Development of a cost-effective medium for Photorhabdus temperata bioinsecticide production from wastewater and exploration of performance kinetic

This study investigates the optimization of the culture conditions for enhancing Photorhabdus temperata biopesticide production using wastewater (WS4) as a raw material. Box-Behnken design (BBD) was used to evaluate the effects of carbon to nitrogen ratio (C/N), sodium chloride concentration and inoculum size on P. temperata biomass production and insecticidal activity. For an enhanced biopesticide production, the optimum operating conditions were as follows: inoculum size = 4%; C/N ratio = 12.5 and [NaCl] = 4 g/L for two responses. 1.95 and 2.75 fold improvements in oral toxicity and biomass production were respectively obtained in the cost-effective medium developed in this study (WS4 I) using the three variables at their optimal values. Under the optimized conditions, WS4 I-grown cells exhibited higher membrane integrity according to flow cytometry analysis since dead cells presented only 9.2% compared to 29.2% in WS4. From batch fermentations carried out in WS4 I and WS4, P. temperata kinetic parameters in terms of biomass production and substrate consumption rates were modeled. The obtained results showed that the maximum specific growth rate in WS4 I was of 0.43 h−1 while that obtained in WS4 was of 0.14 h−1. In addition, the efficiency of P. temperata to metabolize organic carbon was enhanced by optimizing the culture conditions. It reached 72.66% instead of 46.18% in the control fermentation after 10 h of incubation. Under the optimized conditions, P. temperata cells showed the highest specific consumption rate resulting in a toxin synthesis improvement.

Comparative In Silico Analysis of Randomly Selected Heat Shock Proteins in Caenorhabditis elegans and Photorhabdus temperata

Heat shock proteins (HSPs) such as HSP70A, HSP90 etc. (also known as Chaperons) play an important role in folding and unfolding of proteins, an assemblage of multiprotein complexes, transportation and sorting of proteins in subcellular compartments, cell cycle control, signaling pathways, protection against stress and programmed cell death. Studies have also linked heat shock proteins with a sudden rise in temperature, which can be related to anhydrobiosis in nematodes. Considering the significance of HSPs in nematodes and bacteria, the present study was designed for their in silico analysis in Caenorhabditis elegans and Photorhabdus temperata. The availability of a vast amount of sequence data generated through various bioinformatics tools, coupled with computational biology advancements, provides an ideal framework for silico gene expression and its analysis. A detailed in silico insight into these proteins include physicochemical properties, secondary structure prediction, homology modeling, and different models. The amino acid composition data were subjected to multivariate techniques, Pearson correlation, and phylogenetic analysis. In the present study, the authors characterized different HSPs according to different stability parameters and valid structures. A detailed in silico analysis of these proteins and prediction of their activity in different conditions can be very useful in both in vitro and in vivo experiments.

Development of a Cost-effective Medium for Photorhabdus Temperata Bioinsecticide Production From Wastewater and Exploration of Performance Kinetic

This study investigates the optimization of culture conditions for enhancing Photorhabdus temperata biopesticide production using wastewater (WS4) as a raw material. Box-Behnken design (BBD) was used to evaluate the effect of carbon to nitrogen ratio (C/N), NaCl concentration and inoculum size on Photorhabdus temperata biomass production and insecticidal activity. Modelling results suggest that the selected variables had contributed significantly to the responses. For enhanced biopesticide production the optimum operation conditions were as follow: inoculum size=4 %; C/N ratio=12.5 and sodium chloride concentration= 4 g/L for two responses. 1.95 and 2.75 folds improvement in oral toxicity and biomass production, respectively, were obtained when using the three variables at their optimum values. From batch fermentations carried out in the cost-effective medium developed in this study (WS4 I) and WS4 used as control, P. temperata kinetic parameters in term of biomass production and substrate consumption were modeled. The obtained results showed that the maximum specific growth rate was of 0.38 h-1 compared to 0.16 h-1 obtained in WS4. In addition, the efficiency of P. temperata to metabolize organic carbon was enhanced by optimizing culture conditions reaching 70 % instead of 47.2 % in the control fermentation. Under the optimized conditions, P. temperata cells showed higher specific consumption rate resulting in P. temperata toxin synthesis improvement.