Hydrogen production from cellulose in a two-stage process combining fermentation and electrohydrogenesis

A two-stage dark-fermentation and electrohydrogenesis process was used to convert the recalcitrant lignocellulosic materials into hydrogen gas at high yields and rates. Fermentation using Clostridium thermocellum produced 1.67 mol H₂/mol-glucose at a rate of 0.25 L H₂/L-d with a corn stover lignocellulose feed, and 1.64 mol H₂/mol-glucose and 1.65 L H₂/L-d with a cellobiose feed. The lignocelluose and cellobiose fermentation effluent consisted primarily of: acetic, lactic, succinic, and formic acids and ethanol. An additional 800 ± 290 mL H₂/g-COD was produced from a synthetic effluent with a wastewater inoculum (fermentation effluent inoculum; FEI) by electrohydrogensis using microbial electrolysis cells (MECs). Hydrogen yields were increased to 980 ± 110 mL H₂/g-COD with the synthetic effluent by combining in the inoculum samples from multiple microbial fuel cells (MFCs) each pre-acclimated to a single substrate (single substrate inocula; SSI). Hydrogen yields and production rates with SSI and the actual fermentation effluents were 980 ± 110 mL/g-COD and 1.11 ± 0.13 L/L-d (synthetic); 900 ± 140 mL/g-COD and 0.96 ± 0.16 L/L-d (cellobiose); and 750 ± 180 mL/g-COD and 1.00 ± 0.19 L/L-d (lignocellulose). A maximum hydrogen production rate of 1.11 ± 0.13 L H₂/L reactor/d was produced with synthetic effluent. Energy efficiencies based on electricity needed for the MEC using SSI were 270 ± 20% for the synthetic effluent, 230 ± 50% for lignocellulose effluent and 220 ± 30% for the cellobiose effluent. COD removals were ∼90% for the synthetic effluents, and 70–85% based on VFA removal (65% COD removal) with the cellobiose and lignocellulose effluent. The overall hydrogen yield was 9.95 mol-H₂/mol-glucose for the cellobiose. These results show that pre-acclimation of MFCs to single substrates improves performance with a complex mixture of substrates, and that high hydrogen yields and gas production rates can be achieved using a two-stage fermentation and MEC process.     

EU demonstration project for separate discharge and treatment of urine, faeces and greywater--part I: results.

The main aim of this EU demonstration project was to test two new sanitation concepts to determine if these concepts are more sustainable, compared with the conventional sanitation system, particularly with regard to nutrient recycling. Two different sanitation concepts were tested. One concept comprised the use of gravity separation toilets, the other used vacuum separation toilets. Results from a life-cycle-assessment investigation show that the new sanitation concepts are more sustainable. A cost analysis for an existing residential area did not prove lower costs for the new sanitation concepts in this special case. The experience from this demonstration project shows that prior to a widespread use of the new sanitation concepts, several improvements have to be made. One important issue is the improvement of separation toilets. Since nutrient recycling, water saving and reuse as well energy reduction become more and more important, further research should be undertaken in this field.     

Feasibility of Coupling Dehydration-Impregnation by Soaking Treatment of Meat with Fermentation by Lactobacillus sakei

This study examined the feasibility of coupling dehydration-impregnation by soaking (DIS) with a subsequent lactic fermentation in the treatment of meat. A series of beef fillets were subjected to 3 different DIS treatments. The resulting DIS-treated fillets had 3 different characteristics in terms of water activity, salt, and fermentable sugars contents. Fillets treated with the DIS with the shortest immersion time (5 h) and the highest salt concentration in the DIS bath (100 g/L) were inoculated with Lactobacillus sakei. A control group was left without inoculation. After 24 h incubation at 25 °C, only inoculated fillets showed signs of lactic fermentation. At 24 h, these fillets had a d-lactic acid content of 68 μmol/g dry basis and a high population of L. sakei revealed by methods of plate count and quantitative PCR. DIS could therefore be compatible with a subsequent fermentation step by L. sakei. Practical Application: Traditional meat preservation processes often combine unit operations such as salting, smoking, fermentation, and drying. In tropical countries, high temperatures and high relative humidity, poor infrastructure, and improper slaughterhouse practices explain the need for more drastic processes (more salt, more water loss) for meat preservation. Dehydration-impregnation by soaking (DIS) could be used as a rapid pretreatment of meat, in order to counteract tropical conditions. This study validates a novel approach whereby DIS is coupled with lactic fermentation by surface inoculation with Lactobacillus sakei. With a final drying step this process could be used for the treatment of whole meat pieces.     

