• Korean Journal Plant Pathology
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• v.14 no.2
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• pp.177-183
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• 1998

A DNA fragment which is involved in tolassin production was cloned to obtain a molecular marker of Pseudomonas tolaasii, a casual agent of bacterial brown blotch disease of oyster mushroom (Pleurotus ostreatus). Tolaasin is a lipodepsipeptide toxin and known as a primary disease determinant of the P. tolaasii. It is responsible for formation of white line in agar when P. tolaasii were cultured against white line reacting organisms (WLROs). White line negative mutants (WL-) were generated by conjugation between rifampicin resistant strain of P. tolaasii and E. coli carrying suicidal plasmid pSUP2021 : : Tn5. The ability of tolaasin production of the WL- mutants was examined by hemolysis test, pathogenicity test, and high pressure liquid chromatography (HPLC) analysis of culture filtrate. All of the WL- mutants were lost the ability of tolaasin production (Tol-). Genomic library of the Tol- mutant was constructed in pLAFR3 and the cosmid clone containing Tn5 was selected. DNA fragment fro franking region of Tn5 was cloned from the plasmid and used as a probe in Southern blot. DNA-DNA hybridization with the probe to total DNA from group of bacteria ecologically similar to P. tolaasii including WLORs, fluorescent Pseudomonads isolated from oyster mushroom, P. agarici, P. gingeri, and some of other species of Psedomonas showed that some of the tested bacteria do not have any hybridized band and others have bands sowing RFLP. The cloned DNA fragment or its nucleotide sequence will be useful in detection and identification of the P. tolaasii.

• Journal of Mushroom
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• v.21 no.3
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• pp.179-184
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• 2023

The development of automated bottle cultivation systems has facilitated the large-scale production of Pleurotus ostreatus, a commonly cultivated oyster mushroom species in South Korea. However, as the consumption of this product is decreasing and production quantities are exceeding demand, farmers are seeking various other mushroom types and cultivars. In response to this, we have developed a new oyster mushroom cultivar named 'Sena'. This high-yielding cultivar has a white pileus and excellent quality. The white oyster mushroom cultivars 'Goni' and 'Miso' were selected as parental strains from the genetic resources of the National Institute of Horticultural and Herbal Science's Mushroom Division. By crossing their monokaryons, hybrids were developed and subjected to cultivation trials and characteristic evaluations to select the superior cultivar. The optimal temperature for 'Sena' mycelial growth is 25-30℃, with inhibition occurring at temperatures above 30℃, whereas the temperature for mushroom growth is 14-18℃. The mushrooms grow in clusters, with the white pileus having a shallow funnel shape. Optimal mycelial growth occurs in malt extract agar medium. When cultivated in 1,100 cc bottles, the 'Sena' cultivar had 35 available individuals, surpassing the number 16 available from the control cultivar 'Goni'. The yield per bottle also increased by approximately 157 g, a 24% increase over the control cultivar amount. When 300 g samples of harvested mushrooms were packed and stored at 4℃ in a cold storage facility for 28 days, the weight loss rate of 'Sena' was approximately 4.22%, lower than that of 'Goni'. Moreover, the changes in pileus and stipe whiteness (measuring 6.99 and 8.33, respectively) were also lower than those of the control cultivar. Since the appearance of a white cap is crucial for quality assessment, the 'Sena' cultivar is superior to the 'Goni' cultivar in terms of both weight and quality after undergoing low-temperature storage.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.232-240
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• 2001

