Filamentous Blue-green Algae Research Articles

Development of Low-Cost Growing Media with Mungbean as A Source of Carbon for Spirulina

Spirulina is a multicellular, photosynthesis, filamentous blue-green algae which is found naturally in a wide range of fresh, marine, and brackish waters. It is an excellent source of protein, vitamins, minerals, lipids, carbohydrates, and pigments thus considered as the “superfood” of the century. The commercial production of Spirulina depends on many factors such as nutrient availability, temperature, and light. Zarrouk’s medium is known to be the standard media (SM) which contains all the macro and micro-nutrients required for the growth of Spirulina. The cost of nutrients is however found to be the second limiting factor next to labor cost affecting the commercial-scale production of Spirulina. The cost of carbon source is higher than that of N and P sources. Therefore, this study aimed at developing a low-cost medium for large-scale production of Spirulina. This intention was implemented by substituting carbon sources present in SM with cheaper and locally available carbon sources. Two separate experiments were conducted using a complete randomized design (CRD) with 3 replicates. The conventional carbon source in Zarrouk’s medium (NaHCO3) was substituted with low-cost carbon sources i.e., Mungbean flour (before and after germination separately). The carbon content in SM was replaced by 100 %, 75 %, 50 % and 25 % of Mungbean flour. Zarrouk’s medium was used as the control. The culture was maintained at 30 0C ± 2 0C under 4000 Lux, continuous illumination using a white, fluorescent tube for 16 days. Growth was measured using a spectrometer and optical density (OD) values were recorded at 560 nm with two days interval. Data were analyzed using SAS version 9.4. The best growth of Spirulina was recorded at the 50 % replacement of carbon in SM by Mungbean flour (before germination). Mungbean flour (after germination) could also replace 25 % of carbon in Zarrouk’s media. Taking the cost factor into consideration, 50 % replacement of carbon in Zarrouk’s medium by Mungbean flour (before germination) can be recommended for commercial scale cultivation. The comparative cost reduction of this replacement is estimated to be 50 %.

Effects of spirulina (Arthrospira platensis) as a fishmeal replacer in practical diets on growth performance, proximate composition, and amino acids profile of pabda catfish (Ompok pabda)

ABSTRACT Spirulina, Arthrospira platensis (SP), is a filamentous blue-green alga with high nutritional value that makes it a promising component for fish meal (FM) replacement in aqua feeds. With this perspective, the current feeding trial was carried out to find out the effects of inclusion of SP protein instead of FM protein on the growth, carcass composition, and amino acids profile of muscles of pabda catfish, Ompok pabda. The current study was carried out in earthen pits (sized 0.64 m3) at a stocking density of 40 fish/pit. Five experimental diets—S0 (control), S10, S15, S20, and S25—were prepared by replacing 0%, 10%, 15%, 20%, and 25% FM protein with SP protein respectively in triplicates. Fish were fed manually with the experimental diets thrice a day up to satiation level for 8 weeks. The higher growth performance of pabda catfish was significantly (P < 0.05) observed for the SP-containing diets than for the control diet. In terms of weight gain, weight gain percent, and specific growth rate, the S15 diet showed the optimum performance. Feed intake in this fish group was higher than the control diet, but no significant (P > 0.05) changes were observed in feed conversion value and protein efficiency ratio; their ranges were 1.57–1.60 and 1.79–1.82 respectively. High ash content and low lipids contents were found in fish fed with SP-treated diets compared to the control group. Most essential and nonessential amino acids significantly (P < 0.05) increased with increasing SP levels in the diets. From these results, it is concluded that FM protein replaced by SP protein at the 15% level showed the optimum performance with better muscles quality of pabda catfish, O. pabda.

