Sunscreen products increase virus production through prophage induction in marine bacterioplankton

Temperate phage-antibiotic synergy across antibiotic classes reveals new mechanism for preventing lysogeny

A recent demonstration of synergy between a temperate phage and the antibiotic ciprofloxacin suggested a scalable approach to exploiting temperate phages in therapy, termed temperate phage-antibiotic synergy, which specifically interacted with the lysis-lysogeny decision. To determine whether this would hold true across antibiotics, we challenged Escherichia coli with the phage HK97 and a set of 13 antibiotics spanning seven classes. As expected, given the conserved induction pathway, we observed synergy with classes of drugs known to induce an SOS response: a sulfa drug, other quinolones, and mitomycin C. While some β-lactams exhibited synergy, this appeared to be traditional phage-antibiotic synergy, with no effect on the lysis-lysogeny decision. Curiously, we observed a potent synergy with antibiotics not known to induce the SOS response: protein synthesis inhibitors gentamicin, kanamycin, tetracycline, and azithromycin. The synergy results in an eightfold reduction in the effective minimum inhibitory concentration of gentamicin, complete eradication of the bacteria, and, when administered at sub-optimal doses, drastically decreases the frequency of lysogens emerging from the combined challenge. However, lysogens exhibit no increased sensitivity to the antibiotic; synergy was maintained in the absence of RecA; and the antibiotic reduced the initial frequency of lysogeny rather than selecting against formed lysogens. Our results confirm that SOS-inducing antibiotics broadly result in temperate-phage-specific synergy, but that other antibiotics can interact with temperate phages specifically and result in synergy. This is the first report of a means of chemically blocking entry into lysogeny, providing a new means for manipulating the key lysis-lysogeny decision.IMPORTANCEThe lysis-lysogeny decision is made by most bacterial viruses (bacteriophages, phages), determining whether to kill their host or go dormant within it. With over half of the bacteria containing phages waiting to wake, this is one of the most important behaviors in all of biology. These phages are also considered unusable for therapy because of this behavior. In this paper, we show that many antibiotics bias this behavior to "wake" the dormant phages, forcing them to kill their host, but some also prevent dormancy in the first place. These will be important tools to study this critical decision point and may enable the therapeutic use of these phages.

Sunscreen use during recreational activities on a French Atlantic beach: release of UV filters at sea and influence of air temperature

Organic UV filters are emerging contaminants in personal care products such as sunscreens. The toxicity of numerous of these UV filter compounds has been demonstrated in several marine taxa. However, whilst the biological impact has already been largely demonstrated, the anthropogenic drivers leading to UV filter contamination still need to be identified. In this work, a survey was conducted on a site of the French Atlantic Coast (i) to describe beachgoers' behaviours (sunscreen use and beach frequentation), (ii) provide an estimation of the UV filters released at sea and (iii) highlight the effect of air temperature on these behaviours and on the release of UV filters. In parallel with these estimations of the UV filters released at sea, in situ chemical measurements were performed. By comparing the results of both approaches, this interdisciplinary work provides an insight of how the observations of beachgoers' behaviour modulations and attendance level fluctuations could be used to prevent UV filter contaminations and ultimately manage the ecotoxicological risk.

Ultraviolet Filters: Dissecting Current Facts and Myths

Skin cancer is a global and increasingly prevalent issue, causing significant individual and economic damage. UV filters in sunscreens play a major role in mitigating the risks that solar ultraviolet ra-diation poses to the human organism. While empirically effective, multiple adverse effects of these compounds are discussed in the media and in scientific research. UV filters are blamed for the dis-ruption of endocrine processes and vitamin D synthesis, damaging effects on the environment, induction of acne and neurotoxic and carcinogenic effects. Some of these allegations are based on scientific facts while others are simply arbitrary. This is especially dangerous considering the risks of exposing unprotected skin to the sun. In summary, UV filters approved by the respective governing bodies are safe for human use and their proven skin cancer-preventing properties make them in-dispensable for sensible sun protection habits. Nonetheless, compounds like octocrylene and ben-zophenone-3 that are linked to the harming of marine ecosystems could be omitted from skin care regimens in favor of the myriad of non-toxic UV filters.

Effects of the sunscreen ultraviolet filter oxybenzone (benzophenone-3) on the seagrass Posidonia oceanica (L.) Delile and its associated N2 fixers

Oxybenzone/benzophenone-3 (BP-3) is one of the most detrimental organic ultraviolet filters for marine biota, leading to legislative measures banning its presence in commercial sunscreen formulations of several countries. It remains poorly explored how this contaminant is currently threatening the persistence of critical ecosystems for conservation in the Mediterranean, such as Posidonia oceanica meadows, but it is essential for promoting sustainable coastal tourism. Our investigation aimed to determine the effects of BP-3 on P. oceanica under a short-term laboratory setup, recreating summer conditions while testing three environmentally relevant concentrations for Mallorca, Spain (minimum: 53.6 ng L-1, maximum: 557.5 ng L-1 and increased: 1115 ng L-1) and a control (0 ng L-1). Primary productivity was unaffected by the treatments, however, a reduction in leaf chlorophyll content and nitrogen fixation activity associated with rhizomes was evidenced under BP-3 addition. This may be related with oxidative damage, as reactive oxygen species production and catalase activity in P. oceanica leaves were the highest even at minimum BP-3 concentrations. Alkaline phosphatase rates showed inverted trends between old leaves and rhizomes, being enhanced in the former under BP-3 addition and reduced in the latter. These results are of great relevance for the future management of P. oceanica meadows, elucidating that even minimum concentrations of BP-3 reported in coastal waters of Mallorca can induce elevated levels of oxidative stress in the seagrass, that lead to impairments in its photosynthetic pigments production and supply of essential nutrients through belowground tissues.

