Safety aspects of genetically modified lactic acid bacteria

Microorganisms

Volumn 8, Issue 2, 2020, Pages

  Plavec, Tina Vida ^a,b   Berlec, Aleš ^a,b  

^a JO EF STEFAN INSTITUTE   (Slovenia)

^b UNIVERSITY OF LJUBLJANA   (Slovenia)

Author keywords

Cell factory; Engineering; Generally recognized as safe; Lactic acid bacteria; Safety

Indexed keywords

EID: 85096156567     PISSN: None     EISSN: 20762607     Source Type: Journal    
DOI: 10.3390/microorganisms8020297     Document Type: Review

References (181)

1. Stiles, M.E.; Holzapfel, W.H. Lactic acid bacteria of foods and their current taxonomy. Int. J. Food Microbiol. 1997, 36, 1–29. [CrossRef]
2. Chowdhury, M.Y.; Li, R.; Kim, J.H.; Park, M.E.; Kim, T.H.; Pathinayake, P.; Weeratunga, P.; Song, M.K.; Son, H.Y.; Hong, S.P.; et al. Mucosal vaccination with recombinant Lactobacillus casei-displayed CTA1-conjugated consensus matrix protein-2 (sM2) induces broad protection against divergent influenza subtypes in BALB/c mice. PLoS ONE 2014, 9, e94051. [CrossRef]
3. Van Braeckel-Budimir, N.; Haijema, B.J.; Leenhouts, K. Bacterium-like particles for efficient immune stimulation of existing vaccines and new subunit vaccines in mucosal applications. Front. Immunol. 2013, 4, 282. [CrossRef]
4. William Reed. NutraIngredients.com. Available online: https://www.nutraingredients.com/Article/2018/02/22/Consumer-acceptance-Novel-probiotics-are-beneficial-but-the-food-industry-is-its-own-worst-enemy-on-GM-technologies?utm_source=copyright&utm_medium=OnSite&utm_campaign=copyright (accessed on 18 November 2019).
5. Ortiz-Velez, L.; Britton, R. Genetic tools for the enhancement of probiotic properties. Microbiol. Spectr. 2017, 5, 371–387. [CrossRef]
6. Brodmann, T.; Endo, A.; Gueimonde, M.; Vinderola, G.; Kneifel, W.; de Vos, W.M.; Salminen, S.; Gomez-Gallego, C. Safety of novel microbes for human consumption: Practical examples of assessment in the European Union. Front. Microbiol. 2017, 8, 1725. [CrossRef]
7. Laulund, S.; Wind, A.; Derkx, P.M.F.; Zuliani, V. Regulatory and safety requirements for food cultures. Microorganisms 2017, 5, 28. [CrossRef]
8. O’Sullivan, O.; O’Callaghan, J.; Sangrador-Vegas, A.; McAuliffe, O.; Slattery, L.; Kaleta, P.; Callanan, M.; Fitzgerald, G.F.; Ross, R.P.; Beresford, T. Comparative genomics of lactic acid bacteria reveals a niche-specific gene set. BMC Microbiol. 2009, 9, 50. [CrossRef]
9. Platteeuw, C.; van Alen-Boerrigter, I.; van Schalkwijk, S.; de Vos, W.M. Food-grade cloning and expression system for Lactococcus lactis. Appl. Environ. Microbiol. 1996, 62, 1008–1013. [CrossRef]
10. Borner, R.A.; Kandasamy, V.; Axelsen, A.M.; Nielsen, A.T.; Bosma, E.F. Genome editing of lactic acid bacteria: Opportunities for food, feed, pharma and Biotechnol. FEMS Microbiol. Lett. 2019, 366, 31–40. [CrossRef]
11. Hatti-Kaul, R.; Chen, L.; Dishisha, T.; Enshasy, H.E. Lactic acid bacteria: From starter cultures to producers of chemicals. FEMS Microbiol. Lett. 2018, 366, 365. [CrossRef]
12. Tauer, C.; Heinl, S.; Egger, E.; Heiss, S.; Grabherr, R. Tuning constitutive recombinant gene expression in Lactobacillus plantarum. Microb. Cell Fact. 2014, 13, 150. [CrossRef]
13. Ogaugwu, C.E.; Cheng, Q.; Fieck, A.; Hurwitz, I.; Durvasula, R. Characterization of a Lactococcus lactis promoter for heterologous protein production. Biotechnol. Rep. 2017, 17, 86–92. [CrossRef]
14. de Vos, W.M. Gene expression systems for lactic acid bacteria. Curr. Opin. Microbiol. 1999, 2, 289–295. [CrossRef]
15. Mays, Z.J.; Nair, N.U. Synthetic biology in probiotic lactic acid bacteria: At the frontier of living therapeutics. Curr. Opin. Biotechnol. 2018, 53, 224–231. [CrossRef]
16. Dahmane, N.; Robert, E.; Deschamps, J.; Meylheuc, T.; Delorme, C.; Briandet, R.; Leblond-Bourget, N.; Guedon, E.; Payot, S. Impact of cell surface molecules on conjugative transfer of the integrative and conjugative element ICESt3 of Streptococcus thermophilus. Appl. Environ. Microbiol. 2018, 84, 17.
