Evaluation of antifungal volatile compounds on the basis of the elongation rate of a single hypha

Abstract

A novel method is proposed for the evaluation of the activity of an antifungal agent administered as a gas. This system is composed of a batch-flow type reaction vessel, a gas flow system, and a microscopic observation system. The agar plate was prepared on the ceiling of the reaction vessel, and the mycelium of a fungus (Aspergillus niger or Rhizoctonia solani) was inoculated onto it. After preincubation at 25°C for 24 h, the reaction vessel was connected to the gas flow system. An appropriate hypha was selected, and its elongation rate was measured. Then a sample holder containing an antifungal compound was inserted into the reaction vessel from the side hole to saturate the atmosphere inside with its vapor. The retardation or inhibition of the hypha elongation was observed on a television monitor and recorded on a video tape recorder. The antifungal compound was then removed, and the reaction vessel was flushed with air. If the hypha lived, it began to elongate again. By this method, antifungal activity of seven odor compounds could be evaluated quantitatively within several hours.

Antifungal activity of volatile compounds generated by essential oils against fungi commonly causing deterioration of bakery products

“…The antifungal activity of essential oils upon solution contact as measured by the broth dilution and agar dilution methods has been studied by many researchers. However, the activity by vapour contact has been reported more rarely (Matsuoka et al. 1990; Inouye et al.…”

Inhibitory effect of essential oils on apical growth of Aspergillus fumigatus by vapour contact

“…This study was undertaken to determine the antifungal effect of vaporized essential oils using a bio cell tracer, which can measure automatically the rate of elongation of a hypha of a filamentous fungus during a short period of incubation. The method was developed to evaluate the activity of an antifungal agent administered as a gas as well as solution [ 12, 13]. The relative contribution of vapour and solution to the inhibition of hyphal elongation was also studied by comparing accumulations of essential oils on hyphae and agar medium by means of gas chromatography.…”

Antifungal Activity of Lemon Essential Oil, Coriander and Cinnamon Extracts on Foodborne Molds in Direct Contact and the Vapor Phase

“…Matsuoka et al . () noted retardation or inhibition of the hypha elongation by several volatile compounds, including limonene and cinnamic aldehyde, inserted in a reaction container to saturate the atmosphere with steam from the inside, after having pre‐incubated test molds for 24 h at 25C. It is suggested that the components of the essential oils and extracts penetrate through the cell membrane, integrating with the enzymes and proteins of the membrane and causing loss of the cytoplasm's ingredients (Sharma and Tripathi ; Omidbeygi et al .…”