Papers by Author: Zhong Ming Wang

Abstract: Acquisition of lipids mainly in a form of triacylglycerol from microalgae is a potential way for biofuels production. Many unicellular microalgae make little triacylglycerol under favorable growth condition, but accumulate large amounts of it under environmental stress conditions (e.g., nutrient depletion, high light). In this paper, the green microalgae Chlamydomonas reinhardtii BAFJ5 was used as a model to study production of lipid bodies (LBs) which are important lipid storage organelles, particularly under stress. We discovered LBs accumulated dramatically when cells were grown in nitrogen-deplete medium. Using fluorescent microscopy and confocal laser scanning microscopy, intracellular LBs can be successfully visualized. The number and size of LBs were also quantified.

Abstract: Transesterification of soybean oil with methanol to methyl eaters was found proceed in the presence of KOH loaded on five different oxides (CaO, MgO, Al2O3, Bentonite, kaolin) as heterogeneous catalysts. The structure and performance of these catalysts were studied using the techniques of XRD, CO2-TPD, and SEM. It was found that the 15wt% KOH/CaO catalyst provided best activity. In the presence of this catalyst, the yield of fatty acid methyl esters was 97.1%. The reaction conditions were as follows: methanol to soybean oil molar ratio was 16:1, temperature of 65 °C, reaction time of 1 h, and a catalyst amount of 4 wt%. The catalysts of KOH loaded on CaO showed a new crystalline phase of K2O. However, the catalyst of 15-KOH/CaO has more basic sites than the catalyst of 15-KOH/MgO. Therefore, the catalyst of 15-KOH/CaO has been associated with higher transesterification activity.

Abstract: Phosphofructokinase (PFK), which catalyses the phosphorylation of fructose-6-phosphate to fructose-1,6- bisphosphate, a key regulatory step in the glycolytic pathway. The former studies indicated the PFK could enhance glycolysis. The full-length cDNA encoding PFK was obtained from oleaginous microalgae Dunaliella parva, which include 1572 bp open reading frame (ORF), 254 bp 5′-untranslated sequence and 323 bp 3′-untranslated sequence. Dunaliella parva PFK showed the highest sequence similarity with the PFK from Chlamydomonas reinhardtii and Volvox carteri. The Dunaliella parva PFK also showed wide similarity with other species.

Abstract: The vast majority of photosynthetic organisms utilize monovinyl chlorophyll for their photosynthetic reactions. For the biosynthesis of monovinyl chlorophyll, the reduction of the 8-vinyl group which is located on the B-ring of the macrocycle is essential. 3,8-Divinyl protochlorophyllide a 8-vinyl reductase (DVR) catalyzes the reduction of 8-vinyl group on the tetrapyrrole to an ethyl group, which is necessary for monovinyl chlorophyll (Chl) synthesis. The former studies indicated the DVR could enhance photosynthesis. The full-length cDNA encoding DVR was obtained from oleaginous microalgae Dunaliella parva, which include 1326 bp open reading frame (ORF), 22 bp 5′-untranslated sequence and 383 bp 3′-untranslated sequence. Dunaliella parva DVR showed the highest sequence similarity with the DVR from Chlamydomonas reinhardtii and Volvox carteri. The Dunaliella parva DVR also showed wide similarity with other species.

Abstract: Microalgae could modulate their photosynthesis to acclimate to CO2-limiting stress through inducing a carbon-concentrating mechanism (CCM) which included carbonic anhydrases and inorganic carbon (Ci) transporters. However, Ci-specific transporters have not been well described in algae so far. The former studies indicated that low CO2-inducible protein (Lci) played a significant role in the CCM, could increase Ci uptake and intracellular Ci accumulation under low CO2 conditions. The full-length cDNA encoding Lci was obtained from oleaginous microalgae Dunaliella parva, which include 1302 bp open reading frame (ORF), 255 bp 5′-untranslated sequence and 447 bp 3′-untranslated sequence. Similarity analysis revealed that the highest identity was found among Dunaliella parva, Chlamydomonas reinhardtii and Volvox carteri. The Dunaliella parva Lci also showed wide similarity with other species.

