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Binding Property of Aflatoxin by Wild Yeast and their Identification

Jahnavi, S.P. (2009) Binding Property of Aflatoxin by Wild Yeast and their Identification. [Student Project Report]

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Abstract

This Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page.

Item Type: Student Project Report
Additional Information: Aflatoxin binding capacity of yeast was studied. Aspergillus flavus culture from laboratory culture collection was used to infect groundnuts to produce aflatoxin. The extracted toxin was used for aflatoxin binding test. Cultures drawn from the yeast culture collection of the laboratory were treated with aflatoxin. The binding property was confirmed by subjecting the pellet and supernatant samples to Thin Layer Chromatographic analysis. By observing the intensity of fluorescent spots under UV at 360nm, the yeast isolates were screened which were having potential for aflatoxin binding. Based on the efficiency of binding, five cultures were selected for further studies. Culture number 5, 16, 18, 29, 30, 37 and 40 were the cultures selected for further study. Of the cultures selected, culture number 47 did not posses considerable binding ability, hence was delimited from further evaluations. Cultures were treated with aflatoxin and incubated at different intervals of time and subjected to HPLC, compared with standards. Pellet and supernatant of all the treated samples at time intervals of 0, 2 and 4 hours were separately analyzed and recorded. The concentration of B1 at 0 hour of incubation was high in the pellet for samples 5, 16 and 29. However, in the supernatents of 16 and 18, the concentration of B1 was quite high. After 2 hours of incubation, there was change in the binding capacities of G2 was observed in all the cultures tested, which was absent in culture number 16 and 29 at 0 hour. By 4 hours, all the toxins were drawn to culture 5, 16, 18, 29,30 and 37. Where as in 29, G1 and G2 were absent. G1 was absent in both culture and supernatant at 2 hours of incubation, which needs further investigation. Further the results were analyzed using mass spectra, where simultaneous determination of aflatoxin B1, B2, G1 and G2 was carried out. The distribution of B1 and B2 were more in pellet, indicating the efficiency of adhesion by the yeast cells. The isolated cultures were subjected to Scanning Electron Microscopy to study the morphology and their approximate size was also determined. The yeast DNA was isolated from selected cultures which showed potential for aflatoxin binding.The DNA was isolated from the culture number 5, 16, 18, 29, 30 and 37. Further the 18s rRNA gene analysis was carried for the amplification of the isolates specific to the primers by performing polymerase chain reaction. 62 Restriction fragmentation was performed using the enzymes Alu 1 and Hae 111. Results indicate that the Yeast of culture code 16 and 30 had similar restriction pattern, hence concluded to be the same species. By sequence analysis, culture number 5 indicated 97% similarity with Pichia anomala, culture number 18 showed 97% similarity with Clavispora lusitaniae and culture number 37 indicated 96% similarity with Candida tropicalis. Phylogenetic trees for all the cultures were constructed.
Uncontrolled Keywords: Aspergillus flavus aflatoxin binding yeast
Subjects: 600 Technology > 08 Food technology > 29 Microbiological food > 04 Yeast
Divisions: Food Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 04 Jun 2009 06:48
Last Modified: 28 Dec 2011 10:08
URI: http://ir.cftri.com/id/eprint/8994

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