Approximately 80% of the Earth\u2019s biosphere is cold, at an average temperature of 5\u00b0C, and is populated by a diversity of microorganisms that are a precious source of molecules with high biotechnological potential. Biosurfactants from cold-adapted organisms can interact with multiple physical phases \u2013 water, ice, hydrophobic compounds, and gases \u2013 at low and freezing temperatures and be used in sustainable (green) and low-energy-impact (cold) products and processes. We review the biodiversity of microbial biosurfactants produced in cold habitats and provide a perspective on the most promising future applications in environmental and industrial technologies. Finally, we encourage exploring the cryosphere for novel types of biosurfactants via both culture screening and functional metagenomics.
\nTrends<\/p>\n
\u2018Cold\u2019 is becoming \u2018cool\u2019 in microbiology. The cryosphere is becoming more easily accessible to scientific expeditions and is predicted to fuel the discovery of novel natural products.<\/p>\n
Research on biosurfactants from psychrophilic microorganisms is just beginning but is expected to contribute to the development of sustainable (green) and energy-saving (cold) biotechnologies.<\/p>\n
New formulations of washing products containing biosurfactants are being developed, which can enable effective detergency at lower temperatures and will help laundry practices to reduce the environmental impact.<\/p>\n
Advances in unconventional experimental approaches such as functional metagenomics hold great promise for future discovery of entirely new biosurfactant types and producing organisms from cold and extreme environments.
\nCold-Active Microorganisms for Sustainable and Energy-Saving Biotechnologies<\/p>\n
The search for environmentally friendly biomolecules is a recent common theme in biotechnology. Biosurfactants have many desirable features: they are produced by microorganisms from renewable materials; exist in numerous chemical varieties, hence they can perform in a large range of applications; are active at very low concentrations; and are compatible with release into the environment [1, 2]. Biosurfactants are considered a possible green alternative to chemical surfactants for countless commercial products, including detergents and cleaners, personal care products, cosmetics, pharmaceuticals and therapeutics, food additives, emulsifiers, and dispersants for bioremediation [3.<\/p>\n
Another emerging requirement for biotechnological products is to be energy saving. Energy efficiency implies not only saving energy and money but also reducing the environmental impact. New strategies are being implemented at all stages of the energy chain from production and storage to consumption [4. With the policies in this area becoming more stringent, the energy factor will be particularly important to strengthen the biotechnology market. In this context, biomolecules that both function at low temperatures and also can be produced without the need for heating hold great promise. Low-temperature biosurfactants meet both of these criteria.<\/p>\n
Low-temperature microbiology has recently come into the scientific spotlight. The coldest regions of Earth are more easily accessible for scientific expeditions and studies are being fueled not only by pure scientific interest about life under extreme conditions but also by growing concerns about their role in the global climate change dynamics [5, 6, 7]. Cold habitats are also seen as extraordinary reservoirs of biotechnological molecules such as cold-active enzymes, antibiotics, and biosurfactants [8, 9]. In comparison to cold-active enzymes, which represent a mainstream research field, with some already being commercialized, little information is available on biosurfactants from cold-adapted microorganisms, namely, psychrophiles. Here we first describe the different types of biosurfactants and their producing organisms isolated from cryo-habitats and discuss their ecological functions. We then present some possible applications for low-temperature-related biotechnologies such as bioremediation, gas hydrate production, antifreeze additives, and detergents. We finally address the aspect of the bioprocessing of these bioproducts and propose future strategies to increase their industrial competitiveness.
