S. Rajarathnam

Pleurotus mushrooms. Part III. Biotransformations of natural lignocellulosic wastes: Commercial applications and implications

Species of Pleurotus are endowed with the capacity to degrade unfermented natural lignino-cellulosic wastes. From the time the substrate is spawned until the end of cropping, there occurs a spectrum of qualitative and quantitative changes in the various substrate constituents, viz., cellulose, hemicellulose, lignin, sugars, amino acids, phenols, ash, nitrogen, etc. In general, cellulose, hemicellulose, and lignin are degraded, solubility of the substrate is increased, phenolic content is decreased, sugar and amino acid contents are increased, as is the ash content due to a constant utilization of the organic matter. The ability of Pleurotus to effect these degradative changes is discussed under both sterile (monoculture) and nonsterile culturing conditions. The enzymatic aspects affecting these various chemical changes in the lignino-cellulosic substrates are brought out. The various commercial applications and implications of the spent substrate, such as use as an upgraded form of ruminant feed, production of biogas, manufacture of paper/cardboard, recycling into Agaricus compost, garden fertilizer, production of single cell proteins, etc., are critically evaluated.

Improvement of the bioconversion and biotransformation efficiencies of the oyster mushroom (Pleurotus sajor-caju) by supplementation of its rice straw substrate with oil seed cakes

Supplementing the rice straw substrate colonized by the mushroom, Pleurotus sajor-caju, withpowdered oil seed cakes (mustard, niger, sunjower, cotton, and soyabean) increased the mushroom yields between 50 and iOO%, compared to the unsupplemented substrate. Oil seed cake supplementation also effected an increase in the solubility of the rice straw substrate; there was an increase in the contents offree sugars and amino acids, and a decrease in cellulo-hemicellulosics. Correspondingly, there was also an increase in the activities of carboxymethylcellulase, hemicellulase, and protease. In vitro dry matter enzymatic digestibility measured by two-step enzymatic digestibility of the spent straw (material remaining from the straw substrate, supplemented with the oil seed cakes), indicated a signt

Enhancement of bioconversion efficiency and chemistry of the mushroom, Pleurotus sajor-caju (Berk and Br.) Sacc. produced on spent rice straw substrate, supplemented with oil seed cakes.

cant increase over that of the spent straw derived from the unsupplemented lot.

Biopotentialities of the basidiomacromycetes

Abstract The effect of supplementing the spent rice straw substrate, selected at two different levels of bioconversion efficiency (BCE), 8 and 12%, of Pleurotus sajor-caju, with extra organic nitrogen (in the form of oil seed cakes) was studied on further production of mushrooms, their chemistry and the increase in the in vitro dry matter digestibility (IVDMD) of rice straw. The spent rice straw was supplemented with the oil seed cake powders in amounts equivalent to 0.15–0.60% of nitrogen present in the undegraded rice straw, that is used for mushroom culturing. The cotton seed powder proved to be better in enhancing the mushroom yields (up to 12 times those of the unsupplemented spent straw), than the other oil seed cakes such as mustard, niger, soyabean and sunflower. Chemically, the cottonseed powder supplemented mushrooms showed increased protein, fat and decreased carbohydrate contents. Also, there was a significant reduction in the spawnrun period, compared to the unsupplemented rice straw. A considerable increase in the IVDMD of the supplemented spent straw was observed as compared to the IVDMD of the unsupplemented spent straw. Due to cotton seed cake supplementation, there was about a 27% increase in the IVDMD value of the spent straw that resulted in 8% BCE. The mushrooms produced on the spent rice straw substrate, with supplementation of cottonseed powder, did not contain any residues of gossypol, and accordingly, they can be a valuable food or feed.

Status of Bioactive Compounds in Foods, with Focus on Fruits and Vegetables

Publisher Summary Basidiomacromycetes represent a circumscribed group of higher fungi of the class Basidiomycetes, wherein the basidia bearing the exogenously produced basidiospores represent the fertile layer (hymenium), which in turn is lined up, encroached, and covered by tufts of tissues to form distinct objects of the Earths beauty, namely the basidiocarps. Genetic incompatibility factors (bipolarhetrapolar) allow these fungi fungi great diversity in their ability to grow over a range of conditions: fermented or unfermented; pasteurized or unpasteurized; sterilized or unsterilized; on soft woods or hardwoods; on cereal straws or oil crop residues, or plantation crop residues. Moreover, Basidiomacromycetes display an array of physiological properties that have a range of useful applications. Edible species represent the best examples: they grow over a range of lignocellulosic substrates to yield fruiting bodies, and the degarded substrates can in turn be used in a number of useful ways. The search for new species of basidiomacromycetes and research on new and different ways to use these fungi should be a matter of priority. It is a task that requires much intelligence and perseverance. Increasing the list of their applications depends on prolonged and continued research. It can take the ingenuity of mankind, coupled with natures mercy, to unravel the untapped potentialities of the basidiomacromycetes.

