Biocontrol Science
Online ISSN : 1884-0205
Print ISSN : 1342-4815
ISSN-L : 1342-4815
18 巻 , 3 号
選択された号の論文の9件中1~9を表示しています
Review
  • CAROLINE F. AJILOGBA, OLUBUKOLA O. BABALOLA
    2013 年 18 巻 3 号 p. 117-127
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    Fusarium wilt is caused by the fungal pathogens, Fusarium oxysporum or Fusarium solani. It is a devastating disease that affects many important food and vegetable crops and a major source of loss to farmers worldwide. Initial strategies developed to combat this devastating plant disease include the use of cultural, physical and chemical control. None of these strategies have been able to give the best results of completely ameliorating the situation except for the cultural method which is mainly preventive. A good knowledge of the nature, behaviour and environmental conditions of growth of the disease agent is very important to controlling the disease development in that case. Biological control has been shown to be an environmentally friendly alternative. It makes use of rhizospheric and endophytic microorganisms that can survive and compete favourably well with the Fusarium wilt pathogen. They include plant growth-promoting rhizobacteria (PGPR) such as Bacillus spp. and Pseudomonas spp.. For PGPR to control or inhibit the growth of the Fusarium wilt pathogen, they make use of mechanisms such as indole acetic acid production, siderophore production, phosphate solublilization, systemic resistance induction and antifungal volatile production among others.
Original
  • MIHO MORI, MITSUHIRO GOMI, NORIHIKO MATSUMUNE, KAZUMA NIIZEKI, YOSHIKA ...
    2013 年 18 巻 3 号 p. 129-135
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    To evaluate the sanitary conditions of toilets, the bacterial counts of the toilet bowl biofilms in 5 Kansai area and 11 Kansai and Kanto area homes in Japan were measured in winter and summer seasons, respectively. Isolates (128 strains) were identified by analyzing 16S ribosomal RNA sequences. The number of colonies and bacterial species from biofilms sampled in winter tended to be higher and lower, respectively, than those in summer. Moreover, the composition of bacterial communities in summer and winter samples differed considerably. In summer samples, biofilms in Kansai and Kanto areas were dominated by Blastomonas sp. and Mycobacterium sp., respectively. Methylobacterium sp. was detected in all toilet bowl biofilms except for one sample. Methylobacterium sp. constituted the major presence in biofilms along with Brevundimonas sp., Sphingomonas sp., and/or Pseudomonas sp. The composition ratio of the sum of their genera was 88.0 from 42.9% of the total bacterial flora. The biofilm formation abilities of 128 isolates were investigated, and results suggested that Methylobacterium sp. and Sphingomonas sp. were involved in biofilm formation in toilet bowls. The biofilm formation of a mixed bacteria system that included bacteria with the highest biofilm-forming ability in a winter sample was greater than mixture without such bacteria. This result suggests that isolates possessing a high biofilm-forming activity are involved in the biofilm formation in the actual toilet bowl. A bactericidal test against 25 strains indicated that the bactericidal activities of didecyldimethylammonium chloride (DDAC) tended to be higher than those of polyhexamethylene biguanide (PHMB) and N-benzyl-N,N-dimethyldodecylammonium chloride (ADBAC). In particular, DDAC showed high bactericidal activity against approximately 90% of tested strains under the 5 h treatment.
  • HIROYO IKAI, KEISUKE NAKAMURA, TARO KANNO, MIDORI SHIRATO, LUIZ MEIREL ...
    2013 年 18 巻 3 号 p. 137-141
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    The in vitro antibacterial activity of the hydroxyl radical generation system by the photolysis of H2O2 in combination with proanthocyanidin, which refers to a group of polyphenolic compounds, was examined. Bactericidal activity of photo-irradiated H2O2 at 405 nm against Streptococcus mutans, a major pathogen of dental caries, was augmented in the presence of proanthocyanidin, whose bactericidal effect by itself was very poor, in a concentration-dependent manner. This combination was also proven effective against Porphyromonas gingivalis, a major pathogen of periodontitis. It is speculated that H2O2, generated from photo-irradiated proanthocyanidin around the bacterial cells, is photolyzed to the hydroxyl radical, which would in turn affect the membrane structure and function of the bacterial cells, resulting in augmented sensitivity of bacterial cells to the disinfection system utilizing the photolysis of H2O2. The present study suggests that the combination of H2O2 and proanthocyanidin works synergistically to kill bacteria when photo-irradiated.
  • EIJI TANESAKA, HIRONORI TAKEDA, MOTONOBU YOSHIDA
    2013 年 18 巻 3 号 p. 143-149
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    This study examined how the addition of a sawdust extract from Castanopsis cuspidata, several aromatic compounds, and copper affected the expression of a phenol-oxidizing enzyme in the white-rot basidiomycete, Lentinula edodes. Compared to liquid media that had not been supplemented with sawdust extract (MYPG), MYPG containing low (MYPG-S100) or high (MYPG-S500) concentrations of sawdust extract had a marked effect on the promotion of mycelial growth. No manganese peroxidase (MnP) production was observed in either MYPG or MYPG-S100 media until 35 days after inoculation. However, MnP production was enhanced by culture in MYPG-S500, with a marked increase observed suddenly at 14 days after inoculation. Northern blot analysis revealed that the transcription of the lemnp2 gene coding extracellular MnP was initially observed at detectable levels at day 10 after the initial inoculation of MYPG-S500, increasing gradually thereafter until days 22-25. However, laccase (Lcc) production was not observed in any of the media until 35 days after inoculation. Addition of 10 mM aromatic compounds - 1,2-benzenediol, 2-methoxyphenol, hydroquinone, and 4-anisidine - into the MYPG-S500 medium completely inhibited MnP production and did not enhance any Lcc production. While the addition of 1 or 2 mM Cu2+ (CuSO4・5H2O) to MYPG-S500 medium completely inhibited MnP production, this Cu2+ addition caused a marked increase in Lcc production at 17 and 6 days after the addition, respectively.
