• Parasites, Hosts and Diseases
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• 제58권3호
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• pp.321-326
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• 2020

Blastocystis has recently been recognized as the most common eukaryotic microbe of the human gut. We investigated the prevalence of Blastocystis and their subtypes in diarrheal and non-diarrheal groups and the associated clinical parameters. A total of 324 stool samples were obtained from 196 diarrheal and 128 non-diarrheal subjects. Blastocystis subtypes were determined by sequencing the small subunit ribosomal DNA (SSU rRNA) gene. Demographic, clinical and laboratory data were collected and analyzed by diarrhea and Blastocystis status. The overall rate of Blastocystis positivity was 9.0% (29/324) but was significantly higher in the non-diarrheal group (18.0% vs. 3.1%, P<0.0001). Of the 6 Blastocystis-positive diarrheal patients, 3 (50.0%), none (0.0%), 2 (33.3%), and 1 (16.7%) were infected with subtypes ST1, ST2, ST3, and multiple subtypes, respectively. Of the 23 Blastocystis-positive non-diarrheal patients, 4 (17.4%), 1 (4.3%), and 18 (78.3%) were infected with subtypes ST1, ST2, and ST3, respectively. Blastocystis was less common in the diarrheal than the non-diarrheal group (odds ratio, 0.144; 95% confidence interval, 0.057-0.365, P<0.001). Of the 3 subtypes, ST3 was more frequently observed in the non-diarrheal than diarrheal group (78.3% vs. 33.3%, P=0.0341). Collectively, Blastocystis was found in both the diarrheal and non-diarrheal groups and ST3 was the most common subtype in Korea.

• Mycobiology
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• 제48권3호
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• pp.195-203
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• 2020

Marine yeasts have tremendous potential in industrial applications but have received less attention than terrestrial yeasts and marine filamentous fungi. In this study, we have screened marine yeasts for amylolytic activity and identified an amylase-producing strain PH-Gra1 isolated from sea algae. PH-Gra1 formed as a coral-red colony on yeast-peptone-dextrose (YPD) agar; the maximum radial growth was observed at 22 ℃, pH 6.5 without addition of NaCl to the media. Based on the morphology and phylogenetic analyses derived from sequences of internal transcribed spacer (ITS) and a D1/D2 domain of large subunit of ribosomal DNA, PH-Gra1 was designated Sporidiobolus pararoseus. S. pararoseus is frequently isolated from marine environments and known to produce lipids, carotenoids, and several enzymes. However, its amylolytic activity, particularly the optimum conditions for enzyme activity and stability, has not been previously characterized in detail. The extracellular crude enzyme of PH-Gra1 displayed its maximum amylolytic activity at 55 ℃, pH 6.5, and 0%-3.0% (w/v) NaCl under the tested conditions, and the activity increased with time over the 180-min incubation period. In addition, the crude enzyme hydrolyzed potato starch more actively than corn and wheat starch, and was stable at temperatures ranging from 15 ℃ to 45 ℃ for 2 h. This report provides a basis for additional studies of marine yeasts that will facilitate industrial applications.

• 한국버섯학회지
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• 제12권3호
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• pp.145-153
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• 2014

Pleurotus has increased rapidly production and consumption because of highly nutritional value, natural healthy food and so on. The basic studies for Pleurotus need for development of mushroom industry. This study was to investigate the cultural characteristics among 15 strains of 6 species and to analyze their phylogenetic relationships. The cultural characteristics were investigated by mycelial growth activity at different media, temperature and pH. The optimum media for mycelial growth were YM and MCM in most species. The optimum temperature for mycelial growth were $25^{\circ}C$ and $30^{\circ}C$. The optimum pH for mycelial growth were widly range from pH 5.1 to 7.4. Through the RFLP (restriction fragment length polymorphism) of IGS (intergenic spacer) I region in ribosomal DNA, it was analyzed phylogeny of interspecies and intraspecies. Each species was discriminated well as isolates within each species formed clade to be distinguished other species. P. florida was highly similar to P. floridanus, and P. flabellatus was P. cornucopiae. P. fuscus var. ferulae was highly similar to P. eryngii but discriminated different species in analysis of RFLP of IGS I region and showed different characteristics in mycelial culture. RFLP of IGS I region was useful of studying phylogenetic relationships of species and population.

