Comparison of different cultivation modes and light intensities using mono‐cultures and co‐cultures of Haematococcus pluvialis and Chlorella zofingiensis

BACKGROUND: Recent studies indicate that microalgal cultivation using organic carbon sources has the potential to provide high yields. Haematococcus pluvialis and Chlorella zofingiensis, two important carotenoid producers, were selected for co‐culture cultivations to utilize the unique advantages of both organisms. A co‐culture production process was investigated in terms of the effects of organic carbon source, co‐cultivation method, and light intensity on carotenoid production. RESULTS: The addition of 5 g L^?1 glucose resulted in a growth rate of 0.60 day^?1 for H. pluvialis and 0.59 day^?1 for C. zofingiensis, which were higher than those for other carbon sources tested and the control group. Incremental increase of light intensity instead of direct increase to 170 µE m^?2s^? prevented cell loss in both cultures. Co‐cultivation based on cell numbers (60% H. pluvialis and 40% C. zofingiensis) prevented population domination of one microalgae over the other. The biomass production rate of the co‐culture was higher (0.61 g L^?1 day^?1) in glucose‐enriched medium. The total carotenoid content of the co‐culture in the control culture was higher (0.83 mg total carotenoids g^?1 cell) than that obtained in glucose‐enriched medium (0.54 mg total carotenoids g^?1 cell) but not as high as the amounts reached in mono‐cultures. CONCLUSION: Total carotenoid content of the mono‐cultures gave higher yields in standard bold basal medium (BBM). Preliminary high performance liquid chromatography (HPLC) studies indicated a variation in the amounts of astaxanthin isomers produced. Further studies are in progress to determine the effects of carbon‐enriched media and co‐cultivation on the type of isomers and caretenoids produced. Copyright © 2010 Society of Chemical Industry     

CARBON FROM PERIPHYTON SUPPORTS FISH BIOMASS IN WATERHOLES OF A WET–DRY TROPICAL RIVER

The identification of the dominant sources of carbon supporting consumer biomass in aquatic food webs is often difficult but essential to understanding the limits to aquatic secondary production. Stable isotope analysis (SIA) is a powerful tool to estimate the contribution of different sources to consumers, but most food web studies using this approach limit analyses to a few key consumer taxa rather than measuring biomass‐weighted contribution of sources to the entire community. Here we combined stable isotope analysis with standardized measurements of abundance and biomass of fishes and invertebrates in seven waterholes of a wet–dry tropical river sampled early and late in the dry season. We showed that periphyton (as opposed to phytoplankton and terrestrial C3 plant detritus) was responsible for most standing fish biomass (range 42%–97%), whereas benthic invertebrates were reliant on a mixture of the three sources (range 26%–100%). Furthermore, larger, older fishes at high trophic levels (catfish Neoarius spp., sleepy cod Oxyeleotris lineaolatus and barramundi Lates calcarifer) were supported almost exclusively by periphyton. Phytoplankton and detritus supported a considerable biomass of benthic and pelagic invertebrates, but only in taxa that occupied low trophic levels (e.g. snails). These measurements provide further evidence that although periphyton is relatively inconspicuous relative to other sources, it contributes disproportionately to metazoan biomass in wet–dry tropical rivers. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparison of the wound-activated transformation of caulerpenyne by invasive and noninvasive Caulerpa species of the Mediterranean

The invasive green alga, Caulerpa taxifolia, that has spread rapidly after its introduction into the Mediterranean and the North American Pacific, reacts to wounding by transforming its major metabolite caulerpenyne (1). This wound-activated reaction involves the transformation of the bis-enol acetate moiety of 1, releasing reactive 1,4-dialdehydes. The ability to perform this transformation is found also in both the noninvasive Mediterranean C. prolifera and the invasive C. racemosa. Trapping experiments, as well as transformation of the model substrate geranyl acetate, suggest that all three investigated Caulerpa spp. rely on esterases that act upon wounding of the algae by subsequently removing the three acetate residues of caulerpenyne. The resulting reactive 1,4-dialdehyde oxytoxin 2 (9) can be identified by liquid chromatography–mass spectrometry and is unstable in the wounded tissue. Caulerpenyne transformation occurs rapidly, and severe tissue damage caused degradation of more than 50% of the stored caulerpenyne within 1 min in all three algae. Prevention of the enzymatic reaction before extraction, by shock freezing the tissue with liquid nitrogen, was used for the determination of the caulerpenyne content in intact algae. It gives about twofold higher values compared to an established methanol extraction protocol. The speed and mechanism of the wound-activated transformation, as well as the caulerpenyne content in intact tissue of invasive and noninvasive Caulerpa spp., are comparable. Thus, this enzymatic , transformation, despite being fast and efficient, is likely not the key for the success of the investigated invasive species.     