Seasonal trends in lysogeny in an Appalachian oak-hickory forest soil

Since 1989, investigations into viral ecology have revealed how bacteriophages can influence microbial dynamics within ecosystems at global scales. Most of the information we know about temperate phages, which can integrate themselves into the host genome and remain dormant via a process called lysogeny, has come from research in aquatic ecosystems. Soil environments remain under-studied, and more research is necessary to fully understand the range of impacts phage infections have on the soil bacteria they infect. The aims of this study were to compare the efficacy of different prophage-inducing agents and to elucidate potential temporal trends in lysogeny within a soil bacterial community. In addition to mitomycin C and acyl-homoserine lactones, our results indicated that halosulfuron methyl herbicides may also be potent inducing agents. In optimizing chemical induction assays, we determined that taking steps to reduce background virus particles and starve cells was critical in obtaining consistent results. A clear seasonal trend in inducible lysogeny was observed in an Appalachian oak-hickory forest soil. The average monthly air temperature was negatively correlated with inducible fraction and burst size, supporting the idea that lysogeny provides a mechanism for phage persistence when temperatures are low and host metabolism is slower. Furthermore, the inducible fraction was negatively correlated with both soil bacterial and soil viral abundance, supporting the idea that lysogeny provides a mechanism for temperate phage persistence when host density is lower. The present study is the first of its kind to reveal clear seasonal trends in inducible lysogeny in any soil.IMPORTANCELysogeny is a relationship in which certain viruses that infect bacteria (phages) may exist within their bacterial host cell as a segment of nucleic acid. In this state, the phage genome is protected from environmental damage and retains the potential to generate progeny particles in the future. It is thought that lysogeny provides a mechanism for long-term persistence for phages when host density is low or hosts are starved-two conditions likely to be found in soils. In the present study, we provide the first known evidence for a seasonal trend in lysogeny in a forest soil. Based on clear relationships observed between lysogeny, temperature, and soil microbial abundance, we find support for previous hypotheses regarding the factors governing lysogeny.

Sunscreen exposure interferes with physiological processes while inducing oxidative stress in seagrass Posidonia oceanica (L.) Delile

The effects of a commercial sunscreen mixture on the Mediterranean seagrass Posidonia oceanica were investigated, evaluating its response in physiological processes and biochemical indicators of oxidative stress. Short-term laboratory experiments were conducted recreating summer conditions, and two sunscreen concentrations were tested in whole P. oceanica plants placed inside aquaria. Although primary productivity of leaf segments seemed to benefit from sunscreen addition, probably due to inorganic nutrients released, the rest of the biological parameters reflected possible impairments in the overall functioning of P. oceanica as a result of oxidative damages. Chlorophyll production and nitrogen fixation associated with old leaves were inhibited under high sunscreen concentrations, which concurred with elevated reactive oxygen species production, catalase activity and polyphenols content in the seagrass leaves. These results emphasize the importance of directing future investigations on determining which specific components of sunscreen products are likely threatening the wellbeing of critical species, such as P. oceanica.

UV-filters in marine environments: a review of research trends, meta-analysis, and ecotoxicological impacts of 4-methylbenzylidene-camphor and benzophenone-3 on marine invertebrate communities

The potential adverse effects of UV-filter pollution in marine environments have been the focus of research in recent years. This systematic review aims to determine the extent of this emerging problem, both quantitatively and qualitatively, combining temporal and science mapping analyses to explore the development of the field of UV-filters in the marine environment (from 1990 to 2021), and to outline new research frontiers. The temporal trend analysis revealed an exponential growth of published studies over the last decade (70% since 2016), confirming the emerging role of this topic in environmental science. The meta-analysis determined that 4-methylbenzylidene-camphor (4-MBC) and benzophenone-3 (BP-3) are top-priority environmental pollutants due to their increasing usage and, in turn, a frequent occurrence in marine ecosystems. This meta-analysis determined the focus on these two contaminants for this review. A critical discussion of the applications, regulatory aspects, and environmental occurrences of these selected compounds was provided. The present study also focused on the most recent (2015-2021) field and laboratory studies investigating the ecotoxicological impacts of 4-MBC and BP-3 on marine invertebrates. This review highlights the need for more research efforts to fill the knowledge gaps on the realistic effects these compounds may have when considered individually, in combination, or as subsequent exposures. Overall, this review aims to establish guidelines for further studies to understand the effect of UV-filters on marine ecosystems and marine invertebrate communities.

The Life Cycle Transitions of Temperate Phages: Regulating Factors and Potential Ecological Implications

Phages are viruses that infect bacteria. They affect various microbe-mediated processes that drive biogeochemical cycling on a global scale. Their influence depends on whether the infection is lysogenic or lytic. Temperate phages have the potential to execute both infection types and thus frequently switch their infection modes in nature, potentially causing substantial impacts on the host-phage community and relevant biogeochemical cycling. Understanding the regulating factors and outcomes of temperate phage life cycle transition is thus fundamental for evaluating their ecological impacts. This review thus systematically summarizes the effects of various factors affecting temperate phage life cycle decisions in both culturable phage-host systems and natural environments. The review further elucidates the ecological implications of the life cycle transition of temperate phages with an emphasis on phage/host fitness, host-phage dynamics, microbe diversity and evolution, and biogeochemical cycles.

