Aeroterrestrial and Extremophilic Microalgae as Promising Sources for Lipids and Lipid Nanoparticles in Dermal Cosmetics

Microscopic prokaryotic and eukaryotic algae (microalgae), which can be effectively grown in mass cultures, are gaining increasing interest in cosmetics. Up to now, the main attention was on aquatic algae, while species from aeroterrestrial and extreme environments remained underestimated. In these habitats, algae accumulate high amounts of some chemical substances or develop specific compounds, which cause them to thrive in inimical conditions. Among such biologically active molecules is a large family of lipids, which are significant constituents in living organisms and valuable ingredients in cosmetic formulations. Therefore, natural sources of lipids are increasingly in demand in the modern cosmetic industry and its innovative technologies. Among novelties in skin care products is the use of lipid nanoparticles as carriers of dermatologically active ingredients, which enhance their penetration and release in the skin strata. This review is an attempt to comprehensively cover the available literature on the high-value lipids from microalgae, which inhabit aeroterrestrial and extreme habitats (AEM). Data on different compounds of 87 species, subspecies and varieties from 53 genera (represented by more than 141 strains) from five phyla are provided and, despite some gaps in the current knowledge, demonstrate the promising potential of AEM as sources of valuable lipids for novel skin care products.

Major Compatible Solutes and Structural Adaptation of Proteins in Extremophiles

Extremophiles are the most ancient microbes on the Earth and also a center of attraction for the scientific community for research because of their ability to adapt to extreme habitats. Compatible solutes are among those factors which enable these microorganisms to thrive in such extreme habitats. Under osmotic stress, the majority of extremophiles accumulate specific organic solutes such as amino acids, sugars, polyols, and their derivatives. In addition, proteins in extremophiles are found to be evolved by changing their amino acid composition to alter the hydrophobicity of its core and surface charge to maintain activity. This chapter encompasses a comprehensive study about the role of various compatible solutes in the endurance of microorganisms under extremophilic conditions, synthesis of compatible solutes, nature of extremophilic proteins, and their applications. Furthermore, an attempt has been made to cover various strategies adopted by the scientific community while pursuing research on compatible solutes.

Effect of Drought and Heavy Metal Contamination on Growth and Photosynthesis of Silver Birch Trees Growing on Post-Industrial Heaps

Silver birch trees (Betula pendula Roth) are a pioneering species in post-industrial habitats, and have been associated with an expansive breeding strategy and low habitat requirements. We conducted ecophysiological and dendroclimatological studies to check whether there are any features of which the modification enables birch trees to colonise extreme habitats successfully. We characterised the efficiency of the photosynthetic apparatus, the gas exchange, the content of pigments in leaves, and the growth (leaf thickness and tree-ring width) of birch trees on a post-coal mine heap, a post-smelter heap, and a reference site. Birch growth was limited mainly by temperature and water availability during summer, and the leaves of the birch growing on post-industrial heaps were significantly thicker than the reference leaves. Moreover, birch trees growing on heaps were characterised by a significantly higher content of flavonols and anthocyanins in leaves and higher non-photochemical quenching. In addition, birches growing on the post-coal mine heap accumulated a concentration of Mn in their leaves, which is highly toxic for most plant species. Increasing the thickness of leaves, and the content of flavonols and anthocyanins, as well as efficient non-photochemical quenching seem to be important features that improve the colonization of extreme habitats by birches.

Ant Rafting in an Extreme Ecosystem

Ants are among the most abundant organisms on Earth, being adapted for living on different solid surfaces. However, in some habitats, like riparian forests and flooded plains, water can be a constant obstacle, and overcoming this obstacle can be essential to determine the persistence of ants in such habitats. While most ant species avoid the water during a flood by foraging at higher elevations or climbing on trees, a few species developed ways to overcome this obstacle by swimming. Here, we report, for the first time, ants of the species Linepthema micans (Forel 1908) performing rafts. We observed 14 rafts in three consecutive days at approximately 1400 meters a.s.l. in Serra do Cipó, Brazil. Notably, this is the first record of ant rafting in tropical mountaintop grasslands, which are extreme habitats with shallow and sandy soils, and where small temporary water pools are extremely common in the wet season.

Nitzschia anatoliensis sp. nov., a cryptic diatom species from the highly alkaline Van Lake (Turkey)

In this article we describe Nitzschia anatoliensis Górecka, Gastineau & Solak sp. nov., an example of a diatom species inhabiting extreme habitats. The new species has been isolated and successfully grown from the highly alkaline Van Lake in East Turkey. The description is based on morphology (light and scanning electron microscopy), the sequencing of its organellar genomes and several molecular phylogenies. This species could easily be overlooked because of its extreme similarity to Nitzschia aurariae but molecular phylogenies indicate that they are only distantly related. Furthermore, molecular data suggest that N. anatoliensis may occur in several alkaline lakes of Asia Minor and Siberia, but was previously misidentified as Nitzschia communis. It also revealed the very close genetic proximity between N. anatoliensis and the endosymbiont of the dinotom Kryptoperidinium foliaceum, providing additional clues on what might have been the original species of diatoms to enter symbiosis.