17. Chiang, Y.N.; Penades, J.R.; Chen, J. Genetic transduction by phages and chromosomal islands: The new and noncanonical. PLoS Pathog. 2019, 15, e1007878. [CrossRef]
18. Baugher, J.L.; Durmaz, E.; Klaenhammer, T.R. Spontaneously induced prophages in Lactobacillus gasseri contribute to horizontal gene transfer. Appl. Environ. Microbiol. 2014, 80, 3508–3517. [CrossRef]
19. Bron, P.A.; Marcelli, B.; Mulder, J.; van der Els, S.; Morawska, L.P.; Kuipers, O.P.; Kok, J.; Kleerebezem, M. Renaissance of traditional DNA transfer strategies for improvement of industrial lactic acid bacteria. Curr. Opin. Biotechnol. 2019, 56, 61–68. [CrossRef]
20. Samson, J.E.; Moineau, S. Characterization of Lactococcus lactis phage 949 and comparison with other lactococcal phages. Appl. Environ. Microbiol. 2010, 76, 6843–6852. [CrossRef]
21. Pujato, S.A.; Guglielmotti, D.M.; Martinez-Garcia, M.; Quiberoni, A.; Mojica, F.J.M. Leuconostoc mesenteroides and Leuconostoc pseudomesenteroides bacteriophages: Genomics and cross-species host ranges. Int. J. Food Microbiol. 2017, 257, 128–137. [CrossRef]
22. Blokesch, M. Natural competence for transformation. Curr. Biol. 2016, 26, R1126–R1130. [CrossRef] [PubMed]
23. Derkx, P.M.; Janzen, T.; Sorensen, K.I.; Christensen, J.E.; Stuer-Lauridsen, B.; Johansen, E. The art of strain improvement of industrial lactic acid bacteria without the use of recombinant DNA technology. Microb. Cell Fact. 2014, 13, S5. [CrossRef] [PubMed]
24. Chen, J.; Vestergaard, M.; Jensen, T.G.; Shen, J.; Dufva, M.; Solem, C.; Jensen, P.R. Finding the needle in the haystack-the use of microfluidic droplet technology to identify vitamin-secreting lactic acid bacteria. mBio 2017, 8, e00526-517. [CrossRef]
25. Goodarzi, A. UV—Induced mutagenesis in lactic acid bacteria. Int. J. Genet. Genom. 2016, 4, 1–4. [CrossRef]
26. Arihara, K.; Itoh, M. UV-induced Lactobacillus gasseri mutants resisting sodium chloride and sodium nitrite for meat fermentation. Int. J. Food Microbiol. 2000, 56, 227–230. [CrossRef]
27. Almalki, M.A. Production of medically important lactic acid by Lactobacillus Pentosus: A biological conversion method. Indian J. Sci. Technol. 2016, 9, 1–8. [CrossRef]
28. Mierau, I.; Kleerebezem, M. 10 years of the nisin-controlled gene expression system (NICE) in Lactococcus lactis. Appl. Microbiol. Biotechnol. 2005, 68, 705–717. [CrossRef]
29. Nguyen, T.T.; Nguyen, H.M.; Geiger, B.; Mathiesen, G.; Eijsink, V.G.; Peterbauer, C.K.; Haltrich, D.; Nguyen, T.H. Heterologous expression of a recombinant lactobacillal beta-galactosidase in Lactobacillus plantarum: Effect of different parameters on the sakacin P-based expression system. Microb. Cell Fact. 2015, 14, 30. [CrossRef]
30. Karlskas, I.L.; Maudal, K.; Axelsson, L.; Rud, I.; Eijsink, V.G.; Mathiesen, G. Heterologous protein secretion in Lactobacilli with modified pSIP vectors. PLoS ONE 2014, 9, e91125. [CrossRef]
31. Sorvig, E.; Mathiesen, G.; Naterstad, K.; Eijsink, V.G.; Axelsson, L. High-level, inducible gene expression in Lactobacillus sakei and Lactobacillus plantarum using versatile expression vectors. Microbiology 2005, 151, 2439–2449. [CrossRef]
32. Walker, D.C.; Klaenhammer, T.R. Isolation of a novel IS3 group insertion element and construction of an integration vector for Lactobacillus spp. J. Bacteriol. 1994, 176, 5330–5340. [CrossRef]