Cultivation of Spirulina: An innovative approach to boost up agricultural productivity

Limited consumption of natural food stuff in the 21st century has led to deficiency of vitamins and other important minerals in the human body. Due to excess and repetitive use of chemical fertilizers, the crop productivity is declining day by day. Spirulina is multi-cellular and filamentous blue-green algae biomass which belongs to the class of cyanobacteria discovered by non-referenced Mexicans in the 16th century can be a viable solution of all these problems. In recent years, Spirulina has gained enormous attention from research point of view as well as industries as a flourishing source of nutraceutical and pharmaceuticals. It has a very high content of macro as well as micronutrients, essential amino acids, proteins, lipids, vitamins, minerals and anti-oxidants. It is among the most nutritious, concentrated whole food sources that exists in nature, and is known as a superfood. Spirulina exhibits anticancer, antidiabetic, anti-inflammatory, immunomodulatory and many other properties. Spirulina has the potential of reducing the negative impacts of wastewater discharge through bioremediation. Two major technologies are being considered for the cultivation of Spirulina: closed photobioreactors (PBR) and open raceway ponds. In developing countries like India where malnutrition is a renowned social challenge and it can be defeated by the supplementation of Spirulina products in the diet. The commercial cultivation of Spirulina and converting it to consumable forms (tablets or powder) can be a new way of agribusiness. Therefore, Spirulina is emerging as a cost-effective means of improving livestock and crop productivity in a sustainable manner to ensure food and nutritional security.

МІКРОФІТОБЕНТОС ЯК БІОІНДИКАТОР ЗМІНИ ГІДРОМОРФОМЕТРИЧНИХ ПАРАМЕТРІВ ВОДНОГО ОБ’ЄКТУ МІСТА КИЄВА

A great number of water bodies within urban areas of Kyiv City are exposed to human impact. Hydrotechnical construction operations alter their morphometric and hydrological parameters, water bodies are contaminated with various inorganic and organic substances etc.&#x0D; Since human impact upon water bodies has diversified, bioindication is a well-established and effective method of assessing water bodies’ ecological status and measuring the rate of their ecosystems’ disturbance.&#x0D; Microphytobenthos is an important element of aquatic ecosystems and is widely used as a reliable biological indicator.&#x0D; While using microphytobenthos as an ecological community, it is required to evaluate the bioindication efficiency of its indicative structural elements, which respond distinctly to changes in anthropogenic factors on the whole and in the degree of human impact upon water bodies of different types.&#x0D; This paper considers the findings of studying microphytobenthos indicative structural element bioindication characteristics – ecological-morphological group of benthic filamentous blue-green algae and their role in forming the respective parameters among benthonts in the littoral area of Opechen Lower Lake, located within Kyiv City residential community.&#x0D; Large-scale hydrotechnical construction operations conducted in the lake in 2019 greatly affected its hydromorphometric parameters by reducing the shallow-water area and disturbing the bottom sediments stability, which resulted in increase of the human load.&#x0D; The objective of the study was to identify key characteristics of the microphytobenthos indicative structural element under conditions of the lake’s hydromorphometric parameters alteration.&#x0D; Benthic algae were sampled with the MB-TE microbenthometer within the littoral area at aquatic-vegetation-free sites located in the lake’s upper and lower sections.&#x0D; Algae sampling and laboratory processing of samples were performed in accordance with the methods generally accepted in hydrobiology. For diatoms identification permanent slides were made with using special high-resolution mounting media. Autochthonous components in microphytobenthos, the indicative ecological-morphological group of benthic filamentous blue-green algae were distinguished proceeding from algae’s association with particular biotopes. In addition to separate characteristics (species richness, number, biomass), a multimetric index was calculated for the benthonts’ indicative group as an arithmetic average of several characteristics.&#x0D; The degree of human impact upon the lake ecosystem was calculated according to the proven method, consisting in distinguishing the total number of the most obvious human factors with consideration taken of their different intensity.&#x0D; The findings of studying the key characteristics of phytomicrobenthos indicative structural element – benthic filamentous blue-green algae in 2018–2019 confirm their high bioindication efficiency and distinct response to hydromorphometric parameters alteration in Opechen Lower Lake. As a consequence of hydromorphometric alterations the share of these algae in the benthonts’ species richness, number and biomass has decreased by half, and the vegetation-period-average multimetric index has lowered by 1.7. This gives the evidence that the conditions for bottom algae vegetation have worsened.