Depth- and temperature-specific fatty acid adaptations in ctenophores from extreme habitats

Animals are known to regulate the composition of their cell membranes to maintain key biophysical properties in response to changes in temperature. For deep-sea marine organisms, high hydrostatic pressure represents an additional, yet much more poorly understood, perturbant of cell membrane structure. Previous studies in fish and marine microbes have reported correlations with temperature and depth of membrane-fluidizing lipid components, such as polyunsaturated fatty acids. Because little has been done to isolate the separate effects of temperature and pressure on the lipid pool, it is still not understood whether these two environmental factors elicit independent or overlapping biochemical adaptive responses. Here, we use the taxonomic and habitat diversity of the phylum Ctenophora to test whether distinct low-temperature and high-pressure signatures can be detected in fatty acid profiles. We measured the fatty acid composition of 105 individual ctenophores, representing twenty-one species, from deep and shallow Arctic, temperate, and tropical sampling locales (sea surface temperature -2° to 28° C). In tropical and temperate regions, remotely operated submersibles (ROVs) enabled sampling down to 4000 meters. Among specimens with body temperatures 7.5°C or colder, depth predicted fatty acid unsaturation level. In the upper 200 m of the water column, temperature predicted fatty acid chain length. Taken together, our findings suggest that lipid metabolism may be specialized with respect to multiple physical variables in diverse marine environments. Largely distinct modes of adaptation to depth and cold imply that polar marine invertebrates may not find a ready refugium from climate change in the deep.

Novel and Conventional Isolation Techniques to Obtain Planctomycetes from Marine Environments

Bacteria from the distinctive Planctomycetes phylum are well spread around the globe; they are capable of colonizing many habitats, including marine, freshwater, terrestrial, and even extreme habitats such as hydrothermal vents and hot springs. They can also be found living in association with other organisms, such as macroalgae, plants, and invertebrates. While ubiquitous, only a small fraction of the known diversity includes axenic cultures. In this study, we aimed to apply conventional techniques to isolate, in diverse culture media, planctomycetes from two beaches of the Portuguese north-coast by using sediments, red, green, and brown macroalgae, the shell of the mussel Mytilus edulis, an anemone belonging to the species Actinia equina, and seawater as sources. With this approach, thirty-seven isolates closely related to seven species from the families Planctomycetaceae and Pirellulaceae (class Planctomycetia) were brought into pure culture. Moreover, we applied an iChip inspired in-situ culturing technique to successfully retrieve planctomycetes from marine sediments, which resulted in the isolation of three additional strains, two affiliated to the species Novipirellula caenicola and one to a putative novel Rubinisphaera. This work enlarges the number of isolated planctomycetal strains and shows the adequacy of a novel methodology for planctomycetes isolation.

Microbiome of a Reef-Building Coral Displays Signs of Acclimation to a Stressful Shallow Hydrothermal Vent Habitat

Most tropical reef corals live at temperatures near 27°C and pH values near 8. Conditions outside of these can stress corals and lead to bleaching, disease, and death. However, some corals can survive in marginal or extreme habitats outside of these ranges. To date there is a paucity of knowledge about the role that associated microbes may play in the acclimation of corals to such extreme habitats. Here, we explore differences in the compositional and functional profile of the microbiomes of the scleractinian coral Porites panamensis living both on and off potentially stressful shallow-water hydrothermal vents. The environment near the vents is extreme, with temperatures exceeding 80°C and pH values below 6. Coral microbiomes under stress often exhibit increased diversity, increased abundance of pathogenic bacteria, and functional profiles that shift toward pathways associated with pathogenic taxa. Samples from along a transect that crossed an arc of hydrothermal vents were sequenced for the 16S rRNA gene (V4 region). On-vent coral microbiomes were distinct from those of off-vent corals, but did not have increased alpha or beta diversity. On-vent samples had a higher relative abundance of the beneficial endosymbiont, Endozoicomonas. On- and off-vent microbiomes did not differ in overall abundance of the endolithic green alga Ostreobium, however, a single ASV, close to O. quekettii was more abundant in on-vent corals. Ostreobium can provide many of the same benefits to corals as zooxanthellae and their symbiosis is better maintained under thermal stress. Surprisingly, on-vent coral microbiomes had fewer microbial taxa that are known to be pathogenic or associated with stress than did off-vent corals. The predicted functional profiles of on-vent microbiomes revealed enrichment of pathways related to aerobic respiration, fermentation and amino acid biosynthesis, but not of virulence-related pathways. Our results suggest that P. panamensis microbiomes have acclimated to the extreme environment of the hydrothermal vent habitat rather than showing signs of stress. These results exemplify the need to focus efforts on examining the mechanisms of resilience, including symbioses with microbiota, in corals living in extreme environments in an effort to design better management strategies for reef-building corals under thermal and pH stress.

Evolution and Physiology of Amphibious Yeasts

Since the emergence of the first fungi some 700 million years ago, unicellular yeast-like forms have emerged multiple times in independent lineages via convergent evolution. While tens to hundreds of millions of years separate the independent evolution of these unicellular organisms, they share remarkable phenotypic and metabolic similarities, and all have streamlined genomes. Yeasts occur in every aquatic environment yet examined. Many species are aquatic; perhaps most are amphibious. How these species have evolved to thrive in aquatic habitats is fundamental to understanding functions and evolutionary mechanisms in this unique group of fungi. Here we review the state of knowledge of the physiological and ecological diversity of amphibious yeasts and their key evolutionary adaptations enabling survival in aquatic habitats. We emphasize some genera previously thought to be exclusively terrestrial. Finally, we discuss the ability of many yeasts to survive in extreme habitats and how this might lend insight into ecological plasticity, including amphibious lifestyles. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.