• Journal of Mushroom
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• v.19 no.3
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• pp.210-215
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• 2021

For sterilization of microorganisms of the Listeria genus contaminating enoki mushroom, pilot mushroom grower equipped with air sterilization devices were developed. Sterilization experiments were performed using physical and chemical treatments. Internal temperature and humidity were controlled, maintaining 6.62℃±0.30 in the upper shelves, 6.46℃±0.24 in the middle shelves, and 6.48℃±0.25 in the lower shelves. Humidities were 79.97%±4.42, 79.43%±4.06, and 79.94±4.30%, respectively, with a temperature setting of 6.5℃, and a relative humidity of 75%. A suitable enoki mushroom cultivation stage for air sterilizer application was during the growth stage, with temperature in the 6.5~8.5℃ range, and humidity of 70~80%. At these same internal conditions, the ozone concentration in the mushroom cultivator was found to be 160 ppb during ion-cluster generator operation. After physical sterilization, the Listeria innocua survival rate was 0.1 to 0.9% using ion cluster sterilization, and 9.3 to 10.6% using UV air sterilization. The Listeria innocua survival rates on different materials were 9.3~10.6% on the metal specimen, and 9.9~16.2% on the plastic wrapper. The survival rate was particularly high on the rough side of the plastic wrapper. Ion cluster air sterilization is a labor-saving and effective method for suppressing the occurrence of Listeria bacteria on mushroom growers walls and shelves. For the plastic wrapper, chemical sterilization is more effective than physical sterilization.

• Journal of fish pathology
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• v.18 no.1
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• pp.91-97
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• 2005

Bio-secure culture of olive flounder Paralichthys olivaceus in the IBK (Intensive Bioproduction Korean) recirculating system with dry pellet was tested for 6 months. The IBK system consists of 12 rearing tanks, 6 sedimentation tanks. 4-sectioned submerged biofilter chamber and channels. The size of each rearing tank was 3m in diameter and 1m in depth. The size of each biofilter chamber was $3.1\times3.3\times2.0$ m (D) and was filled with corrugated plastic plates as a biofilter medium. Total surface area of the biofilter was 3,789.7 $m^2$ Water was circulated by one of two vertical axial pump and circulating rate was about 34 times per day. A UV light sterilizer was used to treat inlet sea water with the flow rate of 4 ton/hr. All fish were treated with 150 ppm formalin 3 times with 5 day interval before stocking. It took 60 days for 'conditioning' the biofilter with the stocking density of 4.5 kg of fish $m^2$. The concentrations of ammonium-nitrogen, nitrite-nitrogen and nitrate-nitrogen in the system remained at the range of 0.096-0.315 mg/L, 0.015-0.504 mg/L, and 2.530-39.517 mg/L, respectively. Water temperature fluctuated from 17.5 to 25.1$^{\circ}C$ and salinity was from 30.1 to 33.5 ppt during rearing period. The fish grew from the average weight of 615.2 g to 1,201.1 g for 180 days. Initial and final fish densities were 8.4 and 15.9$kg/m^2$, Survival rate was 97.1 %. Neither parasites nor noticeable diseases was observed during the raring period even Vibrio spp. were detected from some fish in the system.