Aspergillus species grow rapidly on most culture media. Microscopically, all cultured Aspergillus spp. produce a swollen vesicle ("aspergillum") at the end of each conidiophore (which is a feature distinct to the genus). Identification at the species level is based on the characteristic colony and microscopic morphologies.
A. fumigatus colonies are blue-green with a distinct white apron and a light-colored or white reverse. Microscopically, the conidiophores terminate in a swollen vesicle with a single row of phialides (uniseriate) that cover only the top 2/3 of the vesicle. Each phialide gives rise to a chain of small (2-4 µm) round conidia.
A. flavus produces yellow-green to olive colonies with a light-colored reverse. Circumferential phialides are seen microscopically. Some strains are uniseriate while others are biseriate. The conidiophores of A. flavus are also often times spiny or rough.
The image to the top right is Aspergillus fumigatus demonstrating a filamentous conidiophore, which terminates in a bulbous, spheroid vesicle. Atop the distal two-thirds of this vesicle, a uniseriate, i.e., single row, of phialides sprout, each of which anchors its respective chain of spherical conidiospores. The bottom right picture is A. flavus demonstrating a biseriate conidial configuration.
24. CDC. Image #15145. This photomicrograph revealed some of the ultrastructural morphology exhibited by the fungal organism, Aspergillus fumigatus. Of particular importance, was the filamentous conidiophore, which ended in a bulbous, spheroid-shaped vesicle. Atop the distal two-thirds of this vesicle, a uniseriate, i.e., single row, of phialides sprout, each of which anchored its respective chain of spherical conidiospores, which are the asexual reproductive structures of this organism. PHIL public domain. Created 2012. Accessed January 14, 2023. https://phil.cdc.gov/Details.aspx?pid=15145 25. CDC/Ajello. Image #4298. This photomicrograph depicts the appearance of a conidiophore of the fungal organism, Aspergillus flavus, displaying a biseriate conidial configuration. PHIL public domain. Created 1963. Accessed January 14, 2023. https://phil.cdc.gov/Details.aspx?pid=4298