33. Law, J.; Buist, G.; Haandrikman, A.; Kok, J.; Venema, G.; Leenhouts, K. A system to generate chromosomal mutations in Lactococcus lactis which allows fast analysis of targeted genes. J. Bacteriol. 1995, 177, 7011–7018. [CrossRef]
34. Russell, W.M.; Klaenhammer, T.R. Efficient system for directed integration into the Lactobacillus acidophilus and Lactobacillus gasseri chromosomes via homologous recombination. Appl. Environ. Microbiol. 2001, 67, 4361–4364. [CrossRef]
35. Neu, T.; Henrich, B. New thermosensitive delivery vector and its use to enable nisin-controlled gene expression in Lactobacillus gasseri. Appl. Environ. Microbiol. 2003, 69, 1377–1382. [CrossRef]
36. Goh, Y.J.; Azcarate-Peril, M.A.; O’Flaherty, S.; Durmaz, E.; Valence, F.; Jardin, J.; Lortal, S.; Klaenhammer, T.R. Development and application of a upp-based counterselective gene replacement system for the study of the S-layer protein SlpX of Lactobacillus acidophilus NCFM. Appl. Environ. Microbiol. 2009, 75, 3093–3105. [CrossRef]
37. Song, L.; Cui, H.; Tang, L.; Qiao, X.; Liu, M.; Jiang, Y.; Cui, W.; Li, Y. Construction of upp deletion mutant strains of Lactobacillus casei and Lactococcus lactis based on counterselective system using temperature-sensitive plasmid. J. Microbiol. Meth. 2014, 102, 37–44. [CrossRef]
38. Lambert, J.M.; Bongers, R.S.; Kleerebezem, M. Cre-lox-based system for multiple gene deletions and selectable-marker removal in Lactobacillus plantarum. Appl. Environ. Microbiol. 2007, 73, 1126–1135. [CrossRef]
39. Campo, N.; Daveran-Mingot, M.L.; Leenhouts, K.; Ritzenthaler, P.; Le Bourgeois, P. Cre-loxP recombination system for large genome rearrangements in Lactococcus lactis. Appl. Environ. Microbiol. 2002, 68, 2359–2367. [CrossRef]
40. van Pijkeren, J.P.; Britton, R.A. High efficiency recombineering in lactic acid bacteria. Nucleic Acids Res. 2012, 40, e76. [CrossRef]
41. Guo, T.; Xin, Y.; Zhang, Y.; Gu, X.; Kong, J. A rapid and versatile tool for genomic engineering in Lactococcus lactis. Microb. Cell Fact. 2019, 18, 22. [CrossRef]
42. Oh, J.H.; van Pijkeren, J.P. CRISPR-Cas9-assisted recombineering in Lactobacillus reuteri. Nucleic Acids Res. 2014, 42, e131. [CrossRef]
43. Hsu, P.D.; Lander, E.S.; Zhang, F. Development and applications of CRISPR-Cas9 for genome engineering. Cell 2014, 157, 1262–1278. [CrossRef] [PubMed]
44. Doudna, J.A.; Charpentier, E. Genome editing. The new frontier of genome engineering with CRISPR-Cas9. Science 2014, 346, 1258096. [CrossRef] [PubMed]
45. Selle, K.; Klaenhammer, T.R.; Barrangou, R. CRISPR-based screening of genomic island excision events in bacteria. Proc. Natl. Acad. Sci. USA 2015, 112, 8076–8081. [CrossRef] [PubMed]
46. van der Els, S.; James, J.K.; Kleerebezem, M.; Bron, P.A. Development of a versatile Cas9-driven subpopulation-selection toolbox in Lactococcus lactis. Appl. Environ. Microbiol. 2018, 84, 8. [CrossRef]
47. Berlec, A.; Škrlec, K.; Kocjan, J.; Olenic, M.; Štrukelj, B. Single plasmid systems for inducible dual protein expression and for CRISPR-Cas9/CRISPRi gene regulation in lactic acid bacterium Lactococcus lactis. Sci. Rep. 2018, 8, 1009. [CrossRef]
