Foci Of Bacteria Research Articles

Fast and sensitive detection of bacteria from a water droplet by means of electric field effects and micro-Raman spectroscopy

A surface-based method that can provide early and label-free detection of target microorganisms in water is presented. The method combines three key features, namely, (a) accelerated transportation to, and focusing of bacteria on, the detection surface by means of alternating current (AC) electrokinetic effects, (b) selective capture of the target microorganism using surface-immobilized antibodies, and (c) sensitive detection of target bacteria with micro-Raman spectroscopy. The non-uniform electric field is created by an AC signal-driven planar, quadrupolar, gold microelectrode array that is deposited on the detection surface (oxidized silicon wafer). AC electroosmosis and dielectrophoresis combine to produce the desired concentration amplification of bacteria on the capture surface within a few minutes. Bacterial detection is, subsequently, accomplished through Raman spectra acquired at pre-determined locations near the electrodes after sample removal and rinsing of the capture surface. Using this technique, detection of Escherichia coli K12 (target microorganism) at concentrations as low as 102 bacteria per mL was reproducibly achieved from 50μL sample droplets. This method also permits the selective retention of a target microorganism from polymicrobial mixtures, as demonstrated here with the capture of E. coli K12 from their mixtures with Micrococcus luteus.

Investigation of Pathological Findings Infected with Aeromonas salmonicida in Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792)

Experimental furunculosis caused by Aeromonas salmonicida was induced in rainbow trout (Oncorhynchus mykiss Walbaum, 1792) using intraperitoneal injection and immersion challenge methods. A total of 65 (50 experimental and 15 control) rainbow trouts (weight 155±15 g and 20-25 cm in size) were used for this experimental work. Aeromonas salmonicida at a concentration of 3x10 cfu/ml (0.1 ml per fish) was intraperitoneally injected to twenty-five fish (first group). A second group of 25 fish was immersed in 30 l water inoculated to which 3 ml of bacterial inoculum (3x10 cfu/ml) had been added for one hour. Sterile saline solution (0.1 ml/fish) was intraperitoneally injected to control group. Necropsy of the fish was performed, macroscopic and microscopic findings were evaluated. The chronic form of disease was observed in both groups. Anorexia, irregular swimming, hemorrhages at the dorsal, ventral and pectoral base of fins were the main clinic and macroscopic findings. However, in some fish, diffused or focal scale eruption on the dermis from operculum to caudal fin, periocular hemorrhages and exophtalmos were observed. Similar microscopic findings were determined in the both experiment groups. Microscopically, foci of bacteria with no inflammatory response especially in the muscles, gills, heart, stomach, pyloric caeca, intestines, kidney, spleen and liquefactive necrosis in the muscles were the main microscopic findings.