• 한국동물위생학회지
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• 제19권2호
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• pp.139-153
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• 1996

Porcine E coli infection is a disease caused by Enterotoxin produced by Enterotoxigenic Escherichia coli(ETEC). Enteric colibacillosis has become an economically important disease in pigs as a result of increasing intensification of farrowing management. The present study undertaken to obtain the antibiotic sensitivity and distribution of serogroups and pili producibility test of ETEC from E. coli isolates in Chonnam. The results obtained were as follows. 1. A total of 71 isolates identified as E, coli employing IMViC system from rectal specimens of 54 piglets with diarrhea. 2. In antibiotic sensitivity test, isolates showed high sensitivity to AN, CM, Fox, GM, but resistance to EM, NA TC. 3. The distribution of 25 Isolates of serogroups were 0141:K85(11.3%), 08:K87(8.5%), 064:K (5.6%), 0138:K8l (4.2%), 0139 :K82(2.8%), 0157:K88ac(1.4%) and 0149:K9l (1.4%). 4. MRHA of guinea pig erythrocytes was detected in 8 out of 25OK serotypes and 9 out of 46 unidentified serotypes. MRHA titers of serotypes showed from 64 to 128 in 0141: K85, 2 in 0138:K8l and no titers in 0139:K82. 5. The production of heat labile enterotoxin of ETEC was detect 39 out of 52 isolates showed $\beta$-hemolysin, 7 out of 52 isolates showed ${\gamma}$-hemolysin and 6 out of 52 isolates showed ${\gamma}$-hemolysin by $GM_1$ganglioside ELISA. The distribution of LT toxin were in 12 isolate showed $\beta$-hemolysin, 2 isolates showed ${\alpha}$-hemolysin and 3 isolates showed ${\gamma}$-hemolysin in 25 OK serotypes.

• 한국미생물·생명공학회지
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• 제21권1호
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• pp.41-46
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• 1993

순수분리된 2,000여 주의 혐기성 세균으로부터 선발된 stain KH-431은 bacteria 및 fungi에 대하여 재현성있는 항균활성을 보이는 물질을 생산하였다. Strain KH-431은 그 형태 및 생리, 생화학적 특성으로 미루어 보아 Clostridium fallax의 근연종으로 동정되었다. strain KH-431의 항생물질 생산을 위한 최적 배양조건에 대해 고찰한 결과 PY배지를 기초배지로 사용하고 sorbitol, yeast extract, d-biotin 그리고 $CaCl_2$를 영양원으로 첨가하였을 때가 양호한 것으로 나타났다. 배지초기 pH 및 배양온도 배양시간에 대한 최적조건은 각각 pH7과 $30^{\circ}C$, 108시간으로 나타났다.20$\ell$ 의 배양액으로부터 solvent extraction, silica gel column chromatography를 거쳐 얻은 sample을 재결정한 결과 KG-431B는 순수한 결정상태로 얻어졌으나 KG-431A의 완전정제에는 많은 문제점이 뒤따른 바 현재 다른 정제방법의 도입을 고려중에 있다.

• 미생물학회지
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• 제8권1호
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• pp.41-51
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• 1970

S.albus subsp.와 S.globosus에서 Tetracyclin과 Streptomycin 같은 항생물질을 생성된다는 것은 이미 전보에서 밝힌 바 있다. 이들 두 種의 생장최적조건과 항생제 생성정도와의 관계를 배지성분과 그 농도에 따라 검토하였다. 그 결과 S.albus subsp.와 S.globosus 모두 배양시간이 130~150시간이 될때 항생물질 생성과 균체량이 최고에 달했다. 그리고 PH는 그 근처에서만 떨어지는 현상을 볼 수 있었다. 또한 두 균주 모두 탄소원으로서는 starch(4~5%)질소원으로서는 soybeam meal(1.5~2.0%)에서 균체의 생장도 양호하고 향균력도 높게 나타났다. 이외의 성분으로는 calcium carbonate(2mg/ml), potassium phosphate' dibasic(0.05M~0.01M), magnesium sulfate(0.01M~0.03M) ferric chloride(0.01M)가 가장 생장에 좋은 배지농도로 추정되며 zinc ion(0.0005M)은 균체생장을 현저하게 억제하였다.

