Advanced Materials Research Vols. 343-344

Abstract: Metallothionein (MT) is one kind of proteins induced in organism under the stress of heavy metal. It plays a great pole in detoxification and tolerance of heavy metal. In this study, according to the rich conservative sequence in MT, we designed corresponding primer, then cloned MT mRNA gene induced by As in earthworm E. andrei and got its nucleotide sequence. The results proved the presence of MT in Eisenia andrei, and showed that roxarsone could induce the expression of arsenic MT gene.

Abstract: Former studies and application of vermifiltration process to organic wastewater treatment has given an affirmative effect for the pollutant removal in wastewater. It could be used for the disperse wastewater treatment, especially for rural living sewage. We developed a new multilayer vermifiltration system in this study, expecting to enhance this ability for the disposal of rural living sewage. The result showed that all the COD, BOD₅ and SS values in outflow after vermifiltration could meet GB18918-2002. The removal rates of COD，BOD₅ and SS were above 75%, 85% and 90% respectively. The N and P could be partly removed. These preliminary results give a positive prospective for the application of multilayer vermifiltration in rural sewage treatment in the future.

Abstract: We investigated the oxidative stress of methamidophos on Mytilus edulis. Sublethal concentrations of methamidophos (5.0, 10.0 and 15.0 μg L^-1) were administered to M. edulis for 5, 15 and 30 days respectively. The biochemical stress response of M. edulis was studied taking into account acetylcholinesterase (AChE), Na⁺-K⁺-adenosine triphosphatase (Na⁺-K⁺-ATPase) and some antioxidant enzyme activities. Protein contents in tissues was also measured. With the increase of methamidophos concentrations the activities of AChE and Na⁺-K⁺-ATPase in tissues decreased, whereas the activities of GPx, SOD and CAT increased. The protein content in tissues decreased after 5 days and then gradually increased until the 15th day of the experiment. On the 30th day, the protein level in organism was observed to have reached to that of the control group. It can be stated that methamidophos exerted its effect even at low concentration , its toxicity increased depending on its dosage and exposure time. This study revealed that M. edulis developed adaptive response to neutralize the oxidative stress following pesticide exposure.

Abstract: The study on the combined probiotics to replace antibiotics becomes more and more important because the by-effects and appearance of “superbug” from abuse of antibiotics in human life and animal production. In order to get the effective combined probiotics for replacing antibiotics and inhibiting pathogenic Escherichia coli (E. coli) prolification, 3 strains of Bacillus subtilis (B. subtilis, named as B1, B2 and B3) were used to determine the pre-combination with experimental design (3 factors×4 levels), and then the pre-combination of B. subtilis was combined with Lactobacillus casei (L. casei) and Hansenula anomala (H. anomala) to achieve the most effective combined probiotics with the same design. The results indicated that the pre-combination ratio of B1, B2 and B3 was 0:1:1, and the most effective combination ratios of the pre-combination, L. casei and H. anomala were 0:1:1, 1:3:0, 2:2:3, 2:3:2, respectively (P<0.05). In addition, the incubating groups containing L. casei had better effect on inhibiting E. coli prolification than those without Lactobacillus, indicating that Lactobacillus had the best effect on inhibiting E. coli prolification, compared with other bacteria.

Abstract: The effects of steam explosion (2.5 MPa, 200s) and Trichoderma koningii (T. koningii) fermentation on corn straw degradation were evaluated according to straw degradation and enzyme activity in the fermented products. The results showed that the steam explosion pre-treatment for corn straw could reduce the contents of cellose, hemicellulose and lignin by 8.47%, 50.45% and 36.65%, respectively (P<0.05). After the pretreated corn straw with steam explosion was fermented by T. koningii for 6 days, the contents of cellulose and hemicellulose in the fermented straw were decreased by 19.37% and 63.54%, compared with the original corn straw (P<0.05); decreased by 11.83% and 26.41%, compared with the exploded straw (P<0.05). The filter paper cellulase, CMCase and amylase protease protease protease;activities in the fermented products were 356.39,5 599.90 and 834.00 U/g, respectively. It is concluded that the corn straw pre-treated by steam explosion and followed by T. koningii fermentation for 6 days seems to be a new prospective method for corn straw degradation and application.