Limited human access is linked to higher effectiveness in a marine sanctuary

Marine Protected Areas (MPAs) are a widely used tool for coral reefs conservation, but massive tourism activities inside MPAs worldwide can challenge their effectiveness. This study investigated the role of different levels of protection strictness (no-entry, low and high tourism-allowed zones) set for a marine sanctuary in shaping benthic cover and reef fish community structure in the richest and largest coral reef system of the Southwestern Atlantic. Reef fish community structure and benthic cover differed between protection levels. No-entry zones showed significant higher coral coverage and biomass of piscivores and herbivores than tourism-allowed zones. Highest differences were found between no-entry and high tourism intensity zones. Despite the fact that protection from fishing by itself can ensure conservation benefits, we show here that the establishment of no-entry zones improve MPAs effectiveness.

Suppression of Sunscreen Leakage in Water by Amyloid-like Protein Aggregates

A sunscreen offers indispensable skin protection against UV damage and related skin diseases. However, due to the poor interfacial stability of sunscreen coatings on the skin, the synthetic ingredients in sunscreen creams easily fall off and enter aquatic environments, causing large ecological hazards and skin protection failure. Herein, we tackle this issue by introducing amyloid-like protein aggregates into a sunscreen to noticeably enhance the interfacial robustness of sunscreen coatings on the skin. The synthesis of such an agent to suppress sunscreen leakage can be achieved by manipulating the phase transition of bovine serum albumin (BSA) in a mild aqueous solution at room temperature. The resulting phase-transitioned BSA (PTB) aggregates effectively entrap the sunscreen ingredients to generate a uniform cream coating on the skin with robust amyloid-mediated interfacial adhesion stability. With continuous flushing in aquatic environments, such as salt water and seawater, this PTB-modified sunscreen (PTB sunscreen) coated on the skin maintains a retention ratio as high as >92%, which is 2-10 times higher than those of commercially available sunscreen products. The high retention ratio of the PTB sunscreen in aquatic environments demonstrates the great potential of amyloid-like protein aggregates in the development of leakage-free sunscreens with low ecosystem hazards and long-lasting UV protection in aquatic environments.

Investigating the exposure and impact of chemical UV filters on coral reef ecosystems: Review and research gap prioritization

Coral reefs are among the world's most productive and biologically diverse ecosystems. In recent decades, they have experienced an unparalleled decline resulting from various anthropogenically induced stressors. Ultraviolet (UV) filters found in personal care products, such as sunscreen, are chemical pollutants that are emerging as a growing toxic threat to reef organisms. In this study, a systematic literature review was conducted to (1) determine the current understanding of spatial distribution and the occurrence of UV filters exposed to the marine environment, (2) synthesize current ecotoxicological thresholds of relevant reef organisms under various UV-filter exposures, (3) identify research gaps related to both exposure and toxicity of UV filters in coral reef ecosystems. With gaps identified, a survey was developed and distributed to experts in the field representing academic, governmental, not-for-profit, and industry researchers in order to prioritize research gaps and inform future research efforts. The survey identified the need for better understanding of the impacts of co-stressors, long-term exposure, mixture, and degradation product exposure and realistic environmental conditions. Ultimately, this review will help guide priority research efforts to understand the risks of UV-filter exposure to coral reef ecosystems. Integr Environ Assess Manag 2021;17:967-981. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Sunscreens: UV filters to protect us: Part 2-Increasing awareness of UV filters and their potential toxicities to us and our environment

BACKGROUND

Sunscreens are topical preparations containing one or more compounds that filter, block, reflect, scatter, or absorb ultraviolet (UV) light. Part 2 of this review focuses on the environmental, ecological effects and human toxicities that have been attributed to UV filters.

METHODS

Literature review using NIH databases (eg, PubMed and Medline), FDA and EPA databases, Google Scholar, the Federal Register, and the Code of Federal Regulations (CFR).

LIMITATIONS

This was a retrospective literature review that involved many different types of studies across a variety of species. Comparison between reports is limited by variations in methodology and criteria for toxicity.

CONCLUSIONS

In vivo and in vitro studies on the environmental and biological effects of UV filters show a wide array of unanticipated adverse effects on the environment and exposed organisms. Coral bleaching receives considerable attention from the lay press, but the scientific literature identifies potential toxicities of endocrine, neurologic, neoplastic and developmental pathways. These effects harm a vast array of aquatic and marine biota, while almost no data supports human toxicity at currently used quantities (with the exception of contact allergy). Much of these data are from experimental studies or field observations; more controlled environmental studies and long-term human use data are limited. Several jurisdictions have prohibited specific UV filters, but this does not adequately address the dichotomy of the benefits of photoprotection vs lack of eco-friendly, safe, and FDA-approved alternatives.

