncakes by 86% and 52%, respectively. The unique properties of PbAsnase may make it a good candidate in industries, especially in food safety.

A specific process to purify 2-methyl-D-erythritol-4-phosphate enzymatically converted from D-glyceraldehyde-3-phosphate and pyruvate.

A one-pot enzymatic cascade was established to synthesize MEP, one of the key intermediates in the MEP terpenoid biosynthetic pathway. D-GAP and sodium pyruvate were converted to MEP in a reaction catalyzed by DXP synthase and DXP reductoisomerase (DXR) in the presence of the coenzymes ThPP, NADPH, and Mg2+. The product was then isolated by using a specific two-step purification process and MEP was obtained in a yield of nearly 60% and high purity. Importantly, MEP prepared by this way was totally free from contamination by minor amounts of DXP that was not completely convertible by DXR.

Study of antiepileptic effect of extracts from Acorus tatarinowii Schott.

PURPOSE: To study the antiepileptic properties of extracts from rhizomes of Acorus tatarinowii Schott (ATS). METHODS: The decoction and volatile oil were extracted from rhizomes of ATS by traditional decocting and supercritical CO(2) fluid extraction (SFE-CO(2)) methods. Maximal electroshock (MES), pentylenetetrazol (PTZ) maximal seizure, and prolonged PTZ kindling models were used to test their anticonvulsive properties. The gamma-aminobutyric acid (GABA) immunohistochemical reaction (IR) was used to study GABAergic neuron changes in the PTZ kindling model and the effects of treatment. RESULTS: Both decoction (dose; 10-20 g/kg) and volatile oil (1.25 g/kg) of ATS decreased the convulsive rate significantly in the MES model. Decoction of ATS was shown to be effective in the PTZ model with both decreased convulsive and mortality rates. The volatile oil of ATS failed to prevent seizures in the dose range tested, although prolonged seizure latency and decreased mortality were found at a dose of 1.25 g/kg. In the PTZ kindling model, GABA-IR neurons decreased obviously compared with the normal group. In the groups treated with the decoction and volatile oil, the seizure intensity decreased significantly after treatment. Increased GABA-IR neurons also were found when compared with PTZ kindling controls. Morphologic observation also showed that GABA-IR neuron damage was less severe in the drug-treated groups. CONCLUSIONS: Both decoction and volatile oil extracted from the rhizome of Acorus tatarinowii Schott have anticonvulsive effects. The volatile oil is shown to be less effective for PTZ-induced convulsions. Both extracts can prevent convulsions as well as convulsion-related GABAergic neuron damage in the brain in the prolonged PTZ kindling model.