Physico-Chemical And Toxicological Profiles Of Five Species Of Mushroom In Anambra State, Nigeria And Their Potential For Bioremediation Of Trace Metal Polluted Soil

ABSTRACT

Five species of Mushroom namely Termitomyces robustus, Agaricus bisporus,

Pleurotus tuber-regium, Amanita phalaoides and Amanita verosa were collected from

eleven locations in Uke, Abatete, Ideani, Nnobi, Nnewi (Okpuno-egbu), Nnewi

(Umudim) and Ozubulu between 2009 and 2012 in Anambra State, Nigeria. They

were kept in clean collection bags and identified by a taxonomist. Some of the

mushroom samples were later oven dried at 75 0 C for 4 hours and kept for chemical

analysis while some were used for cultivation. During cultivation, seeds from matured

mushrooms were scrapped from their veils into already compounded substrates/soil

from their natural habitats and refuse dump soil (Table 3.2). The seeds were allowed

to germinate within 4-5 days, the fruiting bodies/spawns were watered once daily for

14 days. The matured mushrooms were harvested, cleaned and oven dried at 75 0 C

for 4 hours. The dried mushroom samples (wild and cultivated respectively) were

homogenized into fine powder using blender with titanium blade and stored in precleaned

bottles for chemical analysis. These samples were subjected to various

chemical analyses using standard methods by Association of Official Analytical

Chemist (AOAC). The data were subjected to one way analysis of variance

(ANOVA) at 95 % level using Statistical Package for Social Scientists (SPSS) version

16.0. The moisture content (MC) ranged from 81.79 % to 97.84 %, the highest value

was from Amanita phalaoides and the least value was from Agaricus bisporus. Dry

matter (DM) ranged from 2.63 % to 18.36 % showed an indication of high roughages

content of the mushrooms. Crude protein (CP) ranged from 8.16 % to 24.67 % which

compared favourably with values of seeds and legumes. Ash contents ranged from

3.26 % to 14.33 % were indications of high mineral elements present in the studied

mushroom species. Low values of Lipid (fat/oil) ranged from 1.00 % to 6.68 % gave

acceptance of the mushrooms as excellent dietary food for diabetic and coronary heart

disease patients. Crude fibre (CF) ranged from 2.62 % to 15.37 %. There were no

significant differences at p>0.05 between values of wild and cultivated mushrooms.

Carbohydrates contents of 32.00-35.40 %, implied that mushrooms can function

effectively in low fat diet such as those required by patients with cardiovascular

diseases and diabetes. The vitamin C were detectable at levels ranging from 0.01-0.37

mg/100 g, values determined showed that the studied mushrooms were not good

sources of vitamin C, although they could make important contribution to diet. The

mean anti-nutritional factors of phytic acid 0.26 mg/100 g, cyanide 0.16 mg/100 g,

tannins 0.31 mg/100 g were low when compared with 1.00 mg/100 g found in WHO

guideline levels for these toxicants in food. Essential metals concentrations (mg/kg)

for wild mushroom samples ranged as follows: Na (152.36 – 777.42), K (166.88 –

933.81), Ca (83.64 -545.00), Mg (476.57–1191.00), Fe (154.68–684.74) while values