Enhanced Biological Straw Saccharification Through Coculturing of Lignocellulose-Degrading Microorganisms

Abstract

Lignocellulosic waste (LCW) is an abundant, low-cost, and inedible substrate for the induction of lignocellulolytic enzymes for cellulosic bioethanol production using an efficient, environmentally friendly, and economical biological approach. In this study, 30 different lignocellulose-degrading bacterial and 18 fungal isolates were quantitatively screened individually for the saccharification of four different ball-milled straw substrates: wheat, rice, sugarcane, and pea straw. Rice and sugarcane straws which had similar Fourier transform-infrared spectroscopy profiles were more degradable, and resulted in more hydrolytic enzyme production than wheat and pea straws. Crude enzyme produced on native straws performed better than those on artificial substrates (such as cellulose and xylan). Four fungal and five bacterial isolates were selected (based on their high strawase activities) for constructing dual and triple microbial combinations to investigate microbial synergistic effects on saccharification. Combinations such as FUNG16-FUNG17 (Neosartorya fischeri-Myceliophthora thermophila) and RMIT10-RMIT11 (Aeromonas hydrophila-Pseudomonas poae) enhanced saccharification (3- and 6.6-folds, respectively) compared with their monocultures indicating the beneficial effects of synergism between those isolates. Dual isolate combinations were more efficient at straw saccharification than triple combinations in both bacterial and fungal assays. Overall, co-culturing can result in significant increases in saccharification which may offer significant commercial potential for the use of microbial consortia.

The rhizospheric microbial community structure and diversity of deciduous and evergreen forests in Taihu Lake area, China

“…The members of Acidobacteria produce a wide range of enzymes with high activities under acidic conditions, whereas most of them grow along a narrow carbon resource spectrum, including disaccharides and oligosaccharides produced by the decomposition of cellulose, chitin and starch [87, 88]. Similarly, the Proteobacteria group also plays a key role in organic matter decomposition [88–90] by producing many kinds of glycosyl hydrolases, such as cellulases, chitinases, xylanases and amylases [91–94], and then generating a large number of oligosaccharides and aromatic alcohols, which can be used as carbon resource by other bacteria, such as Acidobacteria . Overall, Acidobacteria may play an important ecological role by collaboration with other microorganisms (the members of Proteobacteria ) in the process of degrading polysaccharides of plant and fungal origin [88, 95].…”

Lignin Degradation by Fungal Pretreatment: A Review

“…In a study, pre-treatment of wheat straw for five weeks by Pleurotus ostreatus (white rot fungi) has reduced lignin in the original wheat straw about 34%, but in the un-treated samples only 12% lignin reduction occurred [30]. It has shown by Taha et al [7] that straw digestibility with fungal pre-treatment is more effective than bacteria pre-treatment. The outcome of this study exhibit that gene actions of fungal were two-fold more than those from bacteria.…”

“…Rice straw Trichoderma viride 56% of lignin reduction [29] Poplar wood White rot fungus 85% of lignin removal [6] Wheat straw white rot fungi (Pleurotus ostreatus) 35% of lignin reduction [30] Rice, wheat, sugarcane, and pea straw Fungal consortium 6.6-folds increase in saccharification [7] Eucalyptus grandis saw dust…”

“…Most physical and chemical pre-treatment using acid, alkali, processes require special instrument and consume a lot of energy and generate inhibitors which will affect enzymatic hydrolysis and fermentation [5]. Many researches displayed that biological pretreatment such as bacteria, fungus (white-, brown-, and soft-rot fungi), deuteromycetes and ascomycetes can enhance the hydrolysis productivity because of generating low inhibitors and limited energy utilization [6][7][8]. Furthermore, biological pretreatment compared to other pretreatment process such as organosolvant and ammonium fiber explosion (AFEX) is considered as cheap process and have been less investigated [9].…”

Optimization of laccase production and its application in delignification of biomass

“…Currently, production of biofuels such as cellulosic bioethanol is a challenging task due to the bottle necks related to the saccharification process (Taha et al 2015). The complex recalcitrant structure of lignocellulose comprises of cellulose, hemicelluloses and lignin.…”