African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6574

Full Length Research Paper

Food values, heavy metal accumulation, aflatoxin contamination and detection of exo-polysaccharrides in Lentinus Squarrosulus Berk, a Nigerian mushroom

  Jonathan S. G.1*, Amos-Tautua B. M. W.2 and Olawuyi O. J.3    
  1Department of Botany and Microbiology, University of Ibadan, Oyo State, Nigeria. 2Department of Chemical Sciences, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria. 3Department of Biosciences and Biotechnology, Babcock University, Ilishan Remo, Ogun State, Nigeria.
Email: [email protected]

  •  Accepted: 26 May 2011
  •  Published: 04 July 2011

Abstract

 

Fruit bodies of a wild edible fungus (Lentinus squarrosulus, Berk) were collected from partially buried decaying wood in the swampy area of the Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria. They were taken to the laboratory in aerated bags and evaluated for food values, mineral elements composition, heavy metal accumulation, production of exo-polysaccharides and aflatoxin contamination using standard methods. The results showed that fresh samples of this edible fungus had the  highest nutrient and mineral element compositions followed in order by 4, 8 and 12 weeks old samples,respectively (P<0.05). Protein was the most abundant class of food in the fresh and stored samples. It ranged from 16.87% in the fresh sample and reduced to 15.29% in 12 weeks old samples. Other nutrients detected in significant amount in the fungal samples were ethanol soluble sugars, fat, crude fibre and dried matter. The most abundant mineral element in the fresh samples of L. squarrosulus was potassium with value of 12.77 mg/100 g followed in order by phosphorus, magnesium, calcium and sodium (P≤0.05). Traces of heavy metals such as Pb, Cu and Cd were also detected. Aflatoxin G2 was found to be absent in all the samples. However, 0.005, 0.002 and 0.001 µgKg-1 of aflatoxin AFB1, AFB2 and AFG1,respectively were detected in 12 weeks stored samples of L. squarrosulus. The vegetative growth of this fungus on basal medium after 15 days showed a mycelial biomass yield of 15.57 mg/ 100 ml while 4.63 units of the exo-polysaccharides were produced. The significance of these observations were discussed.

 

Key words: Proximate composition, aflatoxin, exo-polysaccharides, L. squarrosulus, mineral elements.