Boosting Auto-Induction of Recombinant Proteins in Escherichia coli with Glucose and Lactose Additives

Methods for Cas13a expression and purification for use in CRISPR diagnostics

The threat of emerging infectious diseases (e.g., SARS-CoV-2 the RNA virus responsible for the COVID-19 pandemic) has highlighted the importance of accurate and rapid testing for screening, patient diagnosis, and effective treatment of infectious disease. Nucleic acid diagnostic tools such as qPCR are considered the gold standard, providing a sensitive, accurate, and robust method of detection. However, these conventional diagnostic platforms are resource intensive, limited in some applications, and are almost always confined to laboratory settings. With the increasing demand for low-cost, rapid, and accurate point-of-care diagnostics, CRISPR-based systems have emerged as powerful tools to augment detection capabilities. Of note is the potent RNA detection enzyme, Leptotrichia buccalis (Lbu) Cas13a, which is capable of rapid RNA detection in complex mixtures with or without pre-amplification. To support its wide-spread use, we describe a detailed method for the expression, purification, and validation of LbuCas13a for use in molecular diagnostics.

A comprehensive review of recombinant technology in the food industry: Exploring expression systems, application, and future challenges

Biotechnology has significantly advanced the production of recombinant proteins (RPs). This review examines the latest advancements in protein production technologies, including CRISPR, genetic engineering, vector integration, and fermentation, and their implications for the food industry. This review delineates the merits and shortcomings of prevailing host systems for RP production, underscoring molecular and process strategies pivotal for amplifying yields and purity. It traverses the spectrum of RP applications, challenges, and burgeoning trends, highlighting the imperative of employing robust hosts and cutting-edge genetic engineering to secure high-quality, high-yield outputs while circumventing protein aggregation and ensuring correct folding for enhanced activity. Recombinant technology has paved the way for the food industry to produce alternative proteins like leghemoglobin and cytokines, along with enzyme preparations such as proteases and lipases, and to modify microbial pathways for synthesizing beneficial compounds, including pigments, terpenes, flavonoids, and functional sugars. However, scaling microbial production to industrial scales presents economic, efficiency, and environmental challenges that demand innovative solutions, including high-throughput screening and CRISPR/Cas9 systems, to bolster protein yield and quality. Although recombinant technology holds much promise, it must navigate high costs and scalability to satisfy the escalating global demand for RPs in therapeutics and food. The variability in ethical and regulatory hurdles across regions further complicates market acceptance, underscoring an urgent need for robust regulatory frameworks for genetically modified organisms. These frameworks are essential for safeguarding the production process, ensuring product safety, and upholding the efficacy of RPs in industrial applications.

Enhancing recombinant growth factor and serum protein production for cultivated meat manufacturing

The commercial growth factors (GFs) and serum proteins (SPs) contribute to the high cost associated with the serum-free media for cultivated meat production. Producing recombinant GFs and SPs in scale from microbial cell factories can reduce the cost of culture media. Escherichia coli is a frequently employed host in the expression recombinant GFs and SPs. This review explores critical strategies for cost reduction in GFs and SPs production, focusing on yield enhancement, product improvement, purification innovation, and process innovation. Firstly, the review discusses the use of fusion tags to increase the solubility and yield of GFs & SPs, highlighting various studies that have successfully employed these tags for yield enhancement. We then explore how tagging strategies can streamline and economize the purification process, further reducing production costs. Additionally, we address the challenge of low half-life in GFs and SPs and propose potential strategies that can enhance their stability. Furthermore, improvements in the E. coli chassis and cell engineering strategies are also described, with an emphasis on the key areas that can improve yield and identify areas for cost minimization. Finally, we discuss key bioprocessing areas which can facilitate easier scale-up, enhance yield, titer, and productivity, and ultimately lower long-term production costs. It is crucial to recognize that not all suggested approaches can be applied simultaneously, as their relevance varies with different GFs and SPs. However, integrating of multiple strategies is anticipated to yield a cumulative effect, significantly reducing production costs. This collective effort is expected to substantially decrease the price of cultivated meat, contributing to the broader goal of developing sustainable and affordable meat.

