Effect of metals on the regulation of acidogenic metabolism enhancing biohydrogen and carboxylic acids production from brewery spent grains: Microbial dynamics and biochemical analysis

• Published in: Engineering in life sciences Vol. 22; no. 10; pp. 650 - 661
• Main Authors: Sarkar, Omprakash, Rova, Ulrika, Christakopoulos, Paul, Matsakas, Leonidas
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01-10-2022; Wiley-VCH
• Subjects: Accumulation; Acetic acid; acidogenesis; acidogenesis, biohydrogen, carboxylic acids; Ammonium; Biocatalysts; Biochemical analysis; Biochemical Process Engineering; Biogas; biohydrogen; Biokemisk processteknik; Biomass; Biosynthesis; Breweries; Butanol; Butyric acid; caproic acid; caproic acid metals; caproic acid, carboxylic acids, caproic acid metals; Carboxylic acids; Cobalt; Consortia; Dehydrogenases; Ethanol; Fermentation; Glucose; Heavy metals; Iron; Metabolism; Metabolites; Metagenomics; Metals; Microorganisms; Mixed culture; Nanoparticles; Nickel; Raw materials; Reactors; Supplements; Taxonomy; Zinc; United States > US; Sweden; acidogenesis, biohydrogen, carboxylic acids; caproic acid, carboxylic acids, caproic acid metals
• ISSN: 1618-0240; 1618-2863; 1618-2863
• DOI: 10.1002/elsc.202200030

The present study reports the mixed culture acidogenic production of biohydrogen and carboxylic acids (CA) from brewery spent grains (BSG) in the presence of high concentrations of cobalt, iron, nickel, and zinc. The metals enhanced biohydrogen output by 2.39 times along with CA biosynthesis by 1.73 times. Cobalt and iron promoted the acetate and butyrate pathways, leading to the accumulation of 5.14 gCOD/L of acetic and 11.36 gCOD/L of butyric acid. The production of solvents (ethanol + butanol) was higher with zinc (4.68 gCOD/L) and cobalt (4.45 gCOD/L). A combination of all four metals further enhanced CA accumulation to 42.98 gCOD/L, thus surpassing the benefits accrued from supplementation with individual metals. Additionally, 0.36 and 0.31 mol green ammonium were obtained from protein‐rich brewery spent grain upon supplementation with iron and cobalt, respectively. Metagenomic analysis revealed the high relative abundance of Firmicutes (>90%), of which 85.02% were Clostridium, in mixed metal‐containing reactors. Finally, a significant correlation of dehydrogenase activity with CA and biohydrogen evolution was observed upon metal addition.