48. Song, X.; Huang, H.; Xiong, Z.; Ai, L.; Yang, S. CRISPR-Cas9(D10A) nickase-assisted genome editing in Lactobacillus casei. Appl. Environ. Microbiol. 2017, 83, 17. [CrossRef]
49. Qi, L.S.; Larson, M.H.; Gilbert, L.A.; Doudna, J.A.; Weissman, J.S.; Arkin, A.P.; Lim, W.A. Repurposing CRISPR as an RNA-guided platform for sequence-specific control of gene expression. Cell 2013, 152, 1173–1183. [CrossRef]
50. Mougiakos, I.; Mohanraju, P.; Bosma, E.F.; Vrouwe, V.; Finger Bou, M.; Naduthodi, M.I.S.; Gussak, A.; Brinkman, R.B.L.; van Kranenburg, R.; van der Oost, J. Characterizing a thermostable Cas9 for bacterial genome editing and silencing. Nat. Commun. 2017, 8, 1647. [CrossRef]
51. Nakade, S.; Yamamoto, T.; Sakuma, T. Cas9, Cpf1 and C2c1/2/3-What’s next? Bioengineered 2017, 8, 265–273. [CrossRef]
52. Jiang, Y.; Qian, F.; Yang, J.; Liu, Y.; Dong, F.; Xu, C.; Sun, B.; Chen, B.; Xu, X.; Li, Y.; et al. CRISPR-Cpf1 assisted genome editing of Corynebacterium glutamicum. Nat. Commun. 2017, 8, 15179. [CrossRef] [PubMed]
53. Liang, M.; Li, Z.; Wang, W.; Liu, J.; Liu, L.; Zhu, G.; Karthik, L.; Wang, M.; Wang, K.F.; Wang, Z.; et al. A CRISPR-Cas12a-derived biosensing platform for the highly sensitive detection of diverse small molecules. Nat. Commun. 2019, 10, 3672. [CrossRef]
54. Shen, W.; Zhang, J.; Geng, B.; Qiu, M.; Hu, M.; Yang, Q.; Bao, W.; Xiao, Y.; Zheng, Y.; Peng, W.; et al. Establishment and application of a CRISPR-Cas12a assisted genome-editing system in Zymomonas mobilis. Microb. Cell Fact. 2019, 18, 162. [CrossRef] [PubMed]
55. Kim, Y.B.; Komor, A.C.; Levy, J.M.; Packer, M.S.; Zhao, K.T.; Liu, D.R. Increasing the genome-targeting scope and precision of base editing with engineered Cas9-cytidine deaminase fusions. Nat. Biotechnol. 2017, 35, 371–376. [CrossRef] [PubMed]
56. Gaudelli, N.M.; Komor, A.C.; Rees, H.A.; Packer, M.S.; Badran, A.H.; Bryson, D.I.; Liu, D.R. Programmable base editing of A*T to G*C in genomic DNA without DNA cleavage. Nature 2017, 551, 464–471. [CrossRef] [PubMed]
57. Eid, A.; Alshareef, S.; Mahfouz, M.M. CRISPR base editors: Genome editing without double-stranded breaks. Biochem. J. 2018, 475, 1955–1964. [CrossRef]
58. Wang, Y.; Wang, S.; Chen, W.; Song, L.; Zhang, Y.; Shen, Z.; Yu, F.; Li, M.; Ji, Q. CRISPR-Cas9 and CRISPR-assisted cytidine deaminase enable precise and efficient genome editing in Klebsiella pneumoniae. Appl. Environ. Microbiol. 2018, 84, 18. [CrossRef]
59. Zheng, K.; Wang, Y.; Li, N.; Jiang, F.F.; Wu, C.X.; Liu, F.; Chen, H.C.; Liu, Z.F. Highly efficient base editing in bacteria using a Cas9-cytidine deaminase fusion. Commun. Biol. 2018, 1, 32. [CrossRef]
60. Wilson, D.J. NIH guidelines for research involving recombinant DNA molecules. Account. Res. 1993, 3, 177–185. [CrossRef]
61. Lee, P. Biocontainment strategies for live lactic acid bacteria vaccine vectors. Bioeng. Bugs 2010, 1, 75–77. [CrossRef]
62. Steidler, L.; Neirynck, S.; Huyghebaert, N.; Snoeck, V.; Vermeire, A.; Goddeeris, B.; Cox, E.; Remon, J.P.; Remaut, E. Biological containment of genetically modified Lactococcus lactis for intestinal delivery of human interleukin 10. Nat. Biotechnol. 2003, 21, 785–789. [CrossRef]
63. Bahey-El-Din, M.; Gahan, C.G. Lactococcus lactis: From the dairy industry to antigen and therapeutic protein delivery. Discov. Med. 2010, 9, 455–461.
