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

Document Type : Original Article


1 Department of Plant Protection, Fac. of Agric., Ain Shams Univ., Shoubra El-Kheima, Cairo, Egypt.

2 Nematology Lab., Plant Pathology Department, National Research Centre, Dokki, Giza, Egypt

3 Department of Genetic and Cytology, National Research Centre, Dokki, Giza, Egypt


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