Note
  • HIROKAZU OGIHARA, FUMIKO ENDOU, SOICHI FURUKAWA, HIROSHI MATSUFUJI, KO ...
    2013 年 18 巻 3 号 p. 151-155
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    Solvent extracts from the carnivorous plant Dionaea muscipula (Venus flytrap) were prepared using eight different organic solvents, and examined for antibacterial activity against food-related pathogenic and putrefactive bacteria. All solvent extracts showed higher antibacterial activity against gram positive bacteria than against gram negative bacteria. The TLC-bioautography analysis of the extracts revealed that a yellow spot was detected at Rf value of 0.85, which showed strong antibacterial activity. The UV, MS, and NMR analyses revealed that the antibacterial compound was plumbagin.
  • SHIGEKO UEDA, MIKI IWASE, YOSHIHIRO KUWABARA
    2013 年 18 巻 3 号 p. 157-161
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    To rapidly, simply and specifically detect and identify Listeria monocytogenes from food samples, an immunochromatographic assay, based on gold-labeled monoclonal antibodies directed against an antigen common to all serovars of L. monocytogenes, was used. All strains of L. monocytogenes serovars showed a positive reaction to the assay, but all other gram positive and negative bacteria did not. The detection limit of the assay was in the order of 106 cfu/ml in fluid medium. The assay could simply and rapidly identify L. monocytogenes within 30 min by a pure culture without special instruments. Even if the selective enrichment cultivation was employed for the isolation and growth of bacteria from food materials, the application of the assay system could detect and identify L. monocytogenes precisely in various food materials within 2 to 3 days.
  • HO-WON PARK, KYU-DUCK CHOI, IL-SHIK SHIN
    2013 年 18 巻 3 号 p. 163-168
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    The antimicrobial activity of isothiocyanates (ITCs) extracted from horseradish root was investigated against oral microorganisms: 6 strains of facultative anaerobic bacteria, Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, Staphylococcus aureus, Enterococcus faecalis and Aggregatibacter actinomycetemcomitans; one strain of yeast, Candida albicans, and 3 strains of anaerobic bacteria, Fusobacterium nucleatum, Prevotella nigrescens, and Clostridium perfringens. The ITCs extracted from horseradish root showed antimicrobial activity against all oral microorganisms by the paper disk method. The minimum bactericidal concentration (MBC) of the ITCs extracted from horseradish root ranged from 1.25 to 5.00 mg/ml against 6 strains of facultative anaerobic bacteria and one strain of yeast, and 4.17 to 16.67 mg/ml against 3 strains of anaerobic bacteria. The ITCs extracted from horseradish root showed the strongest antimicrobial activity, with a MBC of 1.25 mg/ml, against C. albicans among facultative microorganisms, and 4.17 mg/ml against F. nucleatum among anaerobic bacteria. These results suggest that the ITCs extracted from horseradish root may be a candidate for use as an antimicrobial agent against oral microorganisms.
  • KATSUNORI FURUHATA, AKIKO EDAGAWA, NAOTO ISHIZAKI, MASAFUMI FUKUYAMA
    2013 年 18 巻 3 号 p. 169-173
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    In order to understand the habitation conditions of the bacteria of the genus Legionella in Noyu (unattended natural hot springs in mountains and fields) in Japan, isolation of Legionella spp. was attempted in the Noyu samples from 11 prefectures nationwide between May and September 2012, and the following results were obtained. Overall, Legionella spp. was isolated from 16 of 43 samples (37.2%). The species was isolated from the Hokkaido region to the Chugoku region but not from the Shikoku region to the Kyushu region. The number of bacteria detected was usually small, less than 5.0×101 CFU/100 ml, as found in 11 samples (68.8%), while counts of 102 or more to 103 or less CFU/100 ml were found in two samples (12.5%). Legionella pneumophila was the most commonly found strain, with 19 strains (90.5%) found, and was the dominant species. Regarding the serogrouping, four strains (21.1%) fell under group 1, the most common grouping, followed by three strains (15.8%) in group 3, two strains (10.5%) in group 5, etc. Moreover, the detected bacterial strains other than L. pneumophila included two strains (9.5%) of L. londiniensis. The temperature of the Noyu from which Legionella spp. was isolated was between 33.1°C and 41.5°C with a pH ranging from 5.2 to 8.1. The present report is the first report to clarify the habitation conditions of strains of Legionella spp. isolated from Noyu in Japan.
Communication
  • HIROSHI FUJIKAWA, MOHAMMAD ZAHER SAKHA
    2013 年 18 巻 3 号 p. 175-179
    発行日: 2013年
    公開日: 2013/09/27
    ジャーナル フリー
    In this study, we developed a predictive program for Salmonella Enteritidis growth in ground chicken and liquid egg products at various temperature patterns. The ground chicken samples were sterilized chicken and raw chicken containing high and low levels of natural microflora, and the liquid egg products were pasteurized or unpasteurized. Microbial growth data published in our previous papers were used for prediction with our new logistic model. The program for the bacterial growth in those food materials was developed on a commercially available spread-sheet program. Users can instantly predict the Salmonella growth in those chicken and egg yolk products by inputting their temperature histories. The growth of natural microflora in the chicken products can also be predicted with the program. This program could be a useful tool to ensure the microbial safety of those materials with regards to Salmonella Enteritidis growth.
feedback
Top