One hundred twenty five bacterial isolates were obtained from the brown blotch-diseased oyster mushrooms collected from markets. Among them, 45 were determined as pathogenic bacteria and white line forming organisms(WLFO) were 6 strains and white line reaction organisms (WLRO) were 6 strains. All of the white line forming isolates were identified as Pseudomonas tolaasii which is a known pathogen of brown blotch disease of oyster mushroom by GC-MIS(Gas chromatography-microbial identification system). Six of the white line reacting organisms were identified as P. chlomraphis, P. fluorescens biotype A and type C. The rest of them were P gingeri, P. agarici, P. fluorescens biotype B, P. chloroyaphis, non-pathogenic P. tolaasii, P. putida biotype A and B etc. For spectrum of activity of tolaasin, culture filtrates from pathogenic isolates were examined by browning of mushroom tissue and pitting of mushroom caps. The weak pathogenic bacteria didn't induce browning or pitting of mushroom tissue. On the other hand, strong pathogenic isolates showed browning and pitting reaction on mushroom. An extracellular toxin produced by P. tolaasii, was investigated. The hemolysis activity test of 6 strains identified as P. tolaasii were 0.8∼0.9 at 600 nm and 3 strains of WLRO were 0.9∼1.0 and Pseudomonas app. were 1.0∼1.2. Observation of fresh mushroom tissue using confocal laser scanning microscopy was carried out for images of optical sectioning and vertical sectioning. Also images of brown blotch diseased oyster mushroom tissue after contamination P. tolaasii was obtained by CLSM.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.471-478
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• 2021

Effective microorganisms (EM), which are sources of fermentation byproducts in herbal medicine, were compared with oyster mushrooms(OM) to identify alternative larval feeds for white-spotted flower chafer (Protaetia brevitarsis seulensis). The nutritional composition of each fermented feed was analyzed. The content of crude protein, crude fat, and fiber was higher in the OM fermented feed, except for crude ash. No difference in nutritional content of larvae based on fermented feed was observed. A comparative weekly analysis of the live weights of larvae was based on the fermented feed used. The average weight was significantly higher in the feeds using EM and OM from third week of observation. The larval survival rate in the presence of fermented feed was 96.7% compared with 9.8% with non-fermented feed. The results suggest that fermented food source is essential for the growth of white-spotted flower chafer, and OM was a stable alternative to EM as a fermentation source for the survival of white-spotted flower chafer.

• Journal of Mushroom
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• v.20 no.4
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• pp.218-226
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• 2022

Flammulina velutipes, known as winter mushroom in the family of Physalacriaceae, is the main edible and export mushroom with the third highest production after oyster and king oyster mushroom in Korea. However, as normal consumers regard F. velutipes as a simple subsidiary material, there is a limitation to increasing mushroom demand. In order to overcome the consumption limit and increase the differentiation of new varieties, it is necessary to breed varieties with enhanced functionality in consideration of consumer preferences. Therefore, the study was performed to analyze nutrient components and several useful functional substances with 26 genetic resources of F. velutipes. Analyses of inorganic compound(Ca, K, Mg) and 15 amino acids revealed that Strain 4148 had the highest content among the 26 strains. Beta-glucan, which increases immune activity and polyphenol, which exert antioxidant effects were higher in non-white strains than in white strains with a small number of exceptions. Among the five fatty acids, linoleic acid(an omega-6 fatty acid) and α-linolenic acid(an omega-3 fatty acid), were detected in six mushroom strains. α-linolenic acid, which was not found in five major mushrooms including oyster mushrooms, was identified in F. velutipes. The results of HPLC analysis showed that 'Auram' (Strain 4232) and 'Baekseung'(Strain 4230) had the highest content of the stabilizing neurotransmitter GABA(15.38 ㎍/ml and 20.56 ㎍/ml, respectively) among non-white and white strains, respectively. Our findings provide useful information for breeding F. velutipes to obtain strains with enhanced functionality.

