Enhanced methane production from the anaerobic co-digestion of food waste plus fruit and vegetable waste.

Food waste (FW) and fruit, vegetable waste (FVW) are important components of municipal solid waste, yet the performance and related mechanisms of anaerobic co-digestion of FW and FVW for methane production have been rarely investigated. In order to get a deeper understanding of the mechanisms involved, the mesophilic FW and FVW anaerobic co-digestion in different proportions was investigated. The experimental results showed that when the ratio of FW and FVW was 1/1 (in terms of volatile suspended solid), the maximum biomethane yield of 269.9 mL/g TCOD from the codigested substrate is significantly higher than that in FW or FVW anaerobic digestion alone. FW and FVW co-digestion promoted the dissolution and biotransformation of organic matter. When the recommended mixing ratio was applied, the maximum concentration of dissolved chemical oxygen demand (COD) was high as 11971 mg/L. FW and FVW co-digestion reduced the accumulation of volatile fatty acids (VFA) in the digestive system, thus reducing its negative impact on the methanogenesis process. FW and FVW co-digestion process synergistically enhanced microbial activity. The analysis of microbial population structure showed that when FW and FVW were co-digested at the recommended ratio, the relative abundance of Proteiniphilum increased to 26.5%, and the relative abundances of Methanosaeta and Candidatus Methanofastidiosum were also significantly increased. The results of this work provide a certain amount of theoretical basis and technical support for the co-digestion of FW and FVW.

Map of dimorphic switching­related signaling pathways in Sporothrix schenckii based on its transcriptome.

Sporothrix schenckii (S. schenckii) induces sporotrichosis, which has gained attention in recent years due to its worldwide prevalence. The dimorphic switching process is essential for the pathogenesis of S. schenckii. Previously, overexpression of several signal transduction genes, including SsDRK1 and SsSte20, was observed during the mycelium­to­yeast transition; these were necessary for asexual development, yeast­phase cell formation, cell wall integrity and melanin synthesis. However, the mechanisms of the signaling pathways during dimorphic switching of S. schenckii remain unclear. In the present study, transcriptome sequencing of the 48­h induced yeast forms and mycelium of S. schenckii was performed. In total, 24,904,510 high­quality clean reads were obtained from mycelium samples and 22,814,406 from 48­h induced yeast form samples. Following assembly, 31,779 unigene sequences were obtained with 52.98% GC content (The proportion of guanine G and cytosine C to all bases in nucleic acid). The results demonstrated that 12,217 genes, including genes involved in signal transduction and chitin synthesis, were expressed differentially between the two stages. According to these results, a map of the signaling pathways, including two­component and heterotrimeric G­protein signaling systems, Ras and MAPK cascades associated with the dimorphic switch, was drawn. Taken together, the transcriptome data and analysis performed in the present study lay the foundation for further research into the molecular mechanisms controlling the dimorphic switch of S. schenckii and support the development of anti­S. schenckii strategies targeting genes associated with signaling pathways.

Separation and determination of l-tyrosine and its metabolites by capillary zone electrophoresis with a wall-jet amperometric detection.

A method of capillary electrophoresis with wall-jet amperometric detection (AD) has been developed for separation and determination of l-tyrosine (Tyr) and its metabolites, such as Tyramine (TA), p-hydroxyphenylpyruvic (pHPP), homogentisic acid (HGA) and some dipeptides containing Tyr, such as Tyr-Gly-Gly (YGG), Tyr-Arg (YR) and Tyr-d-Arg (Y-d-R). A carbon disk electrode was used as the working electrode and the optimal detection potential was 1.00V (versus Ag/AgCl). At 18kV of applied voltage, the seven compounds were completely separated within 20min in 110x10(-3)mol/L Na(2)HPO(4)-NaH(2)PO(4) buffer (pH 7.10) containing 3x10(-3)mol/L beta-cyclodextrin (beta-CD). Good linear relationship was obtained for all analytes and the detection limits of seven analytes were in the range of 0.95-4.25ng/mL. The proposed method has been applied to examine the metabolic process of l-tyrosine in rabbit's urine.

Separation and determination of enkephalin-related peptides using capillary electrophoresis.

CZE with UV-absorption detection has been used for the separation and determination of enkephalin-related peptides. The experimental conditions, such as pH and concentration of running buffer, applied voltage, injection method, and time, were investigated in detail. Excellent separation efficiency could be obtained for ten enkephalin-related peptides with a 50 microm (ID) x 58 cm capillary using sodium dihydrogen phosphate as the running buffer (pH 3.11) when 20 kV of applied voltage was used. The concentration detection limits were found to be in the range of 0.31-1.94 microg/mL (defined as S/N = 3). The proposed method has been applied to analyze the spiked cerebrospinal fluid (CSF) sample, and the results showed that CZE is a powerful technique for separation and detection of the above biological peptides.