Nutrient Content of Pleurotus pulmonarius (Fr.) Quel. Grown on Some Local Lignocellulosic Wastes

The aim of study as to determine the effects of some composts on the nutritional value of Pleurotus pulmonarius (Fr.) Quel. The energy, dry matter, moisture, crude protein, fat, ash, organic matter, and nitrogen free extract were 311.3-313.9 (kcal 100 g -1 ), 91.8-92.5, 7.5-8.2, 27.3-38.6, 1.5-1.9, 5.3-6.4, 35.9-46.8 and 86.0-87.1 (g 100 g -1 ) of dry weight, respectively. The contents of polymeric substance were determined 13.6-16.2% of cellulose, 20.4-21.8% of hemicellulose and 0.1-0.3% of lignin. It was observed that the crude fat, energy, lignin and hemicellulose contents of P. pulmonarius were not statistically significant depending on the substrates used in the culture (p>0.05), but there were variations in other nutrients (p<0.05). that the substrate products used in the culture of can affect the nutrient composition of the mushroom such as energy, crude protein and carbohydrate.

It is estimated that over 2300 mushroom species have some medical and nutritional value, but only around 25 are widely accepted as food and few are commercially cultivated. However, the global mushroom cultivation industry and economy is based on five species: button mushroom Agaricus bisporus (J.E. Lange) Imbach, oyster mushroom Pleurotus ostreatus (Jacq.) P. Kumm., shiitake mushroom Lentinula edodes (Berk.) Pegler, wood ear mushroom Auricularia auricula-judae (Bull.) Quél., enoki mushroom Flammulina velutipes (Curtis) Singer and its cultivars (Mleczek et al., 2020). According to the FAO data, global mushroom cultivation amounted almost 9 million tons in 2018, indicating that it was one of the fastest growing branches of horticulture. In the last 10 years, the harvest of fruiting bodies has doubled together with an increase in species diversity (FAO, 2018).
The genus Pleurotus (Fries) Kummer (Basidiomycota, Agaricales) is probably the best known edible mushroom genus in the world due to its gastronomic, nutritional importance and also medicinal properties (Knop et al., 2015;Correa et al., 2016), as much as they achieved the second position in the production of edible mushrooms (Royse et al., 2017). It is estimated that there are more than 200 species of fungi of the genus Pleurotus spp., all of which are edible and appreciated for their taste, aroma, and texture, as well as the health enhancing bioactive potentials (Bazanella et al., 2013;Valverde et al., 2015). The most important Pleurotus species cultivated in large scale are P. ostreatus and P. pulmonarius. The second often marketed by spawn manufacturers and cultivators under the incorrect name "P. sajor-caju". The real P. sajor-caju is in fact a separate species of mushroom, which was returned to the genus Lentinus by Pegler (1975), and is correctly named L. sajor-caju (Buchanan, 1993). P. pulmonarius, also known as the Indian Oyster, Italian Oyster, Phoenix Mushroom, or the Lung Oyster, is most commonly known as the grey oyster mushroom, which is characterized by a grayish colored sporophore, which has a fleshy texture and produces an aromatic, not anise-like aroma (Stamets, 2010). It is widely marketable and sells well in several other countries (Lechner et al., 2004;Li et al., 2015;Wu et al., 2019).
The most produced commercial mushroom in Turkey, which known and constituting market share, are generally A. bisporus and P. ostreatus. Although the P. pulmonarius, known as P. sajor-caju, has been studied in the academic field for years, it is not sufficiently recognized by consumers and has no market share. The simplicity of cultivation of this species, its completion in a short time (2 months), as a result of obtaining 4 harvests, spreading it in terms of earliness and diversity and increasing its market share are important for producers. Determining that it has important nutritional values as a food source increases the importance of the subject.
In this study, it was aimed to determine the nutritional values of the P. pulmonarius by evaluating the Medicago sativa L. straw, Prangos pabularia Lindl. wastes and Poplar sawdust residues, which can be provided abundantly and cheaply in our region, and to spread the production of this species as a cultivated mushroom and to establish a market share.