\nBiodiversity and Ecological Roles of Biosurfactants in Cold Soils<\/p>\n
Cold soils such as those in the polar regions or at high altitudes are exposed to environmental extremes that include low temperature, freeze\u2013thaw cycles, strong UV irradiation, and limited availability of liquid water and nutrients. Not surprisingly they are characterized by a generally low biodiversity (see Glossary) and are inhabited by organisms that have developed specific survival mechanisms (Box 1) [10. The ability to produce biosurfactants seems a common feature among cold-adapted organisms (Table 1), with up to 50% of the members of microbial communities in polar soils and sediments screening positive [11, 12]. Similar to temperate environments, certain phylotypes of biosurfactant producers, for example, Pseudomonas, Burkholderia, Sphingomonas, Rhodococcus, and Bacillus, also prevail in cold habitats [12, 13, 14, 15]. Most of the isolates are able to grow at temperatures as low as 4\u00b0C but under laboratory conditions at around 20\u00b0C and above (Box 1). Less conventional organisms have been also described, for example, Pantoea sp. (Enterobacteriaceae family) isolated from ornithogenic soil in the Frazier Islands, Antarctica, that produce glycolipids over a temperature range of 5\u201340\u00b0C [16 and Enterobacter and Luteibacter (phylum Proteobacteria), Pedobacter, Mucilaginibacter, and Dyadobacter (phylum Bacteroidetes), all of which were found associated with the lichen Peltigera membranacea in an Icelandic soil and screened positive for biosurfactant production [17.<\/p>\n
In many cases the synthesis of biosurfactants was found to be associated with the production of extracellular enzymes such as lipases, proteases, amylases, and in some organisms also with the ability to grow and degrade hydrocarbon contaminants including polycyclic aromatics [17, 18]. Since polar environments are typically pristine, we speculate that the ecological role of biosurfactants is to support the ability of microbial communities to metabolize plant-derived material (e.g., lignin, cellulose, hemicellulose, tannins, phenols), which are naturally enriched in organic hydrocarbon and aromatic compounds. Biosurfactants are likely to act in synergy with extracellular enzymes by increasing solubilization and mobilization, and hence the bioavailability of the hydrophobic residues originating from the hydrolysis of complex biopolymers [19. Thus, it seems plausible that biosurfactants play a primary ecological role in the turnover of carbon and nutrients in extreme cold soils.
\nA Model Organism for Industrial Biosurfactant Production from an Antarctic Lake<\/p>\n
One of the current most-valued biosurfactant-producing microorganisms, Moesziomyces antarcticus (formerly known as Pseudozyma\/Candida antarctica), was originally isolated from a polar habitat, Lake Vanda in the Wright Valley, Antarctica [20. M. antarcticus is a yeast known for the production of industrially relevant molecules including extracellular enzymes (e.g., lipase) and glycolipid biosurfactants of the type mannosylerythritol lipids (MELs) [21. MEL molecules consist of long-chain fatty acids linked to a mannopyranosyl-meso-erythritol hydrophilic head group, and are synthesized in various congeners, mostly diacetylated (MEL-A) and monoacetylated (MEL-B and MEL-C) and several other minor variants (e.g., triacetylated, diastereomers, with mannitol, arabitol, or ribitol replacing the erythritol group). Small differences in the chemical structure can greatly affect the molecular self-assembly in solution and consequently the interfacial properties, with MEL-A forming a sponge phase, and MEL-B and MEL-C forming giant vesicles (Figure 1). It follows that MELs exhibit a broad range of biochemical and biological properties, and thus have high versatility in terms of applications and uses. In addition, they can be produced at high yields (up to 100\u2005g\/L) from vegetable oils by intermittent feeding, which makes them particularly attractive for industry [21. Despite being synthesized under moderate conditions, that is, at around 25\u00b0C or room temperature, MELs display remarkable performance also at subzero temperatures, for example, antiagglomeration of ice crystals [22 and freezing point depression [23, which will be illustrated in the \u2018Biosurfactant Activity and Applications at the Ice\u2013Water Interface\u2019 section.<\/p>\n
Considering the large distribution and biodiversity of yeasts in the cryosphere [24, it is reasonable to think that many more biosurfactant producers can be discovered (Box 2). For example, Rhodotorula is highly represented in polar and glacial environments (e.g., R. arctica, R. glacialis, R. psychrophenolica, R. psychrophila, R. mucilaginosa) and this genus contains several species known to be hyper-producers of sophorolipid biosurfactants. Sophorolipids have already reached an advanced stage of large-scale production and commercialization, but it would be certainly valuable to expand the collection of producing organisms with new extremophilic strains. The bioprospecting of cold-adapted yeasts is currently lacking research directed at biosurfactants and we believe that more attention should be given to explore the biosynthetic potential of psychrophilic eukaryotes.
