Vol.:(0123456789) 1 3 World J Microbiol Biotechnol (2017) 33:131 DOI 10.1007/s11274-017-2303-9 ORIGINAL PAPER Nematicidal efect of rhizobacteria on plant-parasitic nematodes associated with vineyards E. Aballay 1  · S. Prodan 1  · A. Zamorano 1  · C. Castaneda-Alvarez 1   Received: 15 February 2017 / Accepted: 26 May 2017 / Published online: 5 June 2017 © Springer Science+Business Media Dordrecht 2017 Introduction Plant growth-promoting rhizobacteria (PGPR) produce antibiotics, antimicrobial metabolites and hydrolytic enzymes, some of which have been reported to control plant-parasitic nematodes (PPN) (Siddiqui and Shaukat 2003). The increasing demand for environmentally friendly alternatives to control plant pathogens has led to an increase in research and development of new biopesticides from which bacteria currently represent 74% of the world market (Thakore 2006). Investigation into rhizobacteria control of PPN has mainly focused on endoparasitic nema- todes of the genus Meloidogyne while the efectiveness of bacterial strains in the control of other nematode species is poorly understood. Xiphinema index Thorne and Allen and Meloidogyne ethiopica Whitehead are two of the most important nema- todes in Chilean crops (Aballay et al. 2011; Aballay and Merino 2015). These nematodes have diferent feeding habits, found outside and inside of roots, respectively, and causing big damage when they are present in the same host, as it occurs in grapevines. This would imply consid- ering various strategies by the organism used in biological control. The ectoparasitic nematode, X. index, causes dam- age and atrophy of root meristematic zones and is also the vector of grape fanleaf virus (GFLV), a Nepovirus that can cause more than 90% loss in vineyard yield and decrease their production period by 50% (Fiore et al. 2011). On the other hand, the endoparasitic M. ethiopica, is listed as the most aggressive species of the genus found in the country due to the size of galls and the number of eggs produced per gram of root (Aballay et al. 2013). Previous works that have proven the efcacy of PGPR in controlling several Meloi- dogyne species, showed over 70% mortality of larval M. incognita (Radwan et al. 2012), M. javanica (Siddiqui et al. Abstract The action of metabolites and exoenzymes from rhizobacteria on diferent plant-parasitic nematodes has an infuence on the nematicidal efcacy of the microbe. Seven rhizobacteria, divided into two bacterial groups, were eval- uated in vitro for nematicidal activity on Meloidogyne ethi- opica and Xiphinema index. The direct efect of their fl- trates on egg hatching and juveniles of M. ethiopica as well as mobile stages of X. index was evaluated during a 72-h period. The production of four exoenzymes and two metab- olites associated with nematode mortality was investigated. Molecular characterization of three isolates was performed, and the physiological profles and lipase activity of all iso- lates were obtained using the BIOLOG EcoPlate system. While chitinase and collagenase were measured using the BIOLOG MT2 plate system, protease, hydrogen cyanide and hydrogen sulphide were directly determined in Petri dishes. Nematode mobile stages exposure to the bacte- rial fltrate revealed a nematicidal efect up to 93.7% on X. Index and up to 83.3% on M. ethiopica. The control of egg hatching varied between 35 and 85%. A positive correlation was found between the mortality of both nematode mobile stages and the concerted activities of the bacterial enzymes as well as the level of the volatile metabolites. The nemati- cidal efect of rhizobacteria strains varies by nematode gen- era and among the developmental stages evaluated. Keywords Biological control · Exoenzymes · Meloidogyne ethiopica · Metabolites · Plant-parasitic nematodes · Xiphinema index * E. Aballay eaballay@uchile.cl 1 Department of Crop Protection, Faculty of Agronomical Sciences, University of Chile, P.O. Box 1004, Santiago, Chile