Amphidoma parvula (Amphidomataceae), a new planktonic dinophyte from the Argentine Sea

Amphidoma is an old though poorly studied thecate dinophyte that has attracted attention recently as a potential producer of azaspiracids (AZA), a group of lipophilic phycotoxins. A new species, Amphidoma parvula, sp. nov. is described from the South Atlantic shelf of Argentina. With a Kofoidean thecal plate pattern Po, cp, X, 6′, 6′′, 6C, 5S, 6′′′, 2′′′′, the cultivated strain H-1E9 (from which the type material of Am. parvula, sp. nov. was prepared) shared the characteristic plate arrangement of Amphidoma each with six apical, precingular and postcingular plates. Amphidoma parvula, sp. nov. differs from other species of Amphidoma by a characteristic combination of small size (10.7–13.6 µm in length), ovoid shape, high length ratio between epitheca and hypotheca, and small length ratio between apical and precingular plates. Other morphological details, such as the number and arrangement of sulcal plates and the fine structure of the apical pore complex support the close relationship between Amphidoma and the other known genus of Amphidomataceae, Azadinium. However, Am. parvula, sp. nov. lacks a ventral pore, a characteristically structured pore found in all contemporary electron microscopy studies of Amphidoma and Azadinium. As inferred from liquid chromatography coupled with tandem mass spectrometry, Am. parvula, sp. nov. did not produce AZA in measurable amounts. Molecular phylogenetics confirmed the systematic placement of Am. parvula, sp. nov. in Amphidoma (as sister species of Amphidoma languida) and the Amphidomataceae. The results of this study have improved the knowledge of Amphidomataceae biodiversity.     

Photobioreactor cultivation strategies for microalgae and cyanobacteria

The current burden on fossil‐derived chemicals and fuels combined with the rapidly increasing global population has led to a crucial need to develop renewable and sustainable sources of chemicals and biofuels. Photoautotrophic microorganisms, including cyanobacteria and microalgae, have garnered a great deal of attention for their capability to produce these chemicals from carbon dioxide, mineralized water, and solar energy. While there have been substantial amounts of research directed at scaling‐up production from these microorganisms, several factors have proven difficult to overcome, including high costs associated with cultivation, photobioreactor construction, and artificial lighting. Decreasing these costs will substantially increase the economic feasibility of these production processes. Thus, the purpose of this review is to describe various photobioreactor designs, and then provide an overview on lighting systems, mixing, gas transfer, and the hydrodynamics of bubbles. These factors must be considered when the goal of a production process is economic feasibility. Targets for improving microalgae and cyanobacteria cultivation media, including water reduction strategies will also be described. As fossil fuel reserves continue to be depleted and the world population continues to increase, it is imperative that renewable chemical and biofuel production processes be developed toward becoming economically feasible. Thus, it is essential that future research is directed toward improving these processes. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:811–827, 2018     

Cadmium adsorption by the non-living biomass of microalgae grown in axenic mass culture

The freeze-dried (extracted and non-extracted) biomass of 15 microalgal species grown in axenic mass culture and belonging to the Cyanobacteria, Chloro-, Eustigmato-, Phaeo-, Rhodo- and Tribophyceae were investigated for their ability to adsorb cadmium (Cd) ions from aqueous solutions. For comparison, other standard adsorbing materials (activated carbon, silica gel, siliceous earth) were included in the studies. The biomass of 11 microalgae exhibited a higher Cd adsorption than the standard materials. Extraction of the algal biomass increased the Cd adsorption capability of some, but not all microalgae. High Cd adsorption was found inAnabaena lutea, Nodularia harveyana, andNostoc commune (Cyanobacteria),Chlamydomonas sp. (Chlorophyceae),Bumilleriopsis filiformis (Tribophyceae), and inEctocarpus siliculosus, Halopteris scoparia andSpermatochnus paradoxus (Phaeophyceae). The specific surface (m² cm^–3) of the various microalgae was determined by means of laser diffractometry.Anabaena inaequalis andA. lutea (Cyanobacteria) and the Phaeophyceae had especially high Cd adsorption per surface unit. Most of the Cd adsorbed to these various materials could be desorbed subsequently with diluted mineral acid (pH 2).     

Importance of basic research in applied phycology

Utilization of algae has extended considerably from the middle of this century, with the consequence of more and more applied research in various directions and fields, the most important of which deals with phycocolloid production and algal cultivation to provide raw material and foodstuff. It is noteworthy that this research can not avoid the use of knowledge obtained by basic research; applied phycology is especially indebted to basic research in adopting biotechnologies which are typically coming from basic research. In counterpart, such a situation is beneficial to basic research. According to the dependence of applied phycology to basic research and the fact that restricted research programs only are nowadays financially supported, the fate of all research seems to be questionable.     

