Many soil bacteria can degrade the synthetic insecticides chlorpyrifos and deltamethrin by their esterase enzymes and/or by using them as carbon and energy sources. The hypothesis tested was that similar degradation potential could be found in Lactobacillus plantarum (Orla-Jensen, 1919) (Lactobacillales: Lactobacillaceae) which is used in food fermentations. This study was conducted in-vitro in Bursa Uludag University laboratories during 2017-2018 to demonstrate the two degradation mechanisms of L. plantarum strains LB-1 and LB-2, 4 d after inoculation. Significant growth in LB-1 found in mineral salt (MS) medium containing chlorpyrifos and deltamethrin compared with MS medium without insecticide and any carbon source. This strain also exhibited significantly enhanced hydrolysis activity. These capacities were found lower in LB-2 than LB-1. Based on periodically GC-MS analysis, degradation of chlorpyrifos and deltamethrin in MS medium proceeded by strains LB-1 and LB-2 reached the values of 96 and 90% and 24 and 53% after 3 d, respectively. Significant degradation of deltamethrin with both strains (86-82%) determined after 10 d. The study demonstrated that some L. plantarum strains could degrade chlorpyrifos and deltamethrin. Further studies should be conducted to show their effectiveness in the fermentation process of some fruits and vegetables and different bacteria inoculation rates.