Advances in recombinant protein production in microorganisms and functional peptide tags

Recombinant protein production in prokaryotic and eukaryotic cells is a fundamental technology for both research and industry. Achieving efficient protein synthesis is key to accelerating the discovery, characterization, and practical application of proteins. This review focuses on recent advances in recombinant protein production and strategies for more efficient protein production, especially using Escherichia coli and Saccharomyces cerevisiae. Additionally, this review summarizes the development of various functional peptide tags that can be employed for protein production, modification, and purification, including translation-enhancing peptide tags developed by our research group.

Auto-induction, biochemical characterization and application of a novel thermo-alkaline and detergent-stable lipase (S9 peptidase domain) from Thermotoga petrophila as cleaning additive and degrading oil/fat wastes

A peptidase S9 prolyl oligopeptidase domain from Thermotoga petrophila RKU-1T (TpS9) was over-expressed as an active, soluble and hyperstable lipolytic enzyme in the mesophilic host system. The sequence analysis demonstrated, TpS9 is an esterase/lipase-like protein belongs to alpha/beta (α/β)-hydrolase superfamily with a well-conserved penta-peptide (GLSAG) motif and α/β-hydrolase fold. Various approaches (induction and cultivation) were employed to enrich TpS9 production, 6.04- and 7.26-fold increment was observed with IPTG (0.4 mM) and lactose (200 mM) in the modified 4ZB medium (pH 7.0), but with IPTG-independent auto-induction strategy 9.02-fold augmentation was achieved after 16 h incubation at 24 °C (150 rev min-1). Purified TpS9 showed optimal activity in McIlvaine buffer (pH 6.5) at 80-85 °C, and revealed great thermal (30-85 °C) and pH (6.0-9.0) for 8 h. No obvious constraint was perceived with various metal ions, surfactants, commercial laundry detergents, and chemical modulators. Whereas, TpS9 activity was improved with Ca2+, Mn2+, and Mg2+ by 210 %, 142.5 %, and 134.3 %, respectively. With 2.5 M NaCl (215 %), 50 % (v/v) methanol (140 %), 50 % (v/v) ethanol (126.6 %), 50 % (v/v) n-butanol (122.3 %), 50 % (v/v) isopropanol (120.4 %), 50 % (v/v) acetone (118.6 %) and 50 % (v/v) glycerol (113.2 %) TpS9 activity was also enriched. TpS9 demonstrated great affinity toward natural oils and p-nitrophenyl ester substrates, but showed peak activity with p-nitrophenyl palmitate (3160 U mg-1). Km, Vmax, kcat, Vmax Km-1 and kcat Km-1 of TpS9 with pNPP were 0.421 mM, 4015 µmol mg-1 min-1, 906.4 s-1, 9536.8 min-1, and 2152.96 mM-1 s-1, respectively. Moreover, TPS9 has notable ability to clean stains (5 min) and degrade the animals' fat (3 h). Hence, TpS9 is a favorable candidate as cleaning bio-additive in detergent formulation, fat degradation and various other applications.

Delaying production with prokaryotic inducible expression systems

BACKGROUND

Engineering bacteria with the purpose of optimizing the production of interesting molecules often leads to a decrease in growth due to metabolic burden or toxicity. By delaying the production in time, these negative effects on the growth can be avoided in a process called a two-stage fermentation.

MAIN TEXT

During this two-stage fermentation process, the production stage is only activated once sufficient cell mass is obtained. Besides the possibility of using external triggers, such as chemical molecules or changing fermentation parameters to induce the production stage, there is a renewed interest towards autoinducible systems. These systems, such as quorum sensing, do not require the extra interference with the fermentation broth to start the induction. In this review, we discuss the different possibilities of both external and autoinduction methods to obtain a two-stage fermentation. Additionally, an overview is given of the tuning methods that can be applied to optimize the induction process. Finally, future challenges and prospects of (auto)inducible expression systems are discussed.

CONCLUSION

There are numerous methods to obtain a two-stage fermentation process each with their own advantages and disadvantages. Even though chemically inducible expression systems are well-established, an increasing interest is going towards autoinducible expression systems, such as quorum sensing. Although these newer techniques cannot rely on the decades of characterization and applications as is the case for chemically inducible promoters, their advantages might lead to a shift in future inducible expression systems.

