This study was conducted to determine changes in quality and microbial population of intact and fresh-cut button mushrooms (Agaricus bisporus). Freshly collected mushroom was cut into approximately 0.5 cm thick slices and washed in tap water or 100 ㎕L-1 chlorine solution (pH 7) for 60 seconds. Intact mushrooms were washed in the same condition as cut samples. Both intact and fresh-cut samples were then dried, packaged in 50㎛ poly ethylene bags, and stored at 5 ℃ for up to 9 days. Quality and microbial safety parameters such as gas composition, color, off-odor, visual quality, electrical conductivity, E. coli / coliform count, and total aerobic population were evaluated during storage. All sample packages exhibited a rapid depletion of O2 (to ~0 kPa) and accumulation of CO2 (10.3 to 12.6 kPa) throughout the storage period. No significant color difference was found between tap water and chlorine. However, chlorine treatment was effective in reducing off-odor development of intact and fresh-cut samples at the end of storage. The chlorine application also reduced aerobic bacterial populations. Both Intact and cut mushrooms had ≤ 5 log CFU/g of total aerobic plate counts until the end of storage. Fresh-cut samples regardless of chlorine sanitation had higher overall visual quality score than intact samples. Results indicated that fresh-cut mushrooms treated with chlorine maintained quality and shelf-life throughout the 9 day storage period.

This study was conducted to investigate optimum processing procedure of fresh-cut button mushrooms. The experiments were done with different processing parameters including washing method, washing time, sanitation, and cutting time. Fresh mushrooms were washed by swirling water (SW), lift type-immersion washing (LIW), or combined LIW and water spray (LI+WS). Mushroom samples were washed by LIW for 0, 1, 3, and 5 minutes separately. Mushrooms were sanitized with 0, 50, or 100 ㎕L-1 chlorine solution (pH 7) for 60 seconds. Mushrooms were sliced at different times (before washing, after washing, or after drying). The combined washing treatment, LIW+WS was effective in maintaining better appearance and higher Lightness color value among treatments. Optimum washing time to remove foreign materials and maintain color was 3 minutes when mushrooms were washed by LIW. Samples sanitized with 50 ㎕L-1 chlorine reduced initial aerobic bacterial population and had only slight residual chlorine odor. Fresh-cut mushrooms sliced after washing had the lowest loss among samples. The optimized washing, sanitation, and cutting time parameters can be used for sequential processing of fresh-cut button mushrooms.

We investigated 18 amino acid contents in the fruiting bodies of Agaricus strains to understand their variation in the harvesting periods. Total content of amino acid was different depending on the isolates. In the case of A. bitorquis and A. brunnescens, the total amino acid content increased and correlated with the harvesting periods. For commercial strains of A. bisporus, such as Yangsongi-505, Yangsongi-705 and commercial strain A collected in the market, it increased until the second harvesting period, but decreased in the third harvesting period indicating that these three isolates exhibit the exceptions for the general trend. Among isolates we used in our experiments, the isolate of A. brunnescens contained the highest and two isolates of A. bisporus were the lowest in total amino acids. We found two trends for the contents of each amino acid in the fruiting bodies of Agaricus spp.. One is the same with the trend of the total amino acid content and the amino acid content were largely correlated with the harvesting period. The other is the trend of increase of amino acid until the second harvesting period and decrease of amino acid in the third harvesting period, which was also shown in the total amino acid content of A. bisporus. Generally, the most amino acid contained in Agaricus was cysteine and followed by phenylalanine, glutamic acid, lysine, proline and histidine.

To understand the saccharide contents and quantity of winter mushroom (Flammulina velutipes) according to its growth temperature, we measured the saccharide contents at different growth temperature. In our results, the saccharide of its fruiting body turned out to be mainly composed of xylose, trehalose and mannitol in all treatments. In the other hand, Ribose, myo-inositol and sucrose were detected in some treatments. The quantity of trehalose decreased as the growth temperature increased with a variation of its quantity depending on the isolates used in the experiments. In the case of xylose and mannitol, detected in all treatments, the pattern of their quantities was not possible to be profiled and the pattern might be largely depending on the isolates. However, the quantities of xylose and mannitol were largely in a direct proportion and the fluctuation of their quantities was congruent with the exception of ASI 4103, ASI 4166 and ASI 4065. The xylose quantity of ASI 4103 and ASI 4166 increased until the temperature was up to 10℃ and decreased when the temperature was above 10℃. That of ASI 4065 decreased as the temperature rose and increased when above 13℃. The mannitol quantity of ASI　4065 and ASI 4166 decreased until the temperature was up to 10℃ and increased when the temperature was above 10℃. That of ASI 4103 increased as the temperature rose and decreased when above 13℃.

