Engineering carbon source division of labor for efficient α-carotene production in Corynebacterium glutamicum.

Effective utilization of glucose, xylose, and acetate, common carbon sources in lignocellulose hydrolysate, can boost biomanufacturing economics. However, carbon leaks into biomass biosynthesis pathways instead of the intended target product remain to be optimized. This study aimed to enhance α-carotene production by optimizing glucose, xylose, and acetate utilization in a high-efficiency Corynebacterium glutamicum cell factory.

Structure and specificity of an anti-chloramphenicol single domain antibody for detection of amphenicol residues.

Antibiotics in aquaculture prevent bacterial infection of fish, but their misuse is a public health risk and contributes to the unintentional creation of multiresistant pathogens. Regulatory agencies cannot do the rigorous, expensive testing required to keep up with the volume of seafood shipments. Current rapid test kits for these drugs enable the increase in testing needed for adequate monitoring of food supply chains, but they lack a high degree of accuracy.

Heterologous production of α-Carotene in Corynebacterium glutamicum using a multi-copy chromosomal integration method.

The carotenoid, α-carotene, is very beneficial for human health and wellness, but microbial production of this compound is notoriously difficult, due to the asymmetric rings on either end of its terpenoid backbone. Here, we report for the first time the efficient production of α-carotene in the industrial bacterium Corynebaterium glutamicum by using a combined pathway engineering approach including evaluation of the performance of different cyclases and analysis of key metabolic intermediates to determine flux bottlenecks in the carotenoid biosynthesis pathway. A multi-copy chromosomal integration method was pivotal in achieving stable expression of the cyclases.

Optimizing recombineering in Corynebacterium glutamicum.

Owing to the increasing demand for amino acids and valuable commodities that can be produced by Corynebacterium glutamicum, there is a pressing need for new rapid genome engineering tools that improve the speed and efficiency of genomic insertions, deletions, and mutations. Recombineering using the λ Red system in Escherichia coli has proven very successful at genetically modifying this organism in a quick and efficient manner, suggesting that optimizing a recombineering system for C. glutamicum will also improve the speed for genomic modifications.

Modular engineering for microbial production of carotenoids.

There is an increasing demand for carotenoids due to their applications in the food, flavor, pharmaceutical and feed industries, however, the extraction and synthesis of these compounds can be expensive and technically challenging. Microbial production of carotenoids provides an attractive alternative to the negative environmental impacts and cost of chemical synthesis or direct extraction from plants. Metabolic engineering and synthetic biology approaches have been widely utilized to reconstruct and optimize pathways for carotenoid overproduction in microorganisms.

Microfluidic Device to Quantify the Behavior of Therapeutic Bacteria in Three-Dimensional Tumor Tissue.

Microfluidic devices enable precise quantification of the interactions between anti-cancer bacteria and tumor tissue. Direct observation of bacterial movement and gene expression in tissue is difficult with either monolayers of cells or tumor-bearing mice. Quantification of these interactions is necessary to understand the inherent mechanisms of bacterial targeting and to develop modified organisms with enhanced therapeutic properties.

Potent and tumor specific: arming bacteria with therapeutic proteins.

Bacteria are perfect vessels for targeted cancer therapy. Conventional chemotherapy is limited by passive diffusion, and systemic administration causes severe side effects. Bacteria can overcome these obstacles by delivering therapeutic proteins specifically to tumors.

Quorum-sensing Salmonella selectively trigger protein expression within tumors.

Salmonella that secrete anticancer proteins have the potential to eliminate tumors, but nonspecific expression causes damage to healthy tissue. We hypothesize that Salmonella, integrated with a density-dependent switch, would only express proteins in tightly packed colonies within tumors. To test this hypothesis, we cloned the lux quorum-sensing (QS) system and a GFP reporter into nonpathogenic Salmonella.

Bacterial delivery of Staphylococcus aureus α-hemolysin causes regression and necrosis in murine tumors.

Bacterial therapies, designed to manufacture therapeutic proteins directly within tumors, could eliminate cancers that are resistant to other therapies. To be effective, a payload protein must be secreted, diffuse through tissue, and efficiently kill cancer cells. To date, these properties have not been shown for a single protein.

Identification of Staphylococcus aureus α-hemolysin as a protein drug that is secreted by anticancer bacteria and rapidly kills cancer cells.

Targeted bacterial delivery of anticancer proteins has the ability to overcome therapeutic resistance in tumors that limits the efficacy of chemotherapeutics. The ability of bacteria to specifically target tumors allows for delivery of aggressive proteins that directly kill cancer cells and cannot be administered systemically. However, few proteins have been tested for this purpose.

Lipid A controls the robustness of intratumoral accumulation of attenuated Salmonella in mice.

Engineered Salmonella have the potential to treat cancers that are not responsive to standard molecular therapies. This potential has not been realized because colonization in human tumors is insufficient and variable as shown in preliminary phase I trials. Recent studies have shown that Salmonella colonization is associated with an inflammatory response mediated by tumor necrosis factor (TNF).

Construction of an inducible cell-communication system that amplifies Salmonella gene expression in tumor tissue.

Bacterial therapies have the potential to overcome resistances that cause chemotherapies to fail. When using bacteria to produce anticancer agents in tumors, triggering gene expression is necessary to prevent systemic toxicity. The use of chemical triggers, however, is hampered by poor delivery of inducing molecules, which reduces the number of activated bacteria.