Hydrogen production and microbial kinetics of Clostridium termitidis in mono-culture and co-culture with Clostridium beijerinckii on cellulose

Abstract

Cellulose utilization by hydrogen producers remains an issue due to the low hydrogen yields reported and the pretreatment of cellulose prior to fermentation requires complex and expensive steps. Clostridium termitidis is able to breakdown cellulose into glucose and produce hydrogen. On the other hand, Clostridium beijerinckii is not able to degrade cellulose but is adept at hydrogen production from glucose; therefore, it was chosen to potentially enhance hydrogen production when co-cultured with C. termitidis on cellulose. In this study, batch fermentation tests were conducted to investigate the direct hydrogen production enhancement of mesophilic cellulolytic bacteria C. termitidis co-cultured with mesophilic hydrogen producer C. beijerinckii on cellulose at 2 g l−1 compared to C. termitidis mono-culture. Microbial kinetics parameters were determined by modeling in MATLAB. The achieved highest hydrogen yield was 1.92 mol hydrogen mol−1 hexose equivalentadded in the co-culture compared to 1.45 mol hydrogen mol−1 hexose equivalentadded in the mono-culture. The maximum hydrogen production rate of 26 ml d−1 was achieved in the co-culture. Co-culture exhibited an overall 32 % enhancement of hydrogen yield based on hexose equivalent added and 15 % more substrate utilization. The main metabolites were acetate, ethanol, lactate, and formate in the mono-culture, with also butyrate in the co-culture. Additionally, the hydrogen yield of C. beijerinckii only in glucose was 2.54 mol hydrogen mol−1 hexose equivalent. This study has proved the viability of co-culture of C. termitidis with C. beijerinckii for hydrogen production directly from a complex substrate like cellulose under mesophilic conditions.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-016-0256-2) contains supplementary material, which is available to authorized users.

Performance analysis of immobilized and co-immobilized enriched-mixed culture for hydrogen production

“…Dwindling fossil fuel sources with its products in the form of greenhouse emissions make it necessary to search for alternative energy sources [1][2] [3]. Hydrogen is a clean fuel because the final combustion product is water and calorific value is 143 GJ tonne 1 [4].…”

“…Microbial conversion of substrate to H 2 and volatile fatty acid (VFA) [1][5] [6][7] [8]. Hydrogen production through anaerobic fermentation has advantages over the other processes because it has the potential to use wastewater and organic wastes [9].…”

Utilização dos subprodutos da produção fermentativa de hidrogênio para a geração de energia em uma célula microbiana a combustível

“…Dentre as vantagens de uma CCM pode-se citar a conversão direta de energia do substrato em energia elétrica; menor produção de lodo em relação ao processo de digestão anaeróbia; não necessidade de aeração; possibilidade de instalação em áreas sem infraestrutura elétricas; geração de energia sem a necessidade de separação e/ou purificação; e, possibilidade de tratamento de efluentes industriais (GUDE, 2016;HE et al, 2017 (LOGAN et al, 2006;WU et al, 2016).…”

“…O uso de CCM para esse fim envolve algumas reações, entre elas a de oxidação dos compostos orgânicos, catalisada por microrganismos. Essas reações geram eletricidade através da transferência de elétrons para um circuito externo (LOGAN et al, 2006;RACHINSKI et al, 2010;SANTORO et al, 2017).…”

“…LOGAN et al, 2006;GU, 2007).As CCMs em forma de H têm baixas densidades de potência e altas resistências internas e são limitados apenas a uso laboratorial (Figura 7A). Em CCM de câmara única, uma densidade de potência elevada geralmente é alcançada em comparação com uma CCM em forma de H (Figura 7B).…”