Growth promoting and inhibiting effects of extracellular substances of soil microalgae and cyanobacteria on Escherichia coll and Micrococcus luteus

Different taxa of chlorophycean, trebouxiophycean and xanthophycean soil microalgae and of cyanobacteria have been tested for the release of substances that inhibit the growth of either Echerichia coli (Migula) Castellani et Chalmersor Micrococcus luteus (Schroeter) Cohn. Experiments suggest two types of antibacterial effects: one type is constitutive; that is, the antibacterial activity is always present in the algal culture medium, as is the case with the Chroococcus turgidus (medium that inhibits the growth of Escherichia coli). The other type is induced; that is, the antibacterial activity occurs only when algae are in contact with bacteria. This is the case when growth of Micrococcus luteus is inhibited in co‐culture with Chroococcus turgidus (Kützing) Nägeli or with Xanthonema debile (Vischer) Silva and when growth of Escherichia coll is inhibited in co‐culture with Tetracystis sp. As well as inhibition, promotion of bacterial growth was observed. This was probably an unspecific effect resulting from soluble organic and inorganic substances, such as carbohydrates, that are generally present in algal cultures.     

微藻规模化培养研究进展

微藻作为地球上最古老的物种之一,其诞生可追溯到35亿多年前.微藻的种类十分丰富,形态也多种多样.微藻一般都含有叶绿体,因此可进行光合作用,有研究表明微藻固定CO2的能力是陆地植物的10倍.微藻以其丰富的代谢产物及独特的生理特性在可再生能源、生物医药、食品工业和环境监测等方面有着广泛的应用.然而如何在控制成本的前提下对微...     

Biodegradation of phenols by microalgae

Two green microalgae, Ankistrodesmus braunii and Scenedesmus quadricauda, degraded phenols (each tested at 400 mg ml^–1) selected from olive-oil mill wastewaters, within 5 days, with a removal greater than 70%. Green algae may, therefore, represent an alternative to other biological treatment used for the biodegradation of phenol-containing wastewaters.     

植物的特有现象与生物多样性

特有现象是生物多样性的依据,多样性是特有现象的体现,特圾现象是种系分化的结果,特有现象的成因是多方面的,包括地貌因子、土壤因子、气候因子、边缘效应、海洋岛屿隔离以及自然杂交。全球各大的自然条件的多样性,促成了各大陆各异的特有现象和生物多样性,生物多样性是生命运动的属性,它是在系统发育过程中发展壮大的,因此,它的发展有生的,既具有普遍性,又具有特殊性,保护生物多样性是当前的迫切任务。     

The CO2concentrating mechanism in cyanobactiria and microalgae

Over the past 10 years it has become clear that cyanobacteria and microalgae possess mechanisms for actively acquiring inorganic carbon from the external medium and are able to use this to elevate the CO₂ concentration around the active site of the primary photosynthetic carboxylating enzyme, ribulose bisphosphate carboxylase-oxygenase (Rubisco). This results in a vastly enhanced photosynthetic affinity for inorganic carbon (C_i) and improved photosynthetic efficiency. The CO₂ concentrating mechanism is dependent on the existence of membrane bound C_i transport systems, and a microenvironment within the cell where the accumulated C_i can be used to elevate CO₂ at the site of Rubisco. Evidence presented in this review suggests that in cyanobacteria this is achieved by the packaging of Rubisco and carbonic anhydrase (CA) into discrete structures, which are termed carboxysomes. Analogous structures in microalgae, termed pyrenoids, may perform a similar function. The recovery and analysis of high-CO₂-requiring mutants has greatly advanced our understanding of the mechanisms and genes underlying these systems, especially in cyanobacteria, and this review places particular emphasis on the contribution made by molecular genetic approaches.     

Haemagglutinating and antibiotic activities of freshwater microalgae

We analysed the haemagglutinating activity of algal extracts from 44 species of freshwater microalgae against native and trypsin/papain-treated cow, pig, sheep, and human A-, B-, and O-type erythrocytes. Algal extracts obtained with aqueous ethanol exhibited higher haemagglutinating activity than those obtained with aqueous acetone. Most of the algal extracts agglutinated at least one of the erythrocyte types analysed. Human erythrocytes were the most sensitive of the cell types analysed. In the other species, the sensitivity of algal haemagglutinating activity for erythrocytes was pig > sheep > cow. Pre-treating erythrocytes with trypsin and papain improved the detection of most algal agglutinins and increased the haemagglutination titre; pre-treatment with papain was most effective for pig erythrocytes. Algal extracts stored at –20 °C for 4 months lost their haemagglutinating activity. Algal extracts also exhibited strong antibiotic activity against food pathogenic bacteria, especially against Bacillus. Our numerical taxonomy data showed that these microalgae might be grouped into several clusters according to their haemagglutinating activity. The detection of haemagglutinating activity may provide an efficient biochemical or physiological character to classify and differentiate microalgae. Our results suggest that freshwater microalgae might provide a potent source of haemagglutinins and antibacterial compounds for biochemical and medical studies and applications.     

