Flow cytometry as a tool to assess the effects of gamma radiation on the viability, growth and metabolic activity of fungal spores

Abstract

a b s t r a c tFlow cytometry is often used for viability and vitality assessment in bacteria and yeasts. However, its application to the study of fungal spore development is uncommon, probably due to the difficulties in successfully staining these cells.In the current study, we used flow cytometry for the first time to assess the effects of a disinfection treatment on the survival, growth and metabolic activity of fungal spores (Penicillium chrysogenum, Aspergillus nidulans and Aspergillus niger) submitted to gamma radiation (0e15 kGy). The Forward and Side-Scatter parameters of the cytometer were used to assess the differences in size and complexity of particles. Furthermore, two fluorescent dyes were used: Propidium Iodide to assess the membrane integrity and spore viability, in a culture-independent procedure; and Dihydroethidium to measure the changes in metabolic activity of irradiated spores in their first 10 h of growth in a liquid culture medium.Our results support that flow cytometry is a valuable tool in assessing different biological parameters and biocide effects, as it allowed accurate determination of the viability, growth and metabolic activity of gamma-irradiated spores. The fluorescence of Propidium Iodide was 5e7Â more intense in unviable spores. The Dihydroethidium fluorescence increase was associated with faster growth. Control and low radiation doses allowed the germination and growth of spores, while higher doses led to growth inhibition and lower fluorescence.

Flow Cytometry Is a Powerful Tool for Assessment of the Viability of Fungal Conidia in Metalworking Fluids

“…As a result of this need for fine-tuned monitoring techniques, FCM was recently reported for the first time to estimate spore inoculum quality in filamentous bioprocesses (21). Even in nonindustrial settings, there are fewer than 10 reports about the use of FCM to study fungi, including articles on phytopathogenic fungi (22,23), fungal load in aerosols and air (24)(25)(26), disinfection strategies (27), and human-pathogenic fungi in hospital environments (28,29). To date there are no studies available on the use of FCM for viability assessment of conidia in MWF.…”

Effect of low-dose ionizing radiation on luminous marine bacteria: radiation hormesis and toxicity

“…Radiobiological effects of low doses have been studied since the 70s, last century (Burlakova et al, 2004;Feinendegen, 2005;Feinendegen et al, 2007;Ray at al., 2014;Mothersill and Seymour, 2014), including effects on microorganisms (Paul et al, 2013;Tomac et al, 2013: Jo et al, 2012Mesquita et al, 2013;Xavier et al, 2014).…”

Changes in the physiological properties and kinetics of citric acid accumulation via carbon ion irradiation mutagenesis of Aspergillus niger

“…Each experiment was carried out three times. Mesquita et al (2013) reported that flow cytometry can be an effective tool to assess the size and complexity of A. niger conidia after γ radiation, and that forward-scattered light (FSC) can provide information on spore size. Stentelaire et al (2001) reported that MTT assay can be used to measure fungal conidial viability.…”