Expanded polystyrene (EPS) is a synthetic polymer that is widely applicable in the fields of food packaging, equipment protection and civil construction. Aiming to replace EPS, biofoams were developed utilizing mycelia of the macrofungi Pycnoporus sanguineus, Pleurotus albidus and Lentinus velutinus in a medium formulated with sawdust and wheat bran. Sample characterization was obtained by scanning electron microscopy (SEM), thermal analysis and infrared spectroscopy with Fourier Transform; density and compression strength were analysed as mechanical properties. The main results include that the compression strengths of biofoams from P. sanguineus, P. albidus and L. velutinus were 1.3, 0.4, and 1.3 MPa, respectively, which exceed that of EPS (0.4 MPa). The thermal stability of the biofoams was lower than that of EPS; however, they were stable up to 350
C. Biofoams are denser than EPS, with values of 0.3 and 0.03 g cm3 , respectively. The data obtained for biofoams categorize this material as sustainable substitute for EPS in some applications, while at the same time, reducing the environmental impact caused by sawdust and EPS.

Introduction

The growing search for biodegradable materials has shifted the interest of the scientific community towards the development of biodegradable products (Vaisanen et al., 2017). These materials can replace synthetic petroleum-related products, such as expanded polystyrene (EPS), which is used in a huge variety of shapes and applications (Poletto et al., 2011; Song et al., 2009; Treinyte et al., 2018). Polystyrene is a widely employed polymer (Shimomura et al., 2016; Yousif and Haddad, 2013). In its expanded form, EPS is used in the form of plates or blocks for preparing slabs, as protective packaging for domestic appliances, in crash helmets and as electrical or thermal insulators in homes, among other applications (Chen and Liu, 2004; Haghi et al., 2006). However, there are some drawbacks because it is petroleum-related and is not biodegradable, which means that it takes many years to degrade if left in the environment (Araújo et al., 2008). After its use, EPS is unduly disposed of, piling up in landfills or even in the environment, which compromises the conventional degradation processes because certain compounds present in the polymer chains can act as a barrier against degradation by organic compounds (Araújo et al., 2008). Still, EPS contains benzene, which has been classified as a human carcinogen (IARC group 1) since 1979, with sufficient evidence to support the claim that it causes leukaemia (Loomis et al., 2017). EPS also contains styrene, a substance that can also trigger the development of various neoplasms (IARC Monographs Vol 121 Group).

Toxascaris leonina and Trichuris sp. are soil-transmitted helminths (STHs) infecting domestic and wild mammals. The antagonistic effect of the saprophytic filamentous fungi Mucor circinelloides and Verticillium sp. was examined on eggs of T. leonina passed in the feces of captive lynxes (Lynx lynx) kept in a zoological park. The activity of M. circinelloides and Trichoderma atrobrunneum was tested on eggs of Trichuris sp. shed by captive dromedaries (Camelus dromedarius). The parasiticide activity was assessed by measuring the ovistatic (delayed development) and ovicidal (non-viability) effects on eggs placed in Petri plates, and by spraying spores directly onto fecal samples. Based on the observation of that hyphae of M. circinelloides, Verticillium sp. and T. atrobrunneum adhered to the eggshells, penetrated and destroyed the inner embryo, an ovicidal type 3 effect was concluded. Development of eggs of T. leonina and Trichuris sp. in the feces was delayed in the presence of all fungi, and one third remained at the stage of zygote. A significant reduction of T. leonina viable eggs was recorded in the feces sprayed spores of M. circinelloides (58%) or Verticillium sp. (67%). Fifty percent of the eggs of Trichuris sp. became into non-viable by 30 days after the exposure to either M. circinelloides or T. atrobrunneum. It is concluded that distribution of the filamentous fungi M. circinelloides, Verticillium sp. and T. atrobrunneum constitutes a novel approach to conduct the biological control of the STHs (T. leonina and Trichuris sp.) affecting wild animals captive in a zoological park.

