The regions suitable for growing cassava include five provinces in Southern China, with Guangxi alone accounting for over 65% of the total cassava production in the country. In this article, the state-of-the-art development of fuel ethanol production from cassava in China is illustrated by the construction of the cassava fuel ethanol plant with its annual production capacity of 200 000 metric tons. And in the meantime, problems and challenges encountered in the development of China's cassava fuel ethanol are highlighted and the strategies to address them are proposed.
Biofuels ; China ; Conservation of Energy Resources ; Ethanol ; metabolism ; Manihot ; metabolism

Functional improvement to one component of the cellulase, endo-beta-1, 4-glucanase, has been a focus of the recent research in this area. We report here the saturation mutagenesis of the active site of an endoglucanase (CfEG) from termite Coptotermes formosanus. First, three dimensional structure of CfEG was built via homology modeling by using a close-related (79% homology in sequence) endo-beta-1,4-glucanase (NtEG PDB id = 1ks8) from higher termite Nasutitermes takasagoensis as a template. Second, we identified three corresponding amino acid positions at the active site of CfEG by structural superposition onto NtEG. These three putative amino acids for the active site of CfEG, i.e., Asp53, Asp56 and Glu411, were subjected to saturation mutagenesis using degenerate primers. Among the mutants, Asp53Glu and Asp56Cys showed somewhow higher activities than the wildtype, with the latter having more than 3-fold decrease in Km. Double mutation Asp53Leu/Asp56IIe showed nearly 2-fold increase in specific activity and in the same time 2-fold decrease in Km. Saturation mutagenesis to the position Glu411 produced no active mutant, even changing Glu411 explicitly into its similar amino acids such as Glu411Asp and Glu411Gln could not result in any active mutant. These imply that position Glu411 could be extremely important and therefore indispensable for CfEG functionality.
Amino Acids ; genetics ; Animals ; Cellulase ; chemistry ; genetics ; metabolism ; Isoptera ; enzymology ; Mutagenesis, Site-Directed ; Mutation

Exploring excellent new pullulanase genes, and enriching pullulanase theory are of great importance to realize the industrialization of pullulanase. Three genes, pulA, pulB and pulC, encoding pullulanases, were cloned from Bacillus cereus GXBC-3 by bioinformatics analyzing the open reading frame in Bacillus cereus, annotated as putative I and II pullulanases in the GenBank database. Characteristics of these recombinant enzymes were inducible intracellular expressed in Escherichia coli, the results showed PulA was typical II pullulanase. Recombinant PulA could hydrolyze alpha-1,4- and alpha-1,6-glycosidic bonds. Its specific activity was 32.89 U/mg with an optimum temperature of 40 degrees C and optimum pH 6.5 using pullulan as substrate. And for soluble starch substrate, its specific activity was 25.71 U/mg with an optimum temperature of 50 degrees C and optimum pH 7.0. PulB and PulC were I pullulanases and only hydrolyzed alpha-1,6-glycosidic bond. The specific activities, optimum temperature and optimum pH of PulB and PulC for pullulan substrate were 228.54 U/mg, 45 degrees C, 7.0 and 229.65 U/mg, 45 degrees C, 6.5, respectively.
Bacillus cereus ; enzymology ; genetics ; Cloning, Molecular ; Escherichia coli ; Glucans ; metabolism ; Glycoside Hydrolases ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism

Objective:To analyze the differences in whole blood selenium (Se), zinc (Zn), copper (Cu), magnesium (Mg), calcium (Ca), and iron (Fe) levels of rural older adults among areas with different soil selenium levels, and explore the main factors associated with the six nutrient elements status, so as to provide a basis for further evaluating the health risks of people in areas with different soil selenium levels.Methods:Four administrative villages were randomly selected from the Se-deficient (soil Se content < 0.175 mg/kg), Se-sufficient (soil Se content 0.175 - < 0.400 mg/kg), Se-rich (soil Se content 0.400 - < 3.000 mg/kg) and Se-excessive (soil Se content ≥3.000 mg/kg) areas, respectively, in Enshi Tujia and Miao Autonomous Prefecture (Enshi Prefecture) of Hubei Province in 2017 - 2018. And 100 elderly people aged 60 years or older (half male and half female) were randomly selected as the survey subjects in each servey site. The basic information such as general demography and lifestyle was collected through face-to-face questionnaires. Physical examination was performed and fasting venous blood was collected in the morning. The contents of blood Se, Zn, Cu, Mg, Ca, and Fe were determined by inductively coupled plasma mass spectrometry. The main factors associated with the six nutrient elements status were analyzed.Results:A total of 416 subjects were included, including 208 males and 208 females, whose average age was (72.43 ± 5.25) years, and body mass index (BMI) was (22.67 ± 3.49) kg/m 2. There were significant differences of blood Se, Zn, Cu, Mg, Ca and Fe levels between the areas with different Se levels ( Z/F = 288.30, 3.24, 14.81, 29.14, 131.28, 3.37, P < 0.05). Compared with Se-deficient and Se-sufficient areas, blood Se level was higher in Se-rich and Se-excessive areas and blood Zn level was lower in Se-excessive area ( P < 0.05); compared with Se-sufficient area, blood Cu level was lower in Se-deficient, Se-rich and Se-excessive areas, but blood Mg and Ca levels were higher ( P < 0.05), and the blood Fe level was lower in Se-excessive area ( P < 0.05). There were significant differences in the deficiency rates of Se, Zn, Cu, Mg, Ca and Fe among the elderly in different Se level areas (χ 2 = 140.83, 15.39, 31.90, 17.49, 157.60, 30.33, P < 0.01). There were significant differences in blood Zn, Cu, Ca and Fe levels between two gender groups ( P < 0.05); the blood Zn and Fe levels of the smokers were higher than those of the non-smokers, and the blood Cu level was lower than that of the non-smokers ( P < 0.05); the blood Zn and Fe levels of the drinkers were higher than those of the non-drinkers ( P < 0.05). Conclusions:The levels of six nutrient elements in the whole blood of the elderly in areas with different soil Se levels are different. To assess the health risks of the population in areas with different soil Se levels, it is necessary to consider the levels of multiple nutrient elements at the same time.

【Objective】 To establish a routine screening method for unexpected antibodies of blood donors, analyze the results of centralized screening for unexpected antibody of blood donors in the blood center, and compare the cost of centralized and decentralized screening modes. 【Methods】 A total of 35 591 blood donors were screened for unexpected antibodies from March 31, 2021 to July 31, 2021, using microcolumn gel method. Unexpected antibody screening reactive samples were further confirmed by the Transfusion Research Institute of Shenzhen Blood Center, and the demographic characteristics were further determined through the analysis of unexpected antibody positive population. The direct cost and indirect cost of centralized and decentralized unexpected antibody screening mode were compared. 【Results】 Forty unexpected antibody positive samples were confirmed in Shenzhen, with the positive rate at 0.11%(40/35 591), among which MNS, Rh and Lewis system accounted for 35% (14/40), 32.5% (13/40) and 17.5% (7/40), respectively. Males and females accounted for 45% (18/40) and 55% (22/40), respectively (P<0.01). No significant difference was noticed by age and repeated-donor or not (P>0.05). Unexpected antibody screening in a centralized way saved about 1.16 million yuan per year. 【Conclusion】 It is necessary to carry out unexpected antibody screening for all blood donors, and centralized screening is more economical than decentralized screening.