Protective properties of filamentous blue–green alga Spirulina against the oxidative stress induced by cadmium in freshwater mussel Unio ravoisieri

ABSTRACTCadmium (Cd) is a toxic-heavy metal that induces a wide range of behavioural, biochemical and physiological effects in aquatic organisms. Oxidative damage has been proposed as a possible mechanism involved in cadmium toxicity. The current study was carried out to evaluate the antioxidant activity of Spirulina as feed additive (1 mg/L) against the toxicity of cadmium (Cd) 0.5 mg/L in freshwater mussel Unio ravoisieri. At the end of the exposed period of 4 days, digestive gland antioxidant status Superoxide dismutase, Catalase, Glutathione-S-transferase and damage markers such as Malondialdehyde and Protein carbonyl were determined. Associations between biomarkers were assessed by a multivariate analysis technique, principal component analysis (PCA). The results of this study revealed that digestive gland antioxidant status showed a significant decrease when mussels were exposed to Cd. Superoxide dismutase, Catalase and Glutathione-S-transferase activities in the Cd + SP group were significantly higher than the Cd group (p < 0.05). Tissue levels of malondialdehyde and protein carbonyl in the Cd + SP group were significantly lower than the Cd group (P < 0.05). Our results show that the pretreatment with Spirulina protects the mussel from Cadmium-induced tissue damage by its antioxidant properties.

Outdoor Closed System of Algal Mass Culture : In Sight of Comparison on Vertical and Horizontal Photobioreactor for Cultivating the Spirulina sp.

Spirulina are multiceluller and filamentous blue-green algae that has gained considerable popularity in the health food industry and increasingly as a protein and vitamin supplement to aquaculture diets. The challenge for economically and fulfill the requirement for food and medical purposes has create many ways for mass-growth production, that possibly cultivated in the open-system (such as a raceway pond) or closed-system photobioreactors (such as tubular, bubble-column, airlift, flat-panel, and vertical). the cultivation of teh Spirulina on the vertical and horizontal photobioreactor has been studied. The photobioreactor, namely BJVP and BJHP, has a design to be less energy consumption using the air bubbling or circular paddle. The observation was conducted in a whole year with parameters of rainfall, temperature, light intensity, pH, and salinity. Result showed that cultivation of Spirulina on the vertical photobioreactor growth faster than teh horizontal photobioreactor systems and the yield of biomass was about 0.94 gDW/L. Average of temperature ranges of BJHP were 31.0C-35.5C, salinities were 35 per mil level, pH were 8.55-10.86, and light intensity were 427-2001 umol photon s-1m-2. Whereas the BJVP has averages temperature range of 31.4C-33.9C, salinity 33-35 per mil level, pH 8.46-10.75, and light intensity 532-2062 umol photon s-1m-2. The proximate analyses of biomass from BJVP cultivation shows has tendency higher protein content compared to BJHP. The optimization of both reactors has continuing evaluated in order to get the optimum parameters required for economically Spirulina cultivation systems.Keywords: Spirulina, BJVP, BJHP, outdoor mass cultivating system, photobioreactor.

Fish Fry Lake: Perspectives from an Inventor on the Application of Created Floating Islands for Water Quality Renovation

Today Fish Fry Lake is a highly productive wild fishery, and also a long-term experiment tracking how the resource of nonpoint nutrient-loaded water can be optimally managed. The Fish Fry Lake story has relevance to water stewardship across much of the developed world where water quality is impacted by agricultural-based nutrient loading. Fish Fry Lake is located on the east side of Yellowstone County in south-central Montana. The lake covers 6.5 surface acres, is 28 feet deep at its deepest point, and contains about 55 acre-feet of water at full pool. Groundwater influenced by agriculture infiltrates to the lake and discharges at a typical rate of 65-85 gallons per minute. When the lake was converted from a seasonal pond to a perennial one in 2005, it displayed the typical attributes of a eutrophic waterway. The lake surface was occasionally completely covered with filamentous blue-green algae, with occasional patches of cyanobacteria.