UV-Protection Performance of Calophyllum inophyllum Seed Extracts: A Natural Ultraviolet Screening Agent

Demand for sunscreen products has been rising in recent years due to increasing cases of skin damage caused byultraviolet radiation (UVR). Recent studies have proved that some materials in commercial sunscreen products are harmful to the marine ecosystem. Therefore, the development of a photoprotective and environmentally friendly screening agent has been a leading direction for the cosmetic industry. Calophyllum inophyllum is a seaside plant found in the Pacific Rim, regarded as a potential source of biodiesel feedstock given the high oil content of its seeds. Due to the harsh environment of its natural habitat, C. inophyllum has developed UV-absorbing secondary metabolites, which are natural sources for screening agents. In this study, samples of seed extracts of C. inophyllum were subjected to in vitro UV, Fourier-transform infrared (FTIR) spectroscopy, and cytotoxicity analysis; all the samples extracted by solvents of various polarities showed different chemical compositions by FTIR spectroscopy and levels of cytotoxicity. The n-hexane seed extract showed the highest UVA and UVB absorption efficiencies. In the in vitro cytotoxicity test on human skin fibroblast cells, seed oil of C. inophyllum demonstrated low cytotoxicity. Results have shown that seed extracts of C. inophyllum can be an ideal material for a natural high-efficiency screening agent.

Robust natural ultraviolet filters from marine ecosystems for the formulation of environmental friendlier bio-sunscreens

Ultraviolet radiation (UVR) has detrimental effects on human health. It induces oxidative stress, deregulates signaling mechanisms, and produces DNA mutations, factors that ultimately can lead to the development of skin cancer. Therefore, reducing exposure to UVR is of major importance. Among available measures to diminish exposure is the use of sunscreens. However, recent studies indicate that several of the currently used filters have adverse effects on marine ecosystems and human health. This situation leads to the search for new photoprotective compounds that, apart from offering protection, are environmentally friendly. The answer may lie in the same marine ecosystems since molecules such as mycosporine-like amino acids (MAAs) and scytonemin can serve as the defense system of some marine organisms against UVR. This review will discuss the harmful effects of UVR and the mechanisms that microalgae have developed to cope with it. Then it will focus on the biological distribution, characteristics, extraction, and purification methods of MAAs and scytonemin molecules to finally assess its potential as new filters for sunscreen formulation.

Are Titania Photocatalysts and Titanium Implants Safe? Review on the Toxicity of Titanium Compounds

Titanium and its compounds are broadly used in both industrial and domestic products, including jet engines, missiles, prostheses, implants, pigments, cosmetics, food, and photocatalysts for environmental purification and solar energy conversion. Although titanium/titania-containing materials are usually safe for human, animals and environment, increasing concerns on their negative impacts have been postulated. Accordingly, this review covers current knowledge on the toxicity of titania and titanium, in which the behaviour, bioavailability, mechanisms of action, and environmental impacts have been discussed in detail, considering both light and dark conditions. Consequently, the following conclusions have been drawn: (i) titania photocatalysts rarely cause health and environmental problems; (ii) despite the lack of proof, the possible carcinogenicity of titania powders to humans is considered by some authorities; (iii) titanium alloys, commonly applied as implant materials, possess a relatively low health risk; (iv) titania microparticles are less toxic than nanoparticles, independent of the means of exposure; (v) excessive accumulation of titanium in the environment cannot be ignored; (vi) titanium/titania-containing products should be clearly marked with health warning labels, especially for pregnant women and young children; (vi) a key knowledge gap is the lack of comprehensive data about the environmental content and the influence of titania/titanium on biodiversity and the ecological functioning of terrestrial and aquatic ecosystems.

Lysogeny in the oceans: Lessons from cultivated model systems and a reanalysis of its prevalence

In the oceans, viruses that infect bacteria (phages) influence a variety of microbially mediated processes that drive global biogeochemical cycles. The nature of their influence is dependent upon infection mode, be it lytic or lysogenic. Temperate phages are predicted to be prevalent in marine systems where they are expected to execute both types of infection modes. Understanding the range and outcomes of temperate phage-host interactions is fundamental for evaluating their ecological impact. Here, we (i) review phage-mediated rewiring of host metabolism, with a focus on marine systems, (ii) consider the range and nature of temperate phage-host interactions, and (iii) draw on studies of cultivated model systems to examine the consequences of lysogeny among several dominant marine bacterial lineages. We also readdress the prevalence of lysogeny among marine bacteria by probing a collection of 1239 publicly available bacterial genomes, representing cultured and uncultivated strains, for evidence of complete prophages. Our conservative analysis, anticipated to underestimate true prevalence, predicts 18% of the genomes examined contain at least one prophage, the majority (97%) were found within genomes of cultured isolates. These results highlight the need for cultivation of additional model systems to better capture the diversity of temperate phage-host interactions in the oceans.

Dietary prophage inducers and antimicrobials: toward landscaping the human gut microbiome

The approximately 10¹¹ viruses and microbial cells per gram of fecal matter (dry weight) in the large intestine are important to human health. The responses of three common gut bacteria species, and one opportunistic pathogen, to 117 commonly consumed foods, chemical additives, and plant extracts were tested. Many compounds, including Stevia rebaudiana and bee propolis extracts, exhibited species-specific growth inhibition by prophage induction. Overall, these results show that various foods may change the abundances of gut bacteria by modulating temperate phage and suggests a novel path for landscaping the human gut microbiome.

Update About the Effects of the Sunscreen Ingredients Oxybenzone and Octinoxate on Humans and the Environment

As skin cancer prevalence continues to rise, the importance of sun protection, including sunscreen use, has become accepted in the public. Sunscreens are divided into two main categories based on the type of their active ingredient, organic and inorganic ultraviolet (UV) filters. It has been shown that inorganic filters are more effective at blocking forms of UV light, both UVA and UVB, as compared with organic filters because organic sunscreens absorb and convert radiation whereas inorganic sunscreens reflect radiation. The use of the two most common organic filters, oxybenzone and octinoxate, has recently been restricted in Hawaii due to their harmful effect on the coral reefs. Here, we discuss recent studies about these specific filters related to the adverse health risks they pose for humans and other organisms, as well as environmental repercussions.