Abstract: In order to elucidate the role of ascorbate-glutathione (ASC-GSH) cycle to drought stress, the activities of antioxidant enzymes and the levels of molecules involved in the ASC-GSH metabolism were studied in Trifolium repens seedlings subjected to polyethylene glycol (PEG)-induced water deficit. Compared to the control, the contents of ascorbate (ASC), dehydroascorbate (DHA) and glutathione disulfide (GSSG) increased in PEG-treated seedlings, whereas the glutathione (GSH) content kept constant during the drought period. Further more, the values of ASC/DHA and GSH/GSSG ratios decreased in the presence of PEG. Except for that of monodehydroascorbate reductase (MDHAR), the activities of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were upregulated during water deficit, and the increases of APX and DHAR activities were much higher than that of GR activity. These data indicated that fluctuations of the ASC-GSH metabolism resulted from PEG may have a positive effect on drought stress mitigation in T. repens, and the antioxidant protection in ASC-GSH cycle can be attributed mainly to ASC, APX and DHAR.

Abstract: The peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor involved in the transcriptional control of energy, lipid, and glucose homeostasis. In this study, we cloned goose PPARγ gene. The amplified fragment contains coding region sequence with 1731 nucleotides, which putatively codes for 453 amino acids (AA). The homology of nucleotide sequences is from 81.4% to 99.9% among the twelve vertebrates, while the similarity of amino acid sequence ranged from 91.8% to 99.8%. Results showed that the PPARγ gene is conservative among different species. This work constructed the basis for further research on the molecular nature and genetic markers of PPARγ for metabolism traits in goose.

Abstract: An experimental mixture design coupled with data analysis by means of both response surface methodology(RSM) and artificial neural network(ANN) was applied to explore the optimum process parameters for adenosine extraction from cultured mycelium of Cordyceps militaris. With the extraction rate of adenosine as index, the critical factors selected for the investigation were extracting temperature, extracting time and solid-liquid radio. The results obtained by the application of ANN were more reliable since better statistical parameters were obtained. The optimum extraction procedure was as follow: extracting time 2.3 h, extracting temperature 48 °C, solid-liquid ratio 1:38 g⋅mL^-1. Under the optimal conditions, the corresponding response value predicted for adenosine production was 4.59 mg g^-1, which was confirmed by validation experiments.

Abstract: Response surface methodology (RSM) was used to optimize sporulation medium components for improving spores concentration in I. lacteus fermentation broth. Five factors of sporulation medium components, glucose (X₁), peptone (X₂), yeast extract (X₃) MgSO₄·7H₂O (X₄) and VB₁ (X₅), were chosen to optimize through a five-level, five-factor central composite design (CCD) base on single factor experiments. The concentration of medium components which influenced the sporulation of I. lacteus was further optimized using RSM. The results show that The medium that consists of 4.15 g/L peptone, 2.04 g/L yeast extract, 5.10 g/L glucose, 0.17 g/L MgSO₄·7H₂O and 0.03 g/L VB₁ enhance spores concentration significantly . The final spores concentration (2.19×10⁵ /mL) by using the optimized medium was about five times higher than normal medium.

Abstract: CuCr₂O₄ nanoparticles have been successfully synthesized via a facile citric acid (CA)-assisted sol-gel method, and further combined with TiO₂ by solid phase method. These obtained photocatalysts were characterised by X-ray diffraction (XRD) and UV-vis diffuse reflectance spectrum (UV-vis DRS). Then the photocatalytic inactivation of Escherichia coli, a Gram-negative bacterium, was performed with the photocatalysts to investigate the photocatalytic bactericidal capability under simulated solar light irradiation. The results show that CuCr₂O₄/TiO₂ composite photocatalysts exhibited a much better photocatalytic activity than either pure CuCr₂O₄ or TiO₂, and in the composites, the effects of CuCr₂O₄ to TiO₂ mass ratio and calcination temperature on bacterial photocatalytic inactivation were investigated in detail. With a 90% content of TiO₂, calcination temperature at 500 ^◦C, the optimal photocatalytic sterilization amount of CuCr₂O₄/TiO₂ is 1.62 and 1.33 times more than that of CuCr₂O₄ and TiO₂, respectively. And Escherichia coli were almost completely inactivated within about 40 min.