Some Filamentous Blue Green Algae from Sukhana Dam, Aurangabad, Maharashtra

Algae from Sukhana dam, Aurangabad were investigated from 2015-2017. Algal samples were col-lected from 3 different locations of the water body. Several taxa belonging to classChlorophyceae, Bacillariophy-ceae, Cyanophyceae and Euglenophyceae were observed. In the present study 21 species of genusOscillatoria,be-longing to class Cyanophyceae were observed.These areOscillatoriaacuta, O. annae,O. bornetii,O. brevisvar.non granulata,O. calcuttensis,O. chalybea,O. chilkensis,O. cortiana,O. curviceps,O. fracta,O. jenensis,O. limosa,O. mougeotia,O. nigra,O. ornate var. Crassa,O. perornata,O. sancta,O. simplicissima,O. subbrevis,O. tenuis,O. viza-gapatensis.These species are being reported for the first time from the study area.

Biodegradation of Polyethylene by Green Photosynthetic Microalgae

Conventional methods of polyethylene degradation including incineration, landfill and chemical treatment are lethal to the neighboring environment by causing hazardous effects on living organisms. A better solution for the complete degradation of polyethylene has not yet been formulated. However, to solve this global issue biological mode of polyethylene degradation may be evaluated and developed in the upcoming future. In this research investigation, microalgae like green algae, blue-green algae and diatoms were isolated from the domestic polyethylene bags dumped in the suburban water bodies and studied for its potency on deterioration of polyethylene. The dumped waste polyethylene bags were collected from three different sites of (Maduravoyal, Vanagaram and Poonamallee) Chennai, Tamil Nadu, India. Colonized mat of microalgae were isolated from the polyethylene sheets and the most dominant three different groups of microalgae were selected for the biological treatment of LD (low density) and HD (high density) polyethylene sheets. The most dominant microalgae were Scenedesmus dimorphus (Green microalga), Anabaena spiroides (blue-green alga) and Navicula pupula (Diatom). The T. S. (Transverse section) of polyethylene sheet has shown the proliferation of microalgae in both outer and inner sides of the polyethylene sheet and the erosion cum degradation can be seen obviously. The biological treatment of the selected microalgae on the LD and HD polyethylene sheets with their respective culture media resulted that the microalgae proliferated more on the LD than the HD polyethylene sheets followed by the highest percentage of degradation was obtained from Anabaena spiroides treatment (8.18%). Similarly, among the three microalgal groups treated over the LD polyethylene sheets. The scanning electron microscopical study reveals that the degradation was obviously evident in the treatment of LD polyethylene sheets using the microalga Anabaena spiroides (filamentous blue-green alga) and was found to grow feasibly rather than the other microalgae.

A study of newly recorded genera and species of filamentous blue-green algae (Cyanophyceae, cyanobacteria) in Korea

Cyanobacteria were sampled at five sites in the Han River, Nakdong River, and Geum River watershed from June 2014 to May 2015 and then cultivated. Two genera and five species of the cyanobacteria were newly recorded in Korea. The newly recorded species were Limnothrix redekei, Pseudanabaena galeata, Pseudanabaena amphigranulata, Sphaerospermopsis aphanizomenoides, and Calothrix parietina. As a result, the Korean flora of the cyanobacteria now include four orders, 22 families with 73 genera, 143 species, and two varieties, giving a total of 146 taxa.

