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In Vitro Production Of Aflatozin (B1), Its Purification, Estimation And Biodegradation

By: Muhammad Hanif Khan | Dr. Irshad Hussain.
Contributor(s): Dr. Mansur-ud-Din Ahmad | Faculty of Veterinary Sciences.
Material type: materialTypeLabelBookPublisher: 2007Subject(s): Department of MicrobiologyDDC classification: 0977,T Dissertation note: In this study a toxigenic strain of A. parasiticus was used for the production of the aflatoxin Eli. This strain of the fungus was taken from naturally growing fungal samples such as bread, rice, vegetables, fruits, maize etc. from various locations in and around the university. The unpurified sample was culture-purified on Sabouraud Agar through repeated culture technique. This strain was maintained on Sabouraud agar slants at 4 °C. The purified sample of this fungus was harvested with 0.01 % Tween 80 then inoculated to the autoclaved broken rice. The rice was incubated at 28 °C in a dark room for a period of' 7 days and shaken two times a day. After 7 days of incubation the rice as autociaved at 121 °C in order to inactivate the fungus. The rice was dried and crushed to powder in a blender. The toxins were extracted through chloroform methpd and evaporated to dryness in water bath at 6 °C. The toxins were again dissolved in I ml ehiorokrm and stored at 4 °C for further use in the study. The toxins were then purified on silica gel plate in order to get the AFBI only through comparison with the AHII standard. 'l'he aflatoxin BI band was scratched from the silica gel plate and subjected to centrifugation in order to remove the silica gel. The purified Bi toxin was then dissolved in chloroform for further use. The AFB1 was then identified and qilani i lied through the fol lowing three methods namely, 1)High perlirmance Liquid chromatography 2) Thin layer chromatography 3) Spectrophotornetry The sensitivity of the above three methods was determined and compared which was 1 .3 ng/ml for HPLC. 6.3 ng/ml forTLC and 40 ng/mI for Spectrophotometry. The purified AFBI was then estimated by HPLC the amount of which was 238 ± 9.8 jig / ml. however the toxins estimated through TLC were 127.8 ± 24 jig/mi and spectrophotometry were 26 ± 4jig/ml ml. The HPLC method was proved to be the most sensitive method for detection and estimation of the aflatoxin as compared to the other two methods. The HPLC, estimated toxins were then checked for their biodegradation for this purpose the AFBI were kept at three different temperatures and dissolved in three different solvents. As the toxins had previously been dissolved in the chloroform so 400 jil of the chloroform was evaporated to dryness in order to dissolve them in their respective solvents. The toxins were dissolved in 400 j.tl of chloroform, acetone and methanol and kept at 25, 4 and -20 °C. These toxins were then stored for a period of four weeks and the tested for their biodegradation after four weeks by HPLC. The temperature at which the toxins showed less degradation was determined. That temperature at which the toxins showed less degradation was - 20 °C and the amount of the toxin at this temperature after four weeks of storage was 197 jig/ml. The solvent in which the toxins exhibited less degradation was acetone at all the three temperature conditions (25, 4 and -20 o() I lowever chloroform at 25 °C was exhibiting less degradation as compared to the other two solvents. Methanol was proved to be the least good solvent because the toxin was showing degradation in this solvent. The acetone at -20 CC was the most appropriate solvent for toxins storage. In second experiment the fresh toxin was dissolved in acetone and tested fbr their degradation on weekly basis by HPLC. The toxin level at the beginning of the experiment was 447 ± 9 ug/mI which when detected after a weak was 398.67 ± 9.8 jig/mI. The same toxin when tested after 2 weak period storage exhibited a level of 295.9 ± 20 ug/mi followed by 265.7 ± 3Ojig/ml. after the end of the third weak indicating that there was an appreciable level of toxin degradation. The toxin tested on the fourth week of storage were 267± 31 ig/ml which exhibited no degradation as compared to the degradation of the third week.
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Veterinary Science 0977,T (Browse shelf) Available 0977,T
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In this study a toxigenic strain of A. parasiticus was used for the production of the aflatoxin Eli. This strain of the fungus was taken from naturally growing fungal samples such as bread, rice, vegetables, fruits, maize etc. from various locations in and around the university. The unpurified sample was culture-purified on Sabouraud Agar through repeated culture technique. This strain was maintained on Sabouraud agar slants at 4 °C. The purified sample of this fungus was harvested with 0.01 % Tween 80 then inoculated to the autoclaved broken rice. The rice was incubated at 28 °C in a dark room for a period of' 7 days and shaken two times a day. After 7 days of incubation the rice as autociaved at 121 °C in order to inactivate the fungus. The rice was dried and crushed to powder in a blender. The toxins were extracted through chloroform methpd and evaporated to dryness in water bath at 6 °C. The toxins were again dissolved in I ml ehiorokrm and stored at 4 °C for further use in the study. The toxins were then purified on silica gel plate in order to get the AFBI only through comparison with the AHII standard. 'l'he aflatoxin BI band was scratched from the silica gel plate and subjected to centrifugation in order to remove the silica gel. The purified Bi toxin was then dissolved in chloroform for further use. The AFB1 was then identified and qilani i lied through the fol lowing three methods namely,

1)High perlirmance Liquid chromatography

2) Thin layer chromatography

3) Spectrophotornetry

The sensitivity of the above three methods was determined and compared which was 1 .3 ng/ml for HPLC. 6.3 ng/ml forTLC and 40 ng/mI for Spectrophotometry. The purified AFBI was then estimated by HPLC the amount of which was 238 ± 9.8 jig / ml. however the toxins estimated through TLC were 127.8 ± 24 jig/mi and spectrophotometry were 26 ± 4jig/ml ml. The HPLC method was proved to be the most sensitive method for detection and estimation of the aflatoxin as compared to the other two methods. The HPLC, estimated toxins were then checked for their biodegradation for this purpose the AFBI were kept at three different temperatures and dissolved in three different solvents. As the toxins had previously been dissolved in the chloroform so 400 jil of the chloroform was evaporated to dryness in order to dissolve them in their respective solvents. The toxins were dissolved in 400 j.tl of chloroform, acetone and methanol and kept at 25, 4 and -20 °C. These toxins were then stored for a period of four weeks and the tested for their biodegradation after four weeks by HPLC.

The temperature at which the toxins showed less degradation was determined. That temperature at which the toxins showed less degradation was - 20 °C and the amount of the toxin at this temperature after four weeks of storage was 197 jig/ml. The solvent in which the toxins exhibited less degradation was acetone at all the three temperature conditions (25, 4 and -20 o() I lowever chloroform at 25 °C was exhibiting less degradation as compared to the other two solvents. Methanol was proved to be the least good solvent because the toxin was showing degradation in this solvent. The acetone at -20 CC was the most appropriate solvent for toxins storage.

In second experiment the fresh toxin was dissolved in acetone and tested fbr their degradation on weekly basis by HPLC. The toxin level at the beginning of the experiment was 447 ± 9 ug/mI which when detected after a weak was 398.67 ± 9.8 jig/mI. The same toxin when tested after 2 weak period storage exhibited a level of 295.9 ± 20 ug/mi followed by 265.7 ± 3Ojig/ml. after the end of the third weak indicating that there was an appreciable level of toxin degradation. The toxin tested on the fourth week of storage were 267± 31 ig/ml which exhibited no degradation as compared to the degradation of the third week.

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