Guotao Mao

Bio: Guotao Mao is an academic researcher from Henan Agricultural University. The author has contributed to research in topics: Lignocellulosic biomass & Chemistry. The author has an hindex of 3, co-authored 7 publications receiving 31 citations.

Biochemical properties of GH94 cellodextrin phosphorylase THA_1941 from a thermophilic eubacterium Thermosipho africanus TCF52B with cellobiose phosphorylase activity

Abstract: A hypothetic gene (THA_1941) encoding a putative cellobiose phosphorylase (CBP) from Thermosipho africanus TCF52B has very low amino acid identities (less than 12%) to all known GH94 enzymes. This gene was cloned and over-expressed in Escherichia coli BL21(DE3). The recombinant protein was hypothesized to be a CBP enzyme and it showed an optimum temperature of 75 °C and an optimum pH of 7.5. Beyond its CBP activity, this enzyme can use cellobiose and long-chain cellodextrins with a degree of polymerization of greater than two as a glucose acceptor, releasing phosphate from glucose 1-phosphate. The catalytic efficiencies (k cat/K m) indicated that cellotetraose and cellopentaose were the best substrates for the phosphorolytic and reverse synthetic reactions, respectively. These results suggested that this enzyme was the first enzyme having both cellodextrin and cellobiose phosphorylases activities. Because it preferred cellobiose and cellodextrins to glucose in the synthetic direction, it was categorized as a cellodextrin phosphorylase (CDP). Due to its unique ability of the reverse synthetic reaction, this enzyme could be a potential catalyst for the synthesis of various oligosaccharides. The speculative function of this CDP in the carbohydrate metabolism of T. africanus TCF52B was also discussed.

Availability of lignocellulose from forestry waste for use as a biofuel in China.

Abstract: Biomass is a very important renewable energy and plays an important role in the energy structure of China. Here, the role of forestry waste in producing energy in China was analyzed and the availability of forestry waste for biofuel production, theoretically collectable amounts of forest biomass, and density of forestry waste were assessed. Agricultural and forestry waste are important biomass resources. The potential for using forestry waste as a low cost substrate for producing fuel ethanol using existing forestry resources and techniques was analyzed, and the feasibility of producing fuel ethanol in different Chinese provinces was assessed using the specific situation for each province. The results showed that 1081.73 × 106 t of forestry waste could be produced in China, and 270.43 × 106 t (25% of the amount that could be collected) could be used to produce fuel ethanol. Assuming 10 t of sawdust could be converted into 1 t of ethanol, 27 × 106 t of ethanol could be produced from forestry waste. Different provinces have different potentials for producing ethanol from forestry waste, Guangdong Province, Guangxi Province, Sichuan Province, and Yunnan Province having higher potentials than the other provinces. It was predicted that 4478 × 106 t of fuel ethanol could be produced from woodcraft waste by 2020, and the provinces with the most potential were found to be Fujian Province, Heilongjiang Province, Jilin Province, Shanxi Province, Sichuan Province, Xinjiang Province, and Yunnan Province. Using forestry waste to produce ethanol could alleviate the energy shortage in China.

Reassessment of the role of CaCO3 in n-butanol production from pretreated lignocellulosic biomass by Clostridium acetobutylicum.

Abstract: In this study, the role of CaCO3 in n-butanol production was further investigated using corn straw hydrolysate (CSH) media by Clostridium acetobutylicum CICC 8016. CaCO3 addition stimulated sugars utilization and butanol production. Further study showed that calcium salts addition to CSH media led to the increase in Ca2+ concentration both intracellularly and extracellularly. Interestingly, without calcium salts addition, intracellular Ca2+ concentration in the synthetic P2 medium was much higher than that in the CSH medium despite the lower extracellular Ca2+ concentrations in the P2 medium. These results indicated that without additional calcium salts, Ca2+ uptake by C. acetobutylicum CICC 8016 in the CSH medium may be inhibited by non-sugar biomass degradation compounds, such as furans, phenolics and organic acids. Comparative proteomics analysis results showed that most enzymes involved in glycolysis, redox balance and amino acids metabolism were up-regulated with CaCO3 addition. This study provides further insights into the role of CaCO3 in n-butanol production using real biomass hydrolysate.

