ASSESSMENT OF AGRICULTURALLY IMPORTANT METABOLITES FROM THE ENTOMOPATHOGENIC BACTERIUM, Photorhabdus temperata M1021

Abstract

Photorhabdus temperata M1021 is an entomopathogenic enterobacterium, producing an array of metabolites in the culture extract. Photorhabdus spp. produced various classes of toxic proteins and secondary metabolites, which generate mortality in a wide range of insects. Aim of present study was to assess the effects these metabolites towards the insect and plants. Intra-hemocoel injections of whole cell and soluble extract caused 100% mortality in Galleria mellonella larvae within 48 h as compare to control. However, the culture filtrate (CF) took 72 h to kill 100 % larvae. In addition, there was no significant (P<0.05) decrease in the rate of larval mortality, injected with CF, treated at 70°C for 30 min as well as with 50 mg/l proteinase-K. Gas chromatography mass spectrometry analysis revealed 23 compounds, among which "trans-Cinnamic acid" and "indole" were the most important for the insecticidal activities and plant growth promotion. The auxin contents quantified through Salkowski's assay were 28 μg/ml to 30 μg/ml, insignificantly varied the by the addition of L-tryptophan ranged from 0 g/l to 0.5 g/l. The optimum pH for the auxin production was determined to be pH 7.0. The CF treatment increases significantly (P<0.05) plant growth that attributes e.g. total plant length, chlorophyll content and biomass of both Dongjin-beyo and Waito-Crice plants, in a comparison with control. The findings of this study suggest that the P. temperata M1021 could be an ideal candidate, to be exploited in agriculture as biocontrol agent. * Corresponding author KEYWORDS Plant microbe interaction Photorhabdus temperate Plant growth promotion Insecticidal activityGalleria mellonella

Towards a new biological control approach for Photorhabdus temperata bioinsecticide production through the bioconversion of Tunisian industrial wastewater

“…It is characterized by the production of different insecticidal proteins like the toxin complexes (Tc) (Waterfield et al 2001) and the "makes caterpillars floppy" (Mcf ) toxins (Daborn et al 2002). These toxins have been successfully used as bioinsecticides against very diverse insect orders, either by ingestion (Jallouli et al 2013) or injection into the hemolymph (Jang et al 2011;Ullah et al 2017). Investigation of P. temperata oral toxicity has been reported in several studies.…”

“…In addition, an Escherichia coli cosmid clone, containing the mcf gene from P. temperata, was demonstrated to be highly virulent after injection into Galleria mellonella and Tenebrio molitor, by causing the loss of body turgor of both larvae (Ullah et al 2014). Moreover, 100% mortality of G. mellonella was obtained after injecting of P. temperata whole cells, soluble extract or supernatant (Jang et al 2011;Ullah et al 2017).…”