Wood degradation, phenol oxidase activity, and the generation of hydroxyl radicals were examined in cultures of eight basidiomycetes that are usually regarded as white-rot fungi. Six of the fungi degraded Japanese beech wood to a significant extent under the conditions used. These six basidiomycetes also had measurable phenol oxidase activity after 1wk in woodcontaining cultures. With two of the six fungi, phenol oxidase activity peaked after 1wk of incubation. One of the six fungi had the highest activity after 6wk. The other three fungi had relatively constant phenol oxidase activities throughout the 8 wk incubation period. The six basidiomycetes that significantly degraded Japanese beech wood also generated significant amounts of hydroxyl radicals in the wood-containing cultures. The combined production of phenol oxidase and hydroxyl radicals in intact cultures of the eight basidiomycetes correlated roughly with the degree of wood degradation in the cultures. Most of the hydroxyl radicals were produced by agents other than phenol oxidase in cultures of white-rot fungi.
Recently, the incidence of foodborne disease outbreaks associated with contaminated meat, seafood and fresh produce has increased worldwide. Enterohaemorrhagic Escherichia coil(EHEC)O157: H7, Salmonella spp., Listeria monocytogenes and Shigella spp. have been responsible for recent outbreaks associated with the consumption of such contaminated food. Hence, suitable detection methods for monitoring the risk of microbial food contamination are necessary. These bacterial pathogens in food could be detected by enrichment culture in buffered peptone water(BPW)and multiplex PCR analysis of culture broth. After the detection of pathogens by multiplex PCR analysis, each pathogen-positive sample was cultured in an enriched selective broth. After the selective enrichment culture, the culture broth was plated on a selective agar plate to obtain colonies. EHEC(≥13 cells/25 g), S. Enteritidis(≥15 cells/25 g), L. monocytogenes (≥394 cells/25 g)and S. sonnei(≥2.4 cells/25 g)were detected and isolated. These pathogenic bacteria in frozen foods were also detected and isolated.
Serratia marcescens strain B2 is an antagonistic bacterium that inhibits the fungal growth of Rhizoctonia solani Kühn AG-1 IA and suppresses the rice sheath blight caused by R. solani AG-1 IA. The sclerotial germination of R. solani AG-1 IA decreased when the sclerotia were incubated in the culture filtrate of the strain B2. The antifungal activity of the culture filtrate was enhanced by the treatment in combination with low concentrations of the chemical fungicides, flutolanil, pencycuron and validamycin. There was a synergistic antifungal activity produced by the culture filtrate of the strain B2 and chemical fungicides on the sclerotial viability of R. solani AG-1 IA.
The cell suspension (ca. 109 CFU/ml) of an antagonistic bacterium Serratia marcescens strain B2 was inoculated into the soil of the cucumber rhizosphere. The pathogen Rhizoctonia solani Kühn AG-4, which causes damping-off disease, was challenge-inoculated to the cucumber seedlings. Disease incidence with bacterial treatment was reduced to about 45% compared with that of the untreated control. The strain B2 survived in the soil of the rhizosphere under glasshouse conditions at ca. 106 to 107 CFU/g soil for 4 wk after application. Production of lytic enzyme chitinases and antibiotic prodigiosin by the strain B2 was enhanced under the presence of fungal hyphae. These results suggested that the strain B2 has a potential as an effective and long-lasting biological control agent to deal with cucumber damping-off disease.
We investigated the antifungal activities of linalool, geranyl acetate and 1, 8-cineole, the major essential oils from the rhizomes of the greater galangal Alpinia galanga, against some fungi in the Saprolegniaceae. The toxicity to goldfish (Carassius auratus) and platyfish (Xiphophorus maculates) was also investigated.Saprolegnia parasitica NJM 8604, S. diclina NJM 0236, Achlya bisexualis NJM 9905, A. diffusa NJM 0011, and two isolates (NJM 9701 and NJM 0219) of Aphanomyces piscicida were used in this study. The fungistatic concentrations of linalool, geranyl acetate and 1, 8-cineole against the hyphae of the used strains were 2, 000 to 500, 2, 500 to 250 and 5, 000 to 3, 000 μ g/ml, respectively, while the fungicidal concentrations of each chemical against the strains were 1, 250 to 1, 000, over 2, 000 and 4, 000 to 2, 000 μ g/ml, respectively. The zoospores of all isolates exposed to 750 μ g/ml linalool, 500 μ g/ ml geranyl acetate and 1, 500 μ g/ml 1, 8-cineole for 30 min could not germinate. The chemicals, however, were toxic to platyfish and goldfish at the fungicidal concentrations.
After the immunomagnetic beads prepared separately for the capture of Yersinia enterocolitica 03, 05, 27, 08 and 09 were mixed at an equal ratio, the mixemagnetic bead suspension was used for the simultaneous detection of these serovars by IMS-CINplating followed by PCR. The proposed method was shown to be capable of detecting specificallyand simultaneously 03, 05, 27, 08 and 09 from food and fecal samples within 2 days if anyof these bacteria were present at more than 100 cfu/ml in the sample suspension.
We detected Legionella species in 125 samples of hot spring bath water from variousplaces in Japan using the culture and LAMP methods, and compared the results of the 2 methods. Legionella spp. was detected in 40 samples in the culture test, and 38 of these (95.0%) were also positive in the LAMP test, showing a high rate of consistency. Of the 85 negative samples in the culture test, 38 samples (44.7%) were positive in the LAMP test. The positive rate in the LAMP test was higher than that in the current culture test ; the test procedure wassimple, and judgments could be made in a few hours, showing that the LAMP method is useful for the rapid detection of Legionella spp.