Biological assays involving germination or growth are often used to determine viability of fungal spores (1). However many fungal spores, such as those from soil-inhabiting basdiomycetes, are difficult to germinate in the laboratory, and some fungal species require months to germinate (1,2). Other fungal viability assays involve the use of colorimetric assays such as MTT/XTT assays (3,4) or fluorescent stains (5,6). Many fluorescent stains are subject to fluorescence interference from test compounds and may not be ideal for screening situations (7). These factors make activities like screening for sporicides almost impossible. A rapid viability test that works well with fungal spores would be useful for screening for chemicals that inhibit sporulation.
Determining algal viability can be extremely difficult as well, often requiring labor-intensive and expensive spectroscopy methods or methods such as measuring photosynthetic oxygen that are not well-suited to high-throughput screening (8–11). Fluorescent stains have been widely applied in studies of algal viability, but these studies are subject to interference from green autofluorescence that occurs in many species (9). As production of certain crops that require aquaculture (e.g., rice) becomes more prevalent, understanding the effect of herbicides used in those agricultural practices on the normal algal flora becomes important (10). Also, finding effective agents for controlling growth of harmful algal blooms requires being able to rapidly assess algal viability in a screening setting within the laboratory. Some studies have had success with MTS-based assays (12); however, a truly homogeneous assay that can be performed on organisms grown in culture in conjunction with screening assays would be a powerful tool.
In this report we demonstrate the use of the luminescent BacTiter-Glo™ Microbial Cell Viability Assay for screening of fungal sporicidal compounds and show that it can be used to assess viability of yeast and algae.