• The Plant Pathology Journal
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• 제24권4호
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• pp.453-460
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• 2008

In the course of in vitro and in vivo screening for bioherbicidal agents, a hyphomycete fungus, Myrothecium sp. F0252 was selected as a candidate for the biocontrol of weeds. The isolate was identified as Myrothecium roridum Tode ex. Fries based on the morphological characteristics and 18S ribosomal DNA sequence analysis and registered as Myrothecium roridum F0252. In order to evaluate the in vitro effect of M. roridum F0252 on germination of ladino clover and white clover (Trifolium repens L.) seeds, spore solution of the fungus was employed in two concentrations, $6.5{\times}10^6$ and $2.5{\times}10^7$ spores per mL and then inoculated to the seeds. The fungal spores inhibited the seed germination, infected the seedlings, and caused an abnormal withering and inhibition of seedling growth. In addition, when the herbicidal activity of crude ethyl acetate extract from the liquid culture was assessed on a mini-plant, duck-weed (Lemna paucicostata (L.) Hegelm.), the extract showed high inhibitory effect at the level of $12.5{\mu}g$ per mL. On the other hand, in vivo herbicidal activity of M. roridum F0252 was evaluated by a whole plant spray method. M. roridum F0252 exhibited strong and broad-spectrum herbicidal activity. The herbicidal values ranged from 95-100% against 7 weeds, including Abutilon avicennae and Xanthium strumarium, and 70-80% against Digitaria sanguinalis and Sagittaria pygmaea. When the nutritional utilization (95 carbon sources) pattern of M. roridum F0252 was investigated, it varied with water activity ($a_w$) and temperature conditions, supplying good, basic information in regard to nutritional utilization for proper cultivation and formulation. Our results showed that M. roridum F0252 might be used as a potential biocontrol agent against weedy plants.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.809-814
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• 2005

Gibberellins (GAs) play an important role in plant growth and development. Fifteen fungi were isolated from Physalis alkekengi var francheti plant roots, and among them, four isolates showed GA-production activity. A bioassay using waito-c rice was carried out with the culture fluid of the GA-producing fungi. The GA-producing fungi were cultured for 7 days in Czapek's liquid medium at $30^{\circ}C$, 120 rpm, under dark conditions. The culture broth was concentrated 30-fold and 10 ${\mu}l$ of that concentrate was applied to 2-leaf rice sprouts. The height of the rice seedlings treated with the culture fluid of isolate PA08 was 26 cm high, while that of the seedlings treated with the wild-type Gibberella fujikuroi was 13 cm high. As such, the plant growth-promoting activity exhibited by isolate PA08 was 2 times stronger than that exhibited by the wild-type G fujikuroi. The amounts of $GA_l,\;GA_3,\;GA_4,\;GA_7,\;GA_9,\;GA_{20}$, and $GA_{24}$ in the medium were measured using gas chromatography-mass spectrometry (GC-MS), and the quantities produced by isolate PA08 were 4.85 ng/ml, 4.79 ng/ml, 17.30 ng/ml, 6.01 ng/ml, 16.61 ng/ ml, 0.08 ng/ml, and 17.30 ng/ml, respectively. Isolate PA08 was also identified as Fusarium proliferatum KGL0401 by a genetic analysis of the nucleotide sequences of the internal transcribed spacer region of the ribosomal DNA.

• Journal of Microbiology and Biotechnology
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• 제19권8호
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• pp.743-748
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• 2009

Fungal diversity during composting was investigated by culture-independent rDNA sequence analysis. Composting was carried out with pig manure and mushroom cultural waste using a field-scale composter (Hazaka system), and samples were collected at various stages. Based on partial sequence analysis of large subunit (LSU) ribosomal RNA (rRNA) and sequence identity values, a total of 12 different fungal species were found at six sampling sites; Geotrichum sp., Debaryomyces hansenii, Monographella nivalis, Acremonium strictum, Acremonium alternatum, Cladosporium sphaerospermum, Myriangium durosai, Pleurotus eryngii, Malassezia globosa, Malassezia restricta, Rhodotorula glutinis, and Fusarium sporotrichioides. Geotrichum sp. of the class Saccharomycetes was the most predominant fungal species throughout the composting process (185 out of a total of 236 identified clones, or 78.4%), followed by Acremonium strictum (7.6%), Monographella nivalis (5.1%), and Pleurotus eryngii (3.8%). The prevalence of Geotrichum sp. was the lowest (61.1%) at the beginning of composting, and then gradually increased to 92.5% after 10 days of composting.

• Journal of Dairy Science and Biotechnology
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• 제27권2호
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• pp.1-6
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• 2009

Probiotic bacteria have been administered to neonates to serve as maturational stimuli for the developing gut and intestinal immune system, establish and develop the intestinal microbiota, and mediate host-microbe interactions; further, these bacteria have shown beneficial effects In the treatment and reduction of the risk of infectious diseases, necrotizing enterocolitis, and atopic disease. An LAB isolation project to identify effective lactic acid bacteria for Korean people is in progress. The average total counts of lactic acid bacteria, lactobacilli, bifidobacteria, and coliforms in the fecal samples from 2 provinces were estimated as 8.31, 5.98, 8.13, and 3.01 CFU/g. Additional samples from other provinces will be analyzed to examine the changes in the lactic bacterial counts according to the area, sex of the neonate, mode of delivery, and type of feeding. A database containing the 16S rDNA sequences and the ribosomal protein profile of all the lactic acid bacteria isolated from fecal samples will be constructed. For the effective use of probiotics, a number of clinical studies are needed to formulate guidelines for strain, subject, purpose, and dose.

• 한국미생물·생명공학회지
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• 제32권1호
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• pp.29-36
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• 2004

토양으로부터 CGTase를 생산하는 새로운 호열성 세균을 분리하였으며, 형태 및 생리적 특성과 16S ribosomal DNA의 염기서열을 분석한 결과 Geobacillus thermosacchalytycus 로 동정하였다. 호열성 G. thermosacchalytycus가 분비하는 CGTase를 한외여과, 소수성 Phenyl Sephadex CL-4B 클로마토그래피 , 그리고 gel filtration의 순서로 분리 정제하여 정제도 28.2배, 정제수율 12.2%, 그리고 specific activity가 4952.5 units/mg인 CGTase를 얻을 수 있었다. 정제된 CGTase의 분자량은 69,000 dalton이었고, terminal amino sequence는 Asn-Leu-Asn-Lys-Val-Asn-Phe-Thr-Ser-Asp-Val-Val-Tyr-Gln-Ile이었다. 최적 pH 및 온도는 각각 pH 6와$ 50^{\circ}C$였고, pH 6-8과 $60^{\circ}C$에서 장기간 보존할 수 있는 중성 pH의 내열성 효소임을 알 수 있었다. 내열성 CCTase의 cyclization과 coupling 반응의 특정을 검토한 결과 G. thermosacchalytycus가 생산하는 내열성 효소는 $\alpha$-type CGTase이었고, cyclization 반응보다는 coupling반응에 적합한 당전이성이 높은 효소임을 알 수 있었다. 당전이 반응에서 기질 특이성을 검토한 결과 당공여체로는 가용성 전분 그리고 당수용체로는 배당체인 stevioside에 대해 높은 기질 특이성을 보였다. 당전이 반응은 당수용체와 당공여체가 효소와 무작위로 결합하여 진행되는 random ternary complex mechanism으로 반응이 수행되었다.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1568-1577
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• 2015

The purpose of this study was to investigate lactic acid bacteria with antioxidative and probiotic activities isolated from Korean healthy infant feces and kimchi. Isolates A1, A2, S1, S2, and S3 were assigned to Lactobacillus sp. and isolates A3, A4, E1, E2, E3, and E4 were assigned to Leuconostoc sp. on the basis of their physiological properties and 16S ribosomal DNA sequence analysis. Most strains were confirmed as safe bioresources through nonhemolytic activities and non-production of harmful enzymes such as β-glucosidase, β-glucuronidase and tryptophanase. The 11 isolates showed different resistance to acid and bile acids. In addition, they exhibited antibacterial activity against foodborne bacteria, especially Bacillus cereus, Listeria monocytogenes, and Escherichia coli. Furthermore, all strains showed significantly high levels of hydrophobicity. The antioxidant effects of culture filtrates of the 11 strains included 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging capacity, 2.2'-azino-bis (2-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical cation scavenging activity, and superoxide dismutase activity. The results revealed that most of the culture filtrates have effective scavenging activity for DPPH and ABTS radicals. All strains appeared to have effective superoxide dismutase activity. In conclusion, the isolated strains A1, A3, S1, and S3 have significant probiotic activities applicable to the development of functional foods and health-related products. These strains might also contribute to preventing and controlling several diseases associated with oxidative stress, when used as probiotics.

• Journal of Microbiology and Biotechnology
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• 제21권8호
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• pp.777-790
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• 2011

To elucidate the biodiversity of plant growth-promoting rhizobacteria (PGPR) in Korea, 7,638 bacteria isolated from the rhizosphere of plant species growing in many different regions were screened. A large number of PGPR were identified by testing the ability of each isolate to promote the growth of cucumber seedlings. After redundant rhizobacteria were removed via amplified rDNA restriction analysis, 90 strains were finally selected as PGPR. On the basis of 16S ribosomal RNA sequences, 68 Gram-positive (76%) and 22 Gram-negative (24%) isolates were assigned to 21 genera and 47 species. Of these genera, Bacillus (32 species) made up the largest complement, followed by Paenibacillus (19) and Pseudomonas (11). Phylogenetic analysis showed that most of the Grampositive PGPR fell into two categories: low- and high- G+C (Actinobacteria) strains. The Gram-negative PGPR were distributed in three categories: ${\alpha}$-proteobacteria, ${\beta}$- proteobacteria, and ${\gamma}$-proteobacteria. To our knowledge, this is the largest screening study designed to isolate diverse PGPR. The enlarged understanding of PGPR genetic diversity provided herein will expand the knowledge base regarding beneficial plant-microbe interactions. The outcome of this research may have a practical effect on crop production methodologies.