Developing a Microbial Consortium for Enhanced Metabolite Production from Simulated Food Waste

Abstract

Food waste disposal and transportation of commodity chemicals to the point-of-need are substantial challenges in military environments. Here, we propose addressing these challenges via the design of a microbial consortium for the fermentation of food waste to hydrogen. First, we simulated the exchange metabolic fluxes of monocultures and pairwise co-cultures using genome-scale metabolic models on a food waste proxy. We identified that one of the top hydrogen producing co-cultures comprised Clostridium beijerinckii NCIMB 8052 and Yokenella regensburgei ATCC 43003. A consortium of these two strains produced a similar amount of hydrogen gas and increased butyrate compared to the C. beijerinckii monoculture, when grown on an artificial garbage slurry. Increased butyrate production in the consortium can be attributed to cross-feeding of lactate produced by Y. regensburgei. Moreover, exogenous lactate promotes the growth of C. beijerinckii with or without a limited amount of glucose. Increasing the scale of the consortium fermentation proved challenging, as two distinct attempts to scale-up the enhanced butyrate production resulted in different metabolic profiles than observed in smaller scale fermentations. Though the genome-scale metabolic model simulations provided a useful starting point for the design of microbial consortia to generate value-added products from waste materials, further model refinements based on experimental results are required for more robust predictions.

Dynamics and Complexity of Dark Fermentation Microbial Communities Producing Hydrogen From Sugar Beet Molasses in Continuously Operating Packed Bed Reactors

“…The stimulating effect of cross-feeding of lactate on hydrogen synthesis was also observed in co-cultures of two bacterial strains: the butyrate- and hydrogen-producing Clostridium beijerinckii and the lactate-producer Yokenella regensburgei ( Schwalm et al, 2019 ) or the hydrogen- and lactate-producing Bacillus cereus and the hydrogen- and butyrate-producing Brevundimonas naejangsanensis ( Wang et al, 2019 ).…”

Dynamics of dark fermentation microbial communities in the light of lactate and butyrate production

“…Studies on thermophilic DF of sugarcane vinasse also showed lactate as the primary substrate for biohydrogen production and the relevance of pH in this process [24,25]. Cross-feeding of lactate was also observed in reduced MCs composed of two components: butyrate-producing Clostridium beijerinckii and lactateproducer Yokenella regensburgei [26] or butyrateproducing Clostridium butyricum and lactate-producer Sporolactobacillus vineae [27]. Furthermore, pure cultures of Clostridium acetobutylicum [28], Butyribacterium methylotrophicum [29], Clostridium diolis [30], Clostridium butyricum [18] and Clostridium tyrobutyricum [31,32] anaerobically grown in media with acetate and lactate as exclusive carbon sources produced carbon dioxide, hydrogen and butyrate.…”

Dynamics of Dark Fermentation Microbial Communities in the Light of Lactate and Butyrate Production

“…Studies on thermophilic dark fermentation of sugarcane vinasse also showed lactate as the primary substrate for biohydrogen production and relevance of pH in this process [24,25]. Cross-feeding of lactate was also observed in reduced microbial communities composed of two components: butyrateproducing Clostridium beijerinckii and lactate-producer Yokenella regensburgei [26]. Furthermore, pure cultures of Clostridium acetobutylicum [27], Butyribacterium methylotrophicum [28], Clostridium diolis [29], Clostridium buttyricum [18] and Clostridium tyrobutyricum [30,31] anaerobically grown in media with acetate and lactate as exclusive carbon sources produced carbon dioxide, hydrogen and butyrate.…”