The study of the fungal community composition in house dust is useful to assess the cumulative exposure to fungi in indoor environments. The objective of this research was to characterize the fungal diversity of house dust and its association with the environmental conditions of bedrooms. For this, the dust was collected from 41 bedrooms of children between the ages of 8 and 9 with a family history of asthma, residents of Havana, Cuba. The fungal content of each sample was determined by two methods: plate culture with Malt Extract Agar and by direct microscopy. An ecological analysis was carried out from the fungal diversity detected. To describe the factors associated with the fungi detected, bivariate logistic regression was used. Through direct microscopy, between 10-2311 fragments of hyphae and spores corresponding mainly to Cladosporium, Coprinus, Curvularia, Aspergillus/Penicillium, Xylariaceae, and Periconia were identi ed. Through the culture, 0-208 CFU were quanti ed, where Aspergillus, Cladosporium, and Penicillium predominated. The culturability evidenced the differences between the quanti cation determined by both methods. A positive relationship was found between the type of cleaning of the furniture, the presence of trees in front of the bedroom, indoor relative humidity, indoor temperature, the presence of air conditioning by air conditioning and natural ventilation with speci c spore types and genders. The use of two different identi cation methods allowed to detect a greater fungal diversity in the residences evaluated. Monitoring the exposure to these fungal allergens in childhood can help to prevent sensitization in the allergic child, the development of asthma and other respiratory diseases.

In the sugar industry, dextran generates difficulties in the manufacturing process. Using crude dextranase (EC 3.2.1.11) to eliminate dextran in sugar is an effective practice. In this study, a synthetic dextranase-encoding gene of the filamentous fungus Talaromyces minioluteus, lacking its putative native signal peptide (1–20 amino acids) and the next 30 amino acids (r–TmDEX49A–ΔSP–ΔN30), was fused to the Saccharomyces cerevisiae prepro α–factor (MFα–2) signal sequence and expressed in Komagataella phaffii under the constitutive GAP promoter. K. phaffii DEX49A–ΔSP–ΔN30, constitutively producing and secreting the truncated dextranase, was obtained. The specific activity of the truncated variant resulted in being nearly the same in relation to the full-length mature enzyme (900–1000 U·mg−1 of protein). At shaker scale (100 mL) in a YPG medium, the enzymatic activity was 273 U·mL−1. The highest production level was achieved in a fed-batch culture (30 h) at 5 L fermenter scale using the FM21–PTM1 culture medium. The enzymatic activity in the culture supernatant reached 1614 U·mL−1, and the productivity was 53,800 U·L−1·h−1 (53.8 mg·L−1·h−1), the highest reported thus far for a DEX49A variant. Dextran decreased r–TmDEX49A–ΔSP–ΔN30 mobility in affinity gel electrophoresis, providing evidence of carbohydrate–protein interactions. K. phaffii DEX49A–ΔSP–ΔN30 shows great potential as a methanol-free, commercial dextranase production system.

The study of the fungal community composition in house dust is useful to assess the cumulative exposure to fungi in indoor environments. The objective of this research was to characterize the fungal diversity of house dust and its association with the environmental conditions of bedrooms. For this, the dust was collected from 41 bedrooms of children between the ages of 8 and 9 with a family history of asthma, residents of Havana, Cuba. The fungal content of each sample was determined by two methods: plate culture with Malt Extract Agar and by direct microscopy. An ecological analysis was carried out from the fungal diversity detected. To describe the factors associated with the fungi detected, bivariate logistic regression was used. Through direct microscopy, between 10-2311 fragments of hyphae and spores corresponding mainly to Cladosporium, Coprinus, Curvularia, Aspergillus/Penicillium, Xylariaceae, and Periconia were identified. Through the culture, 0–208 CFU were quantified, where Aspergillus, Cladosporium, and Penicillium predominated. The culturability evidenced the differences between the quantification determined by both methods. A positive relationship was found between the type of cleaning of the furniture, the presence of trees in front of the bedroom, indoor relative humidity, indoor temperature, the presence of air conditioning by air conditioning and natural ventilation with specific spore types and genders. The use of two different identification methods allowed to detect a greater fungal diversity in the residences evaluated. Monitoring the exposure to these fungal allergens in childhood can help to prevent sensitization in the allergic child, the development of asthma and other respiratory diseases.

In the sugar industry, dextran generates difficulties in the manufacturing process. Crude dextranase (EC 3.2.1.11) to eliminate dextran in sugar is an effective practice. In this study, a synthetic dextranase encoding gene of the filamentous fungus Talaromyces minioluteus, lacking its putative native signal peptide (1-20 amino acids) and the next 30 amino acids (r-TmDEX49A-ΔSP-ΔN30), was fused to the Saccharomyces cerevisiae prepro -factor (MF-2) signal sequence and expressed in Komagataella phaffii under the constitutive GAP promoter. K. phaffii DEX49A-ΔSP-ΔN30, constitutively producing and secreting the truncated dextranase was obtained. The specific activity of the truncated variant resulted nearly the same in relation to the full-length mature enzyme (900-1000 U.mg-1 of protein). At shaker scale (100 mL) in YPG medium, the enzymatic activity was 273 U.mL-1. The highest production level was achieved in a fed-batch culture (30 h) at 5 L fermenter scale using the FM21-PTM1 culture medium. The enzymatic activity in the culture supernatant reached 1614 U.mL-1 and the productivity was 53800 U.L-1.h-1 (53.8 mg.L-1.h-1), the highest reported so far for a DEX49A variant. Dextran decreased r-TmDEX49A-ΔSP-ΔN30 mobility in affinity gel electrophoresis, providing evidence of carbohydrate-protein interactions. K. phaffii DEX49A-ΔSP-ΔN30 shows great potential as a methanol-free, commercial dextranase production system.

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