Enumeration of Fungal Contaminants in Rice and characterization of Ochratoxigenic Fungi Aspergillus spp

Author: Nandinidevi S. and Paranidharan V.

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Abstract

Rice (Oryza sativa L.), India’s most prominent cereal crop and a staple food for Indian population. Rice is susceptible to a broad spectrum of fungi, the infection of which is associated with quality deterioration and toxin production. Totally ninety samples encompassing (nine paddy and eighty-one brown and polished rice) were collected from markets of various rice growing districts of Tamil Nadu to assess fungal contaminants and occurrence of ochratoxigenic fungi particularly Aspergillus spp. The study documented Aspergillus, Penicillium, and Fusarium were the dominant fungal genera with highest population of 8.24×103–6.03×106 CFU/g was recorded by Aspergillus sp in paddy samples. The isolates of Aspergillus niger and Aspergillus ochraceus was identified based on colony morphology on Czapek Yeast Extract (CYA) medium incubated for 15 days under dark and by microscopic observation. Further, isolates of A.ochraceus were confirmed molecularly by the amplification of polyketide synthase gene (pks) using species specific primer AoLc35F, AoLc35R. The PCR amplification resulted with an amplicon size of 520 bp which confirmed the isolates are Aspergillus ochraceus and found to be ochratoxin A producer

Keywords

Rice, Aspergillus niger, A. ochraceus, Czapek Yeast Extract (CYA) medium, ochratoxin A (OTA)

Conclusion

The present findings investigated the enumeration of fungal contaminants in paddy, brown rice and polished rice samples collected from different establishments viz., petty shop, retail and whole sale markets of various districts of Tamil Nadu. The study documented Aspergillus spp and Penicillium spp as the predominant genera among the collected samples. The ochratoxin A producing fungi such as Aspergillus niger and Aspergillus ochraceus were identified based on macroscopic and microscopic observation. The colour of the colony on CYA medium was typically brown to dark black in A. niger and yellow in A. ochraceus with pale to brownish in colour on reverse side. Further, A. ochraceus isolates were confirmed molecularly using species specific primer pair AoLc35F, AoLc35R and an amplicon size of 520 bp was obtained

References

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How to cite this article

Nandinidevi S. and Paranidharan V. (2024). Enumeration of Fungal Contaminants in Rice and characterization of Ochratoxigenic Fungi Aspergillus spp. Biological Forum – An International Journal, 16(11): 56-62