• 미생물학회지
• /
• 제45권2호
• /
• pp.185-192
• /
• 2009

Bacillus subtilis 028-1 균주는 청국장 발효에 사용하는 균주로 Staphylococcus sp. LS2 뿐만 아니라 여러 yeast 균주의 생장을 억제하는 항생물질을 생산하며, soybean meal 2%와 maltose와 같은 이당류를 1% 첨가하여 15~18시간 진탕 배양하였을 때 최대의 항생물질 생산을 보였으며 배지의 pH는 6.5 이하였다. 항생물질의 활성은 약염기성 조건에서 극대화되었으며, $100^{\circ}C$에서 20분간 가열하여도 활성은 크게 감소하지 않았고, 실온 보관 시 한 달 이상 효과가 지속되며 chymotrypsin과 papain 같은 단백질 분해효소 처리에 의해 서서히 활성이 줄어들었다. 투석에 의해 항생물질의 분자량을 측정한 결과 1,000에서 500 dalton 사이인 것으로 나타났으며 항미생물 효과는 있으나 fibrin 분해 능력이 없으므로 surfactin이 아닌 iturin 계열의 peptide성 항생물질로 보인다.

• 한국식품영양과학회지
• /
• 제30권4호
• /
• pp.594-599
• /
• 2001

혈압상승을 주도하는 효소인 angiotensin converting enzyme(ACE)의 활성을 저해하는 펩타이드를 생산하는 protease 분비 균을 간장으로부터 분리하여 동정하였다. 여러대두 발효식품으로부터 단백질 분해능이 있는 균주를 분리하고, 분리된 균주들 중에서 ACE 저해활성이 가장 높은 균주인 SS103 균주를 선정하였다. 선정된 SS103 균주는 운동성이 있는 gram 양성 간균으로 내생포자를 형성하는 호기성균이었으며, pH 5~9 사이에서 생육하고 생육온도는 2$0^{\circ}C$~$50^{\circ}C$로 내열성이 약한 중온균의 특성을 보였으며, glucose, sucrose, mannitol 및 sorbitol 등의 당 이용 특성을 보였다. 그리고 세포의 지방산 조성은 $C_{15:0}$ anteiso, $C_{17:0}$ cis 형 및 $C_{17:0}$ iso 형이 주된 지방산으로 각각 33.9%, 18.8% 및 16.5%의 분포를 나타내었다. 이상과 같은 분석 겨과를 토대로 SS103 균주는 Bacillus subtilis로 동정되었다. Bacillus subtilis SS103 균주의 최적 배양 조건은 $37^{\circ}C$, 초기배양액 pH 8.0에서 배양시간 48시간으로 나타났으며, 이때 통기량이 높은 경우 효소활성도 높은 특성을 보였다.을 보였다.

• KSBB Journal
• /
• 제28권1호
• /
• pp.42-47
• /
• 2013

This study was performed to find cellulolytic strain of enzymatic saccharification for bioethanol production. Cellulolytic strains were isolated from 59 different feces of herbivores from Seoul Grand Park located in Gwacheon Gyeonggi-Do. The celluloytic strain was selected by congo red staining and DNS method. Among the isolated strains, H9-1 strain isolated from the feces of rabbit has the highest CMCase activity. H9-1 strain was identified as Bacillus sp. based on 16S rDNA gene sequencing. The optimal conditions for CMCase activity by Bacillus sp. H9-1 were at $40^{\circ}C$ and at initial pH 8.

• 생명과학회지
• /
• 제23권2호
• /
• pp.242-248
• /
• 2013

본 연구의 목적은 우수한 미생물 제제 개발용 인산염 가용화 균주의 개발이다. 경작지 토양에서 분리한 인산염 가용화 균주의 특성 및 16S rDNA 염기서열을 조사한 결과 Bacillus subtilis HR-1019로 동정되었다. Bacillus subtilis HR-1019는 hydroxyapatite, tri-calcium phosphate 및 aluminum phosphate 3가지의 난용성 인산염을 모두 가용화하였다. 난용성 인산염의 분해능이 최대가 되는 배양온도는 $37^{\circ}C$이었으며, 배양초기 pH가 5.0이었다. 탄소원으로 glucose를 5% 첨가시 가용화능이 높았으며, 가용화된 유리인산의 함량이 증가함에 따라 pH가 크게 감소하였다. 분리균주 HR-1019가 식물병원균에 대하여 균의 생육을 저지하는 clear zone 확인으로 항균효과를 확인하였다.

• Journal of Microbiology and Biotechnology
• /
• 제18권10호
• /
• pp.1630-1633
• /
• 2008

A novel putative toxin-antitoxin segregational stability system named KyAB system was identified in a novel native plasmid pBMB8240 from Bacillus thuringiensis strain YBT-1520, based on sequences homology with other toxin-antitoxin systems, the lethal activity of the KyB putative toxin in Escherichia coli and the stabilizing effect of the kyAB system in Bacillus thuringiensis. Secondarily, the native plasmid pBMB9741 from the same strain was resequenced and the corrected plasmid was named as pBMB7635. Based on sequence homology with the tasAB system and the lethal activity of toxin protein in Escherichia coli, a tasAB-like putative toxin-antitoxin system was identified on pBMB7635.

