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Na Liu, Yipeng Wang, Fei Ge, Shixiang Liu, Huaixian Xiao
The interaction of nanoparticles with coexisting chemicals affects the fate and transport of nanoparticles, as well as their combined effects on aquatic organisms. Here, we evaluated the joint effect of ZnO nanoparticle (nano-ZnO) and cetyltrimethyl ammonium chloride (CTAC) on the growth of Chlorella vulgaris and explored the possible mechanism. Results showed that an antagonistic effect of nano-ZnO and CTAC (0.1, 0.2 and 0.3 mg L-1) was found because CTAC stop nano-ZnO being broken down into solution zinc ions (Zn2+)...
December 29, 2017: Chemosphere
Shi-Kai Wang, Xu Wang, Jing Miao, Yong-Ting Tian
Tofu whey wastewater (TWW) is an abundant, nutrient riched and safety wastewater and is regarded as an excellent alternative medium in fermentation. In this study, the feasibility of algal cultivation using TWW as the basal medium was investigated. Results indicated that through simple pH adjustment, TWW presented a better culture performance at autotrophic, heterotrophic, and mixotrophic modes compared with that of regular green algae medium, BG-11. The biomass productivities of Chlorella pyrenoidosa at each trophic mode were 4...
January 4, 2018: Bioresource Technology
Francisco J Choix, Cecilia Guadalupe López-Cisneros, Hugo Oscar Méndez-Acosta
Mutualism interactions of microalgae with other microorganisms are widely used in several biotechnological processes since symbiotic interaction improves biotechnological capabilities of the microorganisms involved. The interaction of the bacterium Azospirillum brasilense was assessed with three microalgae genus, Scenedesmus, Chlorella, and Chlamydomonas, during CO2 fixation under high CO2 concentrations. The results in this study have demonstrated that A. brasilense maintained a mutualistic interaction with the three microalgae assessed, supported by the metabolic exchange of indole-3-acetic acid (IAA) and tryptophan (Trp), respectively...
January 11, 2018: Microbial Ecology
Hari Prasad Ratnapuram, S S Vutukuru, Rajasri Yadavalli
Influence of mixotrophic mode and its transition to various trophic modes under stress conditions was assessed during two stage cultivation of Chlorella pyrenoidosa. Significant lipid productivity was triggered under low light intensity, glucose + bicarbonate supplementation and nitrogen starvation. The association between biomass and lipid productivity, fatty acid composition during mixotrophic transition was critically evaluated. Biomass in growth phase (GP) and stress phase (SP) was 6.14 g/l and 5.14 g/l, respectively, in mixotrophic mode...
January 2018: Heliyon
Weiping Huang, Yan Lin, Mingxia He, Yuhao Gong, Junchao Huang
Natural resources of zeaxanthin are extremely limited. A Chlorella zofingiensis mutant (CZ-bkt1), which could accumulate high amounts of zeaxanthin, was generated and characterized. CZ-bkt1 was achieved by treating the algal cells with a chemical mutagen followed by a colour-based colony screening approach. CZ-bkt1 was found to consist of a dysfunctional carotenoid ketolase, leading to the accumulation of zeaxanthin rather than its downstream ketocarotenoid astaxanthin. Light irradiation, glucose, NaCl, and nitrogen deficiency all induced CZ-bkt1 to accumulate zeaxanthin...
January 10, 2018: Journal of Agricultural and Food Chemistry
Guanxun Wu, Zhengquan Gao, Huanmin Du, Bin Lin, Yuchen Yan, Guoqiang Li, Yanyun Guo, Shenggui Fu, Gongxiang Wei, Miaomiao Wang, Meng Cui, Chunxiao Meng
Sustainable renewable energy is being hotly debated globally because the continued use of finite fossil fuels is now widely recognized as being unsustainable. Microalgae potentially offer great opportunities for resolving this challenge. Abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) are involved in regulating many physiological properties and have been widely used in higher plants. To test if phytohormones have an impact on accumulating lipid for microalgae, ABA, JA and SA were used to induce two Chlorella strains in the present study...
December 30, 2017: Journal of General and Applied Microbiology
Ramesh Kakarla, Jung-Woon Choi, Jin-Ho Yun, Byung-Hyuk Kim, Jina Heo, Sujin Lee, Dae-Hyun Cho, Rishiram Ramanan, Hee-Sik Kim
Increased lipid accumulation of algal cells as a response to environmental stress factors attracted much attention of researchers to incorporate this stress response into industrial algal cultivation process with the aim of enhancing algal lipid productivity. This study applies high-salinity stress condition to a two-phase process in which microalgal cells are initially grown in freshwater medium until late exponential phase and subsequently subjected to high-salinity condition that induces excessive lipid accumulation...
