TheCaenorhabditis elegansbacterial microbiome influences microsporidia infection through nutrient limitation and inhibiting parasite invasion

Abstract

AbstractMicrosporidia are eukaryotic obligate intracellular parasites that infect most animals including humans. To understand how the microbiome can impact microsporidia infection, we tested how bacterial isolates that naturally occur withCaenorhabditis elegansinfluence infection by the microsporidianNematocida parisii. Nematodes exposed to two of these bacteria,Chryseobacterium scopthalmumandSphingobacterium multivorum, exhibit reduced pathogen loads. Using untargeted metabolomics, we show that unsaturated fatty acid levels are disrupted by growth on these bacteria and that supplementation with the polyunsaturated fatty acid linoleic acid can restore full parasite growth in animals cultured onS. multivorum. We also found that two isolates,Pseudomonas luridaandPseudomonas mendocina,secrete molecules that inactivateN. parisiispores. We determined thatP. luridainhibitsN. parisiithrough the production of massetolides. We then measured 53 additionalPseudomonasstrains, 64% of which significantly reducedN. parisiiinfection. A mixture ofPseudomonasspecies can greatly limit the amount of infection inC. eleganspopulations over many generations. Our findings suggest that interactions between bacteria andN. parisiiare common and that these bacteria both modulate host metabolism and produce compounds that inhibit microsporidia infection.