Nutrition of the mushroom pleurotus flabellatus during its growth on paddy straw substrate

Components of cereals, legumes, pulses, proteins, sea food, milk, carbohydrates and lipids are being evaluated for their influence on human health, as biofunctional compounds. However, references dealing with fruits and vegetables exceed any other food group and accordingly their focus. Fruits and vegetables abound in a spectacular range of such health influencing compounds and thus, study of their bioactivity, in lieu of their consumption in fresh or processed form. Anti-cancerous phenolics from Phyllanthus, radioprotective Litchi phenolics/flavonoids, hypoglycemic Sygium, quercitin and hydroxyl cinnamates of Sweet cherries, xanthones of Mangosteen, ellagitannins of Pomegranate, ursolic acid of Sea buckthorn, muscle relaxative watermelon, anti-cholesterolemic soluble fibre and sterols, cardioprotective saponins, ACE-inhibitory potato hydrolysates, anti-pancreatic cancerous ascorbic acid, carotenoids including pro-vitamin A are few examples unraveled. Thus, the imminent scope to obviate their structural chemistry, influence on storage and processing conditions, factors favoring their bio-accessibility/bio-availability in the food formulations, influencing human health. It is the meticulous combination of these compounds in daily consumption that determines their usefulness to human body. What is of paramount importance is the actual health benefits accrued from consumption of such functional- compound based fresh/processed fruits,vegetables or other foods.

Biodegradation of gossypol by the white oyster mushroom, Pleurotus florida, during culturing on rice straw growth substrate, supplemented with cottonseed powder

SummaryAcid swelling or alkali delignification of the straw did not increase mushroom yields. The addition of extra carbon as glucose or cellulose to the straw substrate during fructification did not increase yields. Nitrogen supplementation of the substrate in organic forms increased yields and the protein contents of the fruit bodies significantly only after spawn run. Supplementation of the spent straw substrate with cotton seed powder, wheat bran and casein resulted in higher yields and raised the protein content of the fruit bodies. Prolongation of the spawn run by continued disturbance of the mushroom beds over 16 days did not increase yields. Of several mineral salts used as supplements, only ferrous sulphate augmented yield significantly when added to the straw after spawn run.

Vitamin values ofPleurotus mushrooms

The capacity of the white oyster mushroom, Pleurotus florida to biodegrade gossypol was studied, when grown on rice straw supplemented with cottonseed powder. The mushroom fruiting bodies did not contain any residues of gossypol at concentrations of cottonseed powder ≡0.15–0.60% nitrogen contents of rice straw at the end of mycelial ramification. However, the cottonseed supplementation (at 0.30% N level itself) caused a doubling in the mushroom yield and its protein content, per unit weight straw substrate. The mushroom mycelium when grown on synthetic medium in liquid cultures was able to biodegrade gossypol. A pre-incubation period of 5 days before the addition of gossypol into the culture medium, an inoculum load ≡10 mg and an incubation period of 10 days at 25 °C caused the biodegradation of 100 μg gossypol. Increased concentrations of gossypol required increased duration and increased inoculum levels to effect biodegradation. However, the effect was more pronounced with an increase in inoculum density. The fungal monoculture when grown in rice straw (powder) (5%) + glucose (1%) liquid culture medium, showed an increase in hexosamine content and laccase activity that produced an increased degradation of gossypol over an incubation period from 5 to 25 days. Enzymic extracts of the mycelial monoculture raised on the chopped rice straw substrate when incubated with 100 μg of gossypol demonstrated its biodegradability; the increase in enzyme concentration showed enhanced gossypol degradation. This study adds to the world list of organic compounds that Pleurotus is able to biodegrade, and explains the cause of non-yellowing of the white oyster mushroom (P. florida) fruiting bodies, during culture on rice straw with supplementation of cottonseed powder for enhancing the mushroom yields.

Incompatibility and growth in Pleurotus flabellatus

Ascorbic acid, thiamine, niacin, riboflavin, pantothenic acid and folic acid contents were determined in four different species ofPleurotus mushroom grown on wet chopped unfermented rice straw. The estimated values for the respective vitamins ranged from 92–144, 1.36–2.23, 60.6–73.3, 6.66–8.97, 21.1–33.3 mg and 1222–1412 µg per 100g mushrooms on dry weight basis. These vitamin values were comparable with those ofAgaricus bisporus, but were higher than those ofAuricularia, Lentinus andVolvariella.

Somatic embryogenesis in cotyledon cultures of tea (Thea sinensis, L.)

The mating system of Pleurotus flabellatus was investigated using twenty monokaryons obtained from a single sporophore. All matings between pairs of monokaryons fell into four genotypic classes indicating that the fungus has bifactorial incompatibility. Considerable variation in growth rate was observed among monokaryons, the derived dikaryons and their component monokaryons. No correlation was found between growth rates of derived dikaryons and expected combined mean growth rates of their component monokaryons or the individual growth rates of monokaryons. The ability to produce fruit-body primordia in vitro on straw was not solely restricted to the dikaryons. Cultivation trials of derived dikaryons to select better strains over the parental dikaryon were promising.