Introduction

Soil-transmitted helminths (STHs) are parasites involving roundworms (ascarids), hookworms and whipworms which can affect animals and humans. Infection occurs through the accidental ingestion of infective eggs in contaminated soil or food (Vandemark et al., 2010; Elsheika, 2011), which develop in the feces from unembryonated eggs shed by adult female worms localized in the intestine (Mateus et al., 2014; Hoopes et al., 2015). Embryonation happens in the feces or ground after several weeks, resulting in that a second stage larva (L2) originates inside the eggs of ascarids, which becomes into infective (Hendrix, 2014), whereas in the case of whipworms the eggs are infective when a L1 larva develops inside (Felsmann et al., 2017). The role of rodents as paratenic hosts has been indicated in the transmission of Toxocara and Toxascaris (Okulewicz et al., 2012), and thus it has been pointed that the cycles of these nematodes could be considered as non-strictly monoxenous (Reperant et al., 2007). Some ascarid species have zoonotic potential, as Toxocara canis, T. cati, Baylisascaris procyonis, Ascaris suum or Toxascaris leonina, frequently detected in domestic (cats, dogs, pigs) and wild mammals (foxes, wolves, lynxes, raccoons) (Okulewicz and Buńkowska, 2009; Dado et al., 2012; Carver et al., 2012; Beiromvand et al., 2013; Neves et al., 2014; Figueiredo et al., 2016). The zoonotic role of Trichuris spp. has been also reported (Gałęcki et al., 2015; Felsmann et al., 2017; Gawor and Borecka, 2017). As indicated for other STHs, control of ascarids regularly comprises the administration of anthelmintics together with adequate hygiene (Alemu et al., 2011). Despite successful deworming is frequently administered among captive wild carnivores in zoo gardens (lions, lynxes, foxes, wolves), they infected again by helminths because their maintenance in the same parcels enhances that ground is permanently contaminated by eggs passed in the feces (Fagiolini et al., 2010; Maesano et al., 2014). In the same way, frequent infection by Trichuris sp. in dromedaries has been also described (Gurler et al., 2010; Eo et al., 2014). The eggs of ascarids and whipworms are very resistant to chemical and climatic factors, thus can remain infective in the soil for several years (Gavin et al., 2005; Overgaauw and van Knapen, 2013; Gałęcki et al., 2015; Gawor and Borecka, 2017). Nevertheless, there is insufficient information regarding measures to reduce the presence of infective stages in the ground. Prior investigations reported that certain saprophytic soil fungi perform an antagonistic activity on eggs of T. canis and A. suum, based on their ability to adhere to the eggshell, penetrate and destroy the embryo inside (Carvalho et al., 2010; Cortiñas et al., 2015).

Many lowland tropical rainforests are strongly phosphorus (P) depleted (Sollins 1998; Mirmanto et al. 1999; Vitousek et al. 2010; Wright et al. 2011) and they harbour some of the highest plant diversity on the planet (Wright 2002). Biotic forces, including plant-associated soil fungi, play a key role in promoting plant diversity (Klironomos 2002; Bell, Freckleton & Lewis 2006; Petermann et al. 2008; Mangan et al. 2010; *Correspondence author. E-mail: jonesfr@science.oregonstate.edu Schnitzer & Klironomos 2011). Fungi interact with plant communities in mutualistic, pathogenic, and commensal ways (Rosenblueth & Mart
ınez-Romero 2006; Smith & Read 2008b; Van Der Heijden, Bardgett & Van Straalen 2008; Dodds & Rathjen 2010). Fungi play critical roles in ecosystem processes including decomposition and nutrient cycling, and they have been hypothesized to play a critical role in the maintenance of plant diversity via pathogen-mediated negative density dependent survival (Janzen 1970; Connell 1971; Augspurger 1983; Clark & Clark 1984; Carson et al. 2008; Timothy Paine et al. 2008; Hol et al. 2013; Bagchi et al. 2014; Comita et al. 2014; but also see Hyatt et al. 2003) and plant-soil feedbacks (Bever 2002; Mangan et al. 2010; Philippot et al. 2013). Despite their recognized role in these processes, the relative importance of the abiotic and biotic drivers of soil fungal community structure and diversity in lowland tropical forests remains poorly understood. Soil properties can determine soil fungal communities and host-microbe interactions (Lauber et al. 2008; Vinale et al. 2008). For example, arbuscular mycorrhizal (AM) fungi (subphylum Glomeromycotina) form associations with 80% of plant species worldwide (Wang & Qiu 2006; Brundrett 2009), and enhance the uptake of water, inorganic P, and other relatively immobile nutrients by effectively increasing root surface area and therefore increasing the volume of soil explored (Smith, Anderson & Smith 2015). The symbiosis between plants and AM fungi can be facultative and dependent on the plant’s soil nutrient requirements and resource availability (Heijden & Kuyper 2001; Lambers et al. 2008; Dumbrell et al. 2009; Albornoz et al. 2016a). Similarly, P and other soil properties can affect non-AM fungal communities, such as ectomycorrhizal fungi (Albornoz et al. 2016b), saprophytic fungi (Kerekes et al. 2013), and pathogens (Toljander et al. 2006; Tedersoo et al. 2016). Nevertheless, fungi are only partially driven by soil properties, and other factors, such as biotic interactions, simultaneously structure fungal communities. Plant communities can also affect their associated fungal communities (Johnson et al. 2004; Prescott & Grayston 2013) due to differences in fungal host specificity, defined as the taxonomic range of plant host species (Molina & Trappe 1982; Botnen et al. 2014). For example, obligate pathogens experience high selection pressure to infect hosts and reciprocal natural selection can occur between hosts and pathogens. This leads to an ‘evolutionary arms race’ between pathogen effectors and plant immunity genes, resulting in increased host specificity of pathogens (Jones & Dangl 2006; Dodds & Rathjen 2010; Brown & Tellier 2011). In contrast, AM fungi are thought to be generalists in forming host associations (i.e. a broad range of hosts; Davison et al. 2015) compared to other fungal groups such as saprophytes, pathogens, and endophytes (Tedersoo et al. 2010). Because of the host specificity that many fungal clades exhibit, they are thought to be strongly coupled with plant communities (Davey et al. 2015; Gao et al. 2015). However, the effects of plant community composition relative to soil chemistry in structuring fungal communities remains largely unknown, and studies that quantitatively determine the relative impact of each are scarce.