Abstract: Malic enzymes are a class of oxidative decarboxylases which catalyze the oxidative decarboxylation of malate to pyruvate and carbon dioxide. the former studies on lipid pathways and genetic engineering test for enhanced lipid synthesis suggests that ME are the most promising targets gene for enhanced lipid synthesis. The full-length cDNA encoding NADP malic enzyme was obtained from oleaginous microalgae Dunaliella parva, which include 1293 bp open reading frame (ORF) and 26 bp 3′-untranslated sequence. NCBI-CD search revealed that there are two mainly domains predicted in the Dunaliella parva ME protein. In addition, a 724 bp promoter was obtained. The potential regulatory elements associated with hormone and light responses were also found in the ME promoter region. Similarity analysis revealed that the highest identity was found between Dunaliella parva and Chlamydomonas reinhardtii. The Dunaliella parva ME also showed wide similarity with other species.

Abstract: After investigating the effects of each parameter on the esterification of FFA catalyzed by Amberlyst-15 in the trap grease, the optimal values were determined through an orthogonal experimental design. The optimum conditions for the esterification were determined to be 27:1 molar for the methanol to FFA in the trap grease, 95°C for the reaction temperature and 3 h for the reaction time. Stability of Amberlyst-15 was also studied under the optimal reaction conditions. The stability of the catalyst was not decreased much even after 10 times repeated use. The acid value was decreased from 100 mg KOH/g to 1.3 mg KOH/g in this process.

Abstract: Pyruvate phosphate dikinase (PPDK) catalyzes the reversible conversion of AMP, phosphoenolpyruvate (PEP) and pyrophosphate (PPi) to ATP, pyruvate and inorganic phosphate (Pi). It is a key enzyme in gluconeogensis and photosynthesis that is responsible for reversing the reaction performed by pyruvate kinase in Embden-Meyerhof-Parnas glycolysis. A cDNA clone for the Dunaliella parva PPDK was isolated by sequencing. Then the 3'-RACE and 5'-cDNA amplification were conducted based on the obtained sequence. The molecular characterization of the PPDK gene was described.The Dunaliella parva PPDK gene cDNA sequence was 3249 bp, which contained 2595 bp coding region and 654 bp 3'-untranslated regions. The deduced amino acid sequence of Dunaliella parva PPDK showed significant homology to the known PPDK from Volvox carteri and Chlamydomonas reinhardtii. This study provided foundation for further research on the function analysis and overexpression of PPDK genes. To our knowledge this is the first reported.

Abstract: Fe(II)-Zn-based double metal cyanide complex catalysts modified with rare earth metal or transition metal promoters(lanthanum, cerium, zirconium, manganese) for the production of biodiesel were prepared, and the effect of the addition of different metal promoters on the characteristics of the catalyst was studied by using X-ray diffraction (XRD), BET, ICP and Infrared techniques .The experiment results show that the Fe(II)-Zn-based catalyst promoted with 1 wt.% of La(NO₃)₃·nH₂O exhibits the highest catalytic activity for the reaction, being as high as 99.3% of the yield of fatty acid methyl esters (FAME). Fe(II)-Zn-based catalysts have a tentative molecular formula: K₂Zn₃ [Fe(CN)₆]₂·xH₂O· (t-BuOH), where x=3-9 determined by using elemental analysis and ICP. It has been shown that the molecular formula of Fe(II)-Zn-based double metal cyanide complex catalysts did not change by adding 1 wt.% of rare earth metal or transition metal promoters. X-ray diffraction and BET results showed that Fe(II)-Zn-based catalysts with 1 wt.% of metal promoters salts exhibit smaller particle size, higher surface area than the Fe(II)-Zn catalyst ,which may be related to the higher activity of the catalysts.