If looks could kill: Fungal macroscopic morphology and virulence

Abstract

The complexity and diversity of microbial colony morphologies have contributed to the identification of pathogenic microbes for decades. Even as biomarker-based approaches are adopted for diagnosis of fungal infections, culture-based methods remain valuable for the identification of specific etiological agents and determination of antifungal susceptibility [1]. Thus, when obtainable, infectious organisms are observed as macroscopic colony biofilms in clinical settings. We define macroscopic morphologies (a strain's morphotype) as the collective phenotypes of form and/or structure attributed to a group of organisms of the same species within a defined area such as a colony. Clinical isolates of Aspergillus fumigatus, Cryptococcus neoformans, and Candida spp. have been reported for decades to be morphologically variable within and between patients [2-4]. Similarly, diverse population-level macroscopic morphologies of bacterial pathogens have been observed in clinical samples [5,6]. A key question is whether observed microbial morphotypes tell us anything about their virulence. Below, we discuss the intrinsic and extrinsic factors that contribute to macroscopic morphological variation in fungi and bacteria. We then discuss fungal and bacterial examples linking macroscopic morphology with virulence and the challenges faced with studying this relationship. Finally, we discuss the importance of investigating recurring and distinct fungal macroscopic morphologies for furthering our understanding of host-fungal interactions. What features of population-level growth contribute to macroscopic morphologies?

Blocking drug efflux mechanisms facilitate genome engineering process in hypercellulolytic fungus, Penicillium funiculosum NCIM1228

“…Another interesting observation was distinct morphotype displayed by P. funiculosum NCIM1228 on different growth media. Similar phenotype has been observed in Aspergillus species and has been suggested to impact its virulence characteristics [ 27 ]. Ability of a fungus to change its macroscopic morphotype in response to nutrient availability is quite intriguing.…”

Fungal symbionts of Arctic zooplankton induce mortality and reduce swimming activity

“…Penicillium species are globally distributed (Hassett et al 2019b), produce a suite of degradative enzymes (Park et al 2019), are commonly found in seafood (Park et al 2019), and can be abundant in the Arctic (Luo et al 2020). Our mortality experiments indicate that the presence of select P. chrysogenum strains can differentially reduce survival in copepods during a time span of weeks, consistent with variable virulence among strains of the same fungal species (Kowalski and Cramer 2020). Non-consumptive mortality of zooplankton in the Arctic may peak during winter months, as evidenced by sediment traps, which found Calanus carcasses to be the dominant component of sinking carbon outside of the spring bloom (Sampei et al 2012).…”

The brown root rot fungus Phellinus noxius affects microbial communities in different root‐associated niches of Ficus trees

“…showed a similar hyphal growth rate and normal hyphal characteristics, but slightly different colony morphology. Since changes in colony morphology and growth rate can be due to biotic or environmental stresses (Morales et al, 2013;Liu et al, 2017;Orosz et al, 2018;Kowalski and Cramer, 2020), our observations imply that Cosmospora sp. could tolerate the negative effects of the substances secreted by P. noxius.…”