Optimization of dark fermentative biohydrogen production from rice starch by Enterobacter aerogenes MTCC 2822 and Clostridium acetobutylicum MTCC 11274

Mixed culture biotechnology and its versatility in dark fermentative hydrogen production

Over the years, extensive research has gone into fermentative hydrogen production using pure and mixed cultures from waste biomass with promising results. However, for up-scaling of hydrogen production mixed cultures are more appropriate to overcome the operational difficulties such as a metabolic shift in response to environmental stress, and the need for a sterile environment. Mixed culture biotechnology (MCB) is a robust and stable alternative with efficient waste and wastewater treatment capacity along with co-generation of biohydrogen and platform chemicals. Mixed culture being a diverse group of bacteria with complex metabolic functions would offer a better response to the environmental variations encountered during biohydrogen production. The development of defined mixed cultures with desired functions would help to understand the microbial community dynamics and the keystone species for improved hydrogen production. This review aims to offer an overview of the application of MCB for biohydrogen production.

Enhancing biohydrogen production from mono-substrates and co-substrates using a novel bacterial strains

The staggering increase in pollution associated with a sharp tightening in global energy demand is a major concern for organic substances. Renewable biofuel production through simultaneous waste reduction is a sustainable approach to meet this energy demand. This study co-fermentation of dairy whey and SCB was performed using mixed and pure bacterial cultures of Salmonella bongori, Escherichia coli, and Shewanella oneidensis by dark fermentation process for hydrogen production. The maximum H2 production was 202.7 ± 5.5 H2/mL/L, 237.3 ± 6.0 H2/mL/L, and 198 ± 9.9 H2/mL/L obtained in fermentation reactions containing dairy whey, solid and liquid hydrolysis of pretreated sugarcane bagasse as mono-substrates. The H2 production was greater in co-substrate by 347.3 ± 18.5 H2/mL/L under optimized conditions (pH 7.0, temperature 37 °C, substrate concentration 30:50 g/L) than expected in mono-substrate conditions, which confirms that co-fermentation of different substrates enhances the H2 potential. Fermentation medium during bio-H2 production under GC analysis has stated that using mixed cultures in dark fermentation favored acetic acid and butyric acid. Co-substrate degradation produces ethyl alcohol, benzoic acid, propionic acid, and butanol as metabolic by-products. The difference in the treated and untreated substrate and carbon enrichment in the substrates was evaluated by FT-IR analysis. The present study justifies that rather than the usage of mono-substrate for bio-H2 production, the co-substrate provided highly stable H2 production by mixed bacterial cultures. Fabricate the homemade single-chamber microbial fuel cell to generate electricity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03687-9.