Special Issue: “Peter Biely, A Pioneering Researcher in the Enzymology of Plant Biomass Degradation”

As it has been outlined on the website of the Special Issue entitled “Peter Biely, a pioneering researcher in the enzymology of plant biomass degradation” in the journal Molecules (section Macromolecular Chemistry, ISSN 1420-3049), plant biomass is a key renewable resource [...]

Harnessing microbial wealth for lignocellulose biomass valorization through secretomics: a review

The recalcitrance of lignocellulosic biomass is a major constraint to its high-value use at industrial scale. In nature, microbes play a crucial role in biomass degradation, nutrient recycling and ecosystem functioning. Therefore, the use of microbes is an attractive way to transform biomass to produce clean energy and high-value compounds. The microbial degradation of lignocelluloses is a complex process which is dependent upon multiple secreted enzymes and their synergistic activities. The availability of the cutting edge proteomics and highly sensitive mass spectrometry tools make possible for researchers to probe the secretome of microbes and microbial consortia grown on different lignocelluloses for the identification of hydrolytic enzymes of industrial interest and their substrate-dependent expression. This review summarizes the role of secretomics in identifying enzymes involved in lignocelluloses deconstruction, the development of enzyme cocktails and the construction of synthetic microbial consortia for biomass valorization, providing our perspectives to address the current challenges.

Transcriptional Regulation of Plant Biomass Degradation and Carbohydrate Utilization Genes in the Extreme Thermophile Caldicellulosiruptor bescii

To develop functional metabolic engineering platforms for nonmodel microorganisms, a comprehensive understanding of the physiological and metabolic characteristics is critical. Caldicellulosiruptor bescii and other species in this genus have untapped potential for conversion of unpretreated plant biomass into industrial fuels and chemicals. The highly interactive and complex machinery used by C. bescii to acquire and process complex carbohydrates contained in lignocellulose was elucidated here to complement related efforts to develop a metabolic engineering platform with this bacterium.

Enhanced CH4 Production from Corn Stover by Simultaneous Lime Treatment

Calcium hydroxide (lime) treatment and solid-state anaerobic digestion (SSAD) of corn stover (CS) were carried out simultaneously with different lime doses (0, 2, 3.5, and 5%) and feedstock to seed sludge (F/S) ratios (6, 8, and 10). It was found that the addition of 3.5% lime improved CH4 yield from 118 mL/g VS to 182 mL/g VS (54% increase) during SSAD of CS when F/S ratio was at 6. The improved CH4 production is consistent with increased relative abundance of several microbes that might play important roles in biomass degradation and CH4 generation. At higher F/S ratios (8 and 10), SSADs with different lime doses (0–5%) were all upset with accumulation of volatile fatty acids. Addition of 3.5% lime can obtain a net benefit of $18.4/tonne TS which are 44% of the gross benefit of power production ($41.5/tonne TS) via SSAD of CS and combined heat and power system.

Characterization of Feruloyl Esterase from Bacillus pumilus SK52.001 and Its Application in Ferulic Acid Production from De-Starched Wheat Bran

Feruloyl esterase (FAE; EC 3.1.1.73) catalyzes the hydrolysis of the 4-hydroxy-3-methoxycinnamoyl group in an esterified sugar to assist in waste biomass degradation or to release ferulic acid (FA). An FAE-producing strain was isolated from humus soil samples and identified as Bacillus pumilus SK52.001. The BpFAE gene from B. pumilus SK52.001 was speculated and heterogeneously expressed in Bacillus subtilis WB800 for the first time. The enzyme exists as a monomer with 303 amino acids and a molecular mass of 33.6 kDa. Its specific activity was 377.9 ± 10.3 U/ (mg protein), using methyl ferulate as a substrate. It displays an optimal alkaline pH of 9.0, an optimal temperature of 50 °C, and half-lives of 1434, 327, 235, and 68 min at 50, 55, 60, and 65 °C, respectively. Moreover, the purified BpFAE released 4.98% FA of the alkali-acidic extractable FA from de-starched wheat bran (DSWB). When the DSWB was enzymatically degraded by the synergistic effect of the BpFAE and commercial xylanase, the FA amount reached 49.47%. It suggested that the alkaline BpFAE from B. pumilus SK52.001, which was heterologously expressed in B. subtilis WB800, possesses great potential for biomass degradation and achieving high-added value FA production from food by-products.