Abundance and diversity of unicellular, filamentous cyanobacteria (BGA) and other higher algal genera in different rice fields of North 24 Parganas District in West Bengal, India

The distribution of unicellular and filamentous Blue green algae in relation to seasonal variation in rice fields in three major rice growing different blocks of North 24 parganas in west Bengal has been under taken. Present research paper deals with continued three successive years (2011-2014) studied for the first time. The different physicochemical parameters were chosen for this study. The occurrence of Cyanobacteria and altogether 48 species of Nitrogen fixing Cyanobacteria samples belonging to 25 genera and various orders were isolated in different rice growing fields. The increasing range of soil pH was certainly the important factor for the development of BGA up to certain limits. Comparatively more number of filamentous and heterocystous forms were developed in July to October (kharif season) and less number of unicellular forms were in November to June (Rabi season). When water level was low, Starting the crop season the rice growing fields developed mainly Unicellular, colonial and Non-Heterocystous filamentous Cyanobacteria and slight developed water level in the middle of rice growing time, Non-Heterocystous and Heterocystous Cyanobacteria were observed. When water level was more and at the end of rice crop season mostly Heterocystous and filamentous Cyanobacteria (BGA) were developed.

Individual and combined suppressive effects of submerged and floating-leaved macrophytes on algal blooms

Shallow lakes and ponds are often characterised either by clear water with abundant submerged macrophytes or by turbid water with abundant phytoplankton. Blooms of toxic filamentous blue-green algae (cyanobacteria) often dominate the phytoplankton community in eutrophic lakes, which threatens ecological functions and biodiversity of freshwater ecosystems. We studied a simple lake model in order to evaluate individual and combined suppressive effects of rooted submerged and rooted floating-leaved macrophytes on algal blooms. Floating-leaved plants are superior competitors for light, whereas submerged plants absorb and reduce available phosphorus in a water column that rooted floating-leaved plants exploit to a lesser extent. We found that mixed vegetation that includes both submerged and floating-leaved plants is more resistant than vegetation comprised by a single plant type to algal invasion triggered by phosphorus loading. In addition, competitive exclusion of submerged plants by floating-leaved plants may promote an algal bloom. These predictions were confirmed by the decision tree analysis of field data from 35 irrigation ponds in Hyogo Prefecture, Japan.

Municipal wastewater treatment and biomass accumulation with a wastewater-born and settleable algal-bacterial culture

A wastewater-born and settleable algal-bacterial culture, cultivated in a stirred tank photobioreactor under lab conditions, was used to remove the carbon and nutrients in municipal wastewater and accumulate biomass simultaneously. The algal-bacterial culture showed good settleable property and could totally settle down over 20 min, resulting in a reduction of total suspended solids from an initial 1.84 to 0.016 g/l. The average removal efficiencies of chemical oxygen demand, total kjeldahl nitrogen and phosphate were 98.2 ± 1.3%, 88.3 ± 1.6% and 64.8 ± 1.0% within 8 days, respectively, while the average biomass productivity was 10.9 ± 1.1 g/m 2·d. Accumulation into biomass, identified as the main nitrogen and phosphorus removal mechanism, accounted for 44.9 ± 0.4% and 61.6 ± 0.5% of total inlet nitrogen and phosphorus, respectively. Microscopic analysis showed the main algae species in the bioreactor were filamentous blue-green algae. Furthermore, denaturing gradient gel electrophoresis and 16S rDNA gene sequencing revealed that the main bacteria present in the photobioreactor were consortia with sequences similar to those of Flavobacteria, Gammaproteobacteria, Bacteroidia and Betaproteobacteria. This study explores a better understanding of an algae-bacteria system and offers new information on further usage of biomass accumulated during treatment.