Interkingdom Genetic Mix-and-Match To Produce Novel Sunscreens

Sunscreen-containing skincare products protect the skin from damage caused by sun exposure. However, many of them contain oxybenzone and/or octinoxate, which have been reported to be toxic to juvenile coral and to cause coral bleaching. Thus, there is a growing need for new sunscreen compounds that are less harmful to the environment. Here, we report an engineered biosynthetic pathway employing genes from a vertebrate and two Gram-(+) bacteria that forms novel sunscreen compounds with hybrid structures of gadusol and mycosporine-like amino acids, both of which are found in marine environments. These compounds, named gadusporines, have unique UV absorbance at 340 nm, expanding the range of mycosporine- and gadusol-based sunscreen products. The synthesis of gadusporines in Streptomyces coelicolor establishes a platform for the design and production of novel sunscreens.

Massive coastal tourism influx to the Mediterranean Sea: The environmental risk of sunscreens

The Mediterranean region is, by far, the leading tourism destination in the world, receiving more than 330 million tourists in 2016. This tourism is undertaken mostly for seaside holidays, and during the summer season concentrates between 46% and 69% of the total international arrivals; this is equivalent to a density of 2.9 tourists per meter of Mediterranean coast, or double this number taking into account the local/permanent population in addition. Previous studies have reported not only the presence of sunscreen in the various environmental compartments (water, sediments and biota) of the Mediterranean Sea (MS) and other regions, but also show that sunscreen products are toxic for marine biota and are accumulated and biomagnificated. Here, we highlight that the environmental risk of these chemicals is likely to be exacerbated in the MS due to the massive influx of tourists and its densely populated coasts, the basin's limited exchanges with the ocean, the high residence time of surface waters, and its oligotrophic waters.

Sunscreen bans: Coral reefs and skin cancer

WHAT IS KNOWN AND OBJECTIVE

Hawaii will ban two major ingredients of sunscreens. This article reviews the reasons and future directions. Hawaii recently enacted legislation that will ban the use of two major ingredients of the majority of commonly used sunscreens. The reason for the ban is the ingredients' putative deleterious impact on marine ecosystems, particularly coral reefs. But sunscreens also save lives by decreasing the risk of UV-induced skin cancers. We review both sides of the issue and potential implications for the healthcare system.

COMMENT

Coral reefs consist of organisms in delicate equilibria that are susceptible to small changes in their surroundings. Recent natural and man-made disruptions, direct or indirect, such as changes in ocean temperature and chemistry, ingress of invasive species, pathogens, pollution and deleterious fishing practices, have been blamed for the poor health, or even the outright destruction, of some coral reefs. The most popular sunscreen products contain two ingredients-oxybenzone and octinoxate-that have also been implicated in coral toxicity and will be banned. This creates a healthcare dilemma: Will the protection of coral reefs result in an increase in human skin cancers?

WHAT IS NEW AND CONCLUSION

Concentration estimates and mechanism studies support an association-direct or indirect (via promotion of viral infection)-of sunscreens with bleaching of coral reefs. A ban on the two most common sunscreen ingredients goes into effect in Hawaii on January 1, 2021. Proponents suggest that this is a trend, just the first of many such bans worldwide; opponents warn of a dire increase in human skin cancers. As a result, alternative sunscreen compounds are being sought.

A fast and reliable method for monitoring of prophage-activating chemicals

Bacteriophages, that is viruses that infect bacteria, either lyse bacteria directly or integrate their genome into the bacterial genome as so-called prophages, where they remain at a silent state. Both phages and bacteria are able to survive in this state. However, prophages can be reactivated with the introduction of chemicals, followed by the release of a high number of phage particles, which could infect other bacteria, thus harming ecosystems by a viral bloom. The basics for a fast, automatable analytical method for the detection of prophage-activating chemicals are developed and successfully tested here. The method exploits the differences in metabolic heat produced by Escherichia coli with (λ+) and without the lambda prophages (λ-). Since the metabolic heat primarily reflects opposing effects (i.e. the reduction of heat-producing cells by lysis and enhanced heat production to deliver the energetic costs for the synthesis of phages), a systematic analysis of the influence of the different conditions (experimentally and in silico) was performed and revealed anoxic conditions to be best suited. The main advantages of the suggested monitoring method are not only the possibility of obtaining fast results (after only few hours), but also the option for automation, the low workload (requires only few minutes) and the suitability of using commercially available instruments. The future challenge following this proof of principle is the development of thermal transducers which allow for the electronic subtraction of the λ+ from the λ- signal.

Impact of inorganic UV filters contained in sunscreen products on tropical stony corals (Acropora spp.)

Most coral reefs worldwide are threatened by natural and anthropogenic impacts. Among them, the release in seawater of sunscreen products commonly used by tourists to protect their skin against the harmful effects of UV radiations, can affect tropical corals causing extensive and rapid bleaching. The use of inorganic (mineral) filters, such as zinc and titanium dioxide (ZnO and TiO₂) is increasing due to their broad UV protection spectrum and their limited penetration into the skin. In the present study, we evaluated through laboratory experiments, the impact on the corals Acropora spp. of uncoated ZnO nanoparticles and two modified forms of TiO₂ (Eusolex®T2000 and Optisol™), largely utilized in commercial sunscreens together with organic filters. Our results demonstrate that uncoated ZnO induces a severe and fast coral bleaching due to the alteration of the symbiosis between coral and zooxanthellae. ZnO also directly affects symbiotic dinoflagellates and stimulates microbial enrichment in the seawater surrounding the corals. Conversely, Eusolex® T2000 and Optisol™ caused minimal alterations in the symbiotic interactions and did not cause bleaching, resulting more eco-compatible than ZnO. Due to the vulnerability of coral reefs to anthropogenic impacts and global change, our findings underline the need to accurately evaluate the effect of commercial filters on stony corals to minimize or avoid this additional source of impact to the life and resilience ability of coral reefs.