利用菌-藻体系高效快速脱除生活污水中氮、磷的技术研究

利用菌－藻体系中的细菌与藻类生活习性与摄取食物上的差异性，对它们进行有效的组合来处理城市生活污水，结果表明：在一定的条件下该系统可使污水中磷的去除率达94．4％，氮的去除率为48．3％，COD去除率为87．7％。大大减轻了出水中的磷、氮对受纳水体的环境负荷；高效、经济、可操作性强。     

Chemical Defenses of the Sacoglossan Mollusk Elysia rufescens and Its Host Alga Bryopsis sp.

Sacoglossans are a group of opisthobranch mollusks that have been the source of numerous secondary metabolites; however, there are few examples where a defensive ecological role for these compounds has been demonstrated experimentally. We investigated the deterrent properties of the sacoglossan Elysia rufescens and its food alga Bryopsis sp. against natural fish predators. Bryopsis sp. produces kahalalide F, a major depsipeptide that is accumulated by the sacoglossan and that shows in vitro cytotoxicity against several cancer cell lines. Our data show that both Bryopsis sp. and Elysia rufescens are chemically protected against fish predators, as indicated by the deterrent properties of their extracts at naturally occurring concentrations. Following bioassay-guided fractionation, we observed that the antipredatory compounds of Bryopsis sp. were present in the butanol and chloroform fractions, both containing the depsipeptide kahalalide F. Antipredatory compounds of Elysia rufescens were exclusively present in the dichloromethane fraction. Further bioassay-guided fractionation led to the isolation of kahalalide F as the only compound responsible for the deterrent properties of the sacoglossan. Our data show that kahalalide F protects both Bryopsis sp. and Elysia rufescens from fish predation. This is the first report of a diet-derived depsipeptide used as a chemical defense in a sacoglossan.     

桂林桂湖浮游藻类种群组成及水质生物学评价

根据2013年1～12月对桂湖浮游藻类的调查和监测结果,分析藻类种群组成和优势种、细胞密度、马卡列夫（Margalef）和香农—韦弗（Shannon-Weaver）生物多样性指数等生物特征参数的变化,从生物学角度对桂湖水质进行评价,为桂林两江四湖水环境的综合治理和生态保护提供基础资料和理论依据。     

基于Acitiflo^（R）加砂高效沉淀池试验分析

Acitiflo^（R）加砂高效沉淀池工艺在絮凝池中投加微砂作为絮体的核心,增强混凝絮凝沉淀的处理性能,试验进一步验证了Acitiflo^（R）加砂高效沉淀池用于自来水厂初沉池的处理效果和运行数据的初步确定,分析Acitiflo^（R）加砂高效沉淀池工艺对浊度和藻类去除的效果,预加氯不会影响Acitiflo^（R）加砂沉淀池的浊度去除效果,能增加藻类去除率。     

水动力条件对藻华的影响

水动力条件在湖泊富营养化及藻华爆发的过程中起着决定性的作用.研究了水动力条件对藻类生长的影响,从而找出控制藻类生长的关键因素和相关参数.对于防治藻华具有重要意义.     

Radical-scavenging activity of Aegean Sea marine algae

In the present work, thirteen algae from the Aegean Sea were examined for radical-scavenging activity (RSA) using the DPPH and chemiluminescence (CL) tests. Extracts of the brown alga Taonia atomaria exhibited the best RSA in comparison to the extracts of the other investigated species and approached the activity of powerful antioxidant standards. Column chromatography separation of T. atomaria extract, followed by preparative HPLC, resulted in the isolation of six metabolites, which were identified by spectral analyses (¹H NMR, ¹³C NMR and MS). The isolated metabolites taondiol, isoepitaondiol, stypodiol, stypoldione, sargaquinone and sargaol were found to possess marked RSA.