Respiration and ingestion rate of different sized Daphnia pulex fed on four algal species

Respiration rate and ingestion rate for four different algal species (Scenedesmus quadricauda, Asterionella formosa, Aphanizomenon flos-aquae and Planktotrix rubescens) of different sized Daphnia pulex were measured in the laboratory. Population of D. pulex grew maximally when it fed S.quadricauda, but the presence of P. rubescens and A. flos-aquae caused negative population growth rate. Ingestion rates increased with increasing body size for all in- vestigated algae; the lowest b value was obtained for S. quadricauda and the highest one for P. rubescens. The amount of ingested carbon exceeded the required amount for standard metabolism in both small and large sized individuals fed all four algal species. Relatively higher amount of ingested A. flos-aquae and P. rubescens in comparison with A. formosa and S. quadricauda and the results of the growth experiments indicate that the inhibitory effect of filamentous blue-green algae on D. pulex is more due to toxicity, low assimilation efficiency or/and inadequate composition than incapability of ingestion due to mechanical interference with filaments.

Biotic and abiotic determinants of intermediate-consumer trophic diversity in the Florida everglades

Food-web structure can shape population dynamics and ecosystem functioning and stability. We investigated the structure of a food-web fragment consisting of dominant intermediate consumers (fishes and crayfishes) in the Florida Everglades, using stable isotope analysis to quantify trophic diversity along gradients of primary production (periphyton), disturbance (marsh drying) and intermediate-consumer density (a possible indicator of competition). We predicted that trophic diversity would increase with resource availability and decrease after disturbance, and that competition could result in greater trophic diversity by favouring resource partitioning. Total trophic diversity, measured by niche area, decreased with periphyton biomass and an ordination axis representing several bluegreen algae species. Consumers’ basal resource diversity, estimated by δ13C values, was similarly related to algal community structure. The range of trophic levels (δ15N range) increased with time since the most recent drying and reflooding event, but decreased with intermediate-consumer density, and was positively related to the ordination axis reflecting increases in green algae and decreases in filamentous bluegreen algae. Our findings suggest that algal quality, independent of quantity, influences food-web structure and demonstrate an indirect role of nutrient enrichment mediated by its effects on periphyton palatability and biomass. These results reveal potential mechanisms for anthropogenic effects on Everglades communities.

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

BackgroundFairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species.ResultsWe found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments).ConclusionsThe results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment.

Role of rice paddy fields in our finite planet earth

Our ability to control our climatic and financial well-being is being severely challenged, as the IPCC Fourth Evaluation Report of 2007 and the recent global financial crises will testify. At the Summit at Toyo Lake in Hokkaido, Japan in 2008, the delegates gathered to discuss what could be done to tame the global warming phenomenon and the dramatic rise in food and oil prices resulting from globalization. The Japanese Government ratified in June 2007 a strategic plan to make Japan an environmental country for the twenty-first century, as a result of which the Ministry of Environment is committed to the development of what could be called a ‘‘low carbon society’’ or ‘‘natural symbiotic society’’ or ‘‘recycle society’’. The university community has a central role in educating the future leaders of society, especially in environmental science and research so as to enable them to tackle the difficult and complex problems facing us now and in the future. On this point, in this article, I will offer my thoughts on how to deliver practical solutions for many of these problems. In several courses on the environmental science and engineering that I have organized over the years, I have always emphasized lessons learned from natural processes. The most useful source of my inspiration came from the book ‘‘Finite Ecology—Stable and Symbiotic system—’’ by Professor Yasushi Kurihara, which has been re-published as Doujidai-Library194 by Iwanami Publisher. Indeed, more than 30 years ago, when I was a graduate student, Professor Sueshi, my teacher of the ecology class elaborated on the idea of finite ecology as applied to human growth and sustainability. The theory of environmental carrying capacity was central to finite ecology. Since then finite ecology has become my favorite obsession in my teaching and research. Professor Kurihara has experimentally elucidated the intriguing phenomenon that many organisms can survive in a flask where no substrate is supplied. He has named the system of organisms that coexist on subsistent level in this way the co-existence and co-poverty system. Furthermore, Professor Kurihara has proposed other systems, for example, the co-existence and co-prosperity system such as exists in cow rumens, or a system where tension exists always among the constituent members, such as would occur in a space ship. Coming back to the co-poverty system, bacteria first proliferate in a flask under sun light, followed by growth of protozoa. However, as the available substrate is consumed concurrent with a decrease in protozoa, the water surface becomes transparent and changes to green because of chlorella growth by sunlight. After a while, chlorella decrease due to shortage of nutrients, resulting in growth of rotifers in the bulk and of filamentous blue-green algae. As the microorganisms repeat growing and decaying, this ecosystem leads to a steady-state where they stably coexist for a long time. In other words, a sustainable microcosm emerges in the flask. Although a single microorganism decays after substrates are depleted, why can these microorganisms survive in the flask for a long period? Development of such a sustainable microcosm is not created by us; the microorganisms spontaneously design the system in the flask based on light energy and nutrient concentrations in the flask. We can, therefore, learn the basics of material recycling and the energy flow in the natural systems. In addition to the recycle system intertwined with the mechanistically balanced interaction M. Hosomi (&) Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamichi, Koganei, Tokyo 184-8588, Japan e-mail: hosomi@cc.tuat.ac.jp

