Some physiological studies on fungi isolated from poultry feedstuffs

Abstract

A total of 506 isolates of mesophilic, thermophilic and thermotolerant fungi isolated from the poultry feed ingredients included soybean meals, ground maize, cottonseed cake, wheat bran and fish meal, on glucose-Czapek's agar, Littman oxgall agar at 28 degrees C and yeast starch agar (YPSs) at 45 degrees C, were screened for their ability to produce hydrolytic protease enzyme on solid media. Most of the fungal isolates were able to produce such enzymes but with variable capabilities. The highest proteolytic activity was exhibited by some isolates of Penicillium chrysogenum, Aspergillus flavus, Thermoascus thermophilus and Rhizopus chizopodifarmis. Of all fungal isolates screened for proteolytic activity, Penicillium chrysogenum and Thermoascus thermophilus produced the highest amounts of proteases. These two isolates were used to study the effect of some environmental and nutritional factors on their proteolytic activity. It was found that the highest yield of protease by P. chrysogenum (12.5 units) was achieved 3 days after incubation at 30 degrees C. Marked reduction in protease activity was observed at 37 degrees C. The thermophilic fungus T. thermophillus exhibited maximum (18 units) proteolytic activity 6 days after incubation at 45 degrees C. The enzyme yield was reduced to 13 units at 50 degrees C. Among the seven carbon sources tested, sucrose was the most appropriate for maximum protease production by both P. chrysogenum and T. thermophilus (13.2 and 12.8 units, respectively). Of the sixteen nitrogen sources investigated, NaNO3 was the best inorganic additive nitrogenous salt which induced the highest proteolytic activity by P. chrysogenum and T. thermophilus, whereas DL-tryptophan was the most preferable organic nitrogen compound for maximum protease production by the two fungi tested.

Comparative ameliorative actions of extracted bradykinin potentiating fraction from cobra snake venom and synthetic antioxidants on hepatic tissue of aflatoxicosed rats

“…Mycotoxins are secondary metabolites produced by Aspergillus, Penicillium and other genera which contaminate food and exhibit hazardous effects on humans and animals mainly malnutrition, immunosuppression, genotoxicity, carcinogenic and teratogenic effects due to inhibition of macromolecule synthesis and metabolism (Nassar et al 1985;Megalla et al 1990;Maresca and Fantini 2010;Adejumo and Adejoro 2014;Ashiq 2015;Tola and Kebede 2016). The AFs are referred to four different types and their metabolites contaminating the food of animals and humans (Nassar et al 1982;Hafez et al 1985;Rajendra et al 2014).…”