Biodiversity as insurance: from concept to measurement and application

Biological insurance theory predicts that, in a variable environment, aggregate ecosystem properties will vary less in more diverse communities because declines in the performance or abundance of some species or phenotypes will be offset, at least partly, by smoother declines or increases in others. During the past two decades, ecology has accumulated strong evidence for the stabilising effect of biodiversity on ecosystem functioning. As biological insurance is reaching the stage of a mature theory, it is critical to revisit and clarify its conceptual foundations to guide future developments, applications and measurements. In this review, we first clarify the connections between the insurance and portfolio concepts that have been used in ecology and the economic concepts that inspired them. Doing so points to gaps and mismatches between ecology and economics that could be filled profitably by new theoretical developments and new management applications. Second, we discuss some fundamental issues in biological insurance theory that have remained unnoticed so far and that emerge from some of its recent applications. In particular, we draw a clear distinction between the two effects embedded in biological insurance theory, i.e. the effects of biodiversity on the mean and variability of ecosystem properties. This distinction allows explicit consideration of trade-offs between the mean and stability of ecosystem processes and services. We also review applications of biological insurance theory in ecosystem management. Finally, we provide a synthetic conceptual framework that unifies the various approaches across disciplines, and we suggest new ways in which biological insurance theory could be extended to address new issues in ecology and ecosystem management. Exciting future challenges include linking the effects of biodiversity on ecosystem functioning and stability, incorporating multiple functions and feedbacks, developing new approaches to partition biodiversity effects across scales, extending biological insurance theory to complex interaction networks, and developing new applications to biodiversity and ecosystem management.     

微藻废水生物处理技术研究进展

微藻因生长速率快、细胞脂质含量高及具有生物隔离二氧化碳能力,已作为新一代生物质能源受到广泛关注.然而,投入大量淡水资源并需在生长期间持续提供营养物质已成为规模化培育微藻的主要障碍.将微藻培育系统与废水处理相结合是经济可行的污水资源化方案.基于微藻生长期间对氮磷等营养物质的利用机制,本文综述了微藻在各类废水生物处理过程中的应用情况,着重分析了其对废水中有机与无机化合物、重金属以及病原体的去除或抑制能力.同时,考察了废水初始营养物浓度、光照、温度、pH与盐度以及气体交换量等环境因素对微藻生长代谢的影响.此外,结合微藻规模化应用所面临的问题,对微藻废水处理技术的应用前景及发展方向进行了展望,旨在为水生态系统的建设与管理提供参考.     

The molecular and biochemical analyses of CO2-concentrating mechanisms in cyanobacteria and microalgae

Abstract. The supply of dissolved inorganic carbon for photosynthesis in the aquatic environment is much more variable than that experienced by terrestrial plants. In response to this variability, cyanobacteria and many species of microalgae acclimate to rapid changes in the availability of dissolved inorganic carbon by the induction of high affinity/high capacity CO₂-concentrating systems (CCMs). Biochemical and molecular analyses of the acclimation response have recently identified several components that are required for efficient operation of the CCMs and CO₂ assimilation. This has been accomplished using in vivo labelling studies, and characterization of high inorganic carbon (C_i) requiring cyanobacterial and algal mutants. The identification and regulation of expression of polypeptides synthesized in response to limiting C_i concentrations, and the proposed role of the carboxysome and the pyrenoid in the functioning of the CCMs are examined.     

A mechanistic model of photosynthesis in microalgae

A dynamic model of photosynthesis is developed, accounting for factors such as photoadaptation, photoinhibition, and the "flashing light effect." The model is shown to explain the reported photosynthesis-irradiance responses observed under various conditions (constant low light, constant intense irradiance, flashing light, diurnal variation in irradiance). As significant distinguishing features, the model assumes: (1) The stored photochemical energy is consumed in an enzyme-mediated process that obeys Michaelis-Menten kinetics; and (2) photoinhibition has a square-root dependence on irradiance. Earlier dynamic models of photosynthesis assumed a first-order dependence of photoinhibition on irradiance and different kinetics of consumption of the stored energy than used in this work. These earlier models could not explain the photosynthesis-irradiance behavior under the full range of irradiance scenarios-a shortcoming that is overcome in the model developed in this work.     

微藻趋向运动及其靶向运输应用研究进展

微藻主要是指一类能进行光合自养的微生物,且很多藻株还兼具运动特性.因而将微藻与微流控芯片结合,实现精确靶向,或用于分子药物递送,在生物医学治疗和药效学分析等领域有重要的潜在应用价值,也是当今的研究热点之一.然而,目前关于微藻趋向运动的研究及潜在的应用的综述报道却相对较少.本文主要以模式微藻莱茵衣藻为例,概述基于微藻细胞...     

System design for the autotrophic production of microalgae

The mass culture of microalgae has been explored over the past 35 years for the production of food, fuels and chemicals, as well as for waste treatment and gas exchange. Culture systems have evolved over this period from small experimental systems to the commercial systems which are presently in place for treatment of municipal wastewaters and for production of a number of specialty products. Further design innovation and refinement will need to draw heavily on the experience which has been gained through the operation of systems employing a wide variety of designs.     

微藻的药用、保健价值及研究开发现状(综述)

本文综述微藻中的各种药理活性物质及已投入市场的微藻产品的药用,保健价值,以及微藻保健与功能食品的研究开发现状。