Shewanella spp. from wastewater treatment plant-affected environment: isolation and characterization

Bacteria from the genus Shewanella are inhabitants of marine and freshwater ecosystems, recognized fish spoilage bacteria, but less known as fish disease agents. Shewanella spp. isolated from fish living in waters close to effluents of a wastewater treatment plant (WWTP) were not previously characterized. We have tested Shewanella isolates from WWTP-affected waters and related fish. Genotypic characterization identified most strains as S. baltica and S. oneidensis. In order to investigate the sensibility and accuracy of their MALDI-TOF MS identification, they were grown on two culture media enriched by various NaCl concentrations, incubated at different temperatures and duration. We analyzed their antimicrobial susceptibility on a panel of antimicrobial drugs and capacity for biofilm production. With a view to demonstrate their capacity to produce fatty acids, we assessed the impact of different culture media on their lipid profile. We performed zebrafish embryotoxicity tests to simulate the environmental infection of the earliest life stages in S. baltica-contaminated waters. The best MALDI-TOF MS identification scores were for strains cultivated on TSA for 24 h at 22 °C and with supplementation of 1.5% NaCl. Less than 17% of isolates demonstrated antimicrobial resistance. Most isolates were weak biofilm producers. Strain-to-strain variation of MIC and MBC was low. The major fatty acids were C15:0, C16:0, C16:1, C17:1, and iC15:0. Exposure of Danio rerio to different S. baltica concentrations induced severe effects on zebrafish development: decreased heartbeat rate, locomotor activity, and melanin pigmentation. S. baltica passed through chorionic pores of zebrafish.

     

An Analysis of Visual Range in the Eastern United States Under Different Meteorological Regimes

ABSTRACT

The issue of fine particle (PM₂₅) exposures and their potential health effects is a focus of scientific research because of the recently promulgated National Ambient Air Quality Standard for PM_{2 5}. Before final implementation, the health and exposure basis for the standard will be reviewed by the U.S. Environmental Protection Agency within the next five years. As part of this process, it is necessary to understand total particle exposure issues and to determine the relative importance of the origin of PM_{2 5} exposure in various micro-environments. The results presented in this study examine emissions of fine particles from a previously uncharacterized indoor source: the residential vacuum cleaner. Eleven standard vacuum cleaners were tested for the emission rate of fine particles by their individual motors and for their efficiency in collecting laboratory-generated fine particles. An aerosol generator was used to introduce fine potassium chloride (KC1) particles into the vacuum cleaner inlet for the collection efficiency tests. Measurements of the motor emissions, which include carbon, and the KCl aerosol were made using a continuous HIAC/Royco 5130A light-scattering particle detector. All tests were conducted in a metal chamber specifically designed to completely contain the vacuum cleaner and operate it in a stationary position. For the tested vacuum cleaners, fine particle motor emissions ranged from 9.6 x 10⁴ to 3.34 x 10⁸ particles/min, which were estimated to be 0.028 to 176 mg/min for mass emissions, respectively. The vast majority of particles released were in the range of 0.3-0.5 mm in diameter. The lowest particle emission rate was obtained for a vacuum cleaner that had a high efficiency (HEPA) filter placed after the vacuum cleaner bag and the motor within a sealed exhaust system. This vacuum cleaner removed the KC1particles that escaped the vacuum cleaner bag and the particles emitted by the motor. Results obtained for the KC1 collection efficiency tests show >99% of the fine particles were captured by the two vacuum cleaners that used a HEPA filter. A series of tests conducted on two vacuum cleaners found that the motors also emitted ultra-fine particles above 0.01 mm in diameter at rates of greater than 10⁸ ultra-fine particles/CF of air. The model that had the best collection efficiency for fine particles also reduced the ultra-fine particle emissions by a factor of 1 x 10³.     

An assessment of organizational resilience potential in SMEs of the process industry,a fuzzy approach

In order to establish adequate tools for the modern business environment, and with a need for new mechanisms with the goal of overcoming crisis and emerging disorder, the concept of organizational resilience has emerged. A high level of organizational resilience represents one of an organization's target values during a normal period of operation. In a period of crisis, the presence of resilience is even more needed; this is emphasized in the process industry because in these conditions when one process fails it may cause significant problems in other processes. The contribution of this paper is shown through a fuzzy mathematical model for assessment of organizational resilience potential in SMEs of the process industry. The model is verified through an illustrative example where obtained data suggest measures which should enhance business strategy and improve organizational resilience factors. This study forms the basis for a survey that may include a significant number of organizations from one region and future improvement based on benchmark and knowledge sharing.