能源微藻无泡采收新方法及其性能

采用低密度浮珠颗粒代替气泡的无泡采收方法,高效低成本采收能源微藻. 以常见能源微藻小球藻为例,以硅硼酸钠为浮珠,比较了浮珠浮选工艺与传统气浮法的区别,通过响应面法优化了浮珠浮选工艺. 结果表明,以硅硼酸钠为浮珠的无泡采收效果较理想,浮珠颗粒粒径、浓度和搅拌速率对采收率影响显著,颗粒直径56 ?m、浓度0.546 g/L、搅拌速率133 r/min的条件下采收率最好,达83.7%.     

基于CAN的能源微藻培养监控系统的设计与实现

针对能源微藻培养监控系统具体需求,选用CAN总线构建主从式总线网络,研制了一种基于STM32F107来构建采集从节点和控制从节点的软硬件设计方法。监控主机采用组态王6.53来实现现场数据的实时显示、数据库存储、实验流程组态和现场情况的Web发布。经调试结果表明:本监控系统可在波特率为9 600 bit/s下正常运行,有较高的稳定性和功能可扩展性,在生物能源领域中有广阔的应用前景。     

Interaction between Microalgae P. tricornutum and Bacteria Thalassospira sp. for Removal of Bisphenols from Conditioned Media

We studied the efficiency of three culture series of the microalgae Phaeodactylum tricornutum (P. tricornutum) and bacteria Thalassospira sp. (axenic microalgae, bacterial culture and co-culture of the two) in removing bisphenols (BPs) from their growth medium. Bacteria were identified by 16S ribosomal RNA polymerase chain reaction (16S rRNA PCR). The microorganism growth rate was determined by flow cytometry. Cultures and isolates of their small cellular particles (SCPs) were imaged by scanning electron microscopy (SEM) and cryogenic transmission electron microscopy (Cryo-TEM). BPs were analyzed by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). Our results indicate that some organisms may have the ability to remove a specific pollutant with high efficiency. P. tricornutum in axenic culture and in mixed culture removed almost all (more than 99%) of BPC2. Notable differences in the removal of 8 out of 18 BPs between the axenic, mixed and bacterial cultures were found. The overall removals of BPs in axenic P. tricornutum, mixed and bacterial cultures were 11%, 18% and 10%, respectively. Finding the respective organisms and creating microbe societies seems to be key for the improvement of wastewater treatment. As a possible mediating factor, numerous small cellular particles from all three cultures were detected by electron microscopy. Further research on the mechanisms of interspecies communication is needed to advance the understanding of microbial communities at the nano-level.     

Antimicrobial activities of polyhexamethylene biguanide against biofilm-producing Prototheca bovis causing bovine mastitis

Prototheca spp. is a frequent cause of bovine mastitis and is highly resistant to commonly used disinfectants. This study aimed to: (1) evaluate the antimicrobial activity of polyhexamethylene biguanide (PHMB) against mastitis-causing Prototheca spp., and (2) evaluate the biofilm production ability of Prototheca spp. A total of 85 Prototheca bovis and 2 Prototheca blaschkeae isolates from bovine mastitis cases were submitted to biofilm production assays and antimicrobial susceptibility tests against PHMB and disinfectants commonly used in dairy herds (chlorhexidine digluconate, povidone-iodine, sodium dichloroisocyanurate, and sodium hypochlorite). The minimal inhibitory concentration (MIC) and minimal algicidal concentration (MAC) were determined by microdilution assays. We observed that PHMB (MIC₉₀: ≥2 µg/mL and MAC₉₀: ≥4 µg/mL) and chlorhexidine gluconate (MIC₉₀ and MAC₉₀: ≥2 µg/mL) presented the highest antimicrobial activity against P. bovis isolates, followed by sodium dichloroisocyanurate (MIC₉₀ and MAC₉₀: ≥1,400 µg/mL), sodium hypochlorite (MIC₉₀ and MAC₉₀: ≥2,800 µg/mL), and povidone-iodine (MIC₉₀ and MAC₉₀: ≥3,200 µg/mL). Concerning P. blaschkeae isolates, PHMB (MIC and MAC ≥1 µg/mL) and chlorhexidine gluconate (MIC and MAC ≥1 µg/mL) were the disinfectants that presented the lowest concentration values required to inhibit the isolates. Regarding biofilms formation, 63.5% (n = 54/85) of the P. bovis isolates were classified as strong, 28.3% (n = 24/85) moderate, and 8.2% (n = 7/85) weak biofilm producers. In contrast, the P. blaschkeae isolates were classified as weak and moderate biofilm producers. These findings suggest that PHMB has the potential to be used for teat and milking-equipment disinfection for the prevention of mastitis-causing Prototheca spp. in dairy herds.     

The effects of ultraviolet radiation on growth,biomass, lipid accumulation and biodiesel properties of microalgae

The effect of UV light on growth, biomass, lipid accumulation and biodiesel properties of microalgae was studied. A Microalgae strain Chlorella sorokiniana UUIND6 was cultivated for 14 days as under LED light (Control) and microalgae were exposed to UV light (280–320 nm) in the middle of the photoperiod for 3 days. The growth rate of microalgae was analyzed by spectrophotometer and cell counting, while oil accumulation was analyzed by improved Nile red method. Results showed that microalgae under UV light treated algal cells showed less growth. FAMEs profile of UV treated algal cells mainly contains hexadecanoic acid (C16), stearic acid (C18) fatty acids. PUFA found in very less amount in UV treated cells as compared to control.     

