Solid anaerobic digestion: State-of-art, scientific and technological hurdles.

In this paper, a state-of-art about solid anaerobic digestion (AD), focused on recent progress and trends of research is proposed. Solid anaerobic digestion should be the most appropriate process for degradation of by-products with high total solid (TS) content, especially lignocellulosic materials like agricultural waste (straw, manure), household waste and food waste. Solid AD is already widely used in waste water treatment plant for treating plant for sewage sludge but could be more developed for lignocellulosic materials with high TS content. Many research works were carried out in Europe on solid AD, focused on current hurdles (BMP, codigestion, inhibition, microbial population, rheology, water transfers, inoculum, etc.) in order to optimize the solid AD process. In conclusion, hurdles of solid AD process should and must be solved in order to propose better productivity and profitability of such system operating with high TS content (>15%), favouring reliable industrial processes.

Towards a standardization of biomethane potential tests.

Production of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. Although several norms and guidelines for BMP tests exist, inter-laboratory tests regularly show high variability of BMPs for the same substrate. A workshop was held in June 2015, in Leysin, Switzerland, with over 40 attendees from 30 laboratories around the world, to agree on common solutions to the conundrum of inconsistent BMP test results. This paper presents the consensus of the intense roundtable discussions and cross-comparison of methodologies used in respective laboratories. Compulsory elements for the validation of BMP results were defined. They include the minimal number of replicates, the request to carry out blank and positive control assays, a criterion for the test duration, details on BMP calculation, and last but not least criteria for rejection of the BMP tests. Finally, recommendations on items that strongly influence the outcome of BMP tests such as inoculum characteristics, substrate preparation, test setup, and data analysis are presented to increase the probability of obtaining validated and reproducible results.

Passaging impact of H9N2 avian influenza virus in hamsters on its pathogenicity and genetic variability.

INTRODUCTION: Avian influenza viruses of the H9N2 subtype have been reported to cause human infections. This study demonstrates the impact of nasal viral passaging of avian H9N2 in hamsters on its cross species-pathogenic adaptability and variability of amino acid sequences of the hemagglutinin (HA) and neuraminidase (NA) stalk. METHODOLOGY: Three intranasal passagings of avian H9N2 in hamsters P1, P2, and P3 were accomplished. Morbidity signs and lesions were observed three days post viral inoculation. The HA test was used for presumptive detection of H9N2 virus in the trachea and lungs of the hamsters challenged with the differently passaged viruses. Different primers were used for PCR amplification of the HA1 and NA stalk regions of the differently passaged H9N2 viruses, followed by sequence alignment. RESULTS: The morbidity signs indicated low pathogenicity of the differently passaged H9N2 viruses in hamsters. The frequency of gross and microscopic lesions in the tracheas and lungs were insignificantly different among hamsters challenged with the differently passaged H9N2 viruses (p > 0.05). There was 100% similarity in the amino acid sequence of the HA gene of most passaged viruses. The amino acid sequence of the neuraminidase in the third passaged H9N2 virus recovered from lungs showed a R46P mutation that might have a role in the pathogenic adaptability of P3 viruses in hamsters' lungs. CONCLUSIONS: The apparent adaptation of avian H9N2 virus to mammalian cells is in agreement with the World Health Organization's alertness for a possible public health threat by this adaptable virus.

A simple and rapid one-time method to evaluate the non-acidic gas content from bioprocesses.

This paper presents a rapid less than 2 min and low-cost method involving the use of alkali solution to capture the acidic gasses from a biogas, thereby providing an estimate of the percentage of non-acidic gasses. Such a method was mentioned in the literature but never fully described or optimized. After sampling an aliquot of gas from bioprocess, gas was injected in a sealed flask with a 3 M NaOH solution, and after equilibrium was obtained, the non-acidic gas volume was measured. The method was first calibrated with certified gasses with an accuracy observed between 98 and 105%. Regarding the validation step, certified standard gas mixtures and nine biogas-laboratory batch reactors were used, the overall accuracy reported was 103 + 3%. This rapid and low-cost method may either be used in laboratory conditions as a quick and low cost alternative to standard analysis equipment or in addition as a routine field control method used on full-scale plants.

Impact of embryonic passaging of H9N2 virus on pathogenicity and stability of HA1- amino acid sequence cleavage site.

BACKGROUND: Highly virulent Avian Influenza viruses might arise from avirulent strains following viral passaging. This work aims at studying the impact of embryonic passaging of H9N2 on the stability of the HA1 amino acid sequence and its relatedness to pathogenicity. MATERIAL/METHODS: The original H9N2 virus was propagated for 3 consecutive passages in embryonated chicken eggs. Pathogenicity and amino acids sequences at the HA1 gene level of the original (P0), and the once (P1), twice (P2), and three times (P3) passaged viruses were compared. RESULTS: The percent mortality significantly increased in embryos inoculated with P2 (86.7%) and P3 of H9N2 (100%) in comparison to P0 (0.0%) and P1 of H9N2 (46.1%) (P<0.05), while the density of propagated H9N2 declined with passaging. The R-S-S-R motif was stable at the HA1 cleavage site of P0, P1, P2, and P3 viruses. The similarity in the HA1 sequences among the differently passaged viruses ranged between 93.2 to 100%. CONCLUSIONS: The pathogenicity increased significantly upon passaging in chicken embryos in spite of the presence of the same motif at the HA1 cleavage site. Further investigations will target the study of changes in the whole HA protein and of Neuraminidases that could be responsible for a higher pathogenicity.