• Mycobiology
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• v.43 no.3
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• pp.184-194
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• 2015

A compressive description of tropical milky white mushroom (Calocybe indica P&C var. APK2) is provided in this review. This mushroom variety was first identified in the eastern Indian state of West Bengal and can be cultivated on a wide variety of substrates, at a high temperature range ($30{\sim}38^{\circ}C$). However, no commercial cultivation was made until 1998. Krishnamoorthy 1997 rediscovered the fungus from Tamil Nadu, India and standardized the commercial production techniques for the first time in the world. This edible mushroom has a long shelf life (5~7 days) compared to other commercially available counterparts. A comprehensive and critical review on physiological and nutritional requirements viz., pH, temperature, carbon to nitrogen ratio, best carbon source, best nitrogen source, growth period, growth promoters for mycelia biomass production; substrate preparation; spawn inoculation; different supplementation and casing requirements to increase the yield of mushrooms has been outlined. Innovative and inexpensive methods developed to commercially cultivate milky white mushrooms on different lignocellulosic biomass is also described in this review. The composition profiles of milky white mushroom, its mineral contents and non-enzymatic antioxidants are provided in comparison with button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus). Antioxidant assay results using methanol extract of milky white mushroom has been provided along with the information about the compounds that are responsible for flavor profile both in fresh and dry mushrooms. Milky white mushroom extracts are known to have anti-hyperglycemic effect and anti-lipid peroxidation effect. The advantage of growing at elevated temperature creates newer avenues to explore milky white mushroom cultivation economically around the world, especially, in humid tropical and sub-tropical zones. Because of its incomparable productivity and shelf life to any other cultivated mushrooms in the world, milky white mushroom could play an important role in satisfying the growing market demands for edible mushrooms in the near future.

• Journal of Mushroom
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• v.5 no.2
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• pp.71-75
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• 2007

'Sunjung', a new variety of golden oyster mushroom was bred in Mushroom Research Institute, Gyeonggido Agricultural Research & Extension Services in 2006. This oyster mushroom was selected one which mate with monokaryon collected from KME20064 and KME20066. The optimum temperature for the mycelial growth was about 26 ~$28^{\circ}C$ and that for the primordia and growth of fruitbody was about $18{\sim}23^{\circ}C$. Compared to the control which took 25 days of incubation period, Sunjung required 21~22days. It grew primordia after developed a lump of mycelium. In the characteristics of fruit body, pileus was infundibuliform of yellow-color and stripe was slender/long shape of white color. The yield was 112.9g/850cc bottle and 275.5g/2kg P.P bag.

• Journal of Mushroom
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• v.7 no.3
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• pp.130-134
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• 2009

To develop new white variety of Oyster mushroom, all white varieties which have been collected and kept in the lab were revived and screened their cultural characteristics. 84 intra-specific Oyster mushroom hybrids between the white-colored mutants Suhan and Wonhyeong were developed using hyphal anastomosis technique in 2007. The Po2007-63 ($2842-7{\times}0205-7$) was shown the best cultural characteristics, selected to be a new variety and named as 'Goni'. The new commercial strain, 'Goni' has white pilei and grows well under spring and autumn conditions in Korea. The fruiting bodies of 'Goni' are of an excellent quality in that not only the stipe is thick and long but also the pileus is small and hard. The optimum temperatures for mycelial growth and fruiting body development were $25-30^{\circ}C$ and $10-16^{\circ}C$, respectively. Time period required for the initiation of the first fruiting body is about 3 to 5 days depending on the temperatures. The shape of fruiting body is thin funnel shape. Fruiting body production per bottle was about $91{\pm}13$ g which is almost 97% quantity compared to that of other variety 'Miso'. Relatively low temperature incubation ($11^{\circ}C$) resulted in the development of better quality of 'Goni' mushrooms. When two different media including potato dextrose medium and mushroom complete medium were compared, the growth of mushroom were much faster in mushroom complete medium at $20-25^{\circ}C$, but not at $25^{\circ}C$. Similar results were observed with other variety 'Miso'. Analysis of the genetic characteristics of the new commercial strain 'Goni' showed a major DNA profile as that of the parental Suhan when primer URP 1 was used, but different to 'Miso' that was used as a control. When screens were performed with primer URP 2, DNA patterns were similar both to that of the parents and 'Miso'. This new variety of the white Oyster mushroom has a clean and fresh image that corresponds well to "health food". We therefore expect that this new strain will satisfy the consumers demand for variety and excellent mushrooms.