64. Zhou, H.; Li, X.; Wang, Z.; Yin, J.; Tan, H.; Wang, L.; Qiao, X.; Jiang, Y.; Cui, W.; Liu, M.; et al. Construction and characterization of thymidine auxotrophic (∆thyA) recombinant Lactobacillus casei expressing bovine lactoferricin. BMC Vet. Res. 2018, 14, 206. [CrossRef] [PubMed]
65. Hanin, A.; Culligan, E.P.; Casey, P.G.; Bahey-El-Din, M.; Hill, C.; Gahan, C.G. Two-tiered biological containment strategy for Lactococcus lactis-based vaccine or immunotherapy vectors. Hum. Vaccines Immunother. 2014, 10, 333–337. [CrossRef] [PubMed]
66. Callura, J.M.; Dwyer, D.J.; Isaacs, F.J.; Cantor, C.R.; Collins, J.J. Tracking, tuning, and terminating microbial physiology using synthetic riboregulators. Proc. Natl. Acad. Sci. USA 2010, 107, 15898–15903. [CrossRef] [PubMed]
67. Lee, J.W.; Chan, C.T.Y.; Slomovic, S.; Collins, J.J. Next-generation biocontainment systems for engineered organisms. Nat. Chem. Biol. 2018, 14, 530–537. [CrossRef]
68. Gallagher, R.R.; Patel, J.R.; Interiano, A.L.; Rovner, A.J.; Isaacs, F.J. Multilayered genetic safeguards limit growth of microorganisms to defined environments. Nucleic Acids Res. 2015, 43, 1945–1954. [CrossRef]
69. Mandell, D.J.; Lajoie, M.J.; Mee, M.T.; Takeuchi, R.; Kuznetsov, G.; Norville, J.E.; Gregg, C.J.; Stoddard, B.L.; Church, G.M. Biocontainment of genetically modified organisms by synthetic protein design. Nature 2015, 518, 55. [CrossRef]
70. Huang, S.; Lee, A.J.; Tsoi, R.; Wu, F.; Zhang, Y.; Leong, K.W.; You, L. Coupling spatial segregation with synthetic circuits to control bacterial survival. Mol. Syst. Biol. 2016, 12, 859. [CrossRef]
71. Alvarez, Y.; Ponce-Alquicira, E. Antibiotic Resistance in Lactic Acid Bacteria; IntechOpen: London, UK, 2018.
72. Mendelson, M.; Matsoso, M.P. The World Health Organization global action plan for antimicrobial resistance. S. Afr. Med. J. 2015, 105, 325. [CrossRef]
73. Markwart, R.; Willrich, N.; Haller, S.; Noll, I.; Koppe, U.; Werner, G.; Eckmanns, T.; Reuss, A. The rise in vancomycin-resistant Enterococcus faecium in Germany: Data from the German Antimicrobial Resistance Surveillance (ARS). Antimicrob. Resist. Infect. Control. 2019, 8, 147. [CrossRef] [PubMed]
74. Faron, M.L.; Ledeboer, N.A.; Buchan, B.W. Resistance mechanisms, epidemiology, and approaches to screening for vancomycin-resistant Enterococcus in the health care setting. J. Clin. Microbiol. 2016, 54, 2436–2447. [CrossRef] [PubMed]
75. Erginkaya, Z.; Turhan, E.U.; Tatli, D. Determination of antibiotic resistance of lactic acid bacteria isolated from traditional Turkish fermented dairy products. Iran. J. Vet. Res. 2018, 19, 53–56. [PubMed]
76. Gad, G.F.; Abdel-Hamid, A.M.; Farag, Z.S. Antibiotic resistance in lactic acid bacteria isolated from some pharmaceutical and dairy products. Braz. J. Microbiol. 2014, 45, 25–33. [CrossRef] [PubMed]
77. Guo, H.; Pan, L.; Li, L.; Lu, J.; Kwok, L.; Menghe, B.; Zhang, H.; Zhang, W. Characterization of antibiotic resistance genes from Lactobacillus isolated from traditional dairy products. J. Food Sci. 2017, 82, 724–730. [CrossRef] [PubMed]