\nNew Psychrophiles and Omics to Discover Novel Biosurfactants
\nMarine Biosurfactants and Bioremediation<\/p>\n
The marine environment is extremely diverse in the same way that the terrestrial environment is, and this diversity provides a number of different potential habitats for microorganisms. The average surface temperature of the ocean is 17\u00b0C (although this is obviously lower toward the poles), while in the oceanic deep waters it is 0\u20133\u00b0C with a salinity of about 3.5%, which means that the freezing point is \u22121.9\u00b0C. One major feature of the water of the oceans is that the level of organic material is very low. Therefore, we might expect most heterotrophic microorganisms to be recoverable from sources of concentrated organic material, such as particulate detritus or immiscible organic liquids [25.<\/p>\n
The most obvious place to commence a search for marine biosurfactant-producing microorganisms is in areas that are polluted with hydrocarbons from spills or leakages since surfactants are believed to form an important part of the system for the microbial biodegradation of hydrocarbons. Alcanivorax borkumensis is among the first and best-studied microorganisms of this kind. The type strain SK-2, isolated from North Sea sediment, can grow exclusively on hydrocarbons in a temperature range of 4\u201335\u00b0C while producing a well-characterized glucose\u2013lipid biosurfactant [26, 27]. Since then various other marine bacteria, typically Pseudomonas, Pseudoalteromonas, Marinomonas, Halomonas, Rhodococcus, and Cobetia have been described as biosurfactant producers from the polar oceans, deep sea, and marine sediments [28, 29, 30, 31, 32]. Kurata and colleagues [33 developed a novel approach, based on satellite remote sensing, to identify slicks of biosurfactants through their effect of surface tension reduction on the appearance of the sea surface, and demonstrated the involvement of microbial biosurfactants in the uptake of hydrophobic substances in the marine environment. They also confirmed that known microbial biosurfactant producers were present in the subsurface layers below these slicks.<\/p>\n
Considerable emphasis has been placed in recent years on exploiting marine organisms to solve problems of bioremediation of pollutants [34, which has been tackled by large and multidisciplinary research projects (e.g., EU-FP7 projects \u2018Unravelling and exploiting Mediterranean Sea microbial diversity and ecology for xenobiotics and pollutants clean up\u2019 ULIXES and \u2018Integrated biotechnological solutions for combating marine oil spills\u2019 KILL-SPILL). In these projects, biosurfactants played a major part and various ways of using biosurfactants in bioremediation were explored and new surfactants were sought from marine producers [35. One of the main routes explored in the KILL-SPILL project was the use of various formulations using oxygen-generating systems linked to nutrient supplementation and biosurfactant incorporation to stimulate the rate of hydrocarbon degradation in contaminated marine sediments.
\nBiosurfactant Activity and Applications at the Ice\u2013Water Interface<\/p>\n
In nature, cryo-environments where ice and water phases seasonally cycle and occasionally coexist are highly challenging. These environments pose serious threats to microbial life due to not only the physical disruption of cellular structures and proteins by ice crystals but also a reduced mass transfer of liquid water and nutrients [36. Microorganisms living in such extreme settings have evolved, among other adaptations (Box 1), highly specialized cell envelopes of which biosurfactants are usually an integral part and which participate, together with other components such as exopolysaccharides, in protection against high salinity, temperature, and osmotic stress [37.<\/p>\n
Trehalose lipids are the most characteristic biosurfactants in microorganisms, especially of the genus Rhodococcus, adapted to icy environments [38. Compared to other sugars, trehalose has an extraordinary ability to protect biomolecules and living cells subject to freezing. Trehalose displays a dual cryoprotective action; first, it prevents water from crystallizing into ice by taking apart the tetrahedral hydrogen bond network of water molecules, and second, it forms a cage surrounding the proteins that slows the water dynamics in its proximity [39. While it is evident that nature has tailored these biosurfactants to work under extremes of temperature and phase transition, their biotechnological exploitation remains unfortunately low. To a large extent this is because trehalose lipids are cell bound, so they require laborious extraction and purification processes and are generally recovered only in small amounts.<\/p>\n
Other biosurfactants have also shown good performance in ice\u2013water systems. One example is MELs, which have been demonstrated as antiagglomerants for ice\u2013water slurry technologies [22. Ice slurry is a homogeneous mixture of small ice particles and water used in cold-storage systems, for example, ice storage, industrial process cooling, refrigeration, and air conditioning. Because of their high thermal energy storage density, ice slurries have considerable environmental and economic advantages, but long-term ice particle formation and growth are difficult to control. MEL-A in particular, the diacetylated form of MELs, showed a remarkable antiagglomeration activity, achieving a high ice-packing factor comparable to standard chemical surfactants and at a much lower concentration. It was also effective when tested further on a large-scale 300-L ice storage tank. The antiagglomeration effect of MEL-A can be explained by the ability of this biosurfactant, characterized by asymmetric molecular geometry due to the presence of two different hydrophobic alkyl chains, to adsorb to the ice surface in a highly regulated manner that contrasts with the agglomeration and growth of ice particles [22.
