ABSTRACT
A type of chromosome-free cell called SimCells (simple cells) has been generated from Escherichia coli, Pseudomonas putida, and Ralstonia eutropha. The removal of the native chromosomes of these bacteria was achieved by double-stranded breaks made by heterologous I-CeuI endonuclease and the degradation activity of endogenous nucleases. We have shown that the cellular machinery remained functional in these chromosome-free SimCells and was able to process various genetic circuits. This includes the glycolysis pathway (composed of 10 genes) and inducible genetic circuits. It was found that the glycolysis pathway significantly extended longevity of SimCells due to its ability to regenerate ATP and NADH/NADPH. The SimCells were able to continuously express synthetic genetic circuits for 10 d after chromosome removal. As a proof of principle, we demonstrated that SimCells can be used as a safe agent (as they cannot replicate) for bacterial therapy. SimCells were used to synthesize catechol (a potent anticancer drug) from salicylic acid to inhibit lung, brain, and soft-tissue cancer cells. SimCells represent a simplified synthetic biology chassis that can be programmed to manufacture and deliver products safely without interference from the host genome.
Subject(s)
Antineoplastic Agents/pharmacology , Catechols/pharmacology , Cellular Reprogramming , Cupriavidus necator/genetics , Escherichia coli/genetics , Pseudomonas putida/genetics , Synthetic Biology/methods , Cell Proliferation , Chromosomes, Bacterial , Cupriavidus necator/metabolism , Drug Delivery Systems , Escherichia coli/metabolism , Gene Regulatory Networks , Genetic Engineering , Neoplasms/drug therapy , Neoplasms/metabolism , Neoplasms/pathology , Pseudomonas putida/metabolism , Tumor Cells, CulturedABSTRACT
In this work, five Crassulacean Acid Metabolism (CAM) species from the five different genera (Agave, Ananas, Euphorbia, Kalanchoe, and Opuntia) were selected as alternative feedstocks and their biochemical methane potentials (BMP) were investigated. Batch assays were performed using sludge and rumen fluid as inocula under uncontrolled pH and at mesophilic temperature (39⯰C). Mean methane yields from the CAM plants inoculated with AD sludge ranged from 281 to 382â¯ml/gVS. These values were not significantly different from the methane yield obtained from maize, a feedstock for biomethane and volatile fatty acid (VFA), suggesting that CAM plants may be viable as bioenergy crops on poor-quality soils in areas with low rainfall that are unsuitable for cultivation of food crops.
