Diversity of Nematode Microbial Antagonists from Algeria Shows Occurrence of Nematotoxic spp.

Fungi and bacteria associated to phytoparasitic nematodes and spp. in Algeria were identified and characterized. spp. showed the highest prevalence in the cysts of . A number of isolates were identified through PCR amplification and the sequencing of the internal transcribed spacer (ITS)1-2 and gene regions. The most represented species were and . The latter and were reported for the first time in Algeria. spp., including and , comprised a second group of fungi found in cysts. Taxa associated to females of spp. included , spp. and other hyphomycetes. To assess the efficacy of spp., two assays were carried out in vitro with the culture filtrates of two and . isolates, to check their toxicity versus the second stage juveniles of . After 24-48 h exposure, a mortality significantly higher than the control was observed for both filtrates at 1% dilutions. The genes involved in the production of trichothecenes were also amplified with the PCR from some spp. isolates and sequenced, supporting a putative role in nematode toxicity. Bacteria isolated from the cysts of included and spp., identified through 16S rRNA gene sequencing. The potential of the microbial isolates identified and their mechanisms of action are discussed, as part of a sustainable nematode management strategy.