Photosensitization of electro-active microbes for solar assisted carbon dioxide transformation

• Published in: Bioresource technology 2019-01, Vol.272, p.300-307
• Main Authors: Kumar, Manoj, Sahoo, Prakash C., Srikanth, Sandipam, Bagai, Reshmi, Puri, S.K., Ramakumar, S.S.V.
• Format: Article
• Language: English
• Subjects: Acetic Acid - metabolism; Acetobacterium - metabolism; Artificial photosynthesis; Bio-fuels; Biocatalysis; Cadmium Compounds - chemistry; Cadmium sulfide; Carbon dioxide; Carbon Dioxide - chemistry; Carbon Dioxide - metabolism; Clostridium - metabolism; Cysteine - metabolism; Electrons; Hydrogen Sulfide - metabolism; Multi-carbon organics; Myricaceae - metabolism; Pseudomonas - metabolism; Sulfides - chemistry; Sunlight
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2018.10.031

[Display omitted] •Stand alone process with light energy as external energy source.•Photosynthesis mimicked in microbes via enabling light harvesting ability.•Nano inorganic hybrid on microbe surface facilitates electron transfer.•H2S as sulphur source resulted in the production of higher carbon chain length. Tandem bio-inorganic platform by combining efficient light harvesting properties of nano-inorganic semiconductor cadmium sulfide (CdS) with biocatalytic ability of electro-active bacteria (EAB) towards carbon dioxide (CO2) conversion is reported. Sulfur was obtained from either cysteine (EAB-Cys-CdS) or hydrogen sulfide (EAB-H2S-CdS) and experiments were carried out under similar conditions. Anchoring of the nano CdS cluster on the microbe surface was confirmed using electronic microscope. Bio-inorganic hybrid system was able to produce single and multi-carbon compounds from CO2 in visible spectrum (λ > 400 nm). Though, acetic acid was dominant (EAB-Cys-CdS, 1.46 g/l and EAB-H2S-CdS, 1.55 g/l) in both the microbe-CdS hybrids, its concentration as well as product slate varied significantly. EAB-H2S-CdS produced hexanoic acid and less methanol fraction, while the EAB-Cys-CdS produced no hexanoic acid along with almost double the concentration of methanol. Due to easy harvesting process, this bio-inorganic hybrid represents unique sustainable approach for solar-to-chemical production via CO2 transformation.