Fortification of substrates to produce bio-enriched Oyster mushrooms
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Date
2023-01-03
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CSK HPKV, Palampur
Abstract
The present investigation entitled “Fortification of substrates to produce bio-enriched Oyster
mushrooms” were undertaken to evaluate various cultural aspects, morphological and yield attributes on
different agro-based substrates or fortified and non-fortified substrates, nutrient content and analysis of Se
and Zn content after fortification in different doses. Cultural studies were carried out to determine the best
solid, liquid media, temperature, pH and light intensity on mycelial growth of Pleurotus ostreatus. Yeast
malt agar (8.50 cm) and potato dextrose yeast broth (10.17 g/ml) supported the best growth of P. ostreatus.
Temperature of 25oC was found optimum for both solid and liquid media with mycelial growth of 8.53 cm
(YMA) and mycelial mat of weight 9.91 g/ml (PDYB). The maximum mycelial diameter was recorded at pH
6.5 with mycelial growth of 8.19 cm in solid medium (YMA) and in liquid (PDY) broth maximum mycelial
mat of weight 9.98 g/ml was recorded at pH 6. Light intensity of 200 lux supported the best mycelial growth
in solid (8.26 cm) as well as liquid medium (10.11g/ml). Various agricultural waste viz., cereal substrates
(wheat, paddy straw and maize cob), leguminous substrates (soybean and urd bean straw) and oilseed
substrates (linseed and mustard straw) were evaluated. The results revealed that rice straw had the highest
yield (363 g) and biological efficiency (103 %) among cereal substrates. Among leguminous substrates, the
maximum yield (375 g) and biological efficiency (107 %) was found on soybean straw. Whereas, on oilseed
substrates the maximum yield (282 g) and biological efficiency (80 %) was found on mustard straw. The
best cereal (paddy straw), leguminous (soybean straw) and oilseed substrate (mustard straw) on the basis of
highest biological efficiency were further used for fortification with three concentrations (25, 50, 75
mg/1000g) of sodium selenite and zinc sulphate. The results on morphological characters revealed that after
being fortified with selenium and zinc, the size and colour of fruit bodies remain unchanged. Soybean straw
resulted in maximum yield (313 g) and biological efficiency (89 %) after Se fortification at dose 25 mg/kg
followed by 50 mg. Similarly, on rice and mustard straw the maximum yield and biological efficiency was
recorded at dose 25 mg/kg of Se (300 g and 85 %, 279 g and 79 % respectively). After zinc fortification, the
dose of 25 mg/kg on rice straw resulted in maximum yield (335 g) and biological efficiency (95 %) followed
by 50 mg. Soybean and mustard straw also showed maximum yield and biological efficiency at dose 25
mg/kg of Zn (305 g and 87 %, 287 g and 82 % respectively). Among all the substrates, the minimum yield
and biological efficiency was recorded at dose 75 mg/kg of Se and Zn. Nutrient analysis of fruit bodies
harvested after fortification of best substrates with salts of Se and Zn exhibited maximum carbohydrate
(60.29 %) and protein content (32.32 %) at 75 mg in Se fortified mushroom on soybean straw. However, at
50 mg/kg of Zn the maximum fat content (2.74 %) was recorded on soybean straw and maximum fibre
content (18.12 %) was recorded on rice straw. The best dose of both the salts (25 mg/ 1000g of substrate) on
the basis of maximum yield were combined and evaluated. The results revealed that soybean straw produced
the maximum yield (324 g) and nutrient content (55 % of carbohydrate and 27.72 % of protein) followed by
rice straw and mustard straw. Maximum Se uptake (69.95 µg/g) at dose 75 mg was recorded on soybean
straw followed by rice (61.67 µg/g) and mustard straw (57.75 µg/g). Similarly, at dose 75 mg the maximum
Zn uptake was recorded on rice straw (120.67 µg/g) followed by soybean (117.27 µg/g) and mustard straw
(107.23 µg/g). The minimum Se and Zn uptake was recorded on combined dose on mustard straw (37.5 µg/g
of Se and 81.03 µg/g of Zn). Amongst the tested substrates and doses soybean and rice straw were best
suited for Se and Zn fortification at dose 50 and 75 mg