Synergistic role of carbon quantum dots on biohydrogen production

• Published in: Journal of environmental chemical engineering 2024-12, Vol.12 (6), p.114188, Article 114188
• Main Authors: Sivagurunathan, Periyasamy, Sahoo, Prakash C., Kumar, Manoj, Gupta, Ravi Prakash, Srivastva, Umish, Bhattacharyya, Debasis
• Format: Article
• Language: English
• Subjects: Biohybrid; Biohydrogen; Carbon quantum dots; Pathway inducer
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.114188

Biohybrid system has their distinct ability to improve microbial fermentation. This study demonstrates the role of surface-doped carbon quantum dots (CQDs) on dark fermentative biohydrogen production using lactobacillus organic-hybrid biocatalyst. Herein, nitrogen-doped carbon quantum dots (N-CQDs) with < 5 nm (having a surface charge of +2.6 mV) and un-doped carbon quantum dots (CQDs) (having a surface charge of −4.5 mV) were synthesized via chemical assisted process. Subsequently, the biohybrid systems were constructed via augmentation of N-CQDs and CQDs with Lactobacillus delbreuckii and assessed for biohydrogen production. The results revealed that both the biohybrid systems (N-CQDs- Lactobacillus delbreuckii and CQDs- Lactobacillus delbreuckii) provided improved hydrogen production than that of the native bacterial strain. Interestingly, the obtained N-CQDs- Lactobacillus delbreuckii system provided the maximum hydrogen yield of 2.01 mol/mol hexose, followed by 1.86 mol/mol hexose from CQDs- Lactobacillus delbreuckii, which is about 33 % and 19 % higher than the bare bacterial strain. The electron transfer and metabolic alteration of microbes by carbon quantum dots were assessed using cyclic voltammetry (CV) and VFA production. It was concluded that the improved bio-hydrogen production from N-CQDs- Lactobacillus delbreuckii is attributed to enhanced electron transfer, which regulates the central metabolic pathway of acetate and butyrate synthesis with the least production of lactate and other reduced end product formation. [Display omitted] •Carbon quantum dots biohybrid system has been employed for biohydrogen production.•N-CQDs biohybrid stimulates hydrogen production over 33 % than control.•Maximum hydrogen yield of 2.01 mol/mol hexose was attained.•Dehydrogenase activity enhances in the presence of CQDs biohybrid.•NAD+/NADH and FAD+/FADH2 pool increases over 27 % in presence of CQDs.