• KSBB Journal
• /
• 제25권3호
• /
• pp.230-238
• /
• 2010

A microbial strain having high keratinase activity was isolated from the soil of poultry factories of Gyeonggi or Chungcheong-do. The isolated strain was identified as Bacillus sp. based on its morphological and biochemical characteristics. In this study, the optimal conditions for the production of keratinase by this strain were investigated. The optimal medium composition for the keratinase production was determined to be 3.5% chicken feather as carbon source, 1.0% tryptone as organic nitrogen source, 1.0% $KNO_3$ as inorganic nitrogen source and 0.05% KCl, 0.05% $KH_2PO_4$, 0.03% $K_2HPO_4$ as mineral source and 0.01% yeast extract as growth factor. The optimal temperature and pH was $40^{\circ}C$ and 8.5 with shaking culture (200 rpm), respectively. The maximum keratinase production reached to 123 units/ml after 42 hr of cultivation under the optimal condition. When the hair was used as the sole carbon source, the maximum enzyme activity was 88 units/ml after 120 hr and in this case, the hair added in the medium was not degraded completely but got thinner than the control by 20%.

• Journal of Microbiology and Biotechnology
• /
• 제14권3호
• /
• pp.599-606
• /
• 2004

Gram-positive antagonistic bacilli were isolated from agricultural soils for possible use in biocontrol of plant pathogenic fungi, Fusarium oxysporum, Rhizoctonia solani, and/or Pythium ultimum. Among the 65 antagonistic Gram-positive soil isolates, 22 strains were identified as Bacillus species by 16S rDNA sequence analyses. Four strains, including DF14, especially exhibited multiple antagonistic properties against the three damping-off fungi. Genotypic properties of the Bacillus isolates were characterized by rapid molecular fingerprinting methods using repetitive extragenic palindromic-PCR (REP-PCR), ribosomal intergenic spacer-length polymorphisms (RIS-LP), 16S rDNA PCR-restriction fragment length polymorphisms (PCR-RFLP), and strain-specific PCR assays. The results indicated that the REP-PCR method was more valuable than the RIS-LP and 16S rDNA PCR-RFLP analyses as a rapid and reliable approach for bacilli typing and identification. The use of strain-specific primers designed based on 16S rDNA sequence comparisons enabled it to be possible to selectively detect a strain, DF14, which is being used as a biocontrol agent against damping-off fungi.

• Journal of Microbiology and Biotechnology
• /
• 제28권6호
• /
• pp.1030-1036
• /
• 2018

Bacillus strains produce various types of antibiotics, and random mutagenesis has traditionally been used to overproduce these natural metabolites. However, this method leads to the accumulation of unwanted mutations in the genome. Here, we rationally designed a single nucleotide substitution in the degU gene to generate a B. subtilis strain displaying increased plipastatin production in a foreign DNA-free manner. The mutant strain (BS1028u) showed improved antifungal activity against Pythium ultimum. Notably, pps operon deletion in BS1028u resulted in complete loss of antifungal activity, suggesting that the antifungal activity strongly depends on the expression of the pps operon. Quantitative real-time PCR and lacZ assays showed that the point mutation resulted in 2-fold increased pps operon expression, which caused the increase in antifungal activity. Likewise, commercial Bacillus strains can be improved to display higher antifungal activity by rationally designed simple modifications of their genome, rendering them more efficient biocontrol agents.

• 한국식품영양과학회지
• /
• 제27권4호
• /
• pp.609-617
• /
• 1998

A microorganism capable of producing high level of extracellular cyclodextrin glucanotransferase(EC 2.4.1.19 ; CGTase) was isolated from Kimchi. 2-O-$\alpha$-D-glucopyranosyl L-ascorbic acid(AA-2G) was synthesized by transglycosylation reaction of CGTase using starch as a donor and L-ascorbic acid as an acceptor. The isolated strain S-6 was identified as Bacillus sp. S-6. The maximal CGTase production was observed in a medium containing 0.5% soluble starch, 1% yeast extract, 1% NaCO3, 0.1% K2HPO4, and 0.02% MgSO4 with initial pH 8.0. The strain was cultured at 37$^{\circ}C$ for 40 hr with reciprocal shaking. Using the culture supernatant as crude enzyme, the optimal pH and temperature of the CGTase activity of this strain were 7.0 and 4$0^{\circ}C$. In the effects of pH and temperature on the stability of the enzyme, the enzyme was stable in the range of pH 6.0~10.0 and up to 45$^{\circ}C$, respectively.

• 미생물학회지
• /
• 제33권2호
• /
• pp.136-141
• /
• 1997

한국의 전통 발효식품인 된장에서 단백질 분해효소를 분비하는 미생물의 존재를 규명하기 위해, skim milk 한천배지를 이용하여 투명환을 보이는 균주들을 얻었고, 각종 생리 및 생화학적 검사, VITEK system, MIDI system을 통해 이들 중, JH-1, SH-5, SH-7의 3 strain이 Bacillus cereus임을 동정하였다. JH-1과 SH-5 균주가 분비하는 단백질 분해효소는 pH 9와 40^{\circ}C.$에서 최적활성을 보였으며, SH-7 균주는 pH 8과 50^{\circ}C.$에서 최적활성을 보였다. 또한 이들 3균주는 blood agar plate에서 용혈능력을 보였다.