Microbial ecology of fermentative hydrogen producing bioprocesses: useful insights for driving the ecosystem function

Abstract

One of the most important biotechnological challenges is to develop environment friendly technologies to produce new sources of energy. Microbial production of biohydrogen through dark fermentation, by conversion of residual biomass, is an attractive solution for short-term development of bioH2 producing processes. Efficient biohydrogen production relies on complex mixed communities working in tight interaction. Species composition and functional traits are of crucial importance to maintain the ecosystem service. The analysis of microbial community revealed a wide phylogenetic diversity that contributes in different-and still mostly unclear-ways to hydrogen production. Bridging this gap of knowledge between microbial ecology features and ecosystem functionality is essential to optimize the bioprocess and develop strategies toward a maximization of the efficiency and stability of substrate conversion. The aim of this review is to provide a comprehensive overview of the most up-to-date biodata available and discuss the main microbial community features of biohydrogen engineered ecosystems, with a special emphasis on the crucial role of interactions and the relationships between species composition and ecosystem service. The elucidation of intricate relationships between community structure and ecosystem function would make possible to drive ecosystems toward an improved functionality on the basis of microbial ecology principles.

Economic Viability and Environmental Efficiency Analysis of Hydrogen Production Processes for the Decarbonization of Energy Systems

“…These pathways generate byproducts, and the enzymes combine these byproducts to produce hydrogen. Researchers are paying adequate attention to improve the yield (using the same amount of organic matter) and the speed of hydrogen production from fermentation [58]. In fact, the yield has been improved.…”

Work scheme to isolate the different micro-organisms found in hydrogen-producing reactors: a study of effectiveness by pyrosequencing analysis

“…; Cabrol et al . ). The role of the nonhydrogen‐producing micro‐organisms is not clear, they have been associated with negative aspects such as competition for substrate or production of inhibitors (such as bacteriocines), but they may also be involved in consumption of dissolved oxygen, which generates a favourable atmosphere for strict anaerobes (Hung et al .…”

“…; Cabrol et al . ), it is possible to conclude that microbial communities in hydrogen‐producing reactors are composed of four different physiological groups of micro‐organisms: anaerobic spore‐forming fermenters (such as Clostridium ), anaerobic fermenters that do not form spores (such as members of the Veillonelaceae family), facultative aerobic fermenters (such as members of Enterobacteriaceae and other Proteobacteria) and lactic acid bacteria (such as Lactobacillus ). Based on the physiological characteristics of these four groups of micro‐organisms described by Bergey et al .…”

“…The microbes from hydrogen-producing reactors are mainly composed of hydrogenic micro-organisms, such as Clostridium and members of the Enterobacteriaceae family, and other micro-organisms with metabolic pathways that are not associated with hydrogen production (Hung et al 2011;Cabrol et al 2017). The role of the nonhydrogen-producing micro-organisms is not clear, they have been associated with negative aspects such as competition for substrate or production of inhibitors (such as bacteriocines), but they may also be involved in consumption of dissolved oxygen, which generates a favourable atmosphere for strict anaerobes (Hung et al 2011).…”

“…Based on our previous experience (Castell o et al 2009;Perna et al 2013;Etchebehere et al 2016) and the work of other researchers (Hung et al 2011;Elsharnouby et al 2013;Cabrol et al 2017), it is possible to conclude that microbial communities in hydrogen-producing reactors are composed of four different physiological groups of micro-organisms: anaerobic spore-forming fermenters (such as Clostridium), anaerobic fermenters that do not form spores (such as members of the Veillonelaceae family), facultative aerobic fermenters (such as members of Enterobacteriaceae and other Proteobacteria) and lactic acid bacteria (such as Lactobacillus). Based on the physiological characteristics of these four groups of microorganisms described by Bergey et al (2009), it is possible to select specific methods to isolate them from hydrogenproducing reactor samples.…”