The microbial diversity and Trans-kingdom interactions shape the composition of multispecies biofilm in dishwashers.. Dishwasher biome

Household appliances, such as dishwashers, represent an extreme and constantly fluctuating environment, where microbial communities displaying poly-extremotolerant properties, including opportunistic pathogenic fungi, survive. The most obvious choice of living when faced with such extreme conditions is the biofilm mode of growth, where microorganisms are protected against external stresses and can benefit from social interact across species boundaries. Here, we report the first community analysis of the dishwasher machine microbiome. Microbial biofilms from thirty different dishwashers at different geographical locations in Slovenia were sampled with the aim of identifying the species composition and co-variance of dishwasher-associated biofilms using high throughput sequencing. Metagenomic 16s rRNA gene and ITS amplicons sequencing in combination with culture based isolation methods revealed a complex bacterial and fungal communities in all the machines sampled. Network based interaction studies revealed significant positive correlations between bacterial species as well as fungi and bacteria. ANNOVA analysis showed that specific conditions of the dishwashers also had a significant and profound impact on the abundance of certain microbial groups. In-vitro based multispecies biofilm cultivation studies confirmed patterns predicted by co-occurrence analysis, as synergistic interactions in biofilms formation were observed when co-culturing dishwasher isolates identified as co-occurring in the network analysis. Thus, strong interspecies as well as inter-kingdom synergistic interactions shape the dishwasher community and impact survival of opportunistic pathogenic fungi.