Microorganisms can generate thousands of valuable products, including proteins, primary and secondary metabolites. The growing demand for biotechnological products against limited metabolic capacity of industrially used microorganisms has led to an increased interest on strain improvement.
The aim of strain improvement is to short fermentation times, enhance metabolite yield, lower toxicity, improve titer and stability, substrate uptake and tolerance of the strains. Strain improvement also serves other goals, such as the elimination of undesirable products or analogs, discovery of new antibiotics, and deciphering of biosynthetic pathways.
With rich experience of microbial service in industry, Creative BioMart Microbe has established a complete strain improvement platform. Our platform generates new genetic characters by several means involving mutation, genetic recombination, overexpression, and gene editing techniques. With rich experienced experts, Creative BioMart Microbe can offer you with a panel of comprehensive solutions.
As the most commonly method, the main mutation method is to use physical, chemical, biological, or combinations of different mutagenesis to modify the target microorganism’s genome to produce mutants. The naturally occurring mutation rate in microorganism is 10-8~10-5, which can be increased to 10-6~10-3 after mutagenesis.
Figure 1 Diagram of an UV mutagenesis experimental design and arrangement (Lv et al., 2021).
Genetic recombination allows the exchange of genetic information between two DNA molecules in a precise, specific, and faithful manner, regardless of size. We provide genetic recombination services by transformation, transduction, conjugation, and protoplast fusion. Among which, Red/ET recombination technology is the most common used method for DNA engineering. Red/ET recombination technology is based on homologous recombination involving a λ phage-derived protein pair, Redα/Redβ, and 50 bp homology regions. It can help you realize deletion, insertion, point mutation at any position because the sequence of the homology regions can be chosen freely.
Figure 2 The Flowchart of Red/ET recombination technology.
To achieve the high expression of target enzyme or metabolites, overexpression of related genes in target microbial strains is necessary in some cases. Creative BioMart Microbe offer custom one stop strain overexpression service involving gene synthesis, vector construction, transformation, strain screening and verification. The diverse options for vectors with diversified strong promoters and selective markers. Moreover, we can help you realize endogenous overexpression of target genes using the CRISPR activation system. Though overexpression may bring genetic instability, structural instability, and metabolic burden to the host, it brings many advantages for application of improved strains.
Gene editing is a group of technologies that allow us change an organism's DNA. A recent one is known as CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9), which can help you get genetic material to be added, removed, or altered at a particular location. It has gained the favor of many scientists because it is faster, cheaper, more accurate, and more efficient than other existing genome editing methods. Creative BioMart Microbe has developed a well gene editing platform -- λ Red-CRISPR/Cas9 system, which leverages the efficiency of traditional λ Red recombineering with the ease of CRISPR/Cas for seamless, targeted genome editing.
Figure 3 Schematic diagram for the gene knock out by the λ Red-CRISPR/Cas9 system.
In addition, our scientists can help you get improved strains with precise editing by base editors (such as cytosine base editors (CBEs), adenine base editors (ABEs) and glycosylase base editors (GBEs)) or prime editing technology. These technologies don’t need double-stranded DNA breaks (DSBs). Furthermore, you can get mutational strains by constructing CRISPR mutation library.
Figure 4 Functional mechanism of CBEs, ABEs (Rees and Liu, 2018), and GBEs (Zhao et al., 2020).
The capacity of strain improvement services in Creative BioMart Microbe:
Creative BioMart Microbe strives to serve clients by providing strain improvement service that meet the highest industry and production expectations. Please feel free to contact us for more information.
Workflow of Strain Improvement Service in Creative BioMart Microbe