Viable algae in house dust

Freshwater Cyanobacterial Toxins, Cyanopeptides and Neurodegenerative Diseases

Cyanobacteria produce a wide range of structurally diverse cyanotoxins and bioactive cyanopeptides in freshwater, marine, and terrestrial ecosystems. The health significance of these metabolites, which include genotoxic- and neurotoxic agents, is confirmed by continued associations between the occurrence of animal and human acute toxic events and, in the long term, by associations between cyanobacteria and neurodegenerative diseases. Major mechanisms related to the neurotoxicity of cyanobacteria compounds include (1) blocking of key proteins and channels; (2) inhibition of essential enzymes in mammalian cells such as protein phosphatases and phosphoprotein phosphatases as well as new molecular targets such as toll-like receptors 4 and 8. One of the widely discussed implicated mechanisms includes a misincorporation of cyanobacterial non-proteogenic amino acids. Recent research provides evidence that non-proteinogenic amino acid BMAA produced by cyanobacteria have multiple effects on translation process and bypasses the proof-reading ability of the aminoacyl-tRNA-synthetase. Aberrant proteins generated by non-canonical translation may be a factor in neuronal death and neurodegeneration. We hypothesize that the production of cyanopeptides and non-canonical amino acids is a more general mechanism, leading to mistranslation, affecting protein homeostasis, and targeting mitochondria in eukaryotic cells. It can be evolutionarily ancient and initially developed to control phytoplankton communities during algal blooms. Outcompeting gut symbiotic microorganisms may lead to dysbiosis, increased gut permeability, a shift in blood-brain-barrier functionality, and eventually, mitochondrial dysfunction in high-energy demanding neurons. A better understanding of the interaction between cyanopeptides metabolism and the nervous system will be crucial to target or to prevent neurodegenerative diseases.

Toxic or Otherwise Harmful Algae and the Built Environment

This article gives a comprehensive overview on potentially harmful algae occurring in the built environment. Man-made structures provide diverse habitats where algae can grow, mainly aerophytic in nature. Literature reveals that algae that is potentially harmful to humans do occur in the anthropogenic environment in the air, on surfaces or in water bodies. Algae may negatively affect humans in different ways: they may be toxic, allergenic and pathogenic to humans or attack human structures. Toxin-producing alga are represented in the built environment mainly by blue green algae (Cyanoprokaryota). In special occasions, other toxic algae may also be involved. Green algae (Chlorophyta) found airborne or growing on manmade surfaces may be allergenic whereas Cyanoprokaryota and other forms may not only be toxic but also allergenic. Pathogenicity is found only in a special group of algae, especially in the genus Prototheca. In addition, rare cases with infections due to algae with green chloroplasts are reported. Algal action may be involved in the biodeterioration of buildings and works of art, which is still discussed controversially. Whereas in many cases the disfigurement of surfaces and even the corrosion of materials is encountered, in other cases a protective effect on the materials is reported. A comprehensive list of 79 taxa of potentially harmful, airborne algae supplemented with their counterparts occurring in the built environment, is given. Due to global climate change, it is not unlikely that the built environment will suffer from more and higher amounts of harmful algal species in the future. Therefore, intensified research in composition, ecophysiology and development of algal growth in the built environment is indicated.

Algal Toxic Compounds and Their Aeroterrestrial, Airborne and other Extremophilic Producers with Attention to Soil and Plant Contamination: A Review

The review summarizes the available knowledge on toxins and their producers from rather disparate algal assemblages of aeroterrestrial, airborne and other versatile extreme environments (hot springs, deserts, ice, snow, caves, etc.) and on phycotoxins as contaminants of emergent concern in soil and plants. There is a growing body of evidence that algal toxins and their producers occur in all general types of extreme habitats, and cyanobacteria/cyanoprokaryotes dominate in most of them. Altogether, 55 toxigenic algal genera (47 cyanoprokaryotes) were enlisted, and our analysis showed that besides the “standard” toxins, routinely known from different waterbodies (microcystins, nodularins, anatoxins, saxitoxins, cylindrospermopsins, BMAA, etc.), they can produce some specific toxic compounds. Whether the toxic biomolecules are related with the harsh conditions on which algae have to thrive and what is their functional role may be answered by future studies. Therefore, we outline the gaps in knowledge and provide ideas for further research, considering, from one side, the health risk from phycotoxins on the background of the global warming and eutrophication and, from the other side, the current surge of interest which phycotoxins provoke due to their potential as novel compounds in medicine, pharmacy, cosmetics, bioremediation, agriculture and all aspects of biotechnological implications in human life.

