Novel clostridial fusants in comparison with co-cultured counterpart species for enhanced production of biobutanol using green renewable and sustainable feedstock

Abstract

In this work, biobutanol was produced through simultaneous saccharification and fermentation (SSF) of wheat straw (WS) that traditionally produces acetone, butanol and ethanol solvents (ABE). Thermal stability was imparted to two mesophilic clostridial wild strains (Clostridium beijerinckii and Clostridium acetobutylicum) through protoplast fusion with that of a corresponding thermophilic clostridial species (Clostridium thermocellum). Production was pursued by the fused strains at 45 °C compared to that of the corresponding co-cultures at 35 °C. Results showed that the fused strains generally achieved higher production at 45 °C than that of the corresponding co-cultures at 35 °C. Highest butanol production of 13.82 g/L was recorded with C. beijerinckii fusant, with ABE solvents production of 23 g/L (yields of 0.17 and 0.57, respectively). Total sugar consumption of this strain was the highest among all strains and was 84%. Fused strains also showed immense level of tolerance towards butanol toxicity compared to the wild strains. Filter paper enzyme assay demonstrated that fused strains were able to produce cellulolytic enzymes in the range of 58.73-68.52 FPU/ml. Cellulosome producing C. thermocellum and its ability to ferment sugars offers a promising future in biofuels through eliminating the need to add external enzymes. Generally, productions reported in the present study were higher than literature where biobutanol stripping systems were employed to eliminate toxicity during production. This demonstrates a clear potential for improving productivity and yield at a larger-scale facility.

Current progress on engineering microbial strains and consortia for production of cellulosic butanol through consolidated bioprocessing

“…This is particularly advantageous in the case of complex phenotypic traits and generates fusant strains whose application is not subject to limitations that regard genetically modified organisms (Chen et al, 2020 ). Recently, fusants derived from solventogenic C. acetobutylicum ATCC 4259 or C. beijerinckii ATCC BA101 and cellulolytic C. thermocellum ATCC 27405 have been obtained and tested for their ability to directly ferment dilute sulphuric acid‐pretreated wheat straw (Begum & Dahman, 2015 ; Syed & Dahman, 2015 ). This pretreatment is expected to partially hydrolyze the lignocellulosic biomass, especially the hemicellulosic component but leaves unhydrolyzed a significant part of polysaccharides (Begum & Dahman, 2015 ).…”

“… Artificial microbial consortia of (hemi)cellulolytic and solvent‐producing strains (Jiang et al, 2020 ; Wen et al, 2017 ). Development of strains through the fusion of protoplasts of (hemi)cellulolytic and solvent‐producing microorganisms (Begum & Dahman, 2015 ; Syed & Dahman, 2015 ). Engineering (hemi)cellulolytic and/or butanol‐producing phenotype in other suitable microbial paradigms (e.g., showing high genetic tractability or high butanol tolerance) (Shen et al, 2011 ; Zhang et al, 2018 ).…”

“…Development of strains through the fusion of protoplasts of (hemi)cellulolytic and solvent‐producing microorganisms (Begum & Dahman, 2015 ; Syed & Dahman, 2015 ).…”

Enhancing Downstream Processing Of Algal-Based Biofuel Using Novel Fused Bacteria And Green Solvents

“…Previous work conducted in the Nanocomposites and Biomaterials Lab at Ryerson University developed novel fusants using the protoplast fusion technique. The fusion process has been described by Thermal and Dahman (2011), Begum and Dahman, (2015), Syed and Dahman (2015), and Ferhan and Dahman (2016). The protoplast fusion process is comprised of three main steps which included protoplast formation, fusion, and cell wall regeneration (Kao and Michayluk, 1974).…”

Editorial: Microorganisms for Consolidated 2nd Generation Biorefining

“…Yarrowia lipolytica, S. cerevisiae) (Willson et al, 2016;Guo et al, 2018;Stern et al, 2018;Tang et al, 2018;Anandharaj et al, 2020). In addition, promising results have recently been reported by fusion of protoplasts of cellulolytic and compound-producing (i.e., butanol) microorganisms (Begum and Dahman, 2015;Syed and Dahman, 2015) or by biomass fermentation by using natural lignocellulose-degrading microbial communities such as the microbiota of herbivore rumen or termite gut (Auer et al, 2017;Liu et al, 2021;Rajeswari et al, 2021).…”