Expression of soluble moloney murine leukemia virus-reverse transcriptase in Escherichia coli BL21 star (DE3) using autoinduction system

Autoinduction systems in Escherichia coli can control the production of proteins without the addition of a particular inducer. In the present study, we optimized the heterologous expression of Moloney Murine Leukemia Virus derived Reverse Transcriptase (MMLV-RT) in E. coli. Among 4 autoinduction media, media Imperial College resulted the highest MMLV-RT overexpression in E. coli BL21 Star (DE3) with incubation time 96 h. The enzyme was produced most optimum in soluble fraction of lysate cells. The MMLV-RT was then purified using the Immobilized Metal Affinity Chromatography method and had specific activity of 629.4 U/mg. The system resulted lower specific activity and longer incubation of the enzyme than a classical Isopropyl ß-D-1-thiogalactopyranoside (IPTG)-induction system. However, the autoinduction resulted higher yield of the enzyme than the conventional induction (27.8%). Techno Economic Analysis revealed that this method could produce MMLV-RT using autoinduction at half the cost of MMLV-RT production by IPTG-induction. Bioprocessing techniques are necessary to conduct to obtain higher quality of MMLV-RT under autoinduction system.

Essential factors, advanced strategies, challenges, and approaches involved for efficient expression of recombinant proteins in Escherichia coli

Producing recombinant proteins is a major accomplishment of biotechnology in the past century. Heterologous hosts, either eukaryotic or prokaryotic, are used for the production of these proteins. The utilization of microbial host systems continues to dominate as the most efficient and affordable method for biotherapeutics and food industry productions. Hence, it is crucial to analyze the limitations and advantages of microbial hosts to enhance the efficient production of recombinant proteins on a large scale. E. coli is widely used as a host for the production of recombinant proteins. Researchers have identified certain obstacles with this host, and given the growing demand for recombinant protein production, there is an immediate requirement to enhance this host. The following review discusses the elements contributing to the manifestation of recombinant protein. Subsequently, it sheds light on innovative approaches aimed at improving the expression of recombinant protein. Lastly, it delves into the obstacles and optimization methods associated with translation, mentioning both cis-optimization and trans-optimization, producing soluble recombinant protein, and engineering the metal ion transportation. In this context, a comprehensive description of the distinct features will be provided, and this knowledge could potentially enhance the expression of recombinant proteins in E. coli.

Factors involved in heterologous expression of proteins in E. coli host

The production of recombinant proteins is one of the most significant achievements of biotechnology in the last century. These proteins are produced in the eukaryotic or prokaryotic heterologous hosts. By increasing the omics data especially related to different heterologous hosts as well as the presence of new amenable genetic engineering tools, we can artificially engineer heterologous hosts to produce recombinant proteins in sufficient quantities. Numerous recombinant proteins have been produced and applied in various industries, and the global recombinant proteins market size is expected to be cast to reach USD 2.4 billion by 2027. Therefore, identifying the weakness and strengths of heterologous hosts is critical to optimize the large-scale biosynthesis of recombinant proteins. E. coli is one of the popular hosts to produce recombinant proteins. Scientists reported some bottlenecks in this host, and due to the increasing demand for the production of recombinant proteins, there is an urgent need to improve this host. In this review, we first provide general information about the E. coli host and compare it with other hosts. In the next step, we describe the factors involved in the expression of the recombinant proteins in E. coli. Successful expression of recombinant proteins in E. coli requires a complete elucidation of these factors. Here, the characteristics of each factor will be fully described, and this information can help to improve the heterologous expression of recombinant proteins in E. coli.