Obtaining The Materials
The mushroom samples used in this study were was obtained from the previous culture work (Akyuz et al., 2019). For the formation of basidiocarp, Medicago sativa L. (MS), Prangos pabularia Lindl. (PP) and Poplar sawdust (PS) were used as culture media.
These local lignocellulosic wastes were obtained from the vicinity of Bitlis, Turkey. Three types of compost were prepared, consisting of a mixture of MS-PP (1:1), MS-PS (1:1) and MS. In addition, MS was used as the control treatment. The samples were harvested, dried at room temperature for 15 days, placed in locked bags, stored at 25°C in lab, and then samples used in this study.

Methods
The energy, nutrient contents (moisture, protein, ash, fat, carbohydrate) and lignocellulosic content (hemicellulose, cellulose, lignin) were performed in the Faculty of Veterinary Medicine, Fırat University, Turkey. The selected biochemical properties moisture, ash, crude protein, fat, ash (AOAC, 1990) crude cellulose (Crampton and Maynard, 1983) and lignocellulosic contents (Vansoest et al., 1991) were determined by appropriate methods. The lipid content was analysed by the Soxhlet extraction method using ethyl ether as the extraction solvent. Protein content was determined by the Kjeldahl method using 6.25 as converting factor to protein. Calculations were made with the following formulas: Nitrogen-free extract: % dry matter − (% crude fat + % crude ash + % crude protein + % crude cellulose) Organic matter: % dry matter − % crude ash (2) The energy (kcal): 4 x (protein + carbohydrate) + 9 x fat (3) Cellulose: ADF -Lignin  They are also contained the polymeric substances, cellulose, hemicellulose and lignin in the range of 37.2-51.8%, 12.9-17.6% and 12.6-23.1%, respectively (see Table 1). The dry matter, moisture, energy, crude protein, crude fat, crude ash, nitrogen free extract, organic matter, cellulose, lignin and hemicellulose content of lignocellulosic wastes were significantly different among substrates (p<0.05) shown in Table 1. Each value is expressed as mean ± SD of triplicate analysis (n=3), a,b,c : Comparison between substrates, x,y,z : comparison in different culture media Values with different small letters in the same column are significantly different at the level of 0.05 (p< 0.05) Nitrogen free extract: % dry matter − (% crude fat + % crude ash + % crude protein + % crude cellulose) Organic matter: % dry matter − % crude ash The energy (kcal): 4 x (protein + carbohydrate) + 9 x fat Cellulose: ADF-Lignin, Hemicellulose: NDF -ADF The fruit bodies of P. pulmonarius grown on culture medium obtained from different agricultural wastes and their mixture in the present study were determined 91.8-92.5% dry matter, 311.3-313.9 kcal energy, 27.3-38.6% crude protein, 1.5-1.9% crude fat, 5.3-6.4% crude ash, 86.0-87.1% organic matter and 35.9-46.8% nitrogen free extract of dry weight, respectively. At the same time cellulose, hemiselose and lignin contents were determined as 13.6-16.2%, 20.4-21.8% and 0.1-0.3% (see Table 1). The crude fat, energy, lignin and hemicellulose contents of fruiting bodies were not significantly different among substrates (p>0.05), but can changeable in other nutrient composition and polymeric substance (p<0.05) as shown in Table 1. Because analysis of the main components of P. pulmonarius has been revealed differences in their values as depending on the nature of the cultivation substrates.