78. Liu, C.; Zhang, Z.Y.; Dong, K.; Yuan, J.P.; Guo, X.K. Antibiotic resistance of probiotic strains of lactic acid bacteria isolated from marketed foods and drugs. Biomed. Environ. Sci. 2009, 22, 401–412. [CrossRef]
79. Doucet-Populaire, F.; Trieu-Cuot, P.; Andremont, A.; Courvalin, P. Conjugal transfer of plasmid DNA from Enterococcus faecalis to Escherichia coli in digestive tracts of gnotobiotic mice. Antimicrob. Agents Chemother. 1992, 36, 502–504. [CrossRef]
80. Bolotin, A.; Quinquis, B.; Sorokin, A.; Ehrlich, D.S. Recent genetic transfer between Lactococcus lactis and enterobacteria. J. Bacteriol. 2004, 186, 6671–6677. [CrossRef] [PubMed]
81. Mater, D.D.G.; Langella, P.; Corthier, G.; Flores, M.J. A probiotic Lactobacillus strain can acquire vancomycin resistance during digestive transit in mice. J. Mol. Microb. Biotechnol. 2008, 14, 123–127. [CrossRef]
82. International Organization for Standardization. Milk and Milk Products: Determination of the Minimal Inhibitory Concentration (MIC) of Antibiotics Applicable to Bifidobacteria and Non-Enterococcal Lactic Acid Bacteria. Available online: https://www.iso.org/standard/46434.html (accessed on 18 November 2019).
83. Clementi, F.; Aquilanti, L. Recent investigations and updated criteria for the assessment of antibiotic resistance in food lactic acid bacteria. Anaerobe 2011, 17, 394–398. [CrossRef]
84. De, R. Metagenomics: Aid to combat antimicrobial resistance in diarrhea. Gut Pathog. 2019, 11, 47. [CrossRef] [PubMed]
85. Schloss, P.D.; Handelsman, J. Biotechnological prospects from metagenomics. Curr. Opin. Biotechnol. 2003, 14, 303–310. [CrossRef]
86. European Food Safety, A. Technical guidance-Update of the criteria used in the assessment of bacterial resistance to antibiotics of human or veterinary importance. EFSA J. 2008, 6, 732. [CrossRef]
87. Cox, G.; Wright, G.D. Intrinsic antibiotic resistance: Mechanisms, origins, challenges and solutions. Int. J. Med. Microbiol. 2013, 303, 287–292. [CrossRef]
88. Mignon, C.; Sodoyer, R.; Werle, B. Antibiotic-free selection in biotherapeutics: Now and forever. Pathogens 2015, 4, 157–181. [CrossRef]
89. He, S.; Gong, F.; Zhang, D.; Guo, Y. Food-grade selection markers in lactic acid bacteria. TAF Prev. Med. Bull. 2012, 11, 1. [CrossRef]
90. Hughes, B.F.; McKay, L.L. Deriving phage-insensitive Lactococci using a food-grade vector encoding phage and nisin resistance. J. Dairy Sci. 1992, 75, 914–923. [CrossRef]
91. von Wright, A.; Wessels, S.; Tynkkynen, S.; Saarela, M. Isolation of a replication region of a large lactococcal plasmid and use in cloning of a nisin resistance determinant. Appl. Environ. Microbiol. 1990, 56, 2029–2035. [CrossRef]
92. Takala, T.; Saris, P. A food-grade cloning vector for lactic acid bacteria based on the nisin immunity gene nisI. Appl. Microbiol. Biotechnol. 2002, 59, 467–471.
