Engineering Tools for the Development of Recombinant Lactic Acid Bacteria

Abstract

Lactic acid bacteria (LAB) is mainly used in food fermentation. In addition, LAB fermentation technology has been studied in the development of industrial food additives, nutrients, or enzymes used in food processing. In the field of red biotechnology, LAB is approved and is generally recognized as a safe organism and is considered safe for biotherapeutic treatments. Recent clinical trials have demonstrated the medicinal value of therapeutic recombinant LAB and the suitability of innate mechanisms of secretion and anchoring for therapeutic applications such as antibody or vaccine production. However, the gram-positive phenotypic trait of LAB creates challenges for genetic modifications when compared to other conventional workhorse bacteria, resulting in exclusive developments of genetic tools for engineering LAB. In this review, several distinct approaches in gene expression for engineering LAB are discussed.The authors declare no conflict of interest.

Recent biotechnological trends in lactic acid bacterial fermentation for food processing industries

“…5) [25,163]. Although, synthetic biology and genome engineering tools are very limited for LAB due to restrictive legislation and poor consumer acceptance [164,165]. Moreover, GMOs LABs are pioneers in the development of high-throughput genome editing tools for industrial LAB strains for food applications [166].…”

“…7 Genetic transformation and genome editing methods tools are available for LAB in metabolic engineering. a) Gene transformation techniques; (e.g., Conjugation, Transduction, Electroporation, Protoplastbased approach) [190]; b) Integration/ homologous recombination (HR) methods (e.g., Plasmid-based HR and DNA recombineering) [165,191]; c) CRISPR-Cas based methods (e.g., Cas9 counterselection, repurposing endogenous systems and tunable gene silencing) [192,193]; Chr., chromosome; str., strand; ABR, antibiotic resistance; ssDNA, single-stranded DNA; dsDNA, double-stranded DNA; gRNA, guide RNA, which can be either a single guide (sgRNA) or a dual crRNA: tracrRNA acid with high metabolite rates attribute to high activity of lactate dehydrogenase (LDH), catalyzed by accumulation of NADH formed during glycolysis. However, under anaerobic fermentation conditions, this phenomenon is lost leading in the co-production of acetate, ethanol, formate, CO 2 with the reduction in overall conversion yield [207].…”

Recombinant Lactococcus Expressing a Novel Variant of Infectious Bursal Disease Virus VP2 Protein Can Induce Unique Specific Neutralizing Antibodies in Chickens and Provide Complete Protection

“…As a promising candidate for use as antigen carriers [30,31], a major advantage of this system is the ability to safely deliver antigens to the immune system [32]. Therefore, we used L. lactis as a vector to express heterologous proteins, which is a common practice [24,25,[33][34][35][36][37][38]. Moreover, to enhance the antigen presentation of avVP2 and improve the immune protection efficiency, we utilized fusion expression avVP2-RCK following our previous study.…”

Harnessing the Potential of Lactobacillus Species for Therapeutic Delivery at the lumenal-mucosal Interface

“…These bacteria have been studied for both their industrial applications in the production of flavor compounds and other fermentative abilities [15], in addition to their abilities to alleviate medically elusive systemic issues in the large intestine involving inflammation [16]. Lactobacillus belongs to the larger lactic acid bacteria (LAB) group, for which genetic tools have been developed in efforts to increase their potential as immune adjuvants and cell factories charged with the secretion of bioactive molecules [17]. In effect, these microbes can be administered orally, live in the gut and deliver therapeutic benefits as well as targeted compounds through their interactions with the host immune and nervous systems (Figure 1).…”