The highest value of dry matter contents was obtained from MS (92.5%) and MS-PS (1:1) (92.4%), while lowest value was obtained from MS-PP (1:1) substrate (91.8%). In previous studies, it was reported that fresh mushrooms have approximately 90% moisture and 10% dry matter, and dried mushrooms have approximately 90% dry matter and 10% moisture (Ragunathan et al., 1996;Manzi et al., 1999;Ragunathan and Swaminathan, 2003;Kırbag and Volkan, 2014;Sardar et al., 2017;Finimundy et al., 2018). It is seen that the values obtained in the study are consistent when compared with the previous reports. The variation in the moisture percentage of the mushroom depends on the species, time of harvest, growth, storage condition, substrate and other parameters related to the growth environment such as temperature and relative humidity (Guillamon et al., 2010;Reis et al., 2012).
In general, mushrooms are very low in fat; the fat fraction is mainly composed of unsaturated fatty acids. The crude fat contents of P. pulmonarius were not significantly different among substrates (p>0.05, see Table 1). Minimum fat level was 1.5% on MS-PP (1:1) and maximum was 1.9% on MS-PS (1:1) as seen in Table 1. Fat contents were previously reported KSU J. Agric Nat 25 (1) (Ragunathan et al., 1996), 1.16% in P. sajor-caju (Finimundy et al., 2018), 2.6-4.7% in P. sajor-caju (Oyetayo and Akindahunsi, 2004), 2.16% in P. ostreatus (Yang et al., 2001), 4.36-6.4% in P. ostreatus (Rashad and Abdou, 2002), 4.3-4.7% (Wang et al., 2001), 4.30-5.42% in Pleurotus spp., A. bisporus ve L. edodes (Furlani and Godoy, 2007). It has been observed that the fat content of P. pulmonarius was similar to with the fat contents in those studies. Recently, mushroom origin proteins have been gained the attention of food industry players and scientific community, their rich essential amino acid and high nutritional value when compared to vegetables (Bach et al., 2017). Therefore, the use of edible mushrooms for the development of protein-rich food products can encourage its utilization while offering an attractive alternative to an animal protein source (Gonzales et al., 2021). In this study, the highest value of crude protein (38.6%) was obtained from MS while the lowest value (27.3% and 30.9%) was obtained from MS-PS (1:1) and MS-PP (1:1) substrates and was found to be significantly different (p<0.05, see Table  1). Protein contents were previously reported 25.6-44.3% in Pleurotus spp. (Ragunathan and Swaminathan, 2003) (Yang et al., 2001), 29.91-38.01% in P. ostreatus (Rashad and Abdou, 2002), 41-53% in P. ostreatus (Wang et al., 2001), 18.98-28.45% in Pleurotus spp., A. bisporus and L. edodes (Furlani and Godoy, 2007). In this study, it is seen that the crude protein value of P. pulmonarius is higher than some (Yang et al., 2001;Rashad and Abdou, 2002;Oyetayo and Akindahunsi, 2004;Furlani and Godoy, 2007;Akyüz and Kırbag, 2009;Akyüz and Kırbag, 2010;Finimundy et al,. 2018) and more variable than some (Ragunathan et al., 1996;Wang et al., 2001;Ragunathan and Swaminathan, 2003;Akyüz and Kırbag, 2010;Kırbag and Volkan, 2014) compared to previous studies. It is known that the protein content of mushrooms varies according to the genetic structure of the species, physical and chemical differences in the growing environment, the nature and nutrient content of the substrate used for cultivation, the mushroom strain, the post harvest analysis time, and the development stage (Jiskani, 2001;Gothwal et al., 2012).
Based on the crude protein, carbohydrate and fat contents, the energy value of fruit bodies of P. pulmonarius were calculated (p>0.05, see Table 1).

CONCLUSION and RECOMMENDATION
In the present study, it was observed that the type of substrate used for cultivation of P. pulmonarius could influence the nutrient composition such as energy, crude protein and nitrogen free extract of the fruit bodies (shown Table 1). P. pulmonarius contain different amounts of energy, protein, nitrogen free extract, polymeric substrance such as cellulose and lignin depending on the composition of the substrates used for cultivation. The use of P. pulmonarius as food or ingredient for processing functional products is promising because of its nutritional attributes and potential benefits on health.