Update About the Effects of the Sunscreen Ingredients Oxybenzone and Octinoxate on Humans and the Environment

As skin cancer prevalence continues to rise, the importance of sun protection, including sunscreen use, has become accepted in the public. Sunscreens are divided into two main categories based on the type of their active ingredient, organic and inorganic ultraviolet (UV) filters. It has been shown that inorganic filters are more effective at blocking forms of UV light, both UVA and UVB, as compared with organic filters because organic sunscreens absorb and convert radiation whereas inorganic sunscreens reflect radiation. The use of the two most common organic filters, oxybenzone and octinoxate, has recently been restricted in Hawaii due to their harmful effect on the coral reefs. Here, we discuss recent studies about these specific filters related to the adverse health risks they pose for humans and other organisms, as well as environmental repercussions.

Sunscreen products impair the early developmental stages of the sea urchin Paracentrotus lividus

Marine ecosystems are increasingly threatened by the release of personal care products. Among them, sunscreens are causing concern either for the effects on skin protection from UV radiation and for the potential impacts on marine life. Here, we assessed the UVA protective efficacy of three sunscreens on human dermal fibroblasts, including two common products in Europe and USA, and an eco-friendly product. The sunscreens' effects were also tested on Paracentrotus lividus, a marine species possibly threatened by these contaminants. We found that all tested sunscreens had similar efficacy in protecting human fibroblasts from UVA radiation. Conversely, the sunscreens' effects on embryo-larval development of P. lividus were dependent on the product tested. In particular, the USA sunscreen, containing benzophenone-3, homosalate and preservatives, caused the strongest impact on the sea urchin development, whereas the eco-friendly sunscreen determined the weakest effects. These results suggest that although the tested products protected human skin cells from UVA-induced damage, they might severely affect the success of recruitment and survival of the sea urchin. Our findings underline the importance of developing eco-friendly sunscreens for minimising or avoiding the impact on marine life while protecting human skin from UV damage.

Are sunscreens a new environmental risk associated with coastal tourism?

The world coastal-zone population and coastal tourism are expected to grow during this century. Associated with that, there will be an increase in the use of sunscreens and cosmetics with UV-filters in their formulation, which will make coastal regions worldwide susceptible to the impact of these cosmetics. Recent investigations indicate that organic and inorganic UV-filters, as well as many other components that are constituents of the sunscreens, reach the marine environment--directly as a consequence of water recreational activities and/or indirectly from wastewater treatment plants (WWTP) effluents. Toxicity of organic and inorganic UV filters has been demonstrated in aquatic organism. UV-filters inhibit growth in marine phytoplankton and tend to bioaccumulate in the food webs. These findings together with coastal tourism data records highlight the potential risk that the increasing use of these cosmetics would have in coastal marine areas. Nevertheless, future investigations into distribution, residence time, aging, partitioning and speciation of their main components and by-products in the water column, persistence, accumulation and toxicity in the trophic chain, are needed to understand the magnitude and real impact of these emerging pollutants in the marine system.

Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254nm/H2O2

Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people's attention toward their risks on ecological and human health and hence their removal from water. In this study, UV-254nm/H2O2 advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and a structurally similar compound 1H-benzimidazole-2-sulfonic acid (BSA), with a specific focus on their mineralization. At 4.0mM [H2O2]0, a complete removal of 40.0μM parent PBSA and 25% decrease in TOC were achieved with 190min of UV irradiation; SO4(2-) was formed and reached its maximum level while the release of nitrogen as NH4(+) was much lower (around 50%) at 190min. Sulfate removal was strongly enhanced by increasing [H2O2]0 in the range of 0-4.0mM, with slight inhibition in 4.0-12.0mM. Faster and earlier ammonia formation was observed at higher [H2O2]0. The presence of Br(-) slowed down the degradation and mineralization of both compounds while a negligible effect on the degradation was observed in the presence of Cl(-). Our study provides important technical and fundamental results on the HO based degradation and mineralization of SO3H and N-containing UV absorber compounds.

Movers and shakers: influence of bacteriophages in shaping the mammalian gut microbiota

The human intestinal microbiota is one of the most densely populated ecosystems on Earth, containing up to 10 ( 13) bacteria/g and in some respects can be considered an organ itself given its role in human health. Bacteriophages (phages) are the most abundant replicating entities on the planet and thrive wherever their bacterial hosts exist. They undoubtedly influence the dominant microbial populations in many ecosystems including the human intestine. Within this setting, lysogeny appears to be the preferred life cycle, presumably due to nutrient limitations and lack of suitable hosts protected in biofilms, hence the predator/prey dynamic observed in many ecosystems is absent. On the other hand, free virulent phages in the gut are more common among sufferers of intestinal diseases and have been shown to increase with antibiotic usage. Many of these phages evolve from prophages of intestinal bacteria and emerge under conditions where their bacterial hosts encounter stress suggesting that prophages can significantly alter the microbial community composition. Based on these observations, we propose the "community shuffling" model which hypothesizes that prophage induction contributes to intestinal dysbiosis by altering the ratio of symbionts to pathobionts, enabling pathobiont niche reoccupation. The consequences of the increased phage load on the mammalian immune system are also addressed. While this is an area of intestinal biology which has received little attention, this review assembles evidence from the literature which supports the role of phages as one of the biological drivers behind the composition of the gut microbiota.

