• Proceedings of the Korean Biophysical Society Conference
• /
• 2002.06b
• /
• pp.41-41
• /
• 2002

Tolaasin, a pore-forming 1.9 kDa peptide toxin released by Pseudomonas tolaasii, produces brown blotch disease on cultivated oyster mushrooms. To investigate the mechanism of tolaasin-induced cell disruption, we studied the effect of temperature on the hemolytic process. In the kinetic analyses, single exponential function was fitted to the data obtained from temperature-dependent velocity of hemolysis(1/t$\_$50/, implying that there is a major time-limiting factor on the temperature-dependent hemolysis.(omitted)

• Proceedings of the Korean Biophysical Society Conference
• /
• 1999.06a
• /
• pp.47-47
• /
• 1999

Tolaasin is a bacterial paptide toxin which is produced by Pseudomonas tolaasii. It forms pores in the cellular membranes, causing the brown blotch disease on the cultivated oyster mushroom. Previously, we showed that tolaasin-induced pore formation required the multimerization of tolaasin molecules. In order to measure the ionic effect on the tolaasin multimerization, the time course of tolaasin-induced hemolysis was measured in the presence of various cations and anions.(omitted)

• Proceedings of the Korean Biophysical Society Conference
• /
• 1997.07a
• /
• pp.23-23
• /
• 1997

Tolaasin, a 1.9 kDa peptide forming membrane pores, is produced by Pseudomonas tolaasii and causes a brown blotch disease on cultivated oyster mushroom. During the purification of peptide by a gel permeation chromatography, we have found that fractions of molecular weight ranges between ∼2 to 40 kDa have hemolytic activities and the fractions of higher M.W. showed faster hemolysis.(omitted)

• Journal of Mushroom
• /
• v.1 no.1
• /
• pp.28-33
• /
• 2003

Pseudomonas tolaasii causing brown blotch disease was detected by PCR from water samples collected from the oyster mushroom cultivation farms to find the contamination level of the pathogen in water. Sixteen water samples (28.1%) contain less than 1,000 cfu, 31 samples (54.4%) contain 1,001-10,000 cfu, 6 samples (10.5%) contain 10,001-100,000 cfu, and 4 samples (7%) contain of bacteria per milliliter. P. tolaasii-specific DNA band was amplified in 3 samples (5.3%) by nested-PCR and in 20 samples (35.1%) by immunocapture (IC)-nested PCR respectively. These results suggest that IC-nested-PCR was much more sensitive than nested-PCR in detection of P. tolaasii and a quite few waters using for oyster mushroom cultivation were contaminated with P. tolaasii.

• Journal of Applied Biological Chemistry
• /
• v.60 no.2
• /
• pp.179-184
• /
• 2017

Tolaasin, a 1.9 kDa peptide toxin, is produced by Pseudomonas tolaasii and causes the brown blotch disease of cultivated oyster mushroom. It forms pores on the membrane and thus destroys cellular membrane structure, seriously reducing the productivity of mushroom cultivation. The mechanism of tolaasin-induced cytotoxicity is not known in detail. However, it has been reported to form a pore structure in the cytoplasmic membrane through the molecular multimerization. Therefore, food additives which can interact with tolaasin molecules may inhibit the pore formation by hydrophobic interactions with tolaasin molecules. In this study, various food additive materials have been identified as inhibitors of the tolaasin activity and named tolaasin-inhibitory factors (TIF). Most of TIFs are emulsifying agents for food processing procedures. Among various TIFs, polyglycerol and sucrose esters of fatty acids blocked effectively the cytotoxicity of tolaasins at the concentrations $10^{-4}-10^{-5}M$. These TIFs also successfully suppressed the blotch disease development in the shelf cultivation of oyster mushroom.

• The Plant Pathology Journal
• /
• v.22 no.4
• /
• pp.375-380
• /
• 2006

In the survey from 1992 to 2000, twenty-eight parasitic diseases were observed in major apple producing areas in Korea. The predominant apple diseases were white rot(Botryosphaeria dothidea), Marssonina blotch(Marssonina mali), Valsa canker(Valsa ceratosperma), Alternaria leaf spot(Alternaria mali), and bitter rot(Collectotrichum gloeosporioides and C. acutatum). Apple scab that reappeared in 1990 after disappearance for 15 years was disappeared again since 1997. A viroid disease(caused by apple scar skin viroid) was newly found in this survey. The five diseases, fire blight(Erwinia amylovora), black rot(Botryosphaeria obtusa), scab(Cladosporium carpophilum), Monochaetia twig blight(Monochaetia sp.), and brown leaf spot(Hendersonia mali), which had once described in 1928 but no further reports on their occurrence, were not found in this survey. However, blossom blight(Monilinia mali), brown rot(Monilinia fructigena), and pink rot(Trichothecium roseum), which did not occur on apple after mid 1970s, were found in this survey.

