Citric Acid Production From Some Local Isolates Of The Fungus Aspergillus Niger By Rice Husks Filtrate Medium

Research Article
Ali.A.Alsudani and Majid.K.Al-Shibli
DOI: 
xxx-xxxxx-xxxx
Subject: 
science
KeyWords: 
Agrobiodiversity, Sustainable agriculture, urban greening, soil resource, forestry, landscape.
Abstract: 

The current study included isolation and identification some local isolates of the fungus Aspergillus niger from the soil of one of the gardens of Al-Qadisiya University and exclusion the isolates that have the ability to produce aflatoxins and screened to select the more efficient isolate in producing citric acid and biomass after growing the isolates on synthetic medium containing sucrose supplemented with NH4NO3 , KH2PO4 and MgSO4.7H2O and determine some of the optimal conditions for the production of citric acid from the selected isolation after growing it on the rice husks filtrate medium supplemented with some nutrients referred to in the synthetic medium. The results showed isolation and identification 12 local fungal isolates of the fungus A. niger was then screening these isolates by detects its ability to produce aflatoxins and exclusion the toxic isolates, A. niger 4 showed high ability on the production of aflatoxins while A. niger 6 and A. niger 12 showed moderate ability on the production of aflatoxins at the CEA medium and weak ability at the production medium which contain agar, while A. niger 1 and A. niger 10 showed little ability on the production of aflatoxins, while the other isolates did not show the ability to produce aflatoxins. Tasted ability of 7 local fungal isolates of the fungus A. niger on the production of citric acid by using synthetic medium of production, The results showed that for all fungal isolates studied the ability to produce citric acid but in varying degrees, As for the dry biomass for fungal isolates have values ranged between (12.64-19.73) g/l, According to the results of the statistical analysis that showed there were significant differences at the level of 5 % probability between the concentration of citric acid product of fungal isolation A. niger which amounted to 14.683 g/l and the other isolates and the absence of significant differences between the dry biomass of this isolation value which amounted to 18.96 g/l and isolation that gave the highest biomass has therefore selected fungal isolation A. niger 5 to be used in all subsequent production studies. The optimum cultural and environmental conditions for the production of citric acid from the selected isolation were studied it was obtained the highest production of citric acid which amounted to 19.447 g/l by using the rice husks filtrate medium containing 15 % reducing sugars, 0.25 % ammonium sulfate, at temperature 30 ْ◌C and primary pH 4