Molecular and culture-based identification of Aspergillus species in water-impacted homes following Hurricane María in Puerto Rico

Abstract

Flooding caused by Hurricane María promoted fungal growth in homes across Puerto Rico, raising concerns about indoor air quality and health risks. This study focuses on identifying Aspergillus species from water-impacted homes in San Juan using culture-based and molecular methods. Aspergillus is a common indoor contaminant in moisture-damaged environments, with some species associated with significant health risks. However, species-level identification is often limited. To address this, we collected samples from 14 homes, identifying 28 Aspergillus isolates through morphological examination and gene sequencing of ITS2, beta-tubulin (benA), and calmodulin (CaM) genes. Species-level identifications of 22 isolates revealed species belonging to the subgenera Aspergillus, Nidulantes, and Circumdanti. We highlighted the CaM gene's importance in molecular identification by phylogenetic analyses, which showed superior resolution in species differentiation. Culture-based methods also played a crucial role in differentiating closely related species, such as A. flavus and A. oryzae, which molecular methods alone could not reliably separate. Our findings underscore the challenges of Aspergillus identification in post-hurricane, water-impacted indoor environments and emphasize the value of integrating phenotypic and genotypic techniques for accurate species identification. These results contribute to a better understanding of fungal composition and its potential public health implications in disaster-affected settings.