Inter-laboratory Testing of GMO Detection by Combinatory SYBR®Green PCR Screening (CoSYPS)

Combinatory SYBR®Green real-time PCR Screening (CoSYPS) is an efficient, sensitive approach for detecting complex targets such as genetically modified organisms (GMOs) in food and feed products. GMO analysis for legal purposes has become increasingly complex and costly due to the diversity in recombinant targets present in the different GMOs. For this reason, screening for the presence of GMOs is in general the first step in the detection of GM material in a product. CoSYPS allows detecting the large majority of globally commercial GMOs using SYBR®Green real-time PCR methods for six GM targets (P35S, Tnos, CryIAb, CP4-EPSPS, PAT and BAR) combined with species-specific PCR methods (e.g., maize, soy, rapeseed). Here, the results of an inter-laboratory trial on seven samples with different GMO mixtures at different levels are presented. In total, 13 laboratories participated in the trial and the currently most frequently used PCR analysis platforms are represented. The inter-laboratory study clearly demonstrates that PCR methods used in CoSYPS form a very robust GMO screening system. Sensitivity, specificity, positive and negative predictive values are for all PCR methods higher than 95 % for all samples. Together, these results show that the SYBR®Green real-time PCR methods used in CoSYPS are effectively applicable to different PCR platforms and amendable to configuration into a sensitive high-throughput GMO screening and decision support tool.     

Surface film formation on electrodes in a LiCoO2/graphite cell: A step by step XPS study

In this paper, we report on a study of the electrode/electrolyte interfaces of a LiCoO₂/C cell using XPS (X-ray photoelectron spectroscopy). The originality of our work lies in detailed investigations step by step during the first cycle. The results have shown that the formation process of the SEI takes place in different successive stages that are dependent on the potential of the cell. It clearly appears that SEI formation continues in the potential range where lithium ion intercalation proceeds in the carbon electrode. Salt degradation products are formed after solvent decomposition ones. Concerning the LiCoO₂/electrolyte interface, the results obtained have shown the formation of a very thin film on the active material but not on the binders. In all cases, the novel XPS approach applied in the lab, combining core peaks and valence band analyses, allows a precise characterization of the main chemical species of the interface layers. On the basis of these results and in conjunction with literature data, the degradation mechanisms have been discussed.     

Four new SYBR<Superscript>®</Superscript>Green qPCR screening methods for the detection of Roundup Ready<Superscript>®</Superscript>, LibertyLink<Superscript>®</Superscript>, and CryIAb traits in genetically modified products

SYBR^®Green qPCR methods for the detection of the Roundup Ready^® “CP4-EPSPS”, LibertyLink^® “PAT” and “BAR,” and the Bacillus thuringiensis “CryIAb” traits as present in genetically modified organisms (GMO) were developed. Their specificity, sensitivity, and PCR method efficiency were determined. All methods are specific and generate amplicons of 108, 73, 109, and 69 bp, respectively, for “CP4-EPSPS,” “CryIAb,” “PAT,” and “BAR” targets. They perform well at low target levels and can detect down to 5 copies of their respective targets extracted from a sample. The PCR efficiency of the methods ranges between 91 and 109%. Due to their trait-specific nature, these methods allow an efficient screening between the different GMO. In this way, the number of possible GMO candidates present in a sample can be reduced what results in lower global costs due to limiting of further the number of analytical identification steps. The application of these methods in CoSYPS GMO analysis is illustrated using two GEMMA proficiency test samples and a reference material from the GM rapeseed event RF3. This set of SYBR^®Green qPCR trait-specific methods represents a very interesting novel set of GMO analysis methods allowing cost-effective identification of GM materials in products.     

