Fungal-mediated consolidated bioprocessing: the potential of Fusarium oxysporum for the lignocellulosic ethanol industry

Abstract

Microbial bioprocessing of lignocellulose to bioethanol still poses challenges in terms of substrate catabolism. The most important challenge is to overcome substrate recalcitrance and to thus reduce the number of steps needed to biorefine lignocellulose. Conventionally, conversion involves chemical pretreatment of lignocellulose, followed by hydrolysis of biomass to monomer sugars that are subsequently fermented into bioethanol. Consolidated bioprocessing (CBP) has been suggested as an efficient and economical method of manufacturing bioethanol from lignocellulose. CBP integrates the hydrolysis and fermentation steps into a single process, thereby significantly reducing the amount of steps in the biorefining process. Filamentous fungi are remarkable organisms that are naturally specialised in deconstructing plant biomass and thus they have tremendous potential as components of CBP. The fungus Fusarium oxysporum has potential for CBP of lignocellulose to bioethanol. Here we discuss the complexity and potential of CBP, the bottlenecks in the process, and the potential influence of fungal genetic diversity, substrate complexity and new technologies on the efficacy of CPB of lignocellulose, with a focus on F. oxysporum.

Transformation of Lignocellulosic Biomass into Sustainable Biofuels: Major Challenges and Bioprocessing Technologies

“…Consolidated Bioprocessing (CBP) employs the process of integrating hydrolysis and fermentation steps into a single step, resulting in a significant reduction of steps in the refining process (Ali et al, 2016). The goal of CBP is to reduce four basic steps of biomass conversion to single one step in one bioreactor using a single microbe or microbial consortium, converting biomass to biofuels without adding saccharolytic enzymes (van Zyl et al, 2011).…”

Evolution toward the utilization of mango leaves as lignocellulosic material in bioethanol production: A review of process parameter and integrated technologies

“…Although genetic modification have improved the ability of the microorganisms to perform in CBP, this process is still indoubt due to various difficulties faced during the gene transfer phase . The complications include improper folding of several secretory proteins and adverse effects on cell performance due to co‐expression of multiple heterologous genes . Thus, it is very much essential to overcome those challenges for the development of an efficient CBP.…”

“…90,93 The complications include improper folding of several secretory proteins and adverse effects on cell performance due to co-expression of multiple heterologous genes. 94 Thus, it is very much essential to overcome those challenges for the development of an efficient CBP.…”

New approaches in bioprocess‐control: Consortium guidance by synthetic cell‐cell communication based on fungal pheromones

“…However, a recent example illustrates that pheromone‐controlled cell‐cell communication might be implementable even in the absence of full sexual development. Although a functional sexual cycle has not been observed in the plant pathogen Fusarium oxysporum (a promising host for lignocellulosic ethanol production ), this fungus encodes a functional pheromone receptor responsive to both mating pheromones and plant‐derived signal molecules . Hence, if ligands can be identified and secreted by engineered sender cells in a controlled manner, the presence of functional receptors and downstream signaling compounds might be fully sufficient for interfacing these fungi with pheromone‐based communication devices.…”

“…Hundreds of fungal species are currently under investigation or in use for commercial production of these compounds [11], although the fraction of employed fungi is still surprisingly small, considering that 1.5-5 million fungal species may exist [13]. In several applications and fermentation strategies, these fungi might clearly outperform the commonly employed strains of the model yeast Saccharomyces cerevisiae (S. cerevisiae), due to elevated temperature tolerance, resistance against osmotic and ethanol stress, fermentation efficiency and yield as well as tolerance against fermentation inhibitors [14][15][16][17]. Consequently, numerous consortiumbased approaches consisting of multiple fungal species [18][19][20], fungi and bacteria [21][22][23][24][25][26][27][28] as well as fungi and algae [29], covering a wide range of applications, have been reported.…”