• Journal of Mushroom
• /
• v.22 no.1
• /
• pp.22-26
• /
• 2024

Tricholoma matsutake is a traditional favorite food in East Asia, cultivated in fairy rings called "shiro," which are found near Pinus densiflora. For effective artificial cultivation of Tri. matsutake, microorganisms from symbiotic fairy rings are co-cultivated. In this study, one bacterial isolate (Y22_B35) and two fungal isolates (Y22_F64 and Y22_F68) displayed growth-promoting effects on Tri. matsutake mycelium (158.47, 125.00, and 122.26% enhanced growth, respectively). For identification, 16S rRNA or ITS regions from the microorganisms¡¯ genomes were sequenced. Other sequences, including BenA, CaM, and RPB2 were sequenced in the fungal isolates. The bacterial isolate Y22_B35 was identified as Bacillus cereus. Y22_F64 and Y22_F68 were identified as Umbelopsis nana and Aspergillus parvulus, respectively. To identify the effects of the dominant microorganisms on Tri. Matsutake cultivation, metagenomic analyses were performed. Discovery of these Tri. matsutake mycelium growth-promoting microorganisms and metagenomics analyses are expected to contribute to our understanding of Tri. matsutake fruiting body growth and construction of biomimicry.

• Food Science of Animal Resources
• /
• v.32 no.1
• /
• pp.62-67
• /
• 2012

This study calculated kinetic parameters of Escherichia coli O157:H7 and developed a probabilistic model to estimate growth probabilities of E. coli O157:H7 on polyethylene cutting boards as a function of temperature and time. The surfaces of polyethylene coupons ($3{\times}5$ cm) were inoculated with E. coli O157:H7 NCCP11142 at 4 Log $CFU/cm^2$. The coupons were stored at 13 to $35^{\circ}C$ for 12 h, and cell counts of E. coli O157:H7 were enumerated on McConkey II with sorbitol agar every 2 h. Kinetic parameters (maximum specific growth rate, Log $CFU/cm^2/h$; lag phase duration, h; lower asymptote, Log $CFU/cm^2$; upper asymptote, Log $CFU/cm^2$) were calculated with the modified Gompertz model. Of 56 combinations (temperature${\times}$time), the combinations that had ${\geq}$0.5 Log $CFU/cm^2$ of bacterial growth were designated with the value of 1, and the combinations that had increases of <0.5 Log $CFU/cm^2$ were given the value 0. These growth response data were fitted to the logistic regression to develop the model predicting probabilities of E. coli O157:H7 growth. Specific growth rate and growth data showed that E. coli O157:H7 cells were grown at $28-35^{\circ}C$, but there were no obvious growth of the pathogen below $25^{\circ}C$. Moreover, the developed probabilistic model showed acceptable performance to calculate growth probability of E. coli O157:H7. Therefore, the results should be useful in determining upper limits of working temperature and time, inhibiting E. coli O157:H7 growth on polyethylene cutting board.

• Korean Journal of Microbiology
• /
• v.49 no.4
• /
• pp.328-335
• /
• 2013

As a result of conducting a cultural experiment of tomato using chicken feather protein hydrolysate (CPH) which was mass produced by keratin protein degrading bacterium Chryseobacterium sp. FBF-7 (KACC 91463P), we found that the stem and the root of tomato showed significant improvement in growth. For the purpose of phylogenic interpretation, a comparison was drawn between the effect of CPH, a treated CPH and untreated, on the changes of bacterial populations by 454 pyrosequencing based on 16S rRNA gene sequences. Tomato rhizosphere soil untreated with CPH (NCPH) showed 6.54 Shannon index from 3,281 sequence reads, and the rhizosphere soil treated with CPH (TCPH) showed 6.33 Shannon index from 2,167 sequence reads, displaying that it does not affect the diversity. Bacterial populations were composed of 19 phyla in the rhizosphere soil, and the phylum Proteobacteria occupied 40% of total bacterial populations. Bradyrhizobium, Agromonas, Nitrobacter, and Afipia (BANA group) which belong to Bradyrhizobiaceae were abundant and commonly detected in both the treated and untreated soils, suggesting the dominance of bacterial group in rhizosphere soil. The results obtained showed that CPH treatment does not affect the indigenous bacterial populations present in the rhizosphere soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.6
• /
• pp.1100-1107
• /
• 2012

Bacterial endophytes may be important factors in plant growth and ecologically relevant functions in rice. Using pyrosequencing technology, we analyzed the composition of endophytic bacterial communities that colonized the roots of rice cultivated in long-term fertilized (APK) and non-fertilized (NF) paddy soils. A total of 1,900 reads were obtained from 2 samples. All sequences were classified into 177 OTUs (APK sample) or 72 OTUs (NF sample) at a 97% similarity cut-off. Twenty-two OTUs were shared between the 2 samples, and these were also the most dominant OTUs in both samples. Proteobacteria was the most dominant phylum with 90.2%, followed by Actinobacteria (7.1%) and Bacteroidetes (1.1%). Furthermore, Pseudomonas was the most abundant genus in both samples. We observed clear differences in the structure of the endophytic bacterial community structure between the 2 samples. Notably, the distributions of Alphaproteobacteria and Gammaproteobacteria were markedly different. The diversity index of the APK sample was higher than that of the NF sample. These findings showed that the endophytic bacterial community of rice roots was affected by the presence of fertilizers in the rice field soil.