\nBiosurfactants for Gas Hydrate Technologies<\/p>\n
Enhancing the catalysis and recovery of natural gas hydrates using biosurfactants is one of the newest frontiers of microbial biotechnology for energy and resources. Gas hydrates are cagelike lattices of ice inside which molecules of gas, typically methane, are trapped (Figure 2). The gas can originate either from the biological activity of microorganisms (e.g., methane produced by methanogens) or from the decomposition of fossil organic matter [40. Gas hydrates are found in nature beneath the seafloor along ocean margins and in permafrost polar regions, with large accumulations identified in the Gulf of Mexico, North Alaska, the Arctic region of Svalbard and the Barents Sea, and offshore Japan, India, South Korea, and China. Current estimates indicate that natural gas in hydrate deposits may account for up to 120\u2005\u00d7\u20051015\u2005m3, thus representing a huge potential energy resource. Exploration programs as well as technologies for their recovery and exploitation are being developed in many countries worldwide [41.<\/p>\n
Several studies have shown that rhamnolipids and lipopeptides, as well as other biosurfactants, can catalyze the formation of gas hydrates [42, 43, 44]. Biosurfactants can both accelerate the induction and initiation of the hydrates (when hydrate nuclei and then a critical crystal cluster begin to form) and increase the formation rate after crystal initiation. When biosurfactant micelles begin to form above the critical micelle concentration, hydrocarbon gas molecules that interact with the hydrophobic tails remain enclosed in the inner core. In addition, typically for catalysts, biosurfactants can function over time without being consumed [43. Culture-independent studies on the microbial communities associated with gas hydrates and marine sediments have demonstrated the presence of Pseudomonas and Bacillus [45, 46] and some were also isolated [47. A strain of Bacillus subtilis, cultivated anaerobically at 20\u00b0C to simulate the in situ environmental conditions, could produce surfactin with a strong catalytic effect on gas hydrate formation [43.<\/p>\n
Despite the growing scientific evidence, our understanding of the possible synthesis of biosurfactants at gas hydrate sites is still preliminary. The difficulty of accessing natural samples and to reproduce faithfully in the laboratory in situ environmental conditions together with the lack of cultivation-independent techniques to detect biosurfactant producers have so far significantly slowed down this emerging new field of research.
\nEnhanced Cold Flow Properties of Biodiesel<\/p>\n
Biodiesel is a renewable green fuel that can be manufactured from low-cost and waste materials (e.g., vegetable oils, animal fats and recycled cooking oil, and grease) and, compared to petroleum fuels, has similar physical properties but is cleaner burning. Biodiesel utilization is, however, hampered by its poor cold thermal fluidity, which results in molecular aggregation and solid gel formation at low temperatures. Biosurfactants of the MEL type have been successfully tested as fuel additives to improve the flow properties at freezing temperatures [23. Biodiesel phase transition to gel typically begins at around 1.4\u00b0C but when supplemented with MEL-A it significantly decreased to \u22127.3\u00b0C. The performance of MEL-A used in low concentration (0.3% v\/v) was equivalent to traditional chemical pour point depressants that are in general added in much higher amounts (5% v\/v concentration). Furthermore MEL-A was able to decrease the cloud point of biodiesel from 22.5\u00b0C to 19.3\u00b0C. It is likely that the ability of MEL-A molecules to interact with the fatty acid methyl esters, the main components of biodiesel, is the underlying mechanism that prevents agglomeration [23.
\nCold-Active Detergents<\/p>\n
Environmental issues such as climate change and global warming caused by increased greenhouse gas emissions call for a low-carbon and resource sustainability economy. In recent years, companies have been adopting the life-cycle analysis approach to assess the environmental impact of their products. In the specific case of washing detergents, the impact of the consumer use of the product is also taken into account, and the washing temperature is an important factor (Box 3). The International Association for Soaps, Detergents and Maintenance Products (A.I.S.E.) promoted in 2013 a \u2018Low Temperature Washing Campaign\u2019 initiative to encourage low-temperature washing practices and the use of fewer petrochemically derived surfactants as primary detergents, in efforts to reduce carbon footprint and move toward more sustainable formulation components. For example, the SUSCLEAN project initiated by Unilever (2007\u20132010) focused on discovering and selecting new enzymes and biosurfactants for optimum synergy in the absence of inorganic sequestrants and buffers to reduce the level of inorganic materials within laundry detergents, thus chemical loads, volumes, and wash temperatures.<\/p>\n
The Downside of Cold Washing<\/p>\n
Using lower wash water temperatures affect detergency effectiveness and require the detergent to maintain the same cleaning results (Figure 3) [48. Below the Krafft temperature some surfactants crystallize and this leads to loss of surface activities such as dispersion, emulsification, and critical micelle-formation abilities [49. For many ionic and non-ionic surfactants, however, the Krafft point becomes elevated at higher salt concentrations. All of these effects are important and should be considered with any new cold-temperature detergent, including biosurfactants. Many biosurfactants are available in liquid formulations, which are likely to reduce their Krafft point in detergency applications. In addition, they are stable and function across a broad range of temperature (4\u201355\u00b0C), pH, and salinity [50, 51]. In the current work, rhamnolipid-containing mixtures seem to provide a greater degree of tolerance to a temperature reduction from 25\u00b0C to 10\u00b0C than chemical surfactants alone, which suggests that the incorporation of rhamnolipids in detergent formulations would probably improve their operating range at lower temperatures. In addition, monorhamnolipids consistently increased adsorption\/performance at lower temperatures compared with dirhamnolipids (unpublished data). To assist in the behavior study of biosurfactants in solution, deuterium-labeled rhamnolipids produced in adapted strains of Pseudomonas aeruginosa are of great help [52. The structural difference between the two forms (Figure 3), which consists of the additional rhamnose sugar in dirhamnolipids, leads to an increase of molecular weight from 504 to 650 and to a different degree of hydrophobicity. It is possible that smaller monorhamnolipid molecules are better at micelle formation or stronger at partitioning to the surface, while bigger dirhamnolipids have packing constraints [53. It may also be that monorhamnolipids allow a different more favorable self-assembly structure with some of the chemical detergent components in a synergistic way, all of which remains to be further investigated and confirmed.
\nBioprocessing at Industrial Scale<\/p>\n
Psychrophilic microorganisms are generally seen as slow growers, hence not ideal for production at industrial scale. However, in psychrophiles, growth and activity respond differently to temperature, and maximum production of biomass and therefore of biotechnological products is typically reached at temperatures lower than those at which growth is fastest [54. Thus, to compensate for the low growth rates dictated by low temperatures in nature, psychrophilic organisms maximize or maintain their growth yields at temperatures below optimum [55. This physiological aspect should be taken into account when optimizing production conditions for low-temperature biotechnological products. However, the growing market of cold-active enzymes clearly indicates that bioprocessing at industrial scale using psychrophilic strains is well established and profitable.<\/p>\n
The capability of cold-adapted microorganisms to synthesize biosurfactants has only recently begun to be appreciated, and for understanding their application potential as well as their qualities as highly sustainable bioproducts, more work is necessary to scale up to industrial level. Current information is rather preliminary and fragmentary; for example, product yields have only rarely been determined and no production optimization has ever been attempted (Table 1). In addition, in some cases either the organism has not been rigorously identified, or the chemical analytical methods were not appropriate to definitely classify the product. This is a general problem for publications in the field of microbial biosurfactants that we have recently raised [56. We suggest a more systematic approach starting with a thorough direct quantification of biosurfactant yields on purified or crude extracts. Low titer is a major hurdle, and comparable to biosurfactants from mesophilic strains, low-temperature biosurfactants synthesized in batch cultures are also in the order of a couple of grams per liter at best (Table 1). High yields (>100\u2005g\/L) suitable for large-scale production can be currently attained only in eukaryotic organisms such as M. antarcticus, which synthesizes MELs [21. At present, only natural hyperproducer yeasts and fungi meet these requirements (e.g., high titers, easy recovery via filtration, cheap substrates) for bioprocessing at industrial scale [2. In this case, strain engineering routes to produce customized products, for example, via the control of specific structural isoforms, are also becoming available [57. We expect yeast and fungi from cold habitats to be similarly competitive to mesophilic strains and bring the additional advantage of fermentation processes effective at room temperature, thus reducing both production costs and environmental impact.<\/p>\n
Bacterial biosurfactants such as rhamnolipids, despite being synthesized in much lower yields, are also produced at industrial scale by various companies worldwide [3. Here, the latest trend to increase productivity is to bypass the complex regulation of rhamnolipid biosynthetic pathway and reroute the carbon flux of central metabolism to increase rhamnolipid precursors supply [58. These strategies can be tested also on cold-adapted strains once the fundamentals of biosurfactant type, genetic organization, and regulatory factors have been elucidated.<\/p>\n
Finally, the possibility to combine the production of cold-active enzymes and biosurfactants may be highly attractive for industrial bioprocessing. Many psychrophilic isolates [17, 18] have shown concurrent capabilities, but more effort is now needed to characterize the synergistic interactions of the two processes also as a function of temperature and growth conditions.
\nConcluding Remarks<\/p>\n
Extreme environments and extremophilic microorganisms are extraordinary sources of novel biomolecules with unique properties, but unexpectedly, they have so far attracted little attention in the quest for biosurfactants. Biosurfactants play key ecological roles in many cold habitats improving their habitability. They participate in carbon-cycling processes by enhancing the bioavailability of poorly soluble compounds, including pollutants, in cold soils and marine environments; for example, trehalose lipids can prevent ice crystallization in the immediate surroundings of the microbial cells. These natural capabilities can be used to develop new biotechnological products and processes that have low energy demand and operate under low-temperature regimes. There is also growing interest in the potential role and application of microbial biosurfactants in the catalysis and recovery of natural gas hydrates from deep sea or permafrost environments. However, there are aspects of biosurfactants related to both fundamental research and experimental approaches that need to be tackled with greater effort (see Outstanding Questions) to advance further with their use and applications. Undoubtedly, the discovery of new types of biosurfactants from psychrophilic organisms or directly from the cryosphere will boost biosurfactant biotechnological potential and support the spread of sustainable and energy-saving practices.<\/p>\n","protected":false},"excerpt":{"rendered":"
Approximately 80% of the Earth\u2019s biosphere is cold, at an average temperature of 5\u00b0C, and is populated by a diversity of microorganisms that are a precious source of molecules with high biotechnological potential. Biosurfactants from cold-adapted organisms can interact with multiple physical phases \u2013 water, ice, hydrophobic compounds, and gases \u2013 at low and freezing […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","nova_meta_subtitle":"","footnotes":""},"categories":[5572],"tags":[5796,14177,11857],"supplier":[11310],"class_list":["post-50009","post","type-post","status-publish","format-standard","hentry","category-bio-based","tag-biotechnology","tag-microbiology","tag-sustainable","supplier-cell-magazine"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/50009","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=50009"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/50009\/revisions"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=50009"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=50009"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=50009"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=50009"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}