An overview of UV-absorbing compounds (organic UV filters) in aquatic biota

The purpose of this article is to summarize biological monitoring information on UV-absorbing compounds, commonly referred as organic UV filters or sunscreen agents, in aquatic ecosystems. To date a limited range of species (macroinvertebrates, fish, and birds), habitats (lakes, rivers, and sea), and compounds (benzophenones and camphors) have been investigated. As a consequence there is not enough data enabling reliable understanding of the global distribution and effect of UV filters on ecosystems. Both liquid chromatography and gas chromatography coupled with mass spectrometry-based methods have been developed and applied to the trace analysis of these pollutants in biota, enabling the required selectivity and sensitivity. As expected, the most lipophilic compounds occur most frequently with concentrations up to 7112 ng g(-1) lipids in mussels and 3100 ng g(-1) lipids (homosalate) in fish. High concentrations have also been reported for 4-methylbenzilidenecamphor (up to 1800 ng g(-1) lipids) and octocrylene (2400 ng g(-1) lipids). Many fewer studies have evaluated the potential bioaccumulation and biomagnification of these compounds in both fresh and marine water and terrestrial food webs. Estimated biomagnification factors suggest biomagnification in predator-prey pairs, for example bird-fish and fish-invertebrates. Ecotoxicological data and preliminary environmental assessment of the risk of UV filters are also included and discussed.

Resources drive trade-off between viral lifestyles in the plankton: evidence from freshwater microbial microcosms

Viruses have evolved different life strategies for coping with environmental challenges and this is a key explanation for their omnipresence in aquatic systems. However, factors that determine the balance between lytic versus lysogenic decision within natural virioplankton are poorly documented, primarily in freshwaters. This study was designed to investigate the experimental short-term (24 h incubation) effects of added organic and inorganic nutrients on the two viral lifestyles in nutrient-depleted freshwater microbial (i.e. <0.8 microm fraction) microcosms, using mitomycin C as prophage inductor agent. In the absence of mitomycin, viral lytic production increased as a functional response to the strong stimulation of bacterial growth rates (0.7-0.8 day(-1)) by the added nutrients, primarily the organic nutrients which appeared scarcer than inorganic nutrients and was related to the sampling period and the geomorphological peculiarities of Lake Pavin. In the presence of mitomycin, temperate phage production (frequency of lysogenically infected bacterial cells, FLC=17-19% of total cells) significantly exceeded lytic production (frequency of lytically infected bacterial cells, FIC=9-11%) in natural samples (i.e. without nutrient additions) as a result of enhanced prophage induction, which relatively increased with the decreasing contact probability between viruses and their potential hosts. In contrast, addition of nutrients drastically reduced FLC (<4%) and increased FIC (>22%). Both variables were antagonistically correlated as was the correlation between FLC and bacterial growth rates, supporting the idea that lysogeny may represent a maintenance strategy for viruses in harsh nutrient/host conditions which appeared as major instigators of the trade-off between the two viral lifestyles. Overall, at the community level, we reject the hypothesis that nutrients but mitomicyn C stimulate temperate phage induction, and retained the hypotheses that nutrients rather (i) stimulate lytic viruses via enhanced host growth and (ii) when limiting, promote lysogenic conversion in natural waters.

Lysogens and free viruses in fresh, brackish, and marine waters: a Bayesian analysis

A yearlong study was conducted to determine factors that affect the abundance and distribution of lysogens and free viruses at fresh-, brackish-, and saltwater stations in Newport Bay, CA. The viral and bacterial abundance were highest in the freshwater (average 1.1 x 10(8) and 1.1 x 10(7) mL(-1), respectively) and lowest in the marine water (average 0.4 x 10(8) and 0.5 x 10(7) mL(-1), respectively). Bacterial and viral counts were also several times higher during the summer than in winter. Approximately, 35% of the 141 samples were inducible in the presence of mitomycin C. The highest percentage of inducible lysogens was observed in marine waters (42%), while the lowest percentage was observed in the warmer freshwater (23%). A statistical model for the joint occurrence of lysogens and free viruses was formulated and estimated using Bayesian techniques to understand the key environmental determinants of viruses and lysogens. Our results support the existence of significant heterogeneity between the saltwater and freshwater sites. A parsimonious model that combines the two saltwater sites performs best among the specifications that were considered. Bacteria and water temperature were significant determinants of virus counts, whereas lysogen relationships are unclear. Importantly, conditional on the covariates, viruses and lysogen fractions exhibit robust negative correlation.

Sunscreens cause coral bleaching by promoting viral infections

BACKGROUND

Coral bleaching (i.e., the release of coral symbiotic zooxanthellae) has negative impacts on biodiversity and functioning of reef ecosystems and their production of goods and services. This increasing world-wide phenomenon is associated with temperature anomalies, high irradiance, pollution, and bacterial diseases. Recently, it has been demonstrated that personal care products, including sunscreens, have an impact on aquatic organisms similar to that of other contaminants.

