Five hinokitiol-related compounds [hinokitiol (β-thujaplicin), β-dolabrin, γ-thujaplicin, 4-acetyltropolone and α-thujaplicin] isolated from the acid oil of Aomori Hiba (Thujopsis dolabrata Sieb. et Zucc. var hondai MAKINO) showed clear antifungal activity against woodrotting fungi. These compounds have obvious insecticidal effects on termites. They also exhibited potent acaricidal activity against mites. The above-mentioned features suggest that Konjiki-do, a well known national treasure, one of the buildings in Chuson-ji Temple of Iwate Prefecture, Japan, which was built of wood from the tree containing these five compounds, was kept from harm against noxious insects and wood-rotting fungi for a long time of about 840 years, until it was extensively repaired in 1962. In addition to Konjiki-do, there are some old famous Buddhist temples and Shinto shrines using Aomori Hiba. From the results, it was found that Aomori Hiba (Hinokiasunaro) is excellent for use as building materials.
Cladosporium contaminants on materials and utensils that come into contact with food were morphologically investigated. The most common contaminants, C. cladosporioides and C. sphaerospermum, were detected on the samples. The morphological changes of the Cladosporium species were investigated by using stereoscopic, optical light, fluorescent, and scanning electron microscopes. Microscopically the Cladosporium contaminants were observed as aggregated dark brown spots, strongly pigmented, irregularly swollen, and in long chains. Using fluorescent microscopy, the Cladosporium mycelia were clearly stained with fluorescein diacetate as viable cells, but the old cells were mostly non-viable, as shown by staining with propidium iodide. The dynamics of the morphological changes showed that the penetrating mycelia were closely attached to the surface of the materials and utensils under investigation. These results provide information about the significance of Cladosporium contamination on materials and utensils in contact with food and may contribute to the control of fungal contamination.
The cleanability of heat-treated 316L stainless steel particles treated at various temperatures of 100 to 500°C was studied in a plug-flow column fed by a 0.1M NaOH solution. Bovine Serum albumin (BSA) was used as the model fouling agent. Heat treatment resulted in the enrichment of iron in passive films on stainless steel particles depending on temperature. The degree of surface hydroxylation and the apparent surface charge density (σ app) of stainless steel particles decreased markedly with increasing heating temperatures. The saturation amounts of BSA adsorbed (Γsat) were larger on the particles heated at higher temperatures.No correlation was observed between theΓsatand σapp values. With increasing heating temperatures, the rate of BSA desorption from stainless steel particles decreased gradually in the initial and later stages of cleaning, resulting in larger amounts of BSA remaining on the particles at the end of 120-min of cleaning. The susceptibility to BSA adsorption and the cleanability were found to be correlated with the iron content of the passive films on stainless steel particles.It could be suggested that the decrease in the cleanability was probably due tothe formation of iron-enriched passive films with lower degrees of surface hydroxylation of stainless steel particles due to heat treatment.
The accurate detection of Legionella from environmental water samples using conventional plate culture methods is often made difficult by the overgrowth of non-target microorganisms on the selective agar plates. Acid pretreatment is a very effective pretreatment to decrease the overgrowth of heterotrophic bacteria. However, acid pretreatment would not be expected to eliminate molds. We evaluated the effects of four kinds of antifungal agents, individually and in combination, on the growth of Legionella strains and molds. Consequently, it was demonstratedthat the combination of cycloheximide, amphotericin B and thiabendazole was veryeffective in eliminating molds on agar plates, and resulted in the improved detection of Legionella. Examination of 214 cooling tower water samples using the enhanced antifungal selective medium (CAT α) instead of GVPCα selectivemedium demonstrated a decrease in contamination by molds from 13.6 c/3 to 1.9 % without affecting the growth of Legionella.
Pseudomonas fluorescens strain LRB3W1 inhibited the mycelial growth of Fusarium oxysporum f. sp. lycopersici and suppressed the Fusarium wilt of tomato. The chemical fungicide, benomyl, did not suppress the disease incidence at low concentrations. However, the disease incidence was decreased by the combined application of benomyl at low concentrations with strain LRB3W1. Combined application of benomyl with the bacterium was more effective than treatment with the bacterium alone. The survival of strain LRB3W1 was not influenced by the presence of benomyl. This combined use of the biocontrol bacterium, strain LRB3W1, and a fungicide, benomyl, should be an attractive approach for suppressing tomato wilt.
Intergeneric fusants were obtained by protoplast fusion between the thermotolerant yeast, Kluyveromyces marxianus, and the starch-assimilating yeast, Schwanniomyces occidentalis. Two thermotolerant fusants growing at 40°C were screened on the medium containing soluble starch. These fusants showed weak growth in a soluble starch medium and the production of a little amylase. The carbon source assimilation and the chromosome composition of the fusants were similar to those of the K. marxianus parent. However, a chromosomal difference from K. marxianus was recognized in the fusants. These results show the possibility that the fusants are amylase-producing strains rearranged from K. marxianus.
The inactivation of Escherichia coli by infrared (IR) irradiation was quantitatively evaluated and compared to that by thermal conductive heating. After the bulk temperature of the sterile saline irradiated by IR reached a steady given temperature, the E. coli culture was inoculated and IR heating was conducted. A mullite cylinder FIR heater, of which main wavelength is 4-7μm, was used for IR heating. The killing of the E. coli by IR heating and thermal conductive heating both followed first-order reaction kinetics, and the apparent death rate constants (k) under different conditions were obtained. At the same temperatures, pasteurization by IR heating was more effective than that by thermal conductive heating, and its effectiveness increased with a decrease in liquid layer thickness. The values of k due to IR heating were approximately 2-3 times and one order larger than those due to thermal conductive heating at the liquid layer thickness of 10 mm and 1.5 mm, respectively. The activation energy (Ea) for the killing of E. coli by IR irradiation was slightly lower than that by thermal conductive heating, indicating that there are some differences in the action mechanisms.