A deep dive into the diversity of the Aspergillus community in the lakes of northern Iran

TL;DR

This study explores the diversity and antifungal resistance of Aspergillus species in lakes in northern Iran, highlighting the need for better hygiene and monitoring.

Contribution

The study provides a detailed assessment of Aspergillus diversity and antifungal susceptibility in recreational lakes in northern Iran.

Findings

Aspergillus section Terrei was the most abundant, especially in Elimalat lake.

Soil samples had the highest Aspergillus load, while sediment and water samples showed lower levels.

Some isolates showed elevated resistance to itraconazole and voriconazole.

Abstract

This study aimed to evaluate the mycological quality of soil and water from recreational lakes in the Mazandaran region, focusing on the diversity and abundance of Aspergillus species and their antifungal susceptibility profiles.

Sampling was conducted at 42 stations across 7 selected lakes in Mazandaran province during the bathing season (summer months of 2023). Three different types of samples, namely dry soil, sediment (sediment), and water were collected at each station in accordance with the standard operational procedure (SOP) established by the leaders of the Mycosands project. The isolated Aspergilli were identified using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). Antifungal susceptibility testing was performed following the guidelines set by the Clinical Laboratory Standards Institute.

Of 713 Aspergillus isolates, 353 (49.58%) were obtained from soil, 272 (35.8%) from sediment, and 87 (12.2%) from water samples. The Aspergillus section Terrei exhibited the highest abundance (n = 295, 41.37%), particularly in Elimalat (288 CFU/mg/mL), which showed the most diverse range of species. Soil samples revealed A. sec. Terrei as the most prevalent (273 CFU/mg) whereas sediment and water samples showed lower loads of Aspergilli, with the section Nigri identified most frequently (176 CFU/mg and 105 CFU/mL, respectively). Elevated minimum inhibitory concentrations (MICs) against itraconazole and voriconazole were observed in 3.22 and 1% of isolates, respectively.

Summer conditions may have contributed to increased fungal contamination due to increased human activity and organic waste. Therefore, prioritizing microbial contamination control and improving hygienic awareness among visitors remain vital. However, seasonal sampling and section-level identification represent limitations that should be addressed in future studies.

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