• 미생물학회지
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• 제53권4호
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• pp.329-331
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• 2017

식물 내생 세균인 Bacillus velezensis YC7010은 벼의 병원성 세균과 곰팡이에 대해 전신유도저항성을 일으키며, 식물생육촉진 및 항생작용의 특징을 가지고 있다. 대한민국 진주지역 벼의 근권에서 분리된 B. velezensis YC7010의 유전체는 3,790개의 단백질-암호화 유전자(86 tRNAs와 27 rRNA 유전자)로 구성되어 있으며, 3,975,683 염기쌍의 환상 염색체이다. 유전체 분석을 통해 식물의 발달과 생육을 촉진하는 휘발성 화합물, 식물호르몬 생산, surfactin, plipapastatin, bacillibactin, bacillaene 같은 활성 화합물의 생합성, 식물 내부정착 및 군집화와 관련된 유전자들이 유전체에 존재하는 것을 확인하였다

• Journal of Microbiology and Biotechnology
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• 제31권11호
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• pp.1591-1600
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• 2021

Streptomyces coelicolor is a filamentous soil bacterium producing several kinds of antibiotics. S. coelicolor abs8752 is an abs (antibiotic synthesis deficient)-type mutation at the absR locus; it is characterized by an incapacity to produce any of the four antibiotics synthesized by its parental strain J1501. A chromosomal DNA fragment from S. coelicolor J1501, capable of complementing the abs- phenotype of the abs8752 mutant, was cloned and analyzed. DNA sequencing revealed that two complete ORFs (SCO6992 and SCO6993) were present in opposite directions in the clone. Introduction of SCO6992 in the mutant strain resulted in a remarkable increase in the production of two pigmented antibiotics, actinorhodin and undecylprodigiosin, in S. coelicolor J1501 and abs8752. However, introduction of SCO6993 did not show any significant difference compared to the control, suggesting that SCO6992 is primarily involved in stimulating the biosynthesis of antibiotics in S. coelicolor. In silico analysis of SCO6992 (359 aa, 39.5 kDa) revealed that sequences homologous to SCO6992 were all annotated as hypothetical proteins. Although a metalloprotease domain with a conserved metal-binding motif was found in SCO6992, the recombinant rSCO6992 did not show any protease activity. Instead, it showed very strong β-glucuronidase activity in an API ZYM assay and toward two artificial substrates, p-nitrophenyl-β-D-glucuronide and AS-BI-β-D-glucuronide. The binding between rSCO6992 and Zn²⁺ was confirmed by circular dichroism spectroscopy. We report for the first time that SCO6992 is a novel protein with β-glucuronidase activity, that has a distinct primary structure and physiological role from those of previously reported β-glucuronidases.

• Journal of Microbiology and Biotechnology
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• 제32권2호
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• pp.220-227
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• 2022

The spread of antibiotic-resistant strains of Staphylococcus aureus, a gram-positive opportunistic pathogen, has increased due to the frequent use of antibiotics. Inhibition of the quorum-sensing systems of biofilm-producing strains using plant extracts represents an efficient approach for controlling infections. Torilis japonica is a medicinal herb showing various bioactivities; however, no studies have reported the anti-biofilm effects of T. japonica extracts against drug-resistant S. aureus. In this study, we evaluated the inhibitory effects of T. japonica ethanol extract (TJE) on biofilm production in methicillin-sensitive S. aureus (MSSA) KCTC 1927, methicillin-resistant S. aureus (MRSA) KCCM 40510, and MRSA KCCM 40511. Biofilm assays showed that TJE could inhibit biofilm formation in all strains. Furthermore, the hemolysis of sheep blood was found to be reduced when the strains were treated with TJE. The mRNA expression of agrA, sarA, icaA, hla, and RNAIII was evaluated using reverse transcription-polymerase chain reaction to determine the effect of TJE on the regulation of genes encoding quorum sensing-related virulence factors in MSSA and MRSA. The expression of hla reduced in a concentration-dependent manner upon treatment with TJE. Moreover, the expression levels of other genes were significantly reduced compared to those in the control group. In conclusion, TJE can suppress biofilm formation and virulence factor-related gene expression in MSSA and MRSA strains. The extract may therefore be used to develop treatments for infections caused by antibiotic-resistant S. aureus.

• Journal of Microbiology
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• 제42권4호
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• pp.305-314
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• 2004

An exopolysaccharide-producing microalgal dinoflagellate was isolated from a red-tide bloom and des­ignated strain KG03. A bacteria-free culture of strain KG03 was achieved using a modified wash with phototaxis and antibiotic treatment. Combined treatment with neomycin and cephalosporin was the most effective for eliminating the bacteria associated with the microalgae. Strain KG03 was identified as Gyrodinium impudicum by analyzing the ITS regions of the 5.8S rDNA, 18S rDNA, morphological phenotype and fatty acid composition. The exopolysaccharide production and cell growth in a 300-ml photobioreactor were increased 2.7- and 2.4-fold, respectively, compared with that in a flask culture at the first isolation step.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.299-302
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• 2000

Actinoplanes teichomyceticus ATCC 31121 was mutated with UV to obtain a superior mutant strain with increasing level of teicoplanin production. In this investigation lethal curve was obtained and the optimal condition to induce mutagenesis was determined and to isolate the desirable mutant strain. It was also confirmed that teicoplanin activities by agar diffusion method to be compared to the mother strain. One mutant strain, T991014-1 that had the highest teicoplanin productivity was finally selected for further investigation including fermentation pattern. The mutant was characterized by the various tests such as amylase activity, protease activity, antibiotic resistance, autotoxicity, and productivity.

• Asian-Australasian Journal of Animal Sciences
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• 제26권1호
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• pp.116-121
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• 2013

The effects of oligosaccharide supplementation on the growth performance, flock uniformity and GIT development of broiler chickens were investigated. Four diets, one negative control, one positive control supplemented with zinc-bacitracin, and two test diets supplemented with mannoligosaccharide (MOS) and fructooligosaccharide (FOS), were used for the experiment. Birds given MOS or FOS had improved body weight (BW) and feed efficiency (FCR), compared to those fed the negative control diet during the 35-d trial period. The effect on FCR became less apparent when the birds got older. FOS and MOS supplementation reduced the pancreas weight as a percentage of BW, with an effect similar to that of the antibiotic, at 35 d of age. Birds given MOS tended to have a heavier bursa (p = 0.164) and lower spleen/bursa weight ratio (p = 0.102) at 35 d of age. MOS and Zn-bacitracin showed a clear improvement on flock uniformity, compared to FOS. The mortality rate was not affected by FOS or MOS.

• 한국가금학회지
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• 제39권1호
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• pp.53-62
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• 2012

In the past, poultry nutrition has focussed on increasing the production efficiency to meet the progress achieved in the genetic potential of broilers and layers. Future directions in poultry nutrition will be driven by not only by the need to maximise biological and economic performance of birds, but also by societal issues (environment, antibiotic growth promoters, welfare, traceability and use of genetically modified ingredients). Key advances in poultry nutrition are discussed and future directions, which can be expected, are highlighted. Given the tightening supply and ever-increasing cost of raw materials, there will be more pressure to extract every unit of energy and nutrients from feed ingredients. In this context, a number of feed additives are expected to play an increasingly significant role. Feed enzymes and crystalline amino acids, in particular, will have a profound effect on future sustainability of the poultry industry. Future nutritional research need to focus on identifying the barriers to effective digestion and utilisation of nutrients and, to achieve this objective, nutritionists must combine their expertise with those of specialising in other biological sciences, including immunology, microbiology, histology and molecular biology.