Table 1. Examples of engineered probiotics and their expression details.

Application	Bacterial chassis	Peptide	Wild-type/Gene source	Expression details	Purpose	Reference
Antibacterial or Antiviral Activity	Lactiplantibacillus plantarum (formerly Lactobacillus plantarum)	Spike protein Receptor-binding domain (RBD)	Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)	Inducible pSIP411 vector	SARS-CoV-2 vaccine	[17]
	L. plantarum	SARS-CoV-2 spike protein(S)	SARS-CoV-2	Expression plasmid pLP-tS	SARS-CoV-2 vaccine	[18]
	Lactococcus lactis	Reuterin	Limosilactobacillus reuteri (formerly Lactobacillus reuteri)	RecT expression vectors; pJP005 andpJP042	Antimicrobial activity	[19]
	Lacticaseibacillus casei (formerly Lactobacillus casei)	Listeria adhesion protein (LAP)	Listeria innocua, Listeria monocytogenes	Expression vector -pLP401T containing the pAmy promoter	Mitigation of lethal L. monocytogenes infection	[20]
	L.casei ATCC344	Internalins A and B (inlAB)	L. monocytogenes	Expression vector-pLP401-T	Prevention of L. monocytogenes infection	[5]
	Lacticaseibacillus paracasei (formerly Lactobacillus paracasei)	Heavy-chain antibodies (VHHs)	llama	Lactobacillus expression vector pLP501	Protection against Rotavirus-induced diarrhoea	[21]
	Lc. lactis	Alysteserin, CRAMP1 and Laterosporulin	Synthesised by various bacteria	PTKR vector, P1 promoter, usp45 gene	Selective inhibition of Helicobacter pylori	[22]
	Lactobacillus spp	Highly pathogenic avian influenza (HPAI) virus protein hemagglutinin 1 (HA1)	HPAI virus	E. coli-Lactobacillus shuttle vector pLEM415, lactate dehydrogenase (LDH) promoter, ldhL promoter	Avian influenza virus vaccine	[23]
	Lactobacillus gasseri NM713	Streptococcal M6 protein (CRR6)	Streptococcus pyogenes	Expression plasmid-pSLP111.1 based on the xylose operon promoter	Oral vaccine against Streptococcus pyogenes	[24]
	Lactobacillus jensenii	HIV-1 entry inhibitor cyanovirin-N	Cyanobacterium, Nostoc ellipsosporum	Expression cassette containing an L. jensenii promoter for the ribosomal protein subunit (PrpsU)	Antiviral activity	[25]
	Lacticaseibacillus rhamnosus (formerly Lactobacillus rhamnosus)	Anti-lectin griffithsin	Red algae Griffithsia sp.	NICE system, under PnisA control	Targets the HIV virus	[26]
	Lc. lactis	Glutamate-rich protein (GLURP)-Merozoite surface protein 3 (MSP3) chimeric protein	Plasmodium falciparum	P170 expression system	Malarial vaccine	[27]
Cancer Therapy	Lc. lactis	KiSS1	Human melanoma cell lines	Expression plasmid pNZ401, nisin inducible promoter	Cancer therapy for prevention of proliferation and migration of human colon carcinoma HT-29 cells	[28]
	Lc. lactis	Human Papilloma Virus 16 E7 protein Ag (LL-E7) and biologically active murine IL-12	HPV, murine cells	Nisin inducible promoter	Mucosal vaccine for prevention of HPV Type 16-Induced Tumors	[29]
	Lc. lactis	Glycosylated tyrosinase related protein-2	Murine cells	Chinese Hamster Ovary-S cell expression system	Cancer vaccine	[30]
	L. plantarum	Oncofetal antigen (OFA)	Mammalian cancer cells	pSIP system, inducible PsppA promoter	Cancer vaccine delivery	[31]
	Lc. lactis	Cu/Zn superoxide dismutase	Human cells	PTS System, under strong constitutive P32 control	Defence against carcinogenesis and oxidative damages in the human GIT	[32]
Metabolic Activity	L. gasseri	Glucagon-like peptide (GLP) 1 (1-37)	Pancreatic β-cell	SlpA promoter and usp45-LEISS secretion tag	Treatment of Type 2 diabetes	[33]
	Lc. lactis	Glucagon likepeptide-1	Pancreatic β-cell	Plasmid pUB1000 used as expression vector	Treatment of Type 2 diabetes	[34]
	Lc. lactis NZ9000	Osteocalcin	Murine cell	PnisA control	Diabetes and obesity therapy	[35]
	L. reuteri	Phenylalanine lyase	Anabaena variabilis	Lactobacillus high production constitutive promoter and ribosome binding sequence from the erythromycin resistance B gene (ermB)	Treatment of phenylketonuria	[36]
	Lc. lactis	Lipase	Staphylococcus hylicus.	Nisin inducible promoter	Treatment of pancreatic insufficiency	[37]
Biosensing	L. reuteri	Autoinducer peptide-I (AIP-I)	Staphylococcus sp	AgrA-activating promoter P3 for controlled expression of the glucuronidase-expressing gusA reporter gene	Biosensing AIP-I, a quorum sensing molecule produced by Staphylococcus sp. during pathogenesis.	[12]
	Lc. lactis	Enterococcal sex pheromone cCF10	Enterococcus faecalis	Expression vectors derived from pCF10	Biosensing	[38]
Immune Modulation	Lc. lactis	Cathelicidin	Mouse cells	Nisin induced promoter system	Reduction of inflammation in mice with colitis	[28,39]
	Lc. lactis	Gliadin	Human cells	Lc. lactis-specific pT1NX vector (pT1eDQ8d) used for expression, Lactococcal P1 promoter	Immune stimulation	[40]
	Lc. lactis	Myelin peptide fragments	Human cells	pIL253 derivative with the ptcB gene promoter, expressing MOG35-55, MBP85-97, PLP139-151 antigens	Immune stimulation	[41]
	Lc. lactis	Interleukin-10 production	Yersinia pseudotuberculosis	Stress-Induced Controlled Expression (SICE) and usp45 promoter	Trinitrobenzene sulfonic acid (TNBS) induced colitis	[42]
	Lc. lactis	Heat-shock protein 65 (Hsp65)	Mycobacterium leprae	Xylose-inducible expression system	Prevention of atherosclerosis	[43]