Co-culture strategies for increased biohydrogen production

Abstract

SUMMARYBiological hydrogen production from organic wastes is a less expensive, less energy-demanding, and environmentalfriendly process. Pure monoculture delivers low H 2 content and low yield; these limitations are overcome by a defined co-culture system, which outperforms mixed cultures with increased H 2 yield. The strategies used in co-culture systems for increasing H 2 production have been discussed in this review. The strategies include hydrolysis of a variety of complex substrates, such as cellulose, molasses, crude glycerol, and algal biomass into simple fermentable sugars for increased H 2 yield by eliminating the use of exogenous enzymes. The strategies can bring geographically distant isolated microorganisms from different sources to coexist for simultaneous utilization of substrate and end metabolites into H 2 production of 99.99% purity without the expenses of reducing agents. In the case of maximum hydrogen production using co-culture strategies, Clostridium, Enterobacter, and photo-fermenting bacteria in a consolidated bioprocess system will result in increased H 2 yield. A co-culture system is more feasible to achieve theoretical H 2 yield with high conversion efficiency of organic wastes, enhance the economic viability of H 2 production, provide better effluent treatment quality, and concurrently address the limitations of H 2 production.

Different types of H 2 photoproduction by starch-utilizing co-cultures of Clostridium butyricum and Rhodobacter sphaeroides

“…In this case, similarly, the H 2 production by co-culture at 24 С was suppressed as compared to 30 С ( Fig. 2B; Curves 4,5). In monoculture of C butirycum at 24 С (as compared to 30 С) the H 2 production rate was lower during initial two days, but at 4th day the H 2 yield was the same (Fig.…”

“…Effect of YE concentration on H 2 photoproduction at pH 7.3 (A) and 6.7 (B) by Clostridia monoculture (1, 4) and coculture of C. butyricum and R. sphaeroides with initial Bchl content 0.10 ± 0.01(2,5) or 0.86 ± 0.14 mg/L(3,6).…”

Biohydrogen production by co-fermentation of crude glycerol and apple pomace hydrolysate using co-culture of Enterobacter aerogenes and Clostridium butyricum

“…Biological hydrogen production through dark fermentation is less expensive, economically friendly, coupling energy production with waste treatment and is one of the sustainable methods of hydrogen production (Gilroyed et al, 2010;Pachapur et al, 2015b).…”

Seed Pretreatment for Increased Hydrogen Production Using Mixed-Culture Systems with Advantages over Pure-Culture Systems

“…Heat-treatment varies with substrates; in the case of carbohydrates, there is an improvement in hydrogen production, however, in presence of hemicellulose, lignin and cellulose, the mixed-culture consumed the produced hydrogen. The complexity of substrate and non-availability of simple sugars diverts the metabolic pathway of mixed-culture towards solvent production resulting in decreased hydrogen production [58]. Similarly, seed inocula such as cow dung, sewage sludge, and solid waste require additional pretreatment steps to improve their hydrogen production.…”

“…Microbial identification and their community structures need to be determined to qualitatively define the pretreatment methods and conditions to increase hydrogen production [126]. Most of the microbial analysis are studied by collecting the seed inoculum samples, isolating the genomic DNA and by common freeze-thaw methods [58]. After DNA extraction, PCR amplification of the V3 region of 16sDNA was performed by using a universal primer set [127].…”