Characteristics and dynamics of Salmonella diversity and prevalence of biomarker genes in Port Blair Bays, South Andaman, India
MARINE POLLUTION BULLETIN
Authors: Meena, Balakrishnan; Anburajan, Lawrance; Selvaganapathi, Karuppaiya; Vinithkumar, Nambali Valsalan; Dharani, Gopal
Abstract
Salmonella is a major cause of morbidity and mortality in humans worldwide, and the infection with multidrugresistant strains can cause severe diseases. Many coastal cities around the world discharge their wastewaters into the marine environment. These wastewaters contain a variety of pathogenic microorganisms that may have a role in the contamination of this ecosystem and have potential risks for public health. Using an environmental approach, the present study investigated the presence of Salmonella in sediment and water samples collected from Port Blair Bays. In this environmental approach, the provided information about the diversity of the Salmonella serovars, antibiotic resistance and the prevalence of virulence factors in Salmonella, especially from the coastal waters of Port Blair Bays. The occurrence of Salmonellae was significantly higher in water column samples (2.9%) than in those taken from the marine sediments (0.7%). Of the 133 positive Salmonella strains, 22 different serovars were identified. Salmonella enterica serovar Senftenberg was the predominant serovar, being represented by 54 isolates (42.5%), followed by serovar Typhimurium (19 isolates [15%]) and serovar Agona (12 isolates [9.4%]). The presence of virulence genes (filC, sitC, hilA, invA, sipC, hilD, hilC, invF, invE, invH, sipF, aadA, pare, gyrA, spaP and parC) and susceptibility studies with 10 selected antibiotics were also performed. The results of this study revealed that all Salmonella isolates were positive for targeted virulence genes and were resistant to at least one antibiotic. Antibiotic susceptibility studies revealed the presence of multidrug resistant Salmonella strains in coastal water, which usually from land base sources end up in the marine environment and may pose a significant risk on public health.
Assessment of gaseous ozone treatment on Salmonella Typhimurium and Escherichia coli O157:H7 reductions in poultry litter
WASTE MANAGEMENT
Authors: Chang, Ruixue; Pandey, Pramod; Li, Yanming; Venkitasamy, Chandrasekar; Chen, Zhao; Gallardo, Rodrigo; Weimer, Bart; Jay-Russell, Michele; Weimer, Bart
Abstract
Poultry litter is used as soil amendment or organic fertilizer. While poultry litter is enriched with organic matter suitable for land, the presence of pathogens such as Salmonella in poultry litter is a concern. To investigate the effect of gaseous ozone on pathogen reductions in poultry litter, this study conducted a series of experiments that involved understanding of Salmonella Typhimurium and Escherichia coli O157:H7 inactivation at various doses of Ozone (O-3) in wet and dry poultry litter conditions. Previously, ozone treatment has been shown to disinfect the surface of foods and plant materials including fruits, juices, and wastewater, however, additional research are needed to better understand the impacts of ozone on treatment of soil amendments. Sanitizing methods capable of eliminating pathogens of soil amendments are crucial to mitigate disease outbreaks related with litter/manure-based fertilizers. In this study, a bench scale continuous ozone treatment system was designed to produce O-3 gas, with a range O-3 concentrations (7.15-132.46 mg.L-1), monitor ozone concentrations continuously, and control the ozone exposure time (15 to 90 mins) to understand the effectiveness of O-3 in eliminating S. Typhimurium and E. coli O157:H7 in poultry litter. Results showed that 7.15 mg.L-1 did not reduce the counts of S. Typhimurium until exposure to O-3 for 90 min. The O-3 concentrations of 43.26. 132.46 mg.L-1 exposure reduced the bacterial counts. Furthermore, the moisture content of poultry litter was found to be an influencing factor for pathogen reduction. The pathogen reduction rates were reduced when the moisture content was increased. At higher moisture content, high concentrations of O-3 (132.46 mg.L-1) were needed for pathogen reductions. The moisture content of 30% or lower was found to be more effective for controlling pathogen levels in poultry litter. Our study demonstrates that gaseous O-3 treatment could be used as an additional decontamination technique to ensure the certain degree of microbiological safety of poultry litter based soil amendment. (C) 2020 Published by Elsevier Ltd.