Decomposition of detritus plays a crucial role in the recycling of nutrients and organic matter (Swift et al. 1979; Moore et al. 2004). Defined as any resource of nonliving organic matter, detritus is considered the basal trophic level of many terrestrial and aquatic food webs (Swift et al. 1979; Moore et al. 2004; Benbow et al. 2015). In terrestrial ecosystems, detritus may consist of plant-derived matter (e.g. leaf litter, dead wood, root exudates), dead microbes, fecal matter and animal tissue (carrion) (Swift et al. 1979). Plantderived detritus comprises the majority of the resources that undergo decomposition in terrestrial ecosystems but they are nutrient poor and very recalcitrant (Swift et al. 1979; Carter et al. 2007). Contrary, carrion is much more nutrient-rich and decomposes at much faster rates than plant detritus, and, as such, its role in nutrient cycling may be highly relevant (Swift et al. 1979; Barton et al. 2013). Indeed, carrion decomposition is usually associated with the activity of microbes, invertebrate and vertebrate detritivores and scavengers (Carter et al. 2007; Barton et al. 2013). The combined activity of microbes and invertebrates increases the nutrients released from the carrion into the soil; however, vertebrates may reduce this contribution by direct consumption or dispersion (Carter et al. 2007; Barton et al. 2013). In terrestrial ecosystems where carrion releases nutrients into the soil, plants may ultimately mobilize these nutrients entering the belowground detrital pathway (Moore et al. 2004; Carter et al. 2007). Despite its potential importance, only very recently the scientific community has started to acknowledge the role of carrion decomposition in nutrient recycling (DeVault et al. 2003; Carter et al. 2007; Wilson and Wolkovich 2011). Detrital inputs enter any ecosystem via allochthonous or autochthonous sources (Moore et al. 2004). Allochthonous inputs are resources that originate in one habitat but move into another, while autochthonous inputs originate and are consumed in the same habitat (Polis et al. 1997). Many ecosystems experience spatial subsidies as regular seasonal events, but subsidies can also result from sporadic episodes of resource superabundance, named resource pulses (Ostfeld and Keesing 2000; Anderson et al. 2008b; Yang et al. 2008). Examples of resource pulses include periodical cicadas’ emergence in North American forests (e.g. Yang 2004, 2008), El Nin˜o rainfalls in arid ecosystems (e.g. Polis et al. 1997; Meserve et al. 2003; Letnic et al. 2005), seed or fruit mast events (e.g. Woff 1996; Curran and Leighton 2000), and massive spawning events by migratory fish (e.g. Woff and Hershey 1999; Yanai and Kochi 2005). Despite their ecological importance, these studies focused mostly on aboveground processes and just a few assessed belowground effects (Yang 2004; Yang et al. 2010).