Flammulina velutipes, amongst others known as Winter Mushroom or Enokitake is an important economic crop in Asia. The tetrapolarity (having four mating types) of this mushroom obligates mating and results in self-sterile progeny that carries unique genetic traits, making understanding of the genetic base desirable for breeding. Moreover, mating type genes are significant for evolutionary studies as their high polymorphism benefits phylogenetic comparisons. This polymorphism further makes mating type genes interesting candidates for genetic markers that allow identification of specific strains. Mating type loci in Agaricomycotina are classically termed A and B and control two different developmental pathways [for a review see 1]. They consist of tightly linked subloci that encode multiallelic genes. MatA loci contain two groups of divergently transcribed homeodomain proteins (HD1 and HD2) and heterodimerization of HD1 with a non-self HD2 protein forms a functional transcription factor that activates the A pathway. MatB loci hold pheromones and pheromone receptors. Pheromone genes encode small precursor proteins that are characterized by a C-terminal CAAX motif. Pheromone receptors typically contain 7 membrane spanning regions and are coupled to G-proteins. Binding of a pheromone to a receptor, triggers splicing of the (trimeric) G-protein, which activates the B pathway. New genetic data from recent genome sequences is challenging the strict concepts of old mating type models in fungi. MatB loci turn out to be rather diverse and contain considerable varying numbers of pheromone receptors and associated pheromones. To this, pheromone receptors which are not linked to matB loci have now been reported for C. cincerea, S. commune and L. bicolor [2, 3]. Also the organization of the matA locus is less strictly conserved than anticipated. Though far more tightly maintained than the matB locus, substantial differences in HD gene numbers and overall organization are reported [2, 3]. These differences stress the importance of determination of the individual mating type systems from industrially important mushrooms to assist breeding. Our analysis of F. velutipes strain 4019-20 uncovered 7 pheromone receptors together with 3 pheromones. The matB-3 locus of this strain however, is defined by only a single pheromone receptor and pheromone gene and our data strongly indicates that a 2nd pheromone receptor recently lost its function. The other receptor genes are non mating type specific. Finally, we detected three homeodomain genes distributed over two distant subloci. These subloci have been separated by two large inversions. Strikingly the distant matA subloci in S. commune seem to be separated by inversions as well. Synthenic mapping of a large regions from Coprinus cinerea, Laccaria bicolor, S. commune and F. velutipes shows that the matA loci originate from a single locus in a common ancestor of S. commune and F. velutipes that is represented by L. bicolor and C. cinerea. [1] U Kües. Micr Mol Biol Rev 64, 316 (2000) [2] H Niculita-Hirzel, J Labbé, A Kohler, F le Tacon, F Martin, IR Sanders and U Kües. New Phytol 180, 329 (2008). [3] RA Ohm, JF de Jong, LG Lugones, A aerts, E Kothe, JE Stajich, RP de Vries, E Record, A Levasseur, SE Baker, KA Bartholomew, PM Couthino, S Erdmann, TJ Fowler, AC Gathman, V Lombard, B Henrissat, N Knabe, U Kües, WW Lilly, E Lindquist, S Lucas, JK Magnuson, F Piumi, M Rausdaskoski, A Salamov, J Schmutz, FWMr Schwarze, PA van Kuyk, JS Horton, IV Grigoriev and HAB Wösten. Nat. Biotechnol ISSN: 1087-0156 (2010).

Regulations in the EU, Japan, Korea, etc. require that foods and feeds made of or derived from genetically modified organisms (GMOs) should be approved and labeled according to a threshold. Recently, disease resistant transgenic rice was developed in Korea, which resulted from the transformation events involving choline kinase gene, OsCK1. In order to monitor unintended release of the developed GM rice in the near future, as well as to meet GM-labeling requirements, the development of a reliable method for detection of disease resistant GM rice is requisite. Here, specific primer pairs for the detection of GMO was designed on the basis of a introduced gene and the flanking junction sequences between a plant DNA and a integrated gene construct, and also SPS gene was used as an endogenous reference material. Specificities of all designed primers were tested through qualitative PCRs. Clearly, target specific amplicons could be detected from disease resistant GM rice event. In addition, the limits of detection (LOD) using the event-specific primers were approximately 0.1% for the disease resistant GM rice line. This result indicated that the developed detection method is suitable for the traceability of disease resistant GM rice, because of using the primer specifically corresponded to the junction site between plant genomic DNA and inserted DNA. Keywords: genetically modified organisms, disease resistant GM rice, PCR detection, event-specific primer