Toxic Cyanobacteria: A Growing Threat to Water and Air Quality

The global expansion of harmful cyanobacterial blooms (CyanoHABs) poses an increasing threat to public health. CyanoHABs are characterized by the production of toxic metabolites known as cyanotoxins. Human exposure to cyanotoxins is challenging to forecast, and perhaps the least understood exposure route is via inhalation. While the aerosolization of toxins from marine harmful algal blooms (HABs) has been well documented, the aerosolization of cyanotoxins in freshwater systems remains understudied. In recent years, spray aerosol (SA) produced in the airshed of the Laurentian Great Lakes (United States and Canada) has been characterized, suggesting that freshwater systems may impact atmospheric aerosol loading more than previously understood. Therefore, further investigation regarding the impact of CyanoHABs on human respiratory health is warranted. This review examines current research on the incorporation of cyanobacterial cells and cyanotoxins into SA of aquatic ecosystems which experience HABs. We present an overview of cyanotoxin fate in the environment, biological incorporation into SA, existing data on cyanotoxins in SA, relevant collection methods, and adverse health outcomes associated with cyanotoxin inhalation.

Mechanisms protect airborne green microalgae during long distance dispersal

Viable microalgae occur in the air. Whether they can survive the stresses such as UV, desiccation and freezing temperatures at high altitudes during long distance dispersal is rarely studied. If yes, what mechanisms confer the tolerance? Four freshwater airborne green microalgae were isolated from Dongsha Atoll in the South China Sea, classified as Scenedesmus sp. DSA1, Coelastrella sp. DSA2, Coelastrella sp. DSA3 and Desmodesmus sp. DSA6 based on their morphologies and ITS sequences. Their survival rates under UV stress were tightly correlated with their cell wall thickness. All the four airborne green microalgae survived the air-dry stress on benchtop followed by − 20 °C freeze–desiccation stress for 4 weeks, but not the two waterborne green microalgae Desmodesmus sp. F5 and Neodesmus sp. UTEX 2219-4 used as controls. Three of the four airborne microalgae survived the lyophilization treatment, excluding Desmodesmus sp. DSA6 and the two waterborne microalgae. The four airborne microalgae produced carotenoids under prolonged stress conditions, which might help detoxify the reactive oxygen species generated under environmental stresses and shield from the high-light stress in the air. Characterization of these airborne microalgae may help answer how the descendants of green algae survived on the land about 450 MYA.

Building upon current knowledge and techniques of indoor microbiology to construct the next era of theory into microorganisms, health, and the built environment

In the constructed habitat in which we spend up to 90% of our time, architectural design influences occupants' behavioral patterns, interactions with objects, surfaces, rituals, the outside environment, and each other. Within this built environment, human behavior and building design contribute to the accrual and dispersal of microorganisms; it is a collection of fomites that transfer microorganisms; reservoirs that collect biomass; structures that induce human or air movement patterns; and space types that encourage proximity or isolation between humans whose personal microbial clouds disperse cells into buildings. There have been recent calls to incorporate building microbiology into occupant health and exposure research and standards, yet the built environment is largely viewed as a repository for microorganisms which are to be eliminated, instead of a habitat which is inexorably linked to the microbial influences of building inhabitants. Health sectors have re-evaluated the role of microorganisms in health, incorporating microorganisms into prevention and treatment protocols, yet no paradigm shift has occurred with respect to microbiology of the built environment, despite calls to do so. Technological and logistical constraints often preclude our ability to link health outcomes to indoor microbiology, yet sufficient study exists to inform the theory and implementation of the next era of research and intervention in the built environment. This review presents built environment characteristics in relation to human health and disease, explores some of the current experimental strategies and interventions which explore health in the built environment, and discusses an emerging model for fostering indoor microbiology rather than fearing it.

The importance of cyanobacteria and microalgae present in aerosols to human health and the environment - Review study

Airborne microalgae and cyanobacteria are among the least studied organisms in aerobiology. While those of them living in freshwater and seawater are well recognized, those constituting the components of aerosols are rarely the focus of research. However, their presence has been noted by scientists from all over the world. The presence of these organisms is not indifferent to the environment as they participate in the formation of clouds and influence both the hydrological cycle and Earth's climate. Recent studies have concentrated mostly on the negative impact of airborne cyanobacteria and microalgae, as well as the toxic compounds they produce, on human health. This review focuses on measurement results published on those bioaerosols, combining the achievements of scientists from the last century with the latest reports and trends. Within it gaps in current knowledge are discussed, including the role of airborne organisms in the transport of harmful chemicals like PAHs and heavy metals. The current studies on which it is based emphasize the advantages and disadvantages of the measurement methods used in sampling and analysing. It also visualizes, in the form of maps, where research on bioaerosols has so far been conducted, while at the same time determining the share of organisms potentially dangerous to human health. In addition, we have also tried to recommend future research directions for both environmental and laboratory-based studies.