Oxy‐fuel combustion characteristics and kinetics of microalgae and its mixture with rice straw using thermogravimetric analysis

The thermal behavior of rice straw, microalgae, and their mixture was studied by thermogravimetric analysis (TGA). Co‐combustion of rice straw and microalgae broadened the temperature range of combustion, facilitated ignition, and promoted burnout. The blend ratio of microalgae should be less than or equal to 10% in a 20%O₂/80%N₂ atmosphere and 30% in a 20%O₂/80%CO₂ atmosphere to reach a higher comprehensive combustion index (CCI) value than the individual fuels. The co‐combustion with a small ratio of microalgae could remedy partial negative effects on combustion performance caused by the replacement of N₂ using CO₂. The interaction of blends depended on the atmosphere and temperature range. The prediction of the combustion performance of blends by a weighted sum of individual fuels worked better in an O₂/CO₂ atmosphere at low temperatures, while better in an O₂/N₂ atmosphere at high temperatures. The simulation using the model which contained 2 parallel multi‐order reactions matched with the thermogravimetric curves well, and blending reduced activation energies of the second stage.     

The effect of partial substitution of rapeseed meal and faba beans by Spirulina platensis microalgae on milk production,nitrogen utilization,and amino acid metabolism of lactating dairy cows

Alternative protein sources such as microalgae and faba beans may have environmental benefits over rapeseed. We studied the effects of rapeseed meal (RSM) or faba beans (FB) as a sole protein feed or as protein feeds partially substituted with Spirulina platensis (spirulina) microalgae on milk production, N utilization, and AA metabolism of dairy cows. Eight multiparous Finnish Ayrshire cows (113 ± 36.3 d in milk; mean ± SD) were used in a balanced, replicated 4 × 4 Latin square with 2 × 2 factorial arrangement of treatments and 21-d periods. Four cows in one Latin square were rumen cannulated. Treatments were 2 isonitrogenously fed protein sources, RSM or rolled FB, or one of these sources with half of its crude protein substituted by spirulina (RSM-SPI and FB-SPI). Cows had ad libitum access to total mixed rations consisting of grass silage, barley, sugar beet pulp, minerals, and experimental protein feed. The substitution of RSM with FB did not affect dry matter intake (DMI) but decreased neutral detergent fiber intake and increased the digestibility of other nutrients. Spirulina in the diet decreased DMI and His intake. Spirulina had no effect on Met intake in cows on RSM diets but increased it in those on FB diets. Energy-corrected milk (ECM) and protein yields were decreased when RSM was substituted by FB. Milk and lactose yields were decreased in cows on the RSM-SPI diet compared with the RSM diet but increased in those on FB-SPI compared with FB. The opposite was true for milk fat and protein concentrations; thus, spirulina in the diet did not affect ECM. Feed conversion efficiency (ECM:DMI) increased in cows on FB diets with spirulina, whereas little effect was observed for those on RSM diets. The substitution of RSM by FB decreased arterial concentration of Met and essential AA. Spirulina in the diet increased milk urea N and ruminal NH₄-N and decreased the efficiency of N utilization in cows on RSM diets, whereas those on FB diets showed opposite results. Met likely limited milk production in cows on the FB diet as evidenced by the decrease in arterial Met concentration and milk protein yield when RSM was substituted by FB. The results suggest the potential to improve milk production response to faba beans with supplementation of Met-rich feeds such as spirulina. This study also confirmed spirulina had poorer palatability than RSM and FB despite total mixed ration feeding and lower milk production when spirulina partially replaced RSM.     

微藻油脂的研究进展

全球能源危机使可再生能源的开发和利用越来越受到人们的关注。与产油农作物相比,微藻凭借其结构简单、生长速度快、有较高的含油率等特点成为生物能源产业最具竞争力的选择之一。本文首先介绍了微藻的种类、藻体中的油脂,然后从影响油脂积累的因素、微藻中油脂的提取和微藻高油脂化基因工程方面进行了阐述,最后对微藻生产生物柴油产业的发展趋势和研究方向进行了展望,为进一步降低微藻产油成本,提高微藻生物柴油经济性提出了一条极有可能实现工业化的潜在高效生产途径。      

氮胁迫下绿球藻GIEC-38光合固碳富集油脂机理研究

利用Illumina高通量测序对绿球藻(Chlorococcum sp.)GIEC-38的转录组进行测定,分析在氮(N)胁迫(无氮源BG-11)下产油高的藻株与原始培养条件相比光合固碳富集油脂相关的代谢通路和基因表达情况,发现在N胁迫下藻内有14817个基因表达上调、15282个基因表达下调。光合作用、叶绿素代谢和氮代谢等代谢通路均有明显变化,代谢途径可能受到一定的抑制进而增加油脂合成途径。对藻株TAG代谢重建后发现乙酰辅酶A羧化酶等许多与脂类合成相关的基因表达量显著上调,分布在TAG合成中12个步骤中,这些均可促进脂质的合成,提高细胞的油脂产量。