• The Plant Pathology Journal
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• v.18 no.1
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• pp.30-35
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• 2002

The hyphal growth and biocontrol efficacy of Trichodemo harzianum in soil may depend on its interactions with biotic components of the soil environment. The effect of soil microbial biomass on growth and biocontrol efficacy of T. hanianum isolate ThzIDl-M3 (green fluorescent protein transformant) was investigated using artificially prepared different levels of soil microbial biomass (153,328, or 517ug biomass carbon per g of dry soil; BC). The hyphal growth of T. harzanum was significantly inhibited in the soil with 328 or 517 $\mu$g BC compared with 153 ug BC. When ThzIDl-M3 was added to the soils as an alginate pellet formulation, the recoverable population of ThzIDl-M3 varied, but the highest population occurred in 517ug BC. Addition of alginate pellets of ThzIDl-M3 to the soils (10 per 50 g) resulted in increased indigenous microbial populations (total fungi, bacterial fluorescent Pseudomonas app., and actinomycetes). Furthermore, colonizing ability of ThzIDl-M3 on sclerotia of Sclerotinia sclerotiorum was significantly reduced in the soil with high revel of BC. These results suggest that increased soil microbial biomass contributes to increased interactions between introduced T. harzianum and soil microorganisms, consequently reducing the biocontrol efficacy of 1T. harzianum.

• International Journal of Oral Biology
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• v.42 no.3
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• pp.123-128
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• 2017

Recurrent aphthous stomatitis (RAS) is a common oral mucosal disorder for which no curative treatment is available. We previously reported that decreased Streptococcus salivarius and increased Acinetobacter johnsonii on the oral mucosa are associated with RAS risk. The purpose of this study was to identify antibiotics that selectively inhibit A. johnsonii but minimally inhibit oral mucosal commensals. S. salivarius KCTC 5512, S. salivarius KCTC 3960, A. johnsonii KCTC 12405, Rothia mucilaginosa KCTC 19862, and Veillonella dispar KCOM 1864 were subjected to antibiotic susceptibility test using amoxicillin, cefotaxime, gentamicin, clindamycin, and metronidazole in liquid culture. The minimal inhibitory concentration (MIC) was defined as the concentration that inhibits 90% of growth. Only gentamicin presented a higher MIC for A. johnsonii than MICs for S. salivarius and several oral mucosal commensals. Interestingly, the growth of S. salivarius increased 10~200% in the presence of sub-MIC concentrations of gentamicin, which was independent of development of resistance to gentamicin. In conclusion, gentamicin may be useful to restore RAS-associated imbalance in oral microbiota by selectively inhibiting the growth of A. johnsonii but enhancing the growth of S. salivarius.

• Korean Journal of Poultry Science
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• v.27 no.3
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• pp.227-233
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• 2000

Preset study was carried out to evaluate characteristics of lactic acid producing bacteria(LAB) in hen's cecum as probiotics value. Distribution of LAB in intestinal tracts was investigated using 5∼25 weeks - old hens. So, 12 strains to LAB with different morphology were isolated purely. Acid tolerance of LAB tested at pH 1, 2, 3, and 4, and bile resistant also tested at 0, 0.3% and 0.5% bile salt concentration. Growth pattern of LAB observed to 60h. All strains of cecal LAB couldn't survive at pH 1, and decreased linearly survival colony after incubation at pH 2 although some strains could survive for 2h. Most of LAB maintained constant number at pH 3 and 4. The bacterial action could increase linearly at 0% bile salt concentration in all of tested strains. However, only one strain could multiply at 0.3% bile salt, others were influenced by bile salt. That tendency was similar at 0.5% bile salt. Growth was peaked at 12 to 18 h after innoculation. After peak, the decreasing pattern of colony was different to strains which some strains decreased rapidly or maintained for long time. The LAB of hen's cecum was similar to intolerance acidity, but different to resistant to bile salt and growth pattern by strain. So, we choose three strains which have probiocs value, and identified as Lactobacillus amylovorus LLA7, Lactobacillus crispatus LLA9 and Lactobacillus vaginalis LLA11.

• Journal of Mushroom
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• v.15 no.1
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• pp.8-13
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• 2017

An auxin-producing bacterial strain, designated 4-3, was isolated from waste button mushroom compost in Boryeong-si, Chungnam. The strain 4-3 was classified as a novel strain of Leucobacter tardus, based on chemotaxonomic and phylogenetic analyses. TLC and HPLC the isolated L. tardus strain 4-3 produced indole-3-acetic acid (IAA), the auxin. Maximum IAA productionof $94.3mg\;L^{-1}$ was detected for bacteria cultured in R2A medium with 0.1% l-tryptophan, incubated for 24 h at $35^{\circ}C$. Negative correlationwas observed between IAA production and pH of the culture medium, indicating that the increase inIAA caused acidification ofthe medium. The effect of supplementation with varying concentrations of l-tryptophan, a known precursor of IAA, was also assessed. production was maximal at 0.1% l, but decreased at lconcentrations above 0.2%. To investigate the plant growth-promoting effects of the bacterium, L. tardus strain 4-3 culture broth was used to inoculate water cultures and seed pots of mung bean. We found thatadventitious root induction and root growth were 2.2-times higher in thethan in the non-inoculated plants.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.692-699
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• 1994

A bacterial strain which formed a distinct colony on agar plate containing phenol as a vapor phase and grew well in a liquid minimal medium was isolated and identified as Acinetobac- ter sp. GEM2. The optimal temperature and initial pH for the growth of Acinetobacter sp. GEM2 were 30$\circ$C and 7.0, respectively. Cell growth was inhibited by phenol at the concentration over 1500 ppm. Cell growth dramatically increased from 10 hours after cultivation and almost showed a stationary phase within 24 hours at which 95% of phenol was concomitantly degraded. Acinetobac- ter sp. GEM2 was capable of growing on aromatic compounds, such as benzoic acid, phenol, m- cresol, o-cresol, P-cresol, catechol, gentisic acid, and toluene, but did not grow on benzene, salicylic acid, p-toluic acid, and p-xylene. By the analysis of catechol dioxygenase, it seemed that catechol was degraded through both meta- and ortho-cleavage pathway. The growth-limiting log P value of Acinetobacter sp. GEM2 on organic solvents was 2.0.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.174-181
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• 2013

The plant growth-promoting rhizobacterium Ochrobactrum lupini KUDC1013 elicited induced systemic resistance (ISR) in tobacco against soft rot disease caused by Pectobacterium carotovorum subsp. carotovorum. We investigated of its factors involved in ISR elicitation. To characterize the ISR determinants, KUDC1013 cell suspension, heat-treated cells, supernatant from a culture medium, crude bacterial lipopolysaccharide (LPS) and flagella were tested for their ISR activities. Both LPS and flagella from KUDC1013 were effective in ISR elicitation. Crude cell free supernatant elicited ISR and factors with the highest ISR activity were retained in the n-butanol fraction. Analysis of the ISR-active fraction revealed the metabolites, phenylacetic acid (PAA), 1-hexadecene and linoleic acid (LA), as elicitors of ISR. Treatment of tobacco with these compounds significantly decreased the soft rot disease symptoms. This is the first report on the ISR determinants by plant growth-promoting rhizobacteria (PGPR) KUDC1013 and identifying PAA, 1-hexadecene and LA as ISR-related compounds. This study shows that KUDC1013 has a great potential as biological control agent because of its multiple factors involved in induction of systemic resistance against phytopathogens.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.285-290
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• 1989

The biololgical effect of the preemergence rice field herbicide, butachlor(commercial name, Machete) on purple nonsulfur photosynthetic bacterium Rhodospirillum rubrum KS-301 has been studied under cultural conditions. Bacterial growth showed a tendency to decline according to the degree of the concentration of butachlor until $10^{-3}$ M and slmost stopped at $10^{-2}$M. The growth inhibitory action at $10^{-3}$M of butachlor was evident (4.2-18.7% inhibition of growth rate) but had little effect in nitrogen fixation. Conversely, there was a little enhancement effect(1%) in pyruvate, dinitrogen gas growing cultures. At concentration of $10^{-3}$ M, instead of spiral form, rod shapes were observed through phase contrast microscope and instead of vesicular intracytoplasmic membrane, irregular tubular forms were observed through electron microscope. Alkaline pH value slightly reversed tha inhibitory action of butachlor.