• Journal of Applied Biological Chemistry
• /
• v.59 no.4
• /
• pp.351-356
• /
• 2016

Bacterial blotch caused by Pseudomonas tolaasii is one of the major diseases of oyster mushroom, Pleurotus ostreatus. Application of bacteriophages is a very useful tool to decrease the density of pathogens and it has been successful to making disease-free cultivation area, known as phage therapy. Effect of phages on pathogen sterilization is very limited to the specific host strains. Minor variations of the host strains may cause changes in phage sensitivity. The phage-resistant strains of P. tolaasii were isolated and their pathogenic characters were investigated to improve the effectiveness of phage therapy. In the phylogenetic analysis, both phage-resistant strains and the corresponding host strains were identical based on the sequence comparison of 16S rRNA genes. The pathogenic characters, such as hemolytic activity and brown blotch formation, were measured on the phage-resistant strains and no correlation between phage-resistance and pathogenic characters was observed. Nevertheless, pathogenic characters were sometimes changed in the phage-resistant strains depending on the host strains. In order to make the phage therapy successful, the bacteriophages having a wide host range should be isolated.

• The Korean Journal of Mycology
• /
• v.27 no.2 s.89
• /
• pp.164-169
• /
• 1999

This study was carried out in an attempt to select chemicals such as zeolite granules, chitosan, wood-vinegar, $Ca(OCl)_2$, NaOCl, against bacterial brown blotch caused by Pseudomonas tolaasii on Flammulina velutipes in laboratory and mushroom unit. Results obtained using these chemicals were summarized. Inhibitory effect on $Ca(OCl)_2$ and wood-vinegar with 0.5% concentration was shown to caual pathogen, P. tolaasii, by slight damage on the mycelial growth of F. velutipes. Those materials were recognized as promising one for control of bacterial brown bloth on F. velutipes. Disease incidence in control was the highest value as 43.8%; whereas chemical treatment was estimated as 14.6% with 0.5% of $Ca(OCl)_2$. Disease incidence was inhibited about 20% in chemical treatment with 0.5% of wood-vinegar, 1.0% of $Ca(OCl)_2$, and 26.1% with 1.0% of wood-vinegar. For the inhibition effects of chemical concentrations, it was effective at the low concentration which was 0.5% rather than that of 1.0%. Quality of mushrooms was significantly improved, and yields was also increased by 30% in the chemical treatment. In case of $Ca(OCl)_2$ treatment at 1.0% concentration, the yields was increased by 35.6% showed the highest value among tested chemicals. However, the overall effects including disease incidence, quality and yields suggests that $Ca(OCl)_2$ is relatively more effective than wood-vinegar, and the optimal concentration controlling the disease was $0.5{\sim}1.0%$ with $Ca(OCl)_2$ and 0.5% with wood-vinegar.

• The Korean Journal of Mycology
• /
• v.22 no.2
• /
• pp.190-195
• /
• 1994

Studies were conducted to determine the potential of sodium hypochlorite(SHC) on the control of bacterial yellow blotch in cultivated oyster mushroom, Pleurotus ostreatus. SHC at the concentration of 80 ppm was effective on the control of Pseudomonas agarici causing yellow blotch in oyster mushroom except number 916 isolate. In vitro the mycelial growth was slightly inhibited at the concentration higher than 100 ppm of sodium hypochlorite, but retardation of the mycelial growth was soon recovered. Spray of SHC solution at the concentration of 40-50 ppm per day significantly reduced the incidence of the yellow blotch without impairing the growth of oyster mushroom in field culture. However, the higher concentration of SHC(67 ppm) induced yellow brown or dark gray in color and deformed cap and elongated stripe in morphology of fruiting body. Results indicate that periodical spray of sodium hypochlorite seems to be the recommendable method for protection against bacterial yellow blotch disease in oyster mushroom without reducing food quality.

• Proceedings of the Korean Biophysical Society Conference
• /
• 2001.06a
• /
• pp.40-40
• /
• 2001

Tolaasin is a 1.9 kDa peptide produced by Pseudomonas tolaasii and causes a brown blotch disease on cultivated oyster mushrooms. These molecules form channels in the plasma membranes of various cells including red blood cells and destroy cellular structure, known as 'colloid osmotic lysis'. In order to understand the molecular mechanism of tolaasin-mediated channel formation, the effect of Zn$^{2+}$ was investigated on hemolysis and channel formation since Zn$^{2+}$ has been known to block the tolaasin activity.(omitted)ted)