Development of a metagenomic DNA extraction procedure and PCR detection of human enteric bacteria in vegetable salad tissues

Outbreaks of illness due to human enteric pathogenic bacteria via fresh vegetables warrant intensive research on changing strategies of these bacteria in alterning their hosts for survival. The systemic infection of human pathogenic bacteria in plants and the plant growth stage at which they establish endophytic relationship is poorly understood. Since cucumber and carrot are major vegetables consumed in the form of unprocessed salads in India, our study aimed at determination of infection abilities of Salmonella enterica sub sp. enterica and Aeromonas hydrophila in carrot and cucumber, respectively based on a  metagenomic detection system. We report an optimized metagenomic DNA isolation procedure from vegetable tissues co-cultivated with bacteria under laboratory conditions. Colonization of bacteria in vegetable tissues was studied by amplification of bacterial 16S rRNA coding region from the metagenome. DNA obtained from carrot vegetable pieces inoculated with Salmonella resulted in expected amplification of 1.2 kb region of bacterial 16S rRNA source sequences. However, the approach failed to detect Aeromonas in cucumber tissues.  We conclude that carrot could be a symptomless alternate host for  Salmonella sp

of fresh water fish Cyprinus carpio exposed to Zinc oxide (ZnO) nanoparticles

Abstract – Nanotechnology is an advancing field of research which has revolutionized all industrial needs, such as medical, environmental and other industrial applications. Despite the rapid progress and early acceptance of nanotechnology, the potential for adverse health effects due to prolonged exposure at various concentration levels in humans and the environment has not yet been studied. With the widespread application of nanomaterials, numerous nanoscale products might consequently be released into aquatic environments and elicit an impact not only on one particular ecosystem but also on human health. The environmental impact of nanomaterials is expected to increase dramatically in near future. Zinc oxide (ZnO) nanoparticles have wide ranging applications in a diverse array of industrial and consumer products, ceramic manufacturing, paint formulation, sunscreen and hair care products. Toxicological studies indicate that ZnO nanoparticles have adverse impacts on human health and environmental species. Hence it is due process to characterize the health and safety aspects of ZnO nanoparticles to humans and environment. The present study has been conducted to develop first hand information on the acute toxicity (LC50) and gill histopathology of ZnO nanoparticles in fresh water fish, Cyprinus carpio. It was found that the 50 % lethal concentration (LC50) of ZnO nanoparticle for C. carpio is 4.897 mg/L. Gill histopathological damage exposed to sublethal concentration of ZnO nanoparticles for 21 d are also discussed in this paper