93. Leelawatcharamas, V.; Chia, L.G.; Charoenchai, P.; Kunajakr, N.; Liu, C.-Q.; Dunn, N.W. Plasmid-encoded copper resistance in Lactococcus lactis. Biotechnol. Lett. 1997, 19, 639–643. [CrossRef]
94. Liu, C.Q.; Su, P.; Khunajakr, N.; Deng, Y.M.; Sumual, S.; Kim, W.S.; Tandianus, J.E.; Dunn, N.W. Development of food-grade cloning and expression vectors for Lactococcus lactis. J. Appl. Microbiol. 2005, 98, 127–135. [CrossRef] [PubMed]
95. Wong, W.Y.; Su, P.; Allison, G.E.; Liu, C.-Q.; Dunn, N.W. A potential food-grade cloning vector for Streptococcus thermophilus that uses cadmium resistance as the selectable marker. Appl. Environ. Microbiol. 2003, 69, 5767–5771. [CrossRef] [PubMed]
96. El Demerdash, H.A.M.; Heller, K.J.; Geis, A. Application of the shsp gene, encoding a small heat shock protein, as a food-grade selection marker for lactic acid bacteria. Appl. Environ. Microbiol. 2003, 69, 4408–4412. [CrossRef]
97. Sørensen, K.I.; Larsen, R.; Kibenich, A.; Junge, M.P.; Johansen, E. A food-grade cloning system for industrial strains of Lactococcus lactis. Appl. Environ. Microbiol. 2000, 66, 1253–1258. [CrossRef]
98. Bron, P.A.; Benchimol, M.G.; Lambert, J.; Palumbo, E.; Deghorain, M.; Delcour, J.; De Vos, W.M.; Kleerebezem, M.; Hols, P. Use of the alr gene as a food-grade selection marker in lactic acid bacteria. Appl. Environ. Microbiol. 2002, 68, 5663–5670. [CrossRef]
99. Takala, T.; Saris, P.; Tynkkynen, S. Food-grade host/vector expression system for Lactobacillus casei based on complementation of plasmid-associated phospho-β-galactosidase gene lacG. Appl. Microbiol. Biotechnol. 2003, 60, 564–570. [CrossRef]
100. Boucher, I.; Parrot, M.; Gaudreau, H.; Champagne, C.P.; Vadeboncoeur, C.; Moineau, S. Novel food-grade plasmid vector based on melibiose fermentation for the genetic engineering of Lactococcus lactis. Appl. Environ. Microbiol. 2002, 68, 6152–6161. [CrossRef]
101. Labrie, S.; Bart, C.; Vadeboncoeur, C.; Moineau, S. Use of an α-galactosidase gene as a food-grade selection marker for Streptococcus thermophilus. J. Dairy Sci. 2005, 88, 2341–2347. [CrossRef]
102. Jeong, D.-W.; Lee, J.-H.; Kim, K.H.; Lee, H.J. A food-grade expression/secretion vector for Lactococcus lactis that uses an α-galactosidase gene as a selection marker. Food Microbiol. 2006, 23, 468–475. [CrossRef]
103. Peubez, I.; Chaudet, N.; Mignon, C.; Hild, G.; Husson, S.; Courtois, V.; De Luca, K.; Speck, D.; Sodoyer, R. Antibiotic-free selection in E. coli: New considerations for optimal design and improved production. Microb. Cell Fact. 2010, 9, 65. [CrossRef]
104. Shao, Y.; Harrison, E.M.; Bi, D.; Tai, C.; He, X.; Ou, H.-Y.; Rajakumar, K.; Deng, Z. TADB: A web-based resource for type 2 toxin-antitoxin loci in bacteria and archaea. Nucleic Acids Res. 2011, 39, D606–D611. [CrossRef]
105. Diago-Navarro, E.; Hernandez-Arriaga, A.M.; López-Villarejo, J.; Muñoz-Gómez, A.J.; Kamphuis, M.B.; Boelens, R.; Lemonnier, M.; Díaz-Orejas, R. parD toxin–antitoxin system of plasmid R1–basic contributions, biotechnological applications and relationships with closely-related toxin–antitoxin systems. FEBS J. 2010, 277, 3097–3117. [CrossRef]
106. Kawano, M. Divergently overlapping cis-encoded antisense RNA regulating toxin-antitoxin systems from E. coli: Hok/sok, ldr/rdl, symE/symR. RNA Biol. 2012, 9, 1520–1527. [CrossRef]
107. Weaver, K.E. The par toxin-antitoxin system from Enterococcus faecalis plasmid pAD1 and its chromosomal homologs. RNA Biol. 2012, 9, 1498–1503. [CrossRef]
108. Weaver, K.E. The Type I toxin-antitoxin par locus from Enterococcus faecalis plasmid pAD1: RNA regulation by both cis-and trans-acting elements. Plasmid 2015, 78, 65–70. [CrossRef]
109. Mairhofer, J.; Pfaffenzeller, I.; Merz, D.; Grabherr, R. A novel antibiotic free plasmid selection system: Advances in safe and efficient DNA therapy. Biotechnol. J. 2008, 3, 83–89. [CrossRef]
110. Pfaffenzeller, I.; Mairhofer, J.; Striedner, G.; Bayer, K.; Grabherr, R. Using ColE1-derived RNA I for suppression of a bacterially encoded gene: Implication for a novel plasmid addiction system. Biotechnol. J. 2006, 1, 675–681. [CrossRef]
111. Stenler, S.; Blomberg, P.; Smith, C.I.E. Safety and efficacy of DNA vaccines: Plasmids vs. minicircles. Hum. Vaccin. Immunother. 2014, 10, 1306–1308. [CrossRef]
112. Douglas, G.L.; Goh, Y.J.; Klaenhammer, T.R. Integrative food grade expression system for lactic acid bacteria. Methods Mol. Biol. 2011, 765, 373–387.