• Journal of Microbiology
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• v.33 no.4
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• pp.295-301
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• 1995

An antifungal Pseudomonas stutzeri YPL-1 produced extracellular chitinase and .betha.-1, 3-glucanase that were key enzymes in the decomposition of fungal hyphal walls. These lytic extracellular enzymes markedly inhibited mycelial growth of the phytopathogenic fungus Fusarium solani. A chitinase from P. stutzeri YPL-1 inhibited fungal mycelial growth by 87%, whereas a .betha.-1, 3-glucanase from the bacterium inhibited growth by 53%. Furthermore, co-operative action of the enzymes synergistically inhibited 95% of the fungal growth. The lytic enzymes caused absnormal swelling and retreating on the fungal hyphal walls in a dual cultures. Scanning electron microscopy clearly showed hyphal degradation of F. solani in the regions interacting with P. stutzeri YPL-1. In an in vivo pot test, P. stutzeri YPL-1 proved to have biocontrol ability as a powerful agent in controlling plant disease. Planting of kidney bean (Phaseolus vulgaris L.) seedlings with the bacterial suspension in F. solani-infested soil significantly suppressed the development of fusarial root-rot. The characteristics of a crude preparation of .betha.-1, 3-glucanase produced from P. stutzeri YPL-1 were investigated. The bacterium detected after 2 hr of incubation. The enzyme had optimum temperature and pH of 40.deg.C and pH 5.5, respectively. The enzyme was stable in the pH range of 4.5 to 7.0 and at temperatures below 40.deg.C, with a half-life of 40 min at 60.deg.C.

• KSBB Journal
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• v.30 no.1
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• pp.33-37
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• 2015

Recently, several health benefits of rice wine, makgeolli, were known due to the interest on the traditional Korean liquor and the researches on the rice wine are increasing. Organic acids produced during the process of rice wine fermentation play important roles in the taste and flavor. In this study, we have examined the optimal conditions for lactic acid production in rice koji as a carbon source. Skim milk was also used as a supplementary ingredient for the optimization of lactic acid fermentation. Bacterial growth of Lactobacillus sakei was monitored under this condition. The pH, acidity of the culture and the ethanol tolerance of this bacterium were also tested. Through these experiments, we were able to optimize the growth condition of lactic acid bacteria by the addition of skim milk. This was also able to affect the change of pH, acidity, sugar concentration and alcohol tolerance, which might contribute to the improvement of the quality of rice wine. The optimal condition for the growth was 2 days with 10% (w/v) of skim milk concentration. With these results, it was confirmed that rice koji was an effective carbon source for the growth of lactic acid bacteria.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.700-706
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• 2000

Iron- and zinc-containing superoxide dismutase (FeZnSOD) and nickel-containing superoxide dismutase (NiSOD) are cytoplamic enzymes in Streptomyces griseus. The sodF gene coding for FeZnSOD was cloned from genomic Southern hybridization analysis with a 0.5-kb DNA probe, which was PCR-amplified with facing primers corresponding to the N-terminal amino acid of the purified FeZnSOD of S. griseus and a C-terminal region which is conserved among bacterial FeSODs and MnSODs. The sodF open reading frame (ORF) was comprised of 213 amino acid (22,430 Da), and the deduced sequence of the protein was highly homologous (86% identity) to that of FeZnSOD of Streptomyces coelicolor. The FeZnSOD expression of exponentially growing S. griseus cell was approximately doubled as the cell growth reached the early stationary phase. The growth-associated expression of FeZnSOD was mainly controlled at the transcriptional level, and the regulation was exerted through the 110 bp regulatory DNA upstream from the ATG initiation codon of the sodF gene.