Nematicidal Effect of A Wild Type of Serratia Marcescens and Its Mutants Against Meloidogyne Incognita Juveniles

Serratia marcescens (SM) is currently considered as a biocontrol agentagainst plant parasitic nematodes. It is one of the most effective bacteria fordegradation of chitin. This lytic bacteria was evaluated on the survival ofMeloidogyne incognita juveniles under laboratory conditions. The best treatment by(SM 36) mutant achieved zero viable juveniles in either S or S/10 i.e, highlyeffective on juveniles mortality compared to the wild type of SM and untreatedcontrol which recorded 51.8, 49.3 and 49 juveniles, respectively. The numbers ofnon viable juveniles of the best treatment were 6, 4 and 2.8 individuals after 24, 48and 72 hrs, respectively compared to the SM wild type which achieved 26.3. 33.3and 27.3 while the untreated control did not show any effect on the juveniles. Therewere positive relationships between the nematode mortality and each of thebacteria concentration and enzyme production from the mutants. The numbers ofeither viable juveniles or non viable juveniles were reduced at S or S/10 dilutionsand exposure periods of 24, 48 and 72 hr compared to the untreated control. Thisreduction was attributed to the dead nematode bodies which were degraded anddestroyed by these bacterial mutants. Mutation achieved increasing of chitinase andalkaline protease-over producing mutants, which produced two to three times moreendochitinase activity than the wild type of S.marcescens.