113. Johansen, E. Future access and improvement of industrial lactic acid bacteria cultures. Microb. Cell Fact. 2017, 16, 230. [CrossRef]
114. Phumkhachorn, P.; Rattanachaikunsopon, P. A broad host range food-grade cloning vector for lactic acid bacteria. Biologia 2016, 71, 457. [CrossRef]
115. Tagliavia, M.; Nicosia, A. Advanced strategies for food-grade protein production: A new E. coli/lactic acid bacteria shuttle vector for improved cloning and food-grade expression. Microorganisms 2019, 7, 116. [CrossRef]
116. Mathipa, M.G.; Thantsha, M.S. Probiotic engineering: Towards development of robust probiotic strains with enhanced functional properties and for targeted control of enteric pathogens. Gut Pathog. 2017, 9, 28. [CrossRef]
117. Sybesma, W.; Hugenholtz, J.; Vos, W.M.D.; Smid, E.J. Safe use of genetically modified lactic acid bacteria in food. Bridging the gap between consumers, green groups, and industry. Electron. J. Biotechnol. 2006, 9, 424–448. [CrossRef]
118. Salminen, M.K.; Tynkkynen, S.; Rautelin, H.; Saxelin, M.; Vaara, M.; Ruutu, P.; Sarna, S.; Valtonen, V.; Järvinen, A. Lactobacillus bacteremia during a rapid increase in probiotic use of Lactobacillus rhamnosus GG in Finland. Clin. Infect. Dis. 2002, 35, 1155–1160. [CrossRef]
119. Zadravec, P.; Štrukelj, B.; Berlec, A. Heterologous surface display on lactic acid bacteria: Non-GMO alternative? Bioengineered 2015, 6, 179–183. [CrossRef]
120. Hu, S.; Kong, J.; Kong, W.; Guo, T.; Ji, M. Characterization of a novel LysM domain from Lactobacillus fermentum bacteriophage endolysin and its use as an anchor to display heterologous proteins on the surfaces of lactic acid bacteria. Appl. Environ. Microbiol. 2010, 76, 2410–2418. [CrossRef]
121. Hu, S.; Kong, J.; Sun, Z.; Han, L.; Kong, W.; Yang, P. Heterologous protein display on the cell surface of lactic acid bacteria mediated by the s-layer protein. Microb. Cell Fact. 2011, 10, 86. [CrossRef]
122. Plavec, T.V.; Štrukelj, B.; Berlec, A. Screening for new surface anchoring domains for Lactococcus lactis. Front. Microbiol. 2019, 10, 1879. [CrossRef]
123. Plavec, T.V.; Berlec, A. Surface anchoring on Lactococcus lactis by covalent isopeptide bond. Acta Chim. Slov. 2019, 66, 10. [CrossRef]
124. Mao, R.; Wu, D.; Wang, Y. Surface display on lactic acid bacteria without genetic modification: Strategies and applications. Appl. Microbiol. Biotechnol. 2016, 100, 9407–9421. [CrossRef] [PubMed]
125. Song, A.A.; In, L.L.A.; Lim, S.H.E.; Rahim, R.A. A review on Lactococcus lactis: From food to factory. Microb. Cell Fact. 2017, 16, 55. [CrossRef] [PubMed]
126. Berlec, A.; Štrukelj, B. Novel applications of recombinant lactic acid bacteria in therapy and in metabolic engineering. Recent Pat. Biotechnol. 2009, 3, 77–87. [CrossRef]
127. Hugenholtz, J.; Sybesma, W.; Nierop Groot, M.; Wisselink, W.; Ladero, V.; Burgess, K.; van Sinderen, D.; Piard, J.-C.; Eggink, G.; Smid, E.J.; et al. Metabolic engineering of lactic acid bacteria for the production of nutraceuticals. Lactic Acid Bacteria Genet. Metab. Appl. 2002, 82, 217–235.
128. Liu, J.; Chan, S.H.J.; Chen, J.; Solem, C.; Jensen, P.R. Systems Biology-A guide for understanding and developing improved strains of lactic acid bacteria. Front. Microbiol. 2019, 10, 876. [CrossRef]
129. Papagianni, M. Metabolic engineering of lactