Lack of induced mutagenesis in E. coli or human lymphoblast cell line upon long-term sub-culturing in medium from irradiated meat

Abstract

Purpose: Current study was aimed to enhance the confidence of consumers as well as entrepreneurs towards food irradiation program.

Materials and methods: In this work, safety of high dose (25 kGy) irradiated meat samples (HDIMS) was ascertained by scoring mutation frequency through a long-term sub-culturing study in Escherichia coli MG1655 cells (ATCC 700926) up to 1500 generations (at 1%), 250 generations (at 5% and 10%) and human lymphoblast thymidine kinase heterozygote (TK6) cell line (ATCC CRL-8015) [at two gene loci, tk^−/+ (thymidine kinase) and hprt⁺ (Hypoxanthine Phosphoribosyltransferase)] up to 156 generations using goat meat sample. Also these samples were assayed at further radiation doses of 10, 45 and 70 kGy at 2% concentration (in cell line), and 1% (in E. coli). Study was also performed with other meat samples such as chicken, fishes (pomfret and rohu) and shrimps by carrying out limited long-term sub-culturing trials in human lymphoblast cell line. Mutation analysis was also carried out using a novel DPAR (Differential loss of Plasmid Antibiotic Resistance) assay followed by sequencing of tc^R (tetracycline resistance) gene of pBR322 plasmid isolated from E. coli cells grown for 1500 generations on HDIMS medium and RAPD (Random Amplified Polymorphic DNA) analysis of the genome.

Results and conclusion: None of the assays exhibited any induced mutation when analyzed at regular time intervals. RAPD analysis also did not indicate any change in its nucleotide sequence, ruling out the occurrence of any silent mutation. Thus, the present findings report absence of mutagenic effect of high dose irradiated meat samples.

Keywords:

• Meat irradiation
• rifampicin assay
• human lymphoblast mutation (HLM) assay
• thymidine kinase (tk) assay
• RAPD analysis

Disclosure statement

The authors report no conflicts of interest.

Notes on contributors

Dr. Sachin N. Hajare joined Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India in 1998 after completing his Masters in Zoology from Pune University, India. His early work involved control of mycotoxin producing fungi in foods and feeds, for which he was awarded a Ph.D. degree of University of Mumbai in 2014. He is currently working on preservation of foods and food products using gamma radiation technology. He has more than 23 publications in national and international journals and three book chapters. He was also part of two IAEA-CRP projects. Dr. Sachin was a member of a team which developed a novel dip technology for retaining pericarp colour and extending shelf life of litchi fruit for which an Indian patent has been filed.

Ms. Jyoti Tripathi received her Master degree from Banaras Hindu University in 2012. She is currently working in Food Technology Division, BARC, where her research interests include shelf life extension of fruits using gamma radiation and functional characterization of fruits and vegetables for their nutraceutical potential. She has 8 publications in national and international journals.

Dr. Satyendra Gautam joined Food Technology Division, Bhabha Atomic Research Centre, Mumbai, India in 1995. After that he completed his doctorate degree in science from University of Mumbai, and two years post-doctoral studies (2005?07) at University of Medicine and Dentistry, New Jersey, USA. Dr. Gautam has worked extensively on the preservation of foods, primarily fruits and vegetables; development of special purpose ready-to-eat foods for calamity victims, disaster response forces, immune-compromised patients and other targets using radiation technology. He has also worked on understanding the potential nutraceutical applications of fruits and vegetables, and also carried out fundamental studies to reveal the mechanism of cell death in stressed bacterial cells. His work resulted in successful deployment of litchi preservation technology for the benefit of farmers and entrepreneurs. Dr. Gautam has more than 100 publications in peer reviewed journals and books, alongside many abstracts in conferences. Dr. Gautam is also a fellow of Maharashtra Academic Sciences and scientific panel member in the Food Safety and Standards Authority of India (FSSAI).