Fluorescent bacteria were isolated from sporocarps that browned into various mushrooms during survey at places of the production in Korea. We examined the pathogenicity, biodiversity, and genetic characteristics of the 19 strains identified as Pseudomonas tolaasii by sequence analysis of 16S rRNA and White Line Assay. The results emphasize the importance of rpoB gene system, fatty acid profiles, specific and sensitive PCR assays, and lipopeptide detection for the identification of P. tolaasii. As a result of these various analyses, 17 strains (CHM03~CHM19) were identified as P. tolaasii. The phylogenetic analysis based on the 16S rRNA gene showed that all strains were clustered closest to P. tolaasii lineage, two strains (CHM01, CHM02) were not identified as P. tolaasii and have completely different genetic characteristics as a result of fatty acids profile, specific and sensitive PCR, lipopetide detection, rpoB sequence and REP-PCR analysis. Pathogenicity tests showed 17 strains produce severe brown discolouration symptoms to button mushrooms and watersoaking of sporophore tissue within three days after inoculation. But two strains did not produce discolouration symptoms. Therefore, these two strains will be further investigated for correct species identification by different biological and molecular characteristics.

The purpose of this study is to optimize the composition of the medium for turmeric fermentation and to select competent turmeric fermentation strains using bacterial isolates from kimchi. Initially, 30 isolates from kimchi were cultured in 5% (w/v) yeast extract and 1% (w/v) maltodextrin to determine viability. As a result, eight strains showed a tendency to maintain viability until the fifth day of fermentation. Subsequently, the eight isolates were fermented in an optimum medium for turmeric fermentation, 5% (w/v) yeast extract, 1% (w/v) maltodextrin, and 5% (w/v) turmeric for seven days to determine the viable cell count and antioxidant capacity. The antioxidant capacities of turmeric fermented by the eight isolates were similar or higher than turmeric fermented by Lactococcus lactis KCTC 2013, while maintaining high viable cell counts of both the eight isolates and L. lactis KCTC 2013 until the seventh day of fermentation. The antioxidant capacities of the selected five strains during fermentation might increase possibly due to the biological conversion of active compounds in turmeric by fermentation. Consequently, a total of five strains of the isolates showing higher antioxidant capacity (4.81±0.19-5.81±0.04 VCE/mL) than fermentation day 0 were selected for fermentation of turmeric.

We attempted to investigate antibacterial and proteolytic activities of bacteria isolated from three ethnic fermented seafoods in the east coast of South Korea, gajami sikhae, squid jeotgal, and fermented jinuari (Grateloupia filicina). Bacillus cereus ATCC 14579, Listeria monocytogenes ATCC 15313, Staphylococcus aureus KCTC 1916, Escherichia coli O157:H7 ATCC 43895, and Salmonella enterica serovar Typhimurium ATCC 4931 were selected to determine the antibacterial activity of the bacterial isolates. Among 233 isolates from the three foods, 36 isolates (15.5%) showed antibacterial activity against B. cereus ATCC 14579, the highest incidence of inhibition, followed by S. aureus KCTC 1916 (7.7%) and L. monocytogenes ATCC 15313 (6.0%). However, only five and three strains among the isolates exhibited inhibitory activity against Gram-negative indicators, E. coli ATCC 43895 and Sal. enterica ATCC 4931, respectively. The proteolytic activity of the isolates was determined via hydrolysis of skim milk after 24, 48, and 72 h incubation. After 72 h incubation, 72 out of 233 isolates (30.9%) showed proteolytic activity, and the isolates of fermented jinuari exhibited the highest incidence of proteolytic activity (60%, 36 isolates). These results suggest that ethnic fermented seafoods in the east coast of South Korea might be a promising source of bacterial strains producing antibacterial and proteolytic compounds.

선발에 의하여 얻은 벼 흰빛잎마름병균 Xanthomonas oryzae의 Streptomycin 내성균에 대하여 병원성, 배지내에서의 생장량 및 자외선 감수성에 대한 변이성을 조사하여 다음과 같은 결과를 얻었다. (1) SM 내성균은 Wase-Aikoku-3, Rant Emas-2 황옥 및 Kimmase의 4개 판별품종에 대한 병원성 비교에서 75-6의 내성균주가 황옥에 대하여 감수성 반응이 모균과 달리 중정도의 저항성을 나타내었다. 2) SM-내성균은 정상배지에서 모균보다 약간 높은 생장량을 보였고 100ug/ml Agrepto 첨가 배지에서는 접종후 60시간까지 생장이 조지되었으나 70시간 이후에는 모균의 생장량을 능가하였다. (3) SM-내성균은 254mu 파장의 자외선 조사에서 모균과 동일한 감수성을 나타내어 내성인자는 안정된 것으로 생각되었다.

Bacterial blight (BB) of rice, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a significant disease in most rice cultivation areas. The present study was performed to identify new BB R-gene conferring resistance to Korea Xoo isolates, derived from IR65482-7-216-1-2 and to construct a physical map of the candidate gene. An F2 population derived from a cross between 11325 and Anda was used to determine the exact position of the nearest recombination event to the target region. The position of the R-gene was delimited by flanking markers, RM1233 and RM5766, on chromosome 11. Of the 56 markers designed in the flanking region, 20 were selected as anchor markers and the R-gene was mapped to a 295kb region on chromosome 11. To narrow down the interval spanning the R-gene, an additionally SSR marker, 20 STS markers, and CAPS marker between RM27320 and ID55.05-79 were developed using rice reference genome information. From the result the gene was defined by RM27320 and ID55.WA18-5 located in the BAC clone OSJNBa0036K13. The physical distance between these two markers is approximately 80kb. In a further study, gene expression analysis against listed candidate genes was investigated using semi-quantitative transcription PCR. These results will useful for future disease breeding as well as gene function studies regarding resistance genes.

Japonica rice cultivars exhibit high susceptibility to bacterial blight(BB) disease due to genetic vulnerability in Korea. Korean japonica resistant rice cultivars mainly possess one of the genes, Xa1 or Xa3 for BB resistance. These resistance genes are becoming susceptible to K3a, resulting in serious rice yield reduction. This study was carried out to confirm the effect of xa13 gene pyramiding for developing of japonica rice cultivars resistant to BB pathogen breaking down Xa1 or Xa3. IRBB4 conferring Xa4 gene was resistant to K1(HB01013), K2(HB01014), K3(HB01015), and moderately resistant to K3a(HB01009). IRBB5 having xa5 gene was resistant to K1, K2, K3, and K3a. The recessive gene xa13 was resistant to K1 race but susceptible to K2, K3, and K3a. But Xa21 gene is susceptible to predominant K1 race but resistant to other races such as K2, K3, and K3a. Two genes Xa3 and xa13 were susceptible and Xa4 gene was moderate resistant to 24 isolates. xa5 and Xa21 genes were resistant to all isolates including K3a. When xa13 gene combined Xa4, xa5 and Xa21 genes, effect of xa13 gene pyramiding showed higher resistant reaction than that having singe gene out of Xa4, xa5, and Xa21. The order of resistance against 24 isolates breaking down Xa3 gene was IRBB55(xa13+Xa21) > IRBB53 (xa5+xa13) > IRBB51 (Xa4+xa13).

Japonica rice cultivars exhibit high susceptibility to BB disease due to genetic vulnerability in Korea. Korean Japonica rice cultivars mainly posses the genes, Xa1 and Xa3 for BB resistance. These resistance genes are becoming susceptible to K3a, new races of BB, resulting in the breakdown of resistance in high yielding Japonica cultivars. It is imperative to look for novel R-genes for improvement of japonica rice resistant to BB races. This study was carried out to conform useful single gene resistant to 24 BB isolates (including K3a, HB01009) breaking down Xa3 gene. Cultivars and near-isogenic lines (NILs) carrying Xa1, Xa2, xa8, Xa10, Xa11, xa13 genes were susceptible to 24 isolates, whereas IRBB4 carrying Xa4 gene was moderate resistance. IRBB5 and IRBB21 having xa5 and Xa21 genes, respectively, expressed resistance to these isolates. IRBB7 having Xa7 gene showed resistance response to 24 BB isolates, whereas JBB-107 carrying Xa7 gene was susceptible to 10 BB isolates and moderate resistant to 14 BB isolates. Xa7 gene showed different resistance response according to genetic background of used recurrent parent. With these findings, Xa4, xa5, and Xa21 would be the most prospective genes to 24 isolates used in screening.

한국 4균주와 일본 3균주에 대한 진성 저항성 유전자가 단일 혹은 복수로 집적되어 있는 근동질 저항성 유전자계통의 생육시기별 저항성 반응을 검정한 결과를 보면 다음과 같다. 1. 유묘기때, 단일 진성저항성 유전자를 갖는 근동질 유전자 계통들은 한국 균주 K1 균주에 대해 대부분 저항성 반응을 보인 반면, K2,K3 및 K3a는 이병성 반응을 보이는 계통들이 많았다. IRBB5(xa5)만이 4균주 모두에 대해 고도의 저항성을 보였다. 한편, 일본 균주 접종에 대한 반응도 한국 균주의 반응과 유사하였다. 2. 최고분얼기때, 근동질 유전자 계통들의 K1,K3a 균주에 대한 반응은 유묘기와 유사하였으며, K2,K3 균주에 대해서는 유묘기와 비교하여 중도저항성 및 저항성으로 반응하였다. 일본의 RaceI, II 균주는 대부분의 근동질 유전자 계통들이 유묘기 보다 저항성 정도가 증대 되었으나, RaceIII균주는 감수성으로 반응하였다. 모든 균주에 고도의 저항성을 보인 계통은 IRBB205(xa5), IRBB207(Xa7)이었다. 3. 출수기때, Xa1, xa8, Xa10을 보유한 계통들은 K2 균주에 이병성으로 반응하였지만, 다른 근동질 유전자 계통들은 K1,K2 및 K3 균주에 대해 고도의 저항성 반응을 보였다. 이에 반해, K3a는 Xa1, Xa2, Xa3, xa8, Xa10, Xa11 및 xa13을 보유한 계통을 가해하였다. 일본의 RaceI, II, III 균주는 최고분얼기때의 반응과 유사하였다. xa5를 갖는 IRBB5, IRBB105 및 IRBB205 계통은 모든 검정균주에 대해 저항성으로 반응하였다. 4. 2개 이상의 진성 저항성 유전자를 갖는 계통들은 벼 생육시기 전 과정에서 벼흰잎마름병균에 대해 저항성 정도가 현저하게 증가되었다. 결론적으로, 저항성의 안정화를 위해서는 Xa4, xa5, Xa7 등의 유전자의 집적이 유용할 것으로 판단된다.