Jyoti Tripathi

Diversity of bacterial communities in the midgut of Bactrocera cucurbitae (Diptera: Tephritidae) populations and their potential use as attractants

BACKGROUND The microbiota plays an important role in insect development and fitness. Understanding the gut microbiota composition is essential for the development of pest management strategies. Midgut bacteria were isolated from nine wild B. cucurbitae populations collected from different agroecological zones of India. These isolates were further studied for attractant potential of fruit fly adults, and the chemical constituents in the supernatants of gut bacteria were analysed. RESULTS Twenty-six bacterial isolates belonging to the families Enterobacteriaceae, Bacillaceae, Micrococcaceae and Staphylococcaceae were isolated and identified on the basis of 16S rRNA gene sequence analysis. The dominant species in the midgut of melon fly were from the genera Enterobacter (34.6%), Klebsiella (19.2%), Citrobacter (7.7%), Bacillus (15.4%) and Providencia (7.7%), and 3.8% each of Micrococcus, Staphylococcus, Leclercia and Exiguobacterium. Bactrocera cucurbitae and B. dorsalis adults were significantly attracted to bacterial whole cell cultures and their supernatants in the fruit fly attraction bioassays. Bacillus cereus, Enterobacter, Klebsiella, Citrobacter and Providencia species attracted both male and females of Bactrocera species. The supernatants of Klebsiella, Citrobacter and Providencia species attracted a significantly greater number of females than males. The most abundant chemical constituents in supernatants of K. oxytoca and C. freundii were 3-methyl-1-butanol, 2-phenylethanol, butyl isocyanatoacetate, 2-methyl-1-propanol and 3-hydroxy-2-butanone, as identified by gas chromatography-mass spectrometry. CONCLUSIONS The bacterial endosymbionts associated with melon fly exhibited attractant potential which could facilitate eco-friendly insect control strategies.

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 tcR (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.

Radiation Processing for Sprout Inhibition of Stored Potatoes and Mitigation of Acrylamide in Fries and Chips

Acrylamide is well documented to be formed in potato chips and fries due to the presence of its precursors, glucose and asparagine. Storage of potatoes for long period under humid conditions induces sprouting which generates reducing sugars, which when used for processing to fries and chips show a very high content of acrylamide. Control of sprouting by irradiation would limit the reducing sugars, and thereby the acrylamide content. This chapter gives an overview of mechanism of formation of acrylamide, parameters influencing the formation of acrylamide, analytical techniques for estimation of acrylamide, strategies for reduction of acrylamide, effect of postharvest storage on acrylamide content in potato, and finally, radiation processing for mitigation of acrylamide content in potato chips.