• The Korean Journal of Pesticide Science
• /
• v.20 no.1
• /
• pp.41-46
• /
• 2016

Bacterial fruit blotch (BFB) caused by Acidovorax avenae subsp. citrulli is defective disease to watermelon cultivated areas. To control of BFB, we investigated control efficiency to use commercial antibacterial pesticides. Growth inhibition zone on medium were formed as oxolinic acid WP and oxytetracycline WP. Control efficacy of four anti-bacterial pesticides on seed and seedling stage were performed. As a results, oxytetracyclin WP is shown over 90% control efficiency on seed and acibenzolar-S-methyl + mancozeb WP shown over 90% control efficiency on seedling stage Hot-water treatment method could be possible to reduced infection rate on seed. The conditions of hot-water treatments are $50{\sim}55^{\circ}C$ on 20~30 minutes. These results suggested that the methods were helpful watermelon seedling nursery to control of the bacterial fruit blotch by A. avenae subsp. citrulli.

• Journal of Life Science
• /
• v.25 no.2
• /
• pp.189-196
• /
• 2015

Bacterial diversity was studied in the rhizosphere of Suaeda japonica Makino, which is native to Suncheon Bay in South Korea. Soil samples from several sites were diluted serially, and pure isolation was performed by subculture using marine agar and tryptic soy agar media. Genomic DNA was extracted from 29 pure, isolated bacterial strains, after which their 16S rDNA sequences were amplified and analyzed. Phylogenetic analysis was performed to confirm their genetic relationship. The 29 bacterial strains were classified into five groups: phylum Firmicutes (44.8%), Gamma proteobacteria group (27.6%), Alpha proteobacteria group (10.3%), phylum Bacteriodetes (10.3%), and phylum Actinobacteria (6.8%). The most widely distributed genera were Bacillus (phylum Firmicutes), and Marinobacterium, Halomonas, and Vibrio (Gamma proteobacteria group). To confirm the bacterial diversity in rhizospheres of S. japonica, the diversity index was used at the genus level. The results show that bacterial diversity differed at each of the sampling sites. These 29 bacterial strains are thought to play a major role in material cycling at Suncheon Bay, in overcoming the sea/mud flat-specific environmental stress. Furthermore, some strains are assumed to be involved in a positive interaction with the halophyte S. japonica, as rhizospheric flora, with induction of growth promotion and plant defense mechanism.

• Horticultural Science & Technology
• /
• v.28 no.3
• /
• pp.476-483
• /
• 2010

Total bacterial populations were cultured from the Hydroball cultivation media in the rhizospheres of 9 different plants including $Hedera$ $helix$ L. and $Dracaena$ $deremensis$ cv. Warneckii Compacta, etc. These cultured bacterial populations were studied to test if the bacterial populations in the plant growing pots may play a role on removal of volatile organic compounds (VOCs) such as benzene and toluene in the air. To meet this objective, first, we tested the possibility of removal of VOCs by the cultured total bacteria alone. The residual rates of benzene by the inoculation of total bacterial populations from the different plant growth media were significantly different, ranging from 0.741-1.000 of $Spathiphyllum$ $wallisii$ 'Regal', $Pachira$ $aquatica$, $Ficus$ $elastica$, $Dieffenbachia$ sp. 'Marrianne' Hort., $Chamaedorea$ $elegans$, compared to the control with residual rate of 0.596 (LSD, $P$=0.05). This trend was also similar with toluene, depending on different plants. Based on these results, we inoculated the bacterial population cultured from $P.$ $aquatica$ into the plant-growing pots of $P.$ $aquatica$, $F.$ $elastica$, and $S.$ $podophyllum$ inside the chamber followed by the VOCs injection. The inoculated bacteria had significant effect on the removal of benzene and toluene, compared to the removal efficacy by the plants without inoculation, indicating that microbes in the rhizosphere could play a significant role on the removal of VOCs along with plants.

