Identification of bacteria associated with two entomopathogenic nematode species of the genus Steinernema (Rhabditida: Steinernematidae).

RONDAN DUEÑAS, J.C.; MUÑOZ, A.; BELAUS, A.; DEL VALLE, E.; DOUCET, M.E.; LAX, P.

Congreso; XI Congreso Argentino de Microbiología General; 2015

Entomopathogenic nematodes of the genus Steinernema are obligate parasites of insects and are used as biological control agents of insect pests. Third-stage juveniles (J3) carry symbiotic bacteria of the genus Xenorhabdus in their intestine; at the moment of infection, these bacteria are released to the insect hemocoel, where they multiply and become the food source for the nematode. Although this nematode-bacteria relationship is specific, other bacteria related with these parasites have occasionally been identified. The aim of this work was to isolate the bacteria associated with J3 of native isolates of S. rarum and S. diaprepesi, using two treatments (nematodes subjected or not to disinfection of the cuticle using NaClO). In both treatments, J3 were macerated; the supernatant was used to develop a culture with brain-heart agar medium. The colonies were isolated and total DNA was extracted for further identification based on the 16S rRNA gene. Disinfection of J3 allowed isolation of symbiotic bacteria X. szentirmaii and X. doucetiae from S. rarum and S. diaprepesi, respectively. Two strains of Serratia sp. were extracted from the nematodes that were not subjected to external disinfection. The results document the unusual foretic association between Serratia sp. and the two Steinernema species.