A Subchronic Toxicity Study of Spirulina platensis

In this study, we examined the effects of Spirulina platensis, a multicellular filamentous blue-green algae currently used world-wide as a food supplement, upon acute and subchronic treatments to rodents. For short-term treatment, no signs of toxicity were observed within 7 days after feeding male Swiss mice at the high dose of 30 and 10 g/kg body weight of fresh and dried S. platensis, respectively. For the subchronic toxicity study, two separate experiments were also performed to evaluate both forms of S. platensis. In each experiment, four groups of six Sprague-Dawley male and female rats were given fresh or dried alga at various doses by feeding daily for 12 weeks. In all instances, the consumption of algae showed no effect on behavior, food and water intake, growth or health status of these animals during the course of this investigation. The values in clinical chemistry monitored throughout the study period did not reveal significant differences between the control and treated groups. In addition, post-mortem examination found no abnormalities in the gross findings. Our results thus demonstrate for the first time that short-term and long-term consumptions of S. platensis, up to high feeding levels, did not produce any adverse effects in experimental animals.

Spirulina protects against cadmium-induced hepatotoxicity in rats

Cadmium (Cd) is an environmental and industrial cumulative pollutant that most affects many organs specially the liver. The protective effect of Spirulina, filamentous blue green algae, on Cd – induced oxidative stress and hepatotoxicity was evaluated in male rats. Oral administration of water extract of Spirulina for seven days followed by an acute toxic dose of Cd (3.5 mg kg b.wt.-1), reduced the hepatotoxicity and attenuated the Cd-induced oxidative stress. Spirulina treatment showed marked reduction in serum aminotrasferase activities and elevation in lipid peroxidation and recovery of the endogenous levels of antioxidants following Cd-intoxication. The Cd-induced hepatic histopathological changes were also minimized with the tested extract. These results suggest that Spirulina algae might play a role in reducing the toxic effect of Cd and its antioxidant properties seems to mediate such a protective effect.

Treatment of Mine Water by a Microbial Mat: Bench-scale Experiments

We investigated the treatment of acid mine drainage (AMD) by a blue-green algae-microbial consortium and substrate (containing powdered goat manure, wood chips, and soil) in 1 m3 bench scale biological treatment test cells. The microbial mat resulted from the interaction of bacteria and filamentous blue-green algae (predominantly Oscillatoria spp). The experiments were carried out for different water column heights, and were evaluated for 24, 48, 72, 96, and 168 hours of retention. Within 24 hours of retention, the pH increased from 2.93 to 6.78 as net alkalinity went from -125 mg/L to 197 mg/L as CaCO3. Turbidity decreased by 33–54%, sulphate decreased by 23–29%, and hardness decreased by 19 to 26%. We also observed that: 95% of the Fe, 79–97% of the Cu, 84–86% of the Zn, 88% of the Pb, 59–83% of the Co, 22–62% of the Ni, and 28–45% of the Mn were removed. A blue-green algae/microbial mat consortium may be a cost–effective treatment technique for removing metals from AMD.