OBJECTIVES

Our goal was to evaluate the potential impact of sunscreen ingredients on hard corals and their symbiotic algae.

METHODS

In situ and laboratory experiments were conducted in several tropical regions (the Atlantic, Indian, and Pacific Oceans, and the Red Sea) by supplementing coral branches with aliquots of sunscreens and common ultraviolet filters contained in sunscreen formula. Zooxanthellae were checked for viral infection by epifluorescence and transmission electron microscopy analyses.

RESULTS

Sunscreens cause the rapid and complete bleaching of hard corals, even at extremely low concentrations. The effect of sunscreens is due to organic ultraviolet filters, which are able to induce the lytic viral cycle in symbiotic zooxanthellae with latent infections.

CONCLUSIONS

We conclude that sunscreens, by promoting viral infection, potentially play an important role in coral bleaching in areas prone to high levels of recreational use by humans.

Characterization of lysogens in bacterioplankton assemblages of the southern California borderland

Viruses cause significant mortality of marine microorganisms; however, their role in shaping the composition of microbial assemblages has not been fully elucidated. Because viruses may form lysogenic relationships with their hosts, temperate viruses may influence bacterial assemblage structures through direct lysis of hosts when induced by environmental stimuli or by homoimmunity (i.e., immunity to closely related viruses). We investigated the components of bacterioplankton assemblages that bore prophage using the lysogenic induction agent mitomycin C. Seawater was collected at two locations (the San Pedro Ocean Time Series Station and in the Santa Barbara Channel) in the Southern California Borderland and amended with mitomycin C. After 24-h incubation, the community structure of bacterioplankton was compared with unamended controls using automated rRNA intergenic spacer analysis. The addition of mitomycin C to seawater had effects on the community structure of bacterioplankton, stimulating detectable overall diversity and richness of fingerprints and causing the assemblages within incubations to become different to control assemblages. Most negatively impacted operational taxonomic units (OTU) in mitomycin C-amended incubations individually comprised a large fraction of total amplified DNA in initial seawater (5.3-23.3% of amplified DNA fluorescence) fingerprints, and data suggest that these include organisms putatively classified as members of the gamma-Proteobacteria, SAR11 cluster, and Synechococcus groups. The stimulation of assemblage richness by induction of lysogens, and the reduction in the contribution to total DNA of common OTU (and concomitant increase in rare OTU), suggests that temperate phage have the potential to strongly influence the diversity of bacterioplankton assemblages. Because lysogenic OTU may also be resistant to closely related lytic (i.e., free-living) viruses, the impact of lytic virioplankton on assemblages may only be pronounced transiently or when conditions causing lysogenic induction arise.

Effects of solar UV radiation on aquatic ecosystems and interactions with climate change

Recent results continue to show the general consensus that ozone-related increases in UV-B radiation can negatively influence many aquatic species and aquatic ecosystems (e.g., lakes, rivers, marshes, oceans). Solar UV radiation penetrates to ecological significant depths in aquatic systems and can affect both marine and freshwater systems from major biomass producers (phytoplankton) to consumers (e.g., zooplankton, fish, etc.) higher in the food web. Many factors influence the depth of penetration of radiation into natural waters including dissolved organic compounds whose concentration and chemical composition are likely to be influenced by future climate and UV radiation variability. There is also considerable evidence that aquatic species utilize many mechanisms for photoprotection against excessive radiation. Often, these protective mechanisms pose conflicting selection pressures on species making UV radiation an additional stressor on the organism. It is at the ecosystem level where assessments of anthropogenic climate change and UV-related effects are interrelated and where much recent research has been directed. Several studies suggest that the influence of UV-B at the ecosystem level may be more pronounced on community and trophic level structure, and hence on subsequent biogeochemical cycles, than on biomass levels per se.

Impact of heavy metals and PCBs on marine picoplankton

Synergistic/antagonistic effects of multiple contaminants in marine environments are almost completely unexplored. In the present study, we investigated the effects of heavy metals (Zn and Pb) and PCBs on picoplankton abundance, biomass, cell size distribution, and bacterial C production. Natural picoplankton assemblages were exposed to heavy metals (Zn or Pb), organic contaminants (PCBs, Aroclor 1260), and to a mixture of different contaminants. The results of the present study indicate that Zn addition stimulated heterotrophic growth, whereas Pb has a negative impact on heterotrophic picoplankton, particularly significant in the first 24 h. Heavy metals had no effects on the autotrophic component. The addition of Aroclor 1260 had a significant impact on abundance, biomass, and cell size of autotrophic and heterotrophic picoplankton, and reduced significantly bacterial secondary production. Three weeks after PCB treatment, heterotrophic bacteria displayed a clear resilience, both in terms of abundance and biomass, reaching values comparable to those of the controls, but not in terms of bacterial C production. Our results indicate that picoplankton can be sensitive indicators of impact determined by heavy metals and PCBs in coastal marine systems.

Viruses and marine pollution

This short review summarises the present knowledge on pollutant impacts on marine viruses, virus-host systems and their potential ecological implications. Excess nutrients from sewage and river effluents are a primary cause of marine eutrophication and mucilage formation, often related to the development of large viral assemblages. At the same time, hydrocarbons, polychlorinated biphenyl and pesticides alter ecosystem functioning and can determinate changes in the virus-host interactions, thus increasing the potential of viral infection. All these pollutants might have synergistic effects on the virus-host system and are able to induce prophage, thus increasing the impact of viruses on marine ecosystems.