Using cheese whey for hydrogen and methane generation in a two-stage continuous process with alternative pH controlling approaches

This study focuses on the exploitation of cheese whey as a source for hydrogen and methane, in a two-stage continuous process. Mesophilic fermentative hydrogen production from undiluted cheese whey was investigated at a hydraulic retention time (HRT) of 24 h. Alkalinity addition (NaHCO₃) or an automatic pH controller were used, to maintain the pH culture at a constant value of 5.2. The hydrogen production rate was 2.9 ± 0.2 L/Lreactor/d, while the yield of hydrogen produced was approximately 0.78 ± 0.05 mol H₂/mol glucose consumed, with alkalinity addition, while the respective values when using pH control were 1.9 ± 0.1 L/Lreactor/d and 0.61 ± 0.04 mol H₂/mol glucose consumed. The corresponding yields of hydrogen produced were 2.9 L of H₂/L cheese whey and 1.9 L of H₂/L cheese whey, respectively. The effluent from the hydrogenogenic reactor was further digested to biogas in a continuous mesophilic anaerobic bioreactor. The anaerobic digester was operated at an HRT of 20d and produced approximately 1 L CH₄/d, corresponding to a yield of 6.7 L CH₄/L of influent. The chemical oxygen demand (COD) elimination reached 95.3% demonstrating that cheese whey could be efficiently used for hydrogen and methane production, in a two-stage process.     

Molecular characterization and molasses fermentation performance of a wild yeast strain operating in an extremely wide temperature range

Molasses fermentation performance by both a cryotolerant and a thermophilic yeast (strain AXAZ-1) isolated from grapes in Greece was evaluated in an extremely wide temperature range (3–40 °C). Sequence analysis of the 5.8S internal transcribed spacer and the D1/D2 ribosomal DNA (rDNA) regions assigned isolate to Saccharomyces cerevisiae. Restriction fragment length polymorphism of the mitochondrial DNA showed that strain AXAZ-1 is genetically divergent compared to other wild strains of Greek origin or commercial yeast starters. Yeast cells growing planktonically were capable of fermentation in a wide temperature spectrum, ranging from 3 °C to 38 °C. Immobilization of yeast on brewer’s spent grains (BSG) improved the thermo-tolerance of the strain and enabled fermentation at 40 °C. Time to complete fermentation with the immobilized yeast ranged from 20 days at 3 to 38 h at 40 °C. The daily ethanol productivity reached maximum (58.1 g/L) and minimum (2.5 g/L) levels at 30 and 3 °C, respectively. The aroma-related compounds’ profiles of immobilized cells at different fermentation temperatures were evaluated by using solid phase microextraction (SPME) gas chromatography–mass spectrometry (GC–MS). Molasses fermentation resulted in a high quality fermentation product due to the low concentrations of higher and amyl alcohols at all temperatures tested. Strain AXAZ-1 is very promising for the production of ethanol from low cost raw materials, as it was capable to perform fermentations of high ethanol concentration and productivities in both low and high temperatures.     

Inhibition of human poly(A)-specific ribonuclease (PARN) by purine nucleotides: kinetic analysis

Poly(A)-specific ribonuclease (PARN) is a cap-interacting and poly(A)-specific 3'-exoribonuclease that efficiently degrades mRNA poly(A) tails. Based on the enzyme's preference for its natural substrates, we examined the role of purine nucleotides as potent effectors of human PARN activity. We found that all purine nucleotides tested can reduce poly(A) degradation by PARN. Detailed kinetic analysis revealed that RTP nucleotides behave as non-competitive inhibitors while RDP and RMP exhibit competitive inhibition. Mg(2 + ) which is a catalytically important mediator of PARN activity can release inhibition of RTP and RDP but not RMP. Although many strategies have been proposed for the regulation of PARN activity, very little is known about the modulation of PARN activity by small molecule effectors, such as nucleotides. Our data imply that PARN activity can be modulated by purine nucleotides in vitro, providing an additional simple regulatory mechanism.     

Choroidal eye metastases from (recurrent) primary peritoneal carcinoma: case report and review of the literature

Background

Choroidal metastases from gynaecological primary are extremely rare. There is no documented case in the literature of choroid metastasis in a patient with primary peritoneal carcinoma (PPC).

Methods & Results

We describe the first case of a 54-year-old woman with a history of borderline mucinous tumour who presented 17 months later with PPC and 21 months after with recurrent disease metastatic to the eye, and review pertinent literature.

Conclusion

High index of suspicion is warranted when patients with history of primary peritoneal carcinoma present with visual complaints in order to treat and/or relieve symptomatology from metastatic eye disease.

     

Application of a PEG/salt aqueous two-phase partition system for the recovery of monoclonal antibodies from unclarified transgenic tobacco extract

Aqueous two-phase partition systems (ATPS) have been widely used for the separation of a large variety of biomolecules. In the present report, the application of a polyethylene glycol/phosphate (PEG/phosphate) ATPS for the separation of anti-HIV monoclonal antibodies 2G12 (mAb 2G12) and 4E10 (mAb 4E10) from unclarified transgenic tobacco crude extract was investigated. Optimal conditions that favor opposite phase partitioning of plant debris/mAb as well as high recovery and purification were found to be 13.1% w/w (PEG 1500), 12.5% w/w (phosphate) at pH 5 with a phase ratio of 1.3 and 8.25% w/w unclarified tobacco extract load. Under these conditions, mAb 2G12 and mAb 4E10 were partitioned at the bottom phosphate phase with 85 and 84% yield and 2.4- and 2.1-fold purification, respectively. The proposed ATPS was successfully integrated in an affinity-based purification protocol, using Protein A, yielding antibodies of high purity and yield. In this study, ATPS was shown to be suitable for initial protein recovery and partial purification of mAb from unclarified transgenic tobacco crude extract.     

Words,antibodies and their interactions

Jerne’s idiotypic network theory stresses the importance of antibody-to-antibody interactions and provides possible explanations for self-tolerance and increased diversity in the immune repertoire. In this paper, we use an immune network model to build a user profile for adaptive information filtering. Antibody-to-antibody interactions in the profile’s network model correlations between words in text. The user profile has to be able to represent a user’s multiple interests and adapt to changes in them over time. This is a complex and dynamic engineering problem with clear analogies to the immune process of self-assertion. We present a series of experiments investigating the effect of term correlations on the user’s profile performance. The results show that term correlations can encode additional information, which has a positive effect on the profile’s ability to assess the relevance of documents to the user’s interests and to adapt to changes in them.