Heidi Salonen

New biomolecules are prospected for new antimicrobial, antiparasitic and cytostatic drugs. Here, we present bioassay‐guided methods for prospecting indoor bacteria producing non‐protein antibiotic molecules. Out of 650 bacterial colonies tested, 108 antimicrobial isolates representing 15 species and cryptic Actinobacteria , produced non‐protein antibiotics affecting mammalian cells. Methanol extracts of the 108 strains tested with a battery of bioassays revealed four toxicity endpoints: (1) Cell death (CD). (2) Boar sperm motility inhibition (BSMI). (3) Inhibition of cell proliferation (ICP). (4) Mitochondrial toxicity (MT). The battery of endpoints divided the 108 strains into four toxicity profiles: Profile I: Lethal toxins (42 strains). Positive controls: Alamethicin, a channel forming ionophore and a biosurfactant surfactin. Profile II: Sublethal mitochondrial toxins (51 strains). Positive controls: The mitochondrial toxins valinomycin and antimycin A. Profile III: Sublethal cytostatic toxins (7 strains). Positive control: Chaetoglobosin A, a glucose transport inhibitor. Profile IV: Cytostatic toxins (8 strains). Positive controls: Actinomycin D, RNA syntesis inhibitor. Strains of Bacillus, Streptomyces and Paenibacillus produced amylosin, cereulide, surfactins, lichenysins, iturins, fengysin, valinomycin and fusarisidins. Strains of Peribacillus Lysinibacillus , Microbacterium, Nocardiopsis and cryptic Actnobacteria produced possible novel bioactive molecules. The indoor environments were easily accessible habitats for bacteria producing ionophores, surfactants, and mitochondrial toxins.

Floor mopping is a cleaning activity that provokes the release of various chemicals indoors. This study is aimed at estimating the emission rates of indoor particles and total volatile organic compounds (VOCs) using a chamber setting. Eight commercial cleaning products with different perfumes (lemon, lavender, jasmine, ocean fresh, green apple, and green soap) and categorized into two groups (chlorines and all‐purpose cleaners) were tested. Fine particle concentrations (< 300 nm) were increased with all products, but nanoparticle formation was observed during bleach mopping and mopping with the lemon‐perfumed cleaner. Emission rates were one order of magnitude higher with the lemon‐perfumed cleaner (10 ¹² particles/h), followed by bleach mopping (10 ¹¹ particles/h) and the rest of the cleaners (10 ¹⁰ particles/h). Likewise, significant emissions were obtained for VOCs, with higher emissions corresponding to the cleaners (1.2–3.4 mg/h) and especially the lemon product (5.2 mg/h), while for bleach mopping, emissions ranged between 1.2 and 3.8 mg/h again with higher emissions for the lemon‐perfumed chlorine. Contrarily, PM _2.5 preserved a minimal increase with primary emissions lying between 57 and 290 μ g/h, although a significant impact was identified during formation events. Using a higher concentration solution for mopping enhanced emissions of both particles and VOCs, emphasizing that careful dosage is needed to avoid increased rates. The current study demonstrates that the type and fragrances of cleaning products are critical in influencing emissions, with lemon‐scented products potentially leading to more detrimental indoor exposure.

Indoor air quality (IAQ) is influenced by a wide range of chemical, biological and physical agents that can negatively impact physical, immunological and mental health. Adverse health effects depend on the type and concentration of pollutants, duration of exposure, and individual susceptibility. The availability of data on IAQ is limited, as are standardized approaches for evaluating its health impact. This expert review aims to describe the most important indoor air determinants affecting health, and present the IDEAL cluster, which comprises seven EU‐funded scientific projects on the topic of IAQ and human health. Across the IDEAL projects, knowledge is generated on exposure to a wide range of indoor air pollutants, including well‐known hazards and more explorative chemical and microbiological determinants. The projects will also contribute to the implementation of low‐cost and/or real‐time sensors on IAQ, as well as advanced chemical and microbiological analyses, and evaluate various interventions to improve IAQ. Several of them focus on particularly vulnerable groups. Raising public awareness and implementing measures to reduce pollutant levels are essential for safeguarding health, particularly in urban areas with elevated pollution levels.

It is controversial how useful bioassays are for identifying the in vivo toxicity of hazardous environmental exposures. In this study, fruiting bodies of forest mushrooms (n = 46), indoor mold colonies (n = 412), fungal secondary metabolites (n = 18), xenobiotic chemicals such as biocides and detergents (n = 6), and methanol extracts of indoor dusts from urban buildings (n = 26) were screened with two different bioactivity assays: boar sperm motility inhibition (BSMI) and inhibition of cell proliferation (ICP) tests. For the forest mushrooms, the toxicity testing result was positive for 100% of poisonous-classified species, 69% of non-edible-classified species, and 18% of edible-classified species. Colonies of 21 isolates of Ascomycota mold fungal species previously isolated from water-damaged buildings proved to be toxic in the tests. Out of the fungal metabolites and xenobiotic chemicals, 94% and 100% were toxic, respectively. Out of the indoor dusts from moldy-classified houses (n = 12) and from dry, mold-free houses (n = 14), 50% and 57% were toxic, respectively. The bioassay tests, however, could not differentiate the samples from indoor dusts of moldy-classified buildings from those from the mold-free buildings. Xenobiotic chemicals and indoor dusts were more toxic in the BSMI assay than in the ICP assay, whereas the opposite results were obtained with the Ascomycota mold colonies and fungal secondary metabolites. The tests recognized unknown methanol-soluble thermoresistant substances in indoor settled dusts. Toxic indoor dusts may indicate a harmful exposure, regardless of whether the toxicity is due to xenobiotic chemicals or microbial metabolites.

Sport facilities represent extreme indoor environments due to intense cleaning and disinfection. The aim of this study was to describe the composition of the cultivated microbiota in dust samples collected in sport facilities during the COVID-19 pandemic. A dust sample is defined as the airborne dust sedimented on 0.02 m² within 28 d. The results show that the microbial viable counts in samples of airborne dust (n = 9) collected from seven Finnish sport facilities during the pandemic contained a high proportion of pathogenic filamentous fungi and a low proportion of bacteria. The microbial viable counts were between 14 CFU and 189 CFU per dust sample. In seven samples from sport facilities, 20–85% of the microbial viable counts were fungi. Out of 123 fungal colonies, 47 colonies belonged to the potentially pathogenic sections of Aspergillus (Sections Fumigati, Nigri, and Flavi). Representatives of each section were identified as Aspergillus fumigatus, A. flavus, A. niger and A. tubingensis. Six colonies belonged to the genus Paecilomyces. In six samples of dust, a high proportion (50–100%) of the total fungal viable counts consisted of these potentially pathogenic fungi. A total of 70 isolates were considered less likely to be pathogenic, and were identified as Aspergillus section Nidulantes, Chaetomium cochliodes and Penicillium sp. In the rural (n = 2) and urban (n = 7) control dust samples, the microbial viable counts were >2000 CFU and between 44 CFU and 215 CFU, respectively, and consisted mainly of bacteria. The low proportion of bacteria and the high proportion of stress tolerant, potentially pathogenic fungi in the dust samples from sport facilities may reflect the influence of disinfection on microbial communities.