The use of wastewater for the biological production of H-2 (biohydrogen) by dark fermentation has been studied for a variety of waste substrates and mixed or isolated inocula. However, for brewery wastewater (BW), which is generated in large volumes and has characteristics that are highly suitable for acidogenic fermentation, the available studies describe the use of mixed cultures, especially pretreated methanogenic inocula. The aim of this work was to isolate an enterobacterium from aviary litter that was capable of fermenting BW and generating biogas rich in H-2. The biochemical characterization and species confirmation confirmation revealed the isolation of Klebsiella peneumoniae, which provided efficient production of biogas rich in H-2 (30-40%) in batch assays performed for up to 72 h, with the inoculum in suspension, at a small scale (in serum bottles) and using a mechanically-stirred anaerobic reactor (AnBBR), employing crude BW without any supplementation. The hydrogen yield and molar hydrogen flow rate were 0.80-1.67 mol H-2 mol(-1) glucose and 0.2-2.2 mmol H-2 h(-1), respectively, indicating good performance of the inoculum in metabolizing this substrate and the possibility of optimizing the process by varying the duration of the batch. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.