January 2018: Journal of Microbiology / the Microbiological Society of Korea
Shuhei Hashiro, Koyu Fujiuchi, Daisuke Sugimori, Hisashi Yasueda
We have identified an enzyme, galactolipase (ckGL), which hydrolyzes the acyl ester bond of galactolipids such as digalactosyldiacylglycerol (DGDG), in the microalga Chlorella kessleri. Following purification of the enzyme to electrophoretic homogeneity from cell-free extract, the maximum activity toward DGDG was observed at pH 6.5 and 37 °C. ckGL was Ca2+-dependent enzyme and displayed an apparent molecular mass of approx. 53 kDa on SDS-PAGE. The substrate specificity was in the order: DGDG (100%) > monogalactosyldiacylglycerol ≈ phosphatidylglycerol (~ 40%) > sulfoquinovosyldiacylglycerol (~ 20%); the enzyme exhibited almost no activity toward glycerides and other phospholipids...
January 3, 2018: Applied Microbiology and Biotechnology
Shidong Ban, Weitie Lin, Fangyan Wu, Jianfei Luo
In this study, bacterium Pseudomonas sp. strain D was proved to be the main partner assisting Chlamydomonas reinhardtii in improving photolysis-mediated H2 production and a good partner for promoting H2 production by the green algae Chlorella and Scenedesmus. In strain D partnered algal-bacterial co-culture, the relative O2 content in the headspace plus the dissolved oxygen in the culture medium were rapidly consumed by bacterial growth, resulting in a completely anaerobic environment that proved suitable for the activation of algal hydrogenase...
December 26, 2017: Bioresource Technology
Ling Xia, Yinta Li, Rong Huang, Shaoxian Song
This study developed a coagulation-flotation process for microalgae Chlorella sp. XJ-445 harvesting, which was composed of algal surface modification by combined use of Al3+ and cetyltrimethylammonium bromide (CTAB) and followed dispersed bubble flotation. Dissolved organic matter (DOM) in the medium was firstly characterized and mainly consisted of hydrophilic low molecular weight molecules. The dosage of collector (CTAB) and coagulant (Al3+) were optimized, and with the pretreatment of 40 mg Al3+ and 60 mg CTAB per 1 g dry biomass without pH adjustment, a maximum flotation recovery efficiency of 98...
November 2017: Royal Society Open Science
Natthawut Yodsuwan, Pitiya Kamonpatana, Yusuf Chisti, Sarote Sirisansaneeyakul
Suspensions of the model microalga Chlorella sp. TISTR 8990 were pretreated by ohmic heating to facilitate release of lipids from the cells in subsequent extraction and lipase-mediated transesterification to biodiesel. After ohmic pretreatment, the moist biomass was suspended in a system of water, hexane, methanol and immobilized lipase for extraction of lipids and simultaneous conversion to biodiesel. The ohmic pretreatment was optimized using an experimental design based on Taguchi method to provide treated biomass that maximized the biodiesel yield in subsequent extraction-transesterification operation...
December 28, 2017: Journal of Biotechnology
Meram Chalamaiah, Wenlin Yu, Jianping Wu
Bioactive peptides are oligopeptides that consist of 2-20 amino acids that can exert beneficial effects on human health in addition to basic nutritional effects. Food derived protein hydrolysates or peptides with immunomodulatory and anticancer activities have been reported from a variety of food protein sources such as milk, egg, fish, rice, soybean, pea, chlorella, spirulina, oyster and mussel. In vitro hydrolysis of food proteins using commercial proteolytic enzymes is the most commonly employed process for the production of immunomodulatory and anticancer food protein hydrolysates...
April 15, 2018: Food Chemistry
Robert J Bauer, Alexander Zhelkovsky, Katharina Bilotti, Laura E Crowell, Thomas C Evans, Larry A McReynolds, Gregory J S Lohman
DNA ligases catalyze the repair of phosphate backbone breaks in DNA, acting with highest activity on breaks in one strand of duplex DNA. Some DNA ligases have also been observed to ligate two DNA fragments with short complementary overhangs or blunt-ended termini. In this study, several wild-type DNA ligases (phage T3, T4, and T7 DNA ligases, Paramecium bursaria chlorella virus 1 (PBCV1) DNA ligase, human DNA ligase 3, and Escherichia coli DNA ligase) were tested for their ability to ligate DNA fragments with several difficult to ligate end structures (blunt-ended termini, 3'- and 5'- single base overhangs, and 5'-two base overhangs)...
