Advances in the co-culture of microalgae with other microorganisms and applications / 生物工程学报

Intense utilization and mining of fossil fuels for energy production have resulted in environmental pollution and climate change. Compared to fossil fuels, microalgae is considered as a promising candidate for biodiesel production due to its fast growth rate, high lipid content and no occupying arable land. However, monocultural microalgae bear high cost of harvesting, and are prone to contamination, making them incompetent compared with traditional renewable energy sources. Co-culture system induces self-flocculation, which may reduce the cost of microalgae harvesting and the possibility of contamination. In addition, the productivity of lipid and high-value by-products are higher in co-culture system. Therefore, co-culture system represents an economic, energy saving, and efficient technology. This review aims to highlight the advances in the co-culture system, including the mechanisms of interactions between microalgae and other microorganisms, the factors affecting the lipid production of co-culture, and the potential applications of co-culture system. Finally, the prospects and challenges to algal co-culture systems were also discussed.

Efficacy enhancement of a Baculovirus-vectored Newcastle Disease Virus F protein vaccine by chicken GM-CSF and IL-2 / 生物工程学报

To compare with the effects of the GM-CSF and IL-2 used as adjuvants in the baculovirus vaccine, we used genetic engineering to construct the recombinant baculovirus rBV-LMI-F and with GM-CSF and IL-2 to immunized chickens. Then, we compared the concentration of the neutralizing antibody and cytokines to determine the immunostimulatory effects of GM-CSF and IL-2. GM-CSF induced higher levels of antibodies and cytokines in chickens at 28 d and 42 d post-vaccination. In conclusion, GM-CSF could elicit higher serum antibody and cytokines responses and improved the effects of Baculovirus vaccine.

A genome shuffling-generated Saccharomyces cerevisiae isolate that ferments xylose and glucose to produce high levels of ethanol.

Genome shuffling is an efficient approach for the rapid improvement of industrially important microbial phenotypes. This report describes optimized conditions for protoplast preparation, regeneration, inactivation, and fusion using the Saccharomyces cerevisiae W5 strain. Ethanol production was confirmed by TTC (triphenyl tetrazolium chloride) screening and high-performance liquid chromatography (HPLC). A genetically stable, high ethanol-producing strain that fermented xylose and glucose was obtained following three rounds of genome shuffling. After fermentation for 84 h, the high ethanol-producing S. cerevisiae GS3-10 strain (which utilized 69.48 and 100% of the xylose and glucose stores, respectively) produced 26.65 g/L ethanol, i.e., 47.08% higher than ethanol production by S. cerevisiae W5 (18.12 g/L). The utilization ratios of xylose and glucose were 69.48 and 100%, compared to 14.83 and 100% for W5, respectively. The ethanol yield was 0.40 g/g (ethanol/consumed glucose and xylose), i.e., 17.65% higher than the yield by S. cerevisiae W5 (0.34 g/g).

Optimization of xylose fermentation for ethanol production by Candida shehatae HDYXHT-01 / 生物工程学报

Plackett-Burman (PB) design and central composite design (CCD) were applied to optimize of xylose fermentation for ethanol production by Candida shehatae HDYXHT-01. The PB results showed that (NH4)2SO4, KH2PO4, yeast extract and inoculum volume were the main affecting factors. With ethanol productivity as the target response, the optimal fermentation was determined by CCD and response surface analysis (RSM). The optimal fermentation conditions were (NH4)2SO4 1.73 g/L, KH2PO4 3.56 g/L, yeast extract 2.62 g/L and inoculum volume 5.66%. Other fermentation conditions were xylose 80 g/L, MgSO47H20 0.1 g/L, pH 5.0 and 250 mL flask containing 100 mL medium and cultivated at 30 degrees C for 48 h and the agitation speed was 140 r/min. Under this fermentation conditions, ethanol productivity was 26.18 g/L, which was 1.15 times of the initial.

Fermentation optimization by response surface methodology for enhanced production of beta-glucosidase of Aspergillus niger HDF05 / 生物工程学报

In order to obtain high beta-glucosidase productivity, we optimized the fermentation parameters for beta-glucosidase production by Aspergillus niger HDF05. First, we screened the important parameters by Plackeet-Burman design. Second, we used the path of steepest ascent to approach to the biggest response region of parameters affecting beta-glucosidase production. Then, we obtained the optimal parameters by central composite design and response surface analysis. We developed a quadratic polynomial equation for predicting beta-glucosidase production level. The results showed that the important parameters were temperature, packing volume, concentrations of wheat bran and (NH4)2SO4. The optimal fermentation parameters were as follows: temperature 28 degrees C, packing volume 71.4 mL/250 mL, wheat bran 36 g/L and (NH4)2SO4 5.5 g/L. Under the optimal conditions, we obtained the maximum enzyme activity of 60.06 U/mL, with an increase of 23.9% compared to the original fermentation parameters. During enzymatic hydrolysis of acid-pretreated corncob, addition of beta-glucosidase from Aspergillus niger HDF05 greatly reduced the inhibition caused by cellobiose, and the hydrolysis yield was improved from 66.7% to 80.4%.

Research Advances on Taxol Producion by Microbe Fermentation / 微生物学通报

The biodiversity of the taxol-producing endophytic fungi,advantage of taxol production by microbe fermentation,isolation of endophytic fungi,and the separation,purification and determination of taxol in fermentation liquid were reviewed.The pathways to improve the production of taxol by endophytic fungi were also comprehensively discussed.