Associations between paratuberculosis ELISA results and test-day records of cows enrolled in the Irish Johne's Disease Control Program

The effect of the Mycobacterium avium ssp. paratuberculosis (MAP) ELISA status on test-day milk performance of cows from Irish herds enrolled in the pilot national voluntary Johne's disease control program during 2013 to 2015 was estimated. A data set comprising 92,854 cows and 592,623 complete test-day records distributed across 1,700 herds was used in this study. The resulting ELISA outcome (negative, inconclusive, and positive) of each cow within each year of the program was used to allocate the cow into different scenarios representing the MAP status. At MAPscenario₁, all cows testing ELISA nonnegative (i.e., inconclusive and positive) were assigned a MAP-positive status; at MAPscenario₂ only cows testing ELISA-positive were assigned a MAP-positive status; at MAPscenario₃ only cows testing ELISA nonnegative (inconclusive or positive) and gathered exclusively from herds where at least 2 further ELISA nonnegative (inconclusive or positive) cows were found were assigned a MAP-positive status; at MAPscenario₄ only cows testing ELISA-positive that were gathered exclusively from herds where at least 2 further ELISA-positive cows were found were assigned a MAP-positive status. Milk outputs based on test-day records were standardized for fat and protein contents (SMY) and the effect of MAP ELISA status on the SMY was estimated by a linear mixed effects model structure. The SMY mean difference recorded at test day between cows with a MAP-positive status and those with a MAP-negative status within MAPscenario₁ was estimated at ?0.182 kg/test day; the mean difference was ?0.297 kg/test day for MAPscenario₂; for MAPscenario₃ mean difference between MAP-positive status and MAP test-negative cows was ?0.209 kg/test day, and for MAPscenario₄, the difference was ?0.326 kg/test day.     

Diversity of the Volatile Organic Compounds Emitted by 55 Species of Tropical Trees: a Survey in French Guiana

Volatile organic compounds (VOCs) are produced by a broad range of organisms, from bacteria to mammals, and they represent a vast chemical diversity. In plants, one of the preeminent roles of VOCs is their repellent or cytotoxic activity, which helps the plant deter its predators. Most studies on VOCs emitted by vegetative parts have been conducted in model plant species, and little is known about patterns of VOC emissions in diverse plant communities. We conducted a survey of the VOCs released immediately after mechanical damage of the bark and the leaves of 195 individual trees belonging to 55 tropical tree species in a lowland rainforest of French Guiana. We discovered a remarkably high chemical diversity, with 264 distinct VOCs and a mean of 37 compounds per species. Two monoterpenes (α-pinene and limonene) and two sesquiterpenes (β-caryophyllene and α-copaene), which are known to have cytotoxic and deterrent effects, were the most frequent compounds in the sampled species. As has been established for floral scents, the blend of VOCs is largely species-specific and could be used to discriminate among 43 of the 55 sampled species. The species with the most diverse blends were found in the Sapindales, Laurales, and Magnoliales, indicating that VOC diversity is not uniformly distributed among tropical species. Interspecific variation in chemical diversity was caused mostly by variation in sesquiterpenes. This study emphasizes three aspects of VOC emission by tropical tree species: the species-specificity of the mixtures, the importance of sesquiterpenes, and the wide-ranging complexity of the mixtures.     

Testing LED lighting for colour discrimination and colour rendering

Light‐emitting diode (LED) technology offers the possibility of obtaining white light, despite narrow‐band spectra. In order to characterize the colour discrimination efficiency of various LED clusters, we designed a classification test, composed of 32 caps equally distributed along the hue circle at about 3 ΔE* _ab‐unit intervals. Forty normal colour observers were screened under four different LED test light sources adjusted for best colour rendering, and under one control incandescent light of the same colour temperature. We used commercially available red, green, blue, and/or amber LED clusters. These yielded a poor colour rendering index (CRI). They also induced a significantly higher number of erroneous arrangements than did the control light. Errors are located around greenish‐blue and purplish‐red shades, parallel to the yellow‐axis direction, whereas when the distribution of light covers the full spectrum, the LED clusters achieve satisfactory colour discrimination efficiency. With respect to the lights we tested, the colour discrimination is correlated with the CIE CRIs as well as with a CRI based on our sample colours. We stress the fact that increasing the chroma of samples by lighting does not necessarily imply an improvement of colour discrimination. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 8–17, 2009.