Malassezia in environmental studies is derived from human inputs

Area of Science:

• Microbiology
• Marine Biology
• Genomics

Background:

• Malassezia is a lipid-dependent fungus prevalent on human skin.
• It has been detected in diverse marine environments, including those associated with marine animals.
• Its presence suggests potential ecological roles in marine ecosystems.

Purpose of the Study:

• To investigate the presence, distribution, and origins of Malassezia in marine ecosystems using metagenomic data.
• To attempt the assembly of Malassezia genomes from marine samples.
• To clarify the ecological role and diversity of Malassezia in marine environments.

Main Methods:

• Analysis of metagenomic sequences from the Sequence Read Archive database.
• Utilizing various search methods to identify Malassezia sequences.
• Attempting to generate metagenome-assembled genomes from Malassezia-rich datasets.
• Phylogenetic analysis of assembled contigs.

Main Results:

• Malassezia sequences were found in up to 10% of analyzed marine datasets, but at low relative abundance.
• A strong correlation was observed between human and Malassezia sequences, suggesting contamination.
• Assembled Malassezia contigs showed low genome completeness (max 2.2%) and were related to human-associated species.
• Phylogenetic analysis identified species related to human-associated Malassezia.

Conclusions:

• Many reported environmental occurrences of Malassezia likely originate from human sources.
• Widespread contamination of public metagenomic data confounds the study of Malassezia diversity and ecological roles in marine environments.
• Further research is needed to distinguish true marine Malassezia populations from contamination.