Cultivated mushrooms are an important food source for many people around the world, with global production estimated at over 10 million tons per year (Food and Agriculture Organization of the United Nations 2014). Over two thirds of the production of edible mushrooms are harvested in mainland China, where mushrooms form a more traditional role in food and medicine than they do in many Western countries, and where they provide a living for over 25 million mushroom farmers (Zhang et al. 2014b). The most important edible mushroom genus grown commercially is Agaricus (mainly Agaricus bisporus, the button mushroom), which makes up about 30% of the global market (Royse 2014). Other important edible genera include Pleurotus (5–6 species of oyster mushrooms that are cultivated commercially), Lentinula (shiitake), Auricularia (3–4 species of woodear mushrooms), Flammulina (enoki), and Volvariella (paddy straw). Edible mushroom production is dominated by a few species where the technology for large-scale industrial cultivation has been optimized (Chang and Miles 2004), but in many countries large numbers of small-scale farms also exist, and there are increasing attempts to domesticate local wild mushrooms for production purposes (Mwai and Muchane 2016). Cultivated mushrooms are saprophytes which grow by degrading natural lignocellulosic substrates, which are commonly available in large volumes as agricultural or industrial byproducts. The methods for commercial cultivation of mushrooms on these substrates can be divided into three broad groups. The first group includes cultivation of many wooddegrading mushrooms that were traditionally grown on wood logs or harvested from trees. Some of these, such as Lentinula, are now grown on artificial logs of compacted, sterilized sawdust, while others, such as Flammulina, Pholiota (nameko), or Auricularia are cultivated on a partly composted mixture of sawdust and other components (bran, straw, corncobs), which is sterilized at high temperature (121 °C) before inoculation with mycelium (Chang and Miles 2004; Sanchez 2010). Because of the rigorous sterilization process, these mushrooms are essentially grown in axenic culture. The second group of cultivation methods either uses uncomposted substrates directly, or uses partially composted substrates that have not been subjected to a rigorous sterilization process. This includes methods commonly used for Pleurotus and Volvariella species, though Pleurotusis also sometimes grown on sterilized sawdust substrates. These are fast-growing and adaptable genera capable of rapid bioconversion of a broad range of substrates (e.g., rice straw, bagasse, cornstalks, waste cotton, stalks, and leaves of bananas (Chang and Miles 2004; Thongklang and Luangharn 2016). The substrates are usually not sterilized before inoculation, though a pasteurization step may be included in the process, and the mushrooms therefore grow in competition with other microorganisms on the substrate. The most industrially complex process is the cultivation of Agaricus, which is grown on a pasteurized straw-based compost which requires lengthy preparation, but allows selective growth of the Agaricus mycelium over competitor organisms.

Fungi have been used for centuries in Asian cultures due to their sensory, nutritional and medicinal properties. Several studies have developed specific activities to understand them, especially the substances involved and their medicinal effects (Cheung, 2010). In addition to improvements in crops, the type of substrate utilized, different forms of conservation and processing, and technological issues such as developing nutraceuticals and functional foods from fungi must be considered (Barros et al., 2008). Several mushrooms have been recognized as important food sources for their contributions of high-quality protein due to the wide distribution of essential and nonessential amino acids; carbohydrate; dietary fiber; and minerals such as sodium, phosphorus, potassium, iron and zinc (Goyal et al., 2006; Chiu et al., 2000; Mukhopadhyay and Guha, 2015). Food insecurity in Colombia 817 Received 7 March 2017 Revised 3 June 2017 9 June 2017 Accepted 12 June 2017 Nutrition & Food Science Vol. 47 No. 6, 2017 pp. 817-828 © Emerald Publishing Limited 0034-6659 DOver the years, various therapeutic effects have been reported from some macromycetes, and antimicrobial effects have been demonstrated in fungi such as Ganoderma spp., Pleurotus spp., Agaricus spp. and Lentinula edodes on gram-positive and gram-negative bacteria (Alves et al., 2012). Antitumor effects and enhancement or stimulation of the immune system have been reported in L. edodes, Grifola frondosa, Agaricus bisporus and Pleurotus ostreatus. In addition, other properties include antioxidant and antidiabetic effects, cholesterol control, treatment for allergies and anti-inflammatory effects, with results comparable to those of commercial medications (Lindequist et al., 2005; Valverde et al., 2015; Khan and Tania, 2012). Locally, studies have been conducted mainly on Pleurotus spp., Ganoderma spp. and Grifola frondosa to investigate the incidence of variables such as geographical origin, substrates, climatic conditions and physicochemical parameters in obtaining high-valueadded bio-compounds such as fatty acids, polysaccharides, terpenes and lignocellulolytic enzymes in addition to the antioxidant activity and bactericidal activity of these substances (Benavides Calvache et al., 2015; Chegwin and Nieto, 2013; Chegwin-Angarita and NietoRamírez, 2014; Nieto and Chegwin, 2008, 2010, 2013; Guzmán et al., 2009; Moreno et al., 2011; Montoya et al., 2012, 2013, 2014; Quevedo-Hidalgo et al., 2012; Quevedo-Hidalgo et al., 2014). Finally, other studies have evaluated various preservation treatments, such as packaging, storage atmosphere and dehydration, to increase the shelf life of Pleurotus ostreatus and Pleurotus sajor-caju (Castro, 2006; Cortés et al., 2011).