Production of trans-cinnamic acid by whole-cell bioconversion from l-phenylalanine in engineered Corynebacterium glutamicum

Background trans-cinnamic acid (t-CA) is a phenylpropanoid with a broad spectrum of biological activities including antioxidant and antibacterial activities, and it also has high potential in food and cosmetic applications. Although significant progress has been made in the production of t-CA using microorganisms, its relatively low product titers still need to be improved. In this study, we engineered Corynebacterium glutamicum as a whole-cell catalyst for the bioconversion of l-phenylalanine (l-Phe) into t-CA and developed a repeated bioconversion process. Results An expression module based on a phenylalanine ammonia lyase-encoding gene from Streptomyces maritimus (SmPAL), which mediates the conversion of l-Phe into t-CA, was constructed in C. glutamicum. Using the strong promoter PH36 and ribosome binding site (RBS) (in front of gene 10 of the T7 phage), and a high-copy number plasmid, SmPAL could be expressed to levels as high as 39.1% of the total proteins in C. glutamicum. Next, to improve t-CA production at an industrial scale, reaction conditions including temperature and pH were optimized; t-CA production reached up to 6.7 mM/h in a bioreactor under optimal conditions (50 °C and pH 8.5, using NaOH as base solution). Finally, a recycling system was developed by coupling membrane filtration with the bioreactor, and the engineered C. glutamicum successfully produced 13.7 mM of t-CA (24.3 g) from 18.2 mM of l-Phe (36 g) and thus with a yield of 75% (0.75 mol/mol) through repetitive supplementation. Conclusions We developed a highly efficient bioconversion process using C. glutamicum as a biocatalyst and a micromembrane-based cell recycling system. To the best of our knowledge, this is the first report on t-CA production in C. glutamicum, and this robust platform will contribute to the development of an industrially relevant platform for the production of t-CA using microorganisms.

Construction of Leaderless-Bacteriocin-Producing Bacteriophage Targeting E. coli and Neighboring Gram-Positive Pathogens

We demonstrated that we could combine LLB and phage to construct promising novel antimicrobial agents, LLB-phage. The first LLB-phage, lnqQ -T7 phage, can control the growth of both the Gram-negative host strain and neighboring Gram-positive bacteria while preventing the emergence of phage resistance in the host strain.

Mapping the functional landscape of the receptor binding domain of T7 bacteriophage by deep mutational scanning

The interaction between a bacteriophage and its host is mediated by the phage's receptor binding protein (RBP). Despite its fundamental role in governing phage activity and host range, molecular rules of RBP function remain a mystery. Here, we systematically dissect the functional role of every residue in the tip domain of T7 phage RBP (1660 variants) by developing a high-throughput, locus-specific, phage engineering method. This rich dataset allowed us to cross compare functional profiles across hosts to precisely identify regions of functional importance, many of which were previously unknown. Substitution patterns showed host-specific differences in position and physicochemical properties of mutations, revealing molecular adaptation to individual hosts. We discovered gain-of-function variants against resistant hosts and host-constricting variants that eliminated certain hosts. To demonstrate therapeutic utility, we engineered highly active T7 variants against a urinary tract pathogen. Our approach presents a generalized framework for characterizing sequence–function relationships in many phage–bacterial systems.

An Engineered Reporter Phage for the Fluorometric Detection of Escherichia coli in Ground Beef

Despite enhanced sanitation implementations, foodborne bacterial pathogens still remain a major threat to public health and generate high costs for the food industry. Reporter bacteriophage (phage) systems have been regarded as a powerful technology for diagnostic assays for their extraordinary specificity to target cells and cost-effectiveness. Our study introduced an enzyme-based fluorescent assay for detecting the presence of E. coli using the T7 phage engineered with the lacZ operon which encodes beta-galactosidase (β-gal). Both endogenous and overexpressed β-gal expression was monitored using a fluorescent-based method with 4-methylumbelliferyl β-d-galactopyranoside (MUG) as the substrate. The infection of E. coli with engineered phages resulted in a detection limit of 10 CFU/mL in ground beef juice after 7 h of incubation. In this study, we demonstrated that the overexpression of β-gal coupled with a fluorogenic substrate can provide a straightforward and sensitive approach to detect the potential biological contamination in food samples. The results also suggested that this system can be applied to detect E. coli strains isolated from environmental samples, indicating a broader range of bacterial detection.

A medium-firm drug-candidate library of cryptand-like structures on T7 phage: design and selection of a strong binder for Hsp90

We designed and synthesized a library of cryptand-like structures on the T7 phage; a strong binder for a cancer-related protein was selected from the library.

The Assembly of Bacteriophage Functional Enzymatic Models in Association with E. coli Proteins' Profiles

Introduction: The invasion of bacteriophage on the associated host bacterium depends on their receptors' orientation that adsorb them to cell surface. During phage replication a valuable number of proteins acts as lytic enzymes for host puncher at the beginning of the infection and other for burst after lytic cycle compilation. Accordingly, the proteomic relationship among phage and bacterium proteins could easily be studied by their protein profiles analysis. Objective: To detect bacteriophages functional enzymes during lytic cycle. Methods: The isolation and identification of Escherichia coli and their parasitic T7 phage group was done using bacterial culture and common plaque assay techniques. The investigations and protein-protein interactions' assays were inveterate by proteins profile of phage and bacterium using Sodium Dodecyl Sulphate Poly Acrylamide Gel Electrophoresis (SDS-PAGE) to find out their molecular weights, where the scaled location of each mobile band was compared to the standards of identified proteins weights in the molecular ladder. Thereafter, Protein model's assembly and bands migration was done by computer analytical software. Results: Mobilization of the phage' proteins inside the Two Dimensions (2D) gel ranged between 60 and 12 kDa where a model of 4 main bands with molecular weights of (46, 35, 24 and 14 kDa) is corresponded to the host ones, where pure 9 bands with molecular weight ranged between 96-24 kDa. The computational model analysis showed common shared molecular masses of 47, 34 and 16 kDa on plot area of the phage and the bacterium. Model interpretation confirmed that proteins ranged from 47.7 to 34.3 kDa resembles 43.3% of whole phage's proteins that assembled the capsid head and the coil, while the molecular weight mass of 22.5 formed the tail's proteins. The lytic enzymes' molecular weight was ranged between 18-14 kDa according to the function of the enzyme. The study revealed that the 34 kDa band has the common shared peak between T7 phage group and associated Escherichia coli host. Conclusion: Functional models of analysed proteins during phage assembly, ensures lytic enzymes are built in the capsid head and the lysozyme in the tail, they facilitate the enzymatic decay for bacterial host. This enzymatic function is related to the lytic cycle of the bacteriophages and their phenomenon in employing the bacterial DNA in proteins manufacturing during their replication inside host.