Effect of carbon sources on the aggregation of photo fermentative bacteria induced by L-cysteine for enhancing hydrogen production

Abstract

Poor flocculation of photo fermentative bacteria resulting in continuous biomass washout from photobioreactor is a critical challenge to achieve rapid and stable hydrogen production. In this work, the aggregation of Rhodopseudomonas faecalis RLD-53 was successfully developed in a photobioreactor and the effects of different carbon sources on hydrogen production and aggregation ability were investigated. Extracellular polymeric substances (EPS) production by R. faecalis RLD-53 cultivated using different carbon sources were stimulated by addition of L-cysteine. The absolute ζ potentials of R. faecalis RLD-53 were considerably decreased with addition of L-cysteine, and aggregation barriers based on DLVO dropped to 15-43 % of that in control groups. Thus, R. faecalis RLD-53 flocculated effectively, and aggregation abilities of strain RLD-53 cultivated with acetate, propionate, lactate and malate reached 29.35, 32.34, 26.07 and 24.86 %, respectively. In the continuous test, hydrogen-producing activity was also promoted and reached 2.45 mol H/mol lactate, 3.87 mol H/mol propionate and 5.10 mol H/mol malate, respectively. Therefore, the aggregation of R. faecalis RLD-53 induced by L-cysteine is independent on the substrate types, which ensures the wide application of this technology to enhance hydrogen recovery from wastewater dominated by different organic substrates.

Application of Nanotechnology in the Production of Biohydrogen: A Review

“…The lack of carbon sources (malic acid and lactic acid) was not effective for the synthesis of H 2 by a photofermentative process in the presence of PNSB. Hence, the substrate enriched in carbon is highly beneficial for the production of H 2 through the photofermentative process [91,92].…”