• Journal of Mushroom
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• v.14 no.4
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• pp.136-141
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• 2016

The production scale of mushrooms in Korea is approximately 600 billion won, which is 1.6% of Korea's gross agricultural output. In Korea, ca. 190,000 tons of mushrooms are harvested annually. Although the numbers of mushroom farms and cultivators are constantly decreasing, total mushroom yields are increasing owing to large-scale cultivation facilities and automation. The recent expansion of the well-being trend has caused an increase in mushroom consumption in Korea: the annual per capita mushroom was 3.9 kg ('13), whichis a little higher than that in Europe. Thus, mushroom export, mainly Flammulina velutipes and Pleurotus ostreatus, has increased since the mid-2000s. Recently, however, it is slightly reduced. Nevertheless, Vietnam, Hong Kong, the United States, and the Netherlands continue to export mushrooms, and Korea has increased its export to Australia, Canada, Southeast Asia, etc. Canned Agaricus bisporus, the first export of the Korean mushroom industry, reached it speak sales in 1977-1978. When Korea initiated trade with China in 1980, the international prices of mushrooms fell sharply, leading to shrinkage of the domestic markets. Spurred by the high demand to develop substitute goods for A. bisporus, the oyster mushroom (P. ostreatus) gained attention since it seemed to suit the taste of Korean consumers. Although the log cultivation technique for oyster mushroom was developed in the early 1970s, it required a great deal of labor. Thus, we developed the shelf cultivation technique, which is easier to manage and allows for mass production. In this technique, the growing shelf is made mafrom fermented rice straw, whichis the only P. ostreatus medium in the world and isused only in South Korea. After then, the use of cotton wastes as an additional material of medium, the productivity. Currently, we are developing a standard cultivation technique and environmental control system that can stably produce mushrooms throughout the year. The increase of oyster mushroom production may boostthe domestic market and contribute to industrial development. In addition, oyster mushroom production technology played a role in forming the basis for the development of bottle cultivation, which made mass production. In particular, bottle cultivation using liquid spawn could allow for the export of F. velutipes and Pleurotus eryngii. In addition, the white varieties of F. velutipes were second developed in the world after Japan. We also developed the new A. bisporus cultivar 'Saeah', which is easy to grow in Korea. In hopes to advance the mushroom industry, we will continue to develop cultivars with international competitive power and to improve cultivation techniques.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.197-210
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• 1994

This experiment was carried out to study the cause of degeneration and rot of cultivated mushroom. Among 597 bacterial isolates derived from the rots of Button mushroom (Agaricus bisporus), Oyster mushroom (Pleurotus ostreatus) and Oak mushroom (Lentinus edodes) collected from markets of 5 cities (Seoul, Suwon, Taegu, Pohang and Pusan) in Korea (1991~1993), 111 bacterial isolates (18.5%) were proved as pathogenic bacteria. These pathogenic bacteria causing bacterial rots of cultivated mushrooms were identified as Pseudomonas tolasii, P. agarici, and Eriwinia sp., and the main causal bacteria were P. tolaasii. P. fluorescens and Klebsiella plenticola were confirmed as saprophytic non-pathogenic bacteria. One hundred fifty nine isolates (Group No. 39) of the 486 saprophytic bacterial isolates were classified as P. fluorescens, and this species was most often found rot area of cultivated mushrooms. P. tolaasii, the causal organism of bacterial blotch, was classified into two groups; One group can be differentiated from the other by the formation of white precipitation band by white line reacting organisms of Pseudomonas Agar F media. P. tolaasii attacked the cultivated mushrooms relatively well at lower incubation temperature such as 5$^{\circ}C$, but P. agarici rarely attack at below 1$0^{\circ}C$. The temperature for the infection commercial cultivated mushrooms by P. agarici was higher than that of P. tolaasii. Optimum temperature for the infection of mushrooms by P. tolaasii and P. agarici were 2$0^{\circ}C$ and $25^{\circ}C$, respectively.