Abstract
BackgroundNematodes represent important pathogens of humans and farmed animals and cause significant health and economic impacts. The control of nematodes is primarily carried out by applying a limited number of anthelmintic compounds, for which there is now widespread resistance being reported. There is a current unmet need to develop novel control measures including the identification and characterisation of natural pathogens of nematodes.ResultsNematode killing bacilli were isolated from a rotten fruit in association with wild free-living nematodes. These bacteria belong to the Chryseobacterium genus (golden bacteria) and represent a new species named Chryseobacterium nematophagum. These bacilli are oxidase-positive, flexirubin-pigmented, gram-negative rods that exhibit gelatinase activity. Caenorhabditis elegans are attracted to and eat these bacteria. Within 3 h of ingestion, however, the bacilli have degraded the anterior pharyngeal chitinous lining and entered the body cavity, ultimately killing the host. Within 24 h, the internal contents of the worms are digested followed by the final digestion of the remaining cuticle over a 2–3-day period. These bacteria will also infect and kill bacterivorous free-living (L1-L3) stages of all tested parasitic nematodes including the important veterinary Trichostrongylids such as Haemonchus contortus and Ostertagia ostertagi. The bacteria exhibit potent collagen-digesting properties, and genome sequencing has identified novel metalloprotease, collagenase and chitinase enzymes representing potential virulence factors.ConclusionsChryseobacterium nematophagum is a newly discovered pathogen of nematodes that rapidly kills environmental stages of a wide range of key nematode parasites. These bacilli exhibit a unique invasion process, entering the body via the anterior pharynx through the specific degradation of extracellular matrices. This bacterial pathogen represents a prospective biological control agent for important nematode parasites.
Highlights
Nematodes represent important pathogens of humans and farmed animals and cause significant health and economic impacts
In this study, we searched the environment for natural nematode pathogenic bacteria in association with wild Caenorhabditis nematodes
The bacterial strain JUb129 was isolated from the free-living bacterivorous nematode Caenorhabditis briggsae from a rotten apple in Paris, France (NCBI BioSample SAMN09925763) [13]
Summary
Nematodes represent important pathogens of humans and farmed animals and cause significant health and economic impacts. Parasitic nematodes inflict a major burden on public health and on the farming industry worldwide. It is estimated that more than one billion people are suffering from soil-transmitted nematode infestations, such as hookworm infection, Ascariasis and Trichuriasis. These parasites cause significant lifelong morbidity [1]. The veterinary impact of disease caused by nematodes is enormous, with an estimated annual economic loss of. The losses in crop yields caused by plant-parasitic nematodes are estimated to be as much as $125 billion per year [3]. Drug resistance has arisen unexpectedly rapidly, mainly in South Africa, USA and Australia with for example, the first cases of resistance
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