Obtenção e caracterização filogenética de consórcio de bactérias púrpuras não-sulforosas consumidoras de ácidos orgânicos visando a produção de hidrogênio em reator anaeróbio de batelada / Obtaintion and phylogenetic characterization of consortium of phototrophic purple non-sulfur bacteria for hydrogen production from organic acids in the anaerobic batch reactor

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The aim of this work was enrich a mixture of granular sludge of an up flow anaerobic sludge blanket (UASB) under anoxygenic phototrophic conditions. The techniques of molecular biology identified 17 operational taxonomic units (UTO) in the microbial consortium among the sequences analised, which were similar to Rhodobacter, genus widely cited in studies of hydrogen gas production by phototrophic bacteria. Microscopic examinations of the phototrophic consortium showed predominance of Gram-negative bacilli. Tests were conducted under phototrophic conditions with two culture media (RCVB and FANG) and the following organic substrates: acetic, butyric, citric, lactic and malic acids that were used as carbon source for both cell growth and for the hydrogen gas production. The carbon nitrogen ratio (C/N) in the preliminaries tests was 30/4 and then it was changed to15/2 in order to improve the cell growth and hydrogen production. The concentration of substrates was determined for remain the same carbon/nitrogen ratio among the substrates. The cell growth and consumption of organic acids were similar for the two culture media used. However, the production of hydrogen gas was higher in trials with the medium FANG. Among the substrates used, the consumption of malic and citric acids were the highest (~100%) for initial concentrations of 3.3 g/L and 2.6 g/L, respectively. The shortest consumption (25%) was observed for the cells that grew on acetic acid, 2.5 g/L in RCVB culture medium. The growth of the biomass varied from 0.06 g/L to 1.1 g/L, whereas the maximum specific growth rate ranged from 0.4 to 0.2 g VSS/L.d between the substrates used. The lowest and highest concentrations of hydrogen were 8.5 and 22 mmol H IND.2/L for the reactor fed with lactic acid and malic acid in FANGs medium, respectively. It was concluded that the phototrophic consortium was able to use those organic acids for the production of hydrogen gas.

ASSUNTO(S)

bactérias fototróficas púrpuras não-sulfurosas hydrogen gas Ácidos orgânicos filogenia 16s rrna gene sequencing phylogeny organic acids phototrophic purple non-sulfur bacteria gás hidrogênio sequenciamento do gene rnar 16s

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