Application of Milk Permeate as an Inducer for the Production of Microbial Recombinant Lipolytic Enzymes

Recombinantly produced enzymes are applied in many fields, ranging from medicine to food and nutrition, production of detergents, textile, leather, paper, pulp, and plastics. Thus, the cost-effectiveness of recombinant enzyme synthesis is an important issue in biotechnological industry. Isopropyl-β-D-thiogalactoside (IPTG), an analog of lactose, is currently the most widely used chemical agent for the induction of recombinant enzyme synthesis. However, the use of IPTG can lead to production of toxic elements and can introduce physiological stress to cells. Thus, this study aims to find a simpler, cheaper, and safer way to produce recombinant enzymes. In this study, production of several previously designed recombinant lipolytic enzymes (GDEst-95 esterase, GD-95RM lipase, fused GDEst-lip lipolytic enzyme, and putative cutinase Cut+SP from Streptomyces scabiei 87.22) is induced in E. coli BL21 (DE3) using 4 mM milk permeate, a type of waste of the milk manufacturing process possessing >82% lactose. The SDS-PAGE analysis clearly indicates synthesis of all target enzymes during a 2–12 h post-induction timeframe. Further investigation of GDEst-95, GD-95RM, GDEst-lip, and Cut+SP biocatalysts was carried out spectrophotometrically and using zymography method, confirming production of fully active enzymes.

1Progress, applications, challenges and prospects of protein purification technology

Protein is one of the most important biological macromolecules in life, which plays a vital role in cell growth, development, movement, heredity, reproduction and other life activities. High quality isolation and purification is an essential step in the study of the structure and function of target proteins. Therefore, the development of protein purification technologies has great theoretical and practical significance in exploring the laws of life activities and guiding production practice. Up to now, there is no forthcoming method to extract any proteins from a complex system, and the field of protein purification still faces significant opportunities and challenges. Conventional protein purification generally includes three steps: pretreatment, rough fractionation, and fine fractionation. Each of the steps will significantly affect the purity, yield and the activity of target proteins. The present review focuses on the principle and process of protein purification, recent advances, and the applications of these technologies in the life and health industry as well as their far-reaching impact, so as to promote the research of protein structure and function, drug development and precision medicine, and bring new insights to researchers in related fields.

Recombinant Protein Production in E. coli Using the phoA Expression System

Auto-inducible promoter systems have been reported to increase soluble product formation in the periplasm of E. coli compared to inducer-dependent systems. In this study, we investigated the phosphate (PO4)-sensitive phoA expression system (pAT) for the production of a recombinant model antigen-binding fragment (Fab) in the periplasm of E. coli in detail. We explored the impact of non-limiting and limiting PO4 conditions on strain physiology as well as Fab productivity. We compared different methods for extracellular PO4 detection, identifying automated colorimetric measurement to be most suitable for at-line PO4 monitoring. We showed that PO4 limitation boosts phoA-based gene expression, however, the product was already formed at non-limiting PO4 conditions, indicating leaky expression. Furthermore, cultivation under PO4 limitation caused physiological changes ultimately resulting in a metabolic breakdown at PO4 starvation. Finally, we give recommendations for process optimization with the phoA expression system. In summary, our study provides very detailed information on the E. coli phoA expression system, thus extending the existing knowledge of this system, and underlines its high potential for the successful production of periplasmic products in E. coli.

Construction of an AI-2 quorum sensing induced heterologous protein expression system in Escherichia coli

Background

The pET expression system based on T7 promoter which is induced by isopropyl-β-D-1-thiogalactopyranoside (IPTG) is by far the most commonly used system for production of heterogeneous proteins in Escherichia coli. However, this system was limited by obvious drawbacks including the host toxicity and metabolic burden imposed by the presence of IPTG.

Methods

In this study, we incorporated the autoinducer-2 (AI-2) quorum sensing system to realize autoinduction of the pET expression system. The autoinduction expression vector pXWZ1 was constructed by inserting the lsr promoter regions into the pET28a(+) vector. The expression efficiency of the reporter genes gfpuv and lacZ by the pXWZ1 and pET28a(+) vectors were compared.

Results

The results showed that the expression levels of the both report genes in the cells transformed with pXWZ1 without any addition of exogenous inducer were higher than that transformed with pET28a(+) vectors by the induction of IPTG.

Conclusion

This new auto-induction system will exclude the limitations of the IPTG induction including toxic to host and increasing formation of inclusion body and will become a more economical and convenient tool for recombinant protein expression.