2017: PloS One
Bárbara Catarina Bastos de Freitas, Eduarda Holz Brächer, Etiele Greque de Morais, Daniel Ibraim Pires Atala, Michele Greque de Morais, Jorge Alberto Vieira Costa
New strategies for reformulating species-specific culture media are of great interest to increase the productivity of microalgae. In the search for alternative carbon sources for microalgae cultivation, pentoses can be considered interesting alternatives since the most abundant global source of renewable biomass is lignocellulosic waste, which contains significant quantities of pentoses. However, the use of pentoses (C5) in the cultivation of microalgae is still not widely studied and only recently the first metabolic pathway for pentose absorption in microalgae was proposed, so the numbers of works that exploring this subject is still very low...
December 18, 2017: Environmental Technology
Antonín Bednařík, Jan Kuta, Dai Long Vu, Karolína Ranglová, Pavel Hrouzek, Viktor Kanický, Jan Preisler
In this work we present a simple and cost-effective approach for the determination of selenium species in algae and yeast biomass, based on a combination of thin-layer chromatography (TLC) with diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). Extraction of freeze-dried biomass was performed in 4M methanesulphonic acid and the selenium species were vaporized from cellulose TLC plates employing a continuous-wave infrared diode laser with power up to 4 W using a simple laboratory-built apparatus...
December 9, 2017: Journal of Chromatography. A
Imma Gifuni, Giuseppe Olivieri, Antonino Pollio, Antonio Marzocchella
The recent trends in microalgal cultures are focused on the biorefinery of the biomass components. Some of them are not completely valorised, for example starch. Since there is a wide market for starch products in food and non-food industries, the exploitation of microalgal starch fractions could improve the economic sustainability of microalgae production. In this perspective, the optimization of nitrogen and carbon source uptake for starch accumulation is a critical point for reducing the nitrogen requirement footprint and to increase CO2 capture...
December 10, 2017: New Biotechnology
Annalisa Tassoni, Nahid Awad, Gareth Griffiths
The extensive genetic resources of Chlamydomonas has led to its widespread use as a model system for understanding fundamental processes in plant cells, including rates of cell division potentially modulated through polyamines. Putrescine was the major polyamine in both free (88%) and membrane-bound fractions (93%) while norspermidine was the next most abundant in these fractions accounting for 11% and 6%, respectively. Low levels of diaminopropane, spermidine and spermine were also observed although no cadaverine or norspermine were detected...
December 7, 2017: Plant Physiology and Biochemistry: PPB
Bin Xia, Qi Sui, Xuemei Sun, Qian Han, Bijuan Chen, Lin Zhu, Keming Qu
Concerns about the environmental effects of engineered nanoparticles (NPs) on marine ecosystems are increasing. Meanwhile, ocean acidification (OA) has become a global environmental problem. However, the combined effects of NPs and OA on marine organisms are still not well understood. In this study, we investigated the effects of OA (pH values of 7.77 and 7.47) on the bioavailability and toxicity of TiO2 NPs to the marine microalga Chlorella vulgaris. The results showed that OA enhanced the growth inhibition of algal cells caused by TiO2 NPs...
December 7, 2017: Journal of Hazardous Materials
Ehsan Sarayloo, Salim Simsek, Yigit Sabri Unlu, Gul Cevahir, Can Erkey, Ibrahim Halil Kavakli
In this study, we applied a second round of random mutagenesis using ethyl methanesulfonate to further increase the lipid productivity of a Chlorella vulgaris mutant strain. We generated a mutant (UV715-EMS25) with a lipid content and biomass that were respectively 67% and 35% higher than those of the wild type (WT). The highest achieved lipid productivity in UV715-EMS25 was 91 mg L-1 day-1. Gas chromatography-mass spectrophotometric analysis revealed that the fatty acid methyl ester content of the mutant was 3...
December 2, 2017: Bioresource Technology
L-D Zhu, Erkki Hiltunen, Zhaohua Li
Using naked iron oxide (Fe3O4) and yttrium iron oxide (Y3Fe5O12) nanoparticles as flocculants, the harvesting efficiency of Chlorella vulgaris biomass was investigated. The harvesting process includes two steps, which are the separation of microalgae from the culture solution with the magnetic nanoparticles and then the separation of the algae from the magnetic nanoparticles. The optimal dosages and pH values for the magnetic harvesting of microalgal biomass were determined. Results showed that Y3Fe5O12 nanoparticles were more efficient in microalgal biomass harvesting than Fe3O4 nanoparticles...
December 8, 2017: Environmental Technology
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