Photo-Fermentative Bacteria Used for Hydrogen Production

Abstract

Photo-fermentation is an efficient hydrogen production pathway in which purple non-sulfur bacteria (PNSB) play an active role and produce hydrogen as a part of their metabolism under optimal conditions. These bacteria work under the influence of light to advance their metabolism and use various substrates, such as simple sugars and volatile fatty acids, to produce hydrogen. This article presents a comparative review of several bacterial strains that have been efficiently used to produce hydrogen by photo-fermentation under different optimized conditions, including the substrate, its concentration, type and capacity of the bioreactor, light sources and intensities, and process conditions to achieve the maximum biohydrogen production rate. The analysis showed that the Rhodopseudomonas palustris is the main bacterium used for hydrogen production, with a maximum hydrogen production rate of 3.2 mM/h using 27.8 mM of glucose in a 165 mL serum bottle and 3.23 mM/h using 50 mM of glycerol at pH 7, followed by Rhodobacter sphaeroides, which gave a hydrogen production rate as high as 8.7 mM/h, using 40 mM of lactic acid, pH 7, and 30 °C temperature in a single-walled glass bioreactor. However, it is not preferred over R. palustris due to its versatile metabolism and ability to use an alternative mode if the conditions are not carefully adjusted, which can be a problem in hydrogen production.

Biohydrogen Production under Aerial Conditions by a Nitrogen-Fixing Bacterium Isolated from a Steel Signboard

“…The H 2 production rate in an Ar atmosphere was greater or equal for all strains cultured under aerial-phase conditions than was the case under liquid-phase conditions (Figure 3b). Although nitrogenases did not function in the Ar atmosphere and H 2 was produced by hydrogenase activity, the aerial-phase conditions were more efficient than the liquid-phase conditions because of the more uniform light exposure to bacterial cells in the former compared with that in the latter [8]. Comparing the results for N 2 and Ar gas, BRCNF002-004 displayed significantly (p < 0.05) greater H 2 production rates under both aerial-and liquid-phase conditions compared with those of the other strains.…”

“…Currently, the primary method of producing H 2 is steam reformation, which uses methane gas as its main reagent; this method relies on fossil fuels and thus does not solve the fundamental problem of fossil fuel use [4,5]. In a bioprocess using photosynthetic bacteria, H 2 can be produced by an enzymatic reaction that uses light as an energy source and an organic compound as an electron donor [6][7][8]. As such, this reaction has a low environmental impact.…”

“…H 2 production by algae uses water, which is an abundant resource on Earth, but the energy required to decompose water and form H 2 is large (∆G 0 ′ = −242 kJ/mol), and it is difficult to maintain anaerobic conditions because O 2 is produced by photosynthesis. In contrast, H 2 production by non-oxygen-evolving photosynthesis in red non-sulfur bacteria is energetically achievable; for example, ∆G 0 ′ = −25 kJ/mol for glucose [8]. Many bacterial species are also able to use various carbon sources as substrates for H 2 production, including starch and aromatic compounds [15].…”

An Updated Review of Recent Applications and Perspectives of Hydrogen Production from Biomass by Fermentation: A Comprehensive Analysis

“…Another essential genus is Enterobacter, with species such as Enterobacter aerogenes also contributing to hydrogen production under anaerobic conditions [63,232,233]. Photofermentation depends on solar energy to generate hydrogen, with phototrophic bacteria such as Rhodobacter sphaeroides and Rhodopseudomonas palustris leading this process [234][235][236]. These microorganisms work by capturing solar energy, allowing the transformation of organic substrates into hydrogen [232,235].…”

Valorization of Purple Phototrophic Bacteria Biomass Resulting from Photo Fermentation Aimed at Biohydrogen Production

“…The majority of literature studies on PPB have utilized pure cultures focusing on specific metabolic pathways (photo fermentation aimed at hydrogen production or photoorganoheterotrophy for biomass production). For instance, Rhodobacter and Rhodopseudomonas species, Rhodospirillum rubrum and Rhodovulum sulfidophilum, have been extensively studied for their ability to produce high rates (from 0.4 to 3.2 mM/h) of molecular hydrogen [5]. Rhodopseudomonas palustris and Rhodobacter capsulatus have been reported to produce PHAs from 30 to 90% of their CDW under photoorganoheterotrophic growth [6].…”