• Journal of Marine Life Science
• /
• v.4 no.2
• /
• pp.53-62
• /
• 2019

Heterotrophic bacteria are a major member of the microbial loop in the marine ecosystem and play an important role in the biogeochemical cycle decomposing organic matter. Therefore study of bacterial variation is important to understand the material cycle and energy flow of marine ecosystems. We investigated the monthly variations of bacteria and environmental factors in the Youngsan River estuary, and the correlation between bacteria and phytoplankton biomass (chlorophyll-a) including size-structure. As a result, bacteria of the Youngsan River estuary were higher in the surface than in the bottom layer, and higher in the summer than in winter. And the closer to the dike, the abundance increased, and it increased to the peaks in August, September, and June 2019 at the station closest to the dike. The chlorophyll-a also increases at the stations and time when the bacterial abundance was high and they correlates positively displaying no difference between size fractions. The results indicate that organic matter derived from phytoplankton has an effect on bacterial variation but no size-dependent effects. In addition, the seasonal pattern of bacteria increasing in proportion to the water temperature suggests the effect of water temperature on the growth of bacteria. No association of bacterial abundance variation with nutrient supply due to freshwater input was observed. In this study, dissolved oxygen was depleted and hypoxia was observed for a short time when a strong stratification was not developed. This may be resulted from the supply of organic matter from phytoplankton and the consumption of oxygen due to bacterial decomposition.

• The Korean Journal of Pesticide Science
• /
• v.19 no.2
• /
• pp.119-124
• /
• 2015

Bacterial leaf spot, caused by Pseudomonas syringae pv. syrinage, is a very damaging disease to green pumpkin in Gong-ju and Non-san nursery. However, there is no good method to control the disease in Korea. Growth inhibition of pathogen on medium, control efficacy on seedling stage, and seed treatment effect of 6 anti-bacterial pesticides were investigated for selection of the best pesticide for seed treatment and control of the disease. Growth inhibition zone on King's B medium were the largest by oxytetracycline 170 ppm and oxytetracycline 15 ppm + streptomycin sulfate 188 ppm, oxolinic acid 200 ppm, streptomycin 200 ppm were next respectively. Control efficacy of oxytetracycline 1.5% + streptomycin sulfate 18.8% WP and oxytetracycline 17% WP on seedling stage were 71.4% and 49.4%, respectively. Seed treatment of oxytetracycline 15 ppm + streptomycin sulfate 188 ppm on the artificially inoculated seeds inhibits pathogen growth completely from the treated seeds and 96% control efficacy on grow-out test of the treated seeds. Seed treatment of streptomycin 100 ppm (2,000 dilution of streptomycin 20%) on the artificially inoculated seeds allow 280 cfu/g of pathogen growth from the treated seeds and 60% control efficacy on grow-out test of the treated seeds. Seed treatment of oxytetracycline 85 ppm (2000 dilution of oxytetracycline 17% WP) on the artificially inoculated seeds allow 80 cfu/g of pathogen growth from the treated seeds and 90% control efficacy on grow-out test of the treated seeds. These results suggested that oxytetracycline 1.5% + streptomycin sulfate 18.8% WP was the best pesticide for seed treatment to control of the bacterial spot disease by Pseudomonas syringae pv. syringae.

• Preventive Nutrition and Food Science
• /
• v.6 no.3
• /
• pp.192-196
• /
• 2001

Ethanol extracts from 36 vegetable samples were assayed for their growth-promoting effects on Bifidobacterium bifidum, B. longum, and Lactobacillus casei The growth-promoting effects varied according to bacterial strain and vegetable species. In modified Gy rgy broth, extracts of Lactuca sativa, Lycopersicon esculentum and L escutentum var. cerasiforme exhibited strong growth-promoting responses toward B. longum, and significant and strong growth- promoting response toward B. bifidum was observed in extracts of Actinidia arguta, Allium cepa, A. sativum, Brassica campestris subsp. napus vats. pekinensis, Capsicum frutescens, Daucus carota var. sativa, L sativa, 1. esculentum and L. esculentum var. cerasforme, Nelumbo nucifera, Cucurbita moschata, Lackca sativa var. capitata, and Rubus coreanus. For L casei, extracts of A. fshlosum, A. hberosum, Cichorium intbus, Cucurbita moschat\ulcorner Ipomoea batatas, 1. sativa var. capitata, L. esculentum, P. brachycarpa, Raphanus sativus, R. coreanus, and S. melongena strongly enhanced the growth of this bacteria. In modified Gy rgy broth, the promoting effect was most pronounced with B. bifidum and L. casei among lactic acid bacteria used. In MRS broth, A. arguta, A. cepa, A. sativum, B. campestris subsp. napus var. pekinensis, C. frutescens, and D. carota var. sativa L. satiw var. capitata, and R. coreanus strongly enhanced the growth of B. bifidum, Growth of B. longum was strongly affected by the addition of extracts from L. sativa var. capitata. For L casei, moderate growth-promoting responses were observed in 9 vegetable extracts. The promoting effect in MRS broth was most pronounced with B. bifidum among lactic acid bacteria used.