A comprehensive state-of-technology review for upgrading bio-oil to renewable or blended hydrocarbon fuels

Abstract: Bioenergy sources are being advanced as a meaningful environmental solution and a substitute for conventional energy sources. Bioenergy from biomass feedstocks currently comprises the largest portion of renewables in the United States. Thus, more effective process-level solutions can result in scaling-up biomass-derived energy production (e.g., biofuels). Pyrolysis, a thermochemical conversion technology, offers a commercially viable pathway to produce bio-oil from a wide range of biomass feedstocks (e.g., algae and terrestrial). Bio-oil requires further upgrading to produce final bioproducts (e.g., transportation fuels and biochemicals). This article focuses on the upgrading of bio-oil to transportation fuels (liquid hydrocarbons), highlights the critical challenges of existing upgrading technologies, and identifies the potential research directions to meet the market needs. A comprehensive overview and classification of bio-oil upgrading pathways and their competencies are presented through both comparative and systematic literature reviews. It is concluded that the biofuel production cost is highly dependent on post-conversion pathways, particularly their hydrogenation and deoxygenation capacity. Thermochemical treatments are effective, but less cost-competitive due to the intensive process requirements (e.g., heat or pressure). Biochemical treatments are inadequate as a standalone process for upgrading bio-oil. Physicochemical treatments are less effective, however, they operate under mild process conditions and could be integrated with other treatments. It is further concluded that the electrochemical approach can be effective due to the retention of hydrogen from bio-oil water content during deoxygenation.

Steam explosion of lignocellulosic biomass for multiple advanced bioenergy processes: A review

Abstract: The utilization of lignocellulosic biomass to produce fuels and chemicals is an effective way to gradually relieve the global threats of petroleum exhaustion and climate change. However, the recalcitrant nature and complex structure of biomass have become the biggest obstacle for utilization during the bioenergy conversion processes. Steam explosion, a mild and fast treatment process integrating the high-temperature autohydrolysis and structural disruption by explosive decompression, has been proven as an effective, environment-friendly and industrially scalable method for biomass pretreatment, which can significantly improve the fuel properties and processability of the feedstock, for several bioenergy conversion techniques. This article aimed at reviewing the impact of steam explosion pretreatment on the bioenergy conversion processes and product properties. Based on those findings in the literature, a steam explosion step is beneficial to subsequent conversion processes of biomass, including densification, hydrolysis, fermentation, pyrolysis and gasification, by improving biomass properties such as durability, heating value and cellulose accessibility. Improved yields and properties of final products in solid (e.g. pellet fuel, biochar), liquid (e.g. bio-oil, bioethanol, biobutanol) and gaseous (e.g. syngas, biogas) states were also analyzed. Overall, this review provided a historical and comprehensive understanding of how the steam explosion benefits the subsequent bioenergy conversion process and product quality.

Steam explosion of lignocellulosic biomass for multiple advanced bioenergy processes: A review

Abstract: The utilization of lignocellulosic biomass to produce fuels and chemicals is an effective way to gradually relieve the global threats of petroleum exhaustion and climate change. However, the recalcitrant nature and complex structure of biomass have become the biggest obstacle for utilization during the bioenergy conversion processes. Steam explosion, a mild and fast treatment process integrating the high-temperature autohydrolysis and structural disruption by explosive decompression, has been proven as an effective, environment-friendly and industrially scalable method for biomass pretreatment, which can significantly improve the fuel properties and processability of the feedstock, for several bioenergy conversion techniques. This article aimed at reviewing the impact of steam explosion pretreatment on the bioenergy conversion processes and product properties. Based on those findings in the literature, a steam explosion step is beneficial to subsequent conversion processes of biomass, including densification, hydrolysis, fermentation, pyrolysis and gasification, by improving biomass properties such as durability, heating value and cellulose accessibility. Improved yields and properties of final products in solid (e.g. pellet fuel, biochar), liquid (e.g. bio-oil, bioethanol, biobutanol) and gaseous (e.g. syngas, biogas) states were also analyzed. Overall, this review provided a historical and comprehensive understanding of how the steam explosion benefits the subsequent bioenergy conversion process and product quality.

Physical and Chemical Methods for Reduction in Aflatoxin Content of Feed and Food.

Abstract: Aflatoxins (AFs) are among the most harmful fungal secondary metabolites imposing serious health risks on both household animals and humans. The more frequent occurrence of aflatoxins in the feed and food chain is clearly foreseeable as a consequence of the extreme weather conditions recorded most recently worldwide. Furthermore, production parameters, such as unadjusted variety use and improper cultural practices, can also increase the incidence of contamination. In current aflatoxin control measures, emphasis is put on prevention including a plethora of pre-harvest methods, introduced to control Aspergillus infestations and to avoid the deleterious effects of aflatoxins on public health. Nevertheless, the continuous evaluation and improvement of post-harvest methods to combat these hazardous secondary metabolites are also required. Already in-use and emerging physical methods, such as pulsed electric fields and other nonthermal treatments as well as interventions with chemical agents such as acids, enzymes, gases, and absorbents in animal husbandry have been demonstrated as effective in reducing mycotoxins in feed and food. Although most of them have no disadvantageous effect either on nutritional properties or food safety, further research is needed to ensure the expected efficacy. Nevertheless, we can envisage the rapid spread of these easy-to-use, cost-effective, and safe post-harvest tools during storage and food processing.