Pakistan Research Repository Home

Title of Thesis

Zakia Bil Grami
Institute/University/Department Details
Department of Botany/ University of Karachi
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
aflatoxins, mycoflora, almond seeds, mycotoxins, alflatoxins, a. flavus, fusarium spp., sorbic acid, propionic acid

Using ISTA techniques, a total number of 14 genera and 39 species of fungi viz., Alternaria alternata*, A. tenuissima*, Alternaria spp. *, Aspergillus candidus*, A. carneus*, A. clavatus*, A. fischeri* A. flavus, A. flavipes*, A. fumigacus*, A. glaucus*, A. jaul4S*, A. niger, A. ochraceus*, A. restrictus*, A. sydowi*, A. sulphureus*, A. terreus*, A. versicolor*, A. wentii*, Chaetomium spp. *, Cladiosporium fulvum*, Drechslera australiensis*, D. hawaiensis*, D. State of Cochliobolus spicifer*, Fusarium equiseti*, F. moniliforme*, F. solani*, Fusarium spp. *, Nigrospora sp. *, Paecilomyces liladnus*, Pe1icillium camemberti*, P. frequentans*, Penicillium spp. *, Rhizopus sp., Rhizoctonia solani*, Trichoderma harziallum*, Trichothecium roseum and Uloclodium sp. *, were isolated from 40 almond seed samples collected from different. localities of Pakistan. Of these only A. niger, A. flavus, Rhizopus sp., and Trichothecium roseum have previously been reported and the remaining 35 species of fungi marked with an asterisk are new records. Agar plate method yielded greater number of fungi (34 species) as compared to blotter (29 specie3) and deep freezing method (28). Component plating showed that seed coat was infected by greater number of fungi follower! by cotyledons, shell and axis. Almond seeds collected from Sindh showed precominace of mold fungi as compared to samples collected from Balochistan. At least 39 (97.5 %) seed samples were found infected with Aspergillus flavus showing a mean infection percentage of upto 49.7%.

Similarly 15 almond seed samples collected from different countries like Dubai, Abudhabi, Saudi Arabia (Mecca and Madina), Kuwait, Iran, Germany, England, Australia, USA and Egypt showed the occurrence of 7 genera and 21 species of fungi. Seeds collected from Iran were found more moldy (14 species) as compared to samples collected from U.K. (5 species of fungi) with very low intensity of infection.

A number of fungi isolated from almond seeds are known to produce mycotoxin harmful for human health. Aspergillus flavus which produces aflatoxin B1 and B2, G1 and G2 was detected in 49.7% almond seeds. Using AOAC method, out of 25 seed samples analysed, 5 were infected with aflatoxin B1 ranging from 5.8-140 µg/kg which included 2 samples showing the presence of aflatoxin B2 (7.0 and 140 µg /kg) as well. Using plug method and comparing with B1 standard, out of 29 different isolates of A. flavus only 9 were found to be toxigenic showing the presence of aflatoxin B\. The ratio of toxigenic and non-toxigenic strains was approximately 1 :2. Similarly using TLC technique, out of 25 seed samples, 5 were infected with zeralenol and only one sample with zeralenone toxin secreted by Fusarium sp.

In experiments on the control of mycoflora associated with almond seed where the effect of sorbic acid, propionic acid, NaCl, sunlight, colour rays and heat treatments from autoclave, even and microwave oven was examined, autoclaving was found to be most effective in killing all the fungi present on almond seed. Prorionic acid used @1000 ppm reduced infection of mold fungi by upto 90% and green colour rays reduced A. flavus infection by upto 80%. Propionic acid used @ 2000 ppm completely eliminated aflatoxin B1 in almond seed samples artificially inoculated with aflatoxin B1 whereas sorbic add was not effective. S Similarly propionic acid used @ 2000 ppm reduced aflatoxin collceatration by 50% in almond seeds artificially inoculated by a toxigenic strain of A. flavus while no aflatoxin could be detected in seeds where higher doses of propionic acid @ 4000,8000, and 16000 ppm were used. NaCl used @ 2% w/w reduced the at1atoxin by 20% while autoclaving showed complete control of A. flavus infection and upto 93 % reduction in aflatoxin concentration.

Download Full Thesis
1273.86 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Content
98.47 KB
2 1 Introduction 1
40.91 KB
3 2 Materials And Methods 5
62.95 KB
  2.1 Collection Of Samples 5
  2.2 Ista Techniques For Isolation Of Fungi 5
  2.3 Component Plating Method 6
  2.4 Dilution Of Technique For Cfu 7
  2.5 Moisture Content Of Dry Seed By Oven Dry Method 7
  2.6 Detection Of Aflatoxins ( Aoac Method ) 7
  2.7 Detection Of Mycotoxin And Other Secondary Metabolites Of Fusarium Spp ., By Tlc Method 9
  2.8 Detection Of Aflatoxin From Strains Of Aspergillus Flavus By Plug Method 9
  2.9 Statistical Analysis Of The Data 10
4 3 Results 11
258.53 KB
  3.1 Mycoflora In Almond Seeds Collected From Different Localities Of Pakistan 11
  3.2 Mycoflora In Almond Sees Collected From Different Countries 20
  3.3 Infection Of Almond Seed Collected From Pakistan As Compared To Other Countries 30
  3.4 Location Of Fungi In Almond Seeds 32
  3.5 Effect Of Moisture Content On Spore Load 32
  3.6 Fungi Associated With Almond Seeds During Storage 38
5 4 Mycotoxins 45
90.38 KB
  4.1 Detection Of Alflatoxins In Almond Seeds 46
  4.2 Detection Of Mycotoxins And Other Secondary Metabolites Of Fusarium Spp ., By Tlc Method 49
  4.3 Detection Of Alfatoxin From Different Strains Of A. Flavus By Plug Method 49
6 5 Control Of Mycoflora Associated With Almond Seed 57
96.89 KB
  5.1 Use Of Sorbic Acid 57
  5.2 Use Of Propionic Acid 59
  5.3 Use Of Nac1 59
  5.4 Effect Of Light Rays 61
  5.5 Heat Treatment 65
7 6 Control Of Alflatoxins In Almond Seed 69
86.48 KB
  6.1 Effect Of Propionic And Acid Sorbic Acid On Seeds Induced With Alflatoxins B 1 70
  6.2 Effect Of Propionic Acid On Seeds Induced With Toxigenic Strain Of A. Flavus 70
  6.3 Control Of Mycoflora/Aflatoxin In Contaminated Seeds 75
8 7 Discussion 79
99.06 KB
9 8 References 88
103.09 KB
10 9 Annexure-Fungi Isolated From Almond Seed Samples 99
161.18 KB
11 10 Appendices-Anova Tables 123
205.73 KB
12 11 Acknowledgement 150
17.26 KB
13 12 Research Publications 151
187.84 KB