Two-year microbial adaptation during hydrogen-mediated biogas upgrading process in a serial reactor configuration.

Microbial dynamics in an upgrading biogas reactor system undergoing a more than two years-period at stable operating conditions were explored. The carbon dioxide generated during biomass degradation in the first reactor of the system was converted to methane into the secondary reactor by addition of external hydrogen. Considering the overall efficiency, the long-term operation period resulted in an improved biogas upgrading performance (99% methane content). However, a remarkable accumulation of acetate was revealed, indicating the enhancement of homoacetogenic activity. For this reason, a shift in the anaerobic digestion microbiome was expected and evaluated by 16S rRNA amplicon analysis. Results demonstrated that the most abundant archaeal species identified in the first time point, Candidatus Methanoculleus thermohydrogenotrophicum, was replaced by Methanothermobacter thermautotrophicus, becoming dominant after the community adaptation. The most interesting taxonomic units were clustered by relative abundance and six main long-term adaptation trends were found, characterizing functionally related microbes (e.g. homoacetogens).

Efeito da aplicação de bissulfato de sódio sobre cama de frangos na sobrevivência de Escherichia coli e coliformes / Effect of sodium bisulfite application on the bed of broiler on survival of Escherichia coli and coliforms

Avaliou-se o efeito do bissulfato de sódio, aplicado sobre a cama de frangos, criados em diferentes densidades, na sobrevivência de Escherichia coli e coliformes, utilizando-se as densidades de 12, 16 e 20 aves/m², com a inoculação de uma cepa de E. coli. Houve maior desenvolvimento microbiano no 21° dia de criação, com tendência de redução a partir daí. A eficácia do bissulfato de sódio foi maior nos primeiros dias do experimento.

The effect of sodium bisulfate has been evaluated on survival of Escherichia coli and coliforms, when applied on the broiler beds, adopting different densities. It has been adopted densities of 12, 16 and 20 birds/m², using inoculations of E. coli strains. The results have shown the highest microbial development on the 21st day of inoculation, with a trend of a microbial reduction afterwards. The sodium bisulfate was efficient during the first days of analyses, reducing its efficacy during the experiment.