Fungal Biotechnology

This study was conducted with a fungal strain isolated from a mining soil contaminated with total petroleum hydrocarbons (TPH) and properly identified by polymerase chain reaction (PCR) technique as  Aspergillus terreus KP862582. The biodegradation potential of this pure culture was evaluated at laboratory scale; a wide diesel concentration range, from 10,000 to 50,000 mg diesel/kg soil (ppm), was tested using sterile soil microcosm over a 90-day period. Aerobic    biodegradation of diesel by Aspergillus terreus  KP862582 was significantly greater (p < 0:05) for 10,000, 20,000, and 30,000 ppm, with rate constant values of 0.025, 0.023, and 0.012 1/day, respectively. Cell viability at these concentrations was favored because it showed a significant increase during the first period of biodegradation (0-30 days), from this time onwards eciency removal and cell viability decreased  considerably. This pattern was observed as concentration of diesel increased, resulting in a much lower biodegradation rate for 40,000 ppm (0.005 1/day) and 50,000 ppm (0.002 1/day). Based on the results of this study it is concluded that the strain of Aspergillus terreus KP862582 can be used in the bioremediation
of soils contaminated with petroleum hydrocarbons at concentrations of 10,000 and 20,000 ppm, and comply with the MPL established by the Mexican regulation.

The use of mushroom for the bioconversion of low quality lignocellulosic agricultural waste into nutritional food and animal feed rich in protein and minerals offers an alternative food and feed supplement. The genus Pleurotus comprises of edible lignolytic mushrooms capable of selective delignification of lignocellulolytic crop residue converting into edible protein and mineral salts. The effect of raw untreated rice straw and pre-treated (composted for 0, 4, 8 and 12 days supplemented with either 5, 10 and 15% rice bran 1% CaCO 3 on growth rate, yield performance and Biological Efficiency (BE) of Pleurotus eous Strain P-31 was investigated using the conventional pasteurized bagged technique. The traditional ''wawa'' (Triplochiton scleroxylon) sawdust was used for comparison purposes only. The growth parameters (pH, moisture, spawn running time, fruit body formation, interval between flushes, total number of fruiting bodies during the cropping time and mushroom yield (Biological Efficiency) as well as the nutrient and mineral profiles of the fruiting bodies were determined by the conventional techniques. It was observed that amendment or supplementation of the substrate (rice straw) did not significantly (p≤0.05)enhance mushroom yield of Pleurotus eous such that growth on the composted substrates (4-8 days) gave the best yield with BE 67.1 – 75.1%. Yield on the unfermented rice straw was comparatively good (BE = 53.3-72.8)%. Both the pH and moisture content for all the substrates were within the optimum range of 6.0-8.0, 60 – 70% RH respectively. The standard substrate, ''wawa'' sawdust, currently in use for cultivation of Pleurotus spp. gave BE of 55.6 – 64.8%. The fruiting body contained high fat, protein, crude fibre and carbohydrates but differed depending on the type of substrate used. The carpophore contained mineral elements Ca, Mg, K, Na, and P in appreciable amounts useful for good health. Although heavy metals such as Cu, Fe, Mn, Pb and Zn were detected they were far below the WHO stipulated safe limits. The presence of high potassium over sodium makes P. eous fruiting body suitable for therapeutic treatment of hypertension.