Fresh water, marine and terrestrial cyanobacteria display distinct allergen characteristics

During the last decades, global cyanobacteria biomass increased due to climate change as well as industrial usage for production of biofuels and food supplements. Thus, there is a need for thorough characterization of their potential health risks, including allergenicity. We therefore aimed to identify and characterize similarities in allergenic potential of cyanobacteria originating from the major ecological environments. Different cyanobacterial taxa were tested for immunoreactivity with IgE from allergic donors and non-allergic controls using immunoblot and ELISA. Moreover, mediator release from human FcεR1-transfected rat basophilic leukemia (RBL) cells was measured, allowing in situ examination of the allergenic reaction. Phycocyanin content and IgE-binding potential were determined and inhibition assays performed to evaluate similarities in IgE-binding epitopes. Mass spectrometry analysis identified IgE-reactive bands ranging between 10 and 160kDa as phycobiliprotein compounds. Levels of cyanobacterial antigen-specific IgE in plasma of allergic donors and mediator release from sensitized RBL cells were significantly higher compared to non-allergic controls (p<0.01). Inhibition studies indicated cross-reactivity between IgE-binding proteins from fresh water cyanobacteria and phycocyanin standard. We further addressed IgE-binding characteristics of marine water and soil-originated cyanobacteria. Altogether, our data suggest that the intensive use and the strong increase in cyanobacterial abundance due to climate change call for increasing awareness and further monitoring of their potential health hazards.

Anaphylaxis to Spirulina confirmed by skin prick test with ingredients of Spirulina tablets

Spirulina (Arthrospira platensis), blue-green microalgae, has high content in proteins, γ-linoleic acid and vitamins and therefore gained popularity as food supplement. According to the Food and Agriculture Organization of the United Nations Spirulina is also an interesting alternative and sustainable protein source with the growing world population. We present a case of a 17-year-old male, who developed anaphylaxis the first time he ingested a Spirulina tablet. Skin prick test with diluted Spirulina tablet was positive. Further skin prick testing with separated ingredients (Spirulina platensis algae, silicon dioxide, inulin and magnesium stearate) was only positive for Spirulina platensis algae and negative in controls, confirming the allergy was caused by Spirulina and not by one of the additives. This case report shows that diagnosis of Spirulina allergy can safely be made by skin prick test with dilutions of the A. platensis or even more simple by skin prick test with the diluted tablet. Since Spirulina has gained popularity as food and nutritional supplement, it is important to realize the potential risk of this dietary supplement. Before Spirulina is produced and consumed on a wider scale, allergenicity risk assessment should be performed, including investigation of potential crossreactivity with well-known inhalant allergens and foods.

Allergenicity of airborne cyanobacteria Phormidium fragile and Nostoc muscorum

In recent times, airborne microorganisms and their constituents have become prominent safety and health concern. Ongoing climatic changes coupled with unwarranted human activities have significantly deteriorated the ambient air quality. In certain environments, airborne algae contribute significantly to the total biological load of the atmosphere, hitherto dominated by bacteria and fungi. Present study was aimed to investigate the allergenic potency of two frequent viable algal forms i.e., Phormidium fragile and Nostoc muscorum found in the atmosphere of Varanasi City, India. To test the allergenic potency, crude extracts of these strains were subjected to intra-dermal allergy test and subsequent leukocyte counts, which revealed their allergenic nature. Both the species varied in their allergenic potency. N. muscorum appeared to be more allergenic than P. fragile. However, when the allergens were mixed in equal amounts, the severity of allergenicity increased significantly. A limited pattern of cross-reactivity between the species was also evident.

Detection of Chlorella-specific IgE in mould-sensitized children

The content of IgE, specific to the unicellular green alga Chlorella sp., was analysed in sera from 46 atopic children sensitized to moulds, using radioallergosorbent test (RAST), immunoblotting and crossed immunoelectrophoresis/crossed radioimmunoelectrophoresis (CIE/CRIE). Chlorella-specific IgE was found in 23/46 sera by RAST, in 28/41 sera by immunoblotting and in 6/30 sera by CIE/CRIE. The Chlorella components most frequently binding IgE as analysed by gradient gel electrophoresis and immunoblotting were of molecular weights of approximately 13, 17, 19, 26 and 49 kD. Twenty-nine precipitating antigens, including seven IgE-binding precipitates were detected by CIE/CRIE. The study shows that low concentrations of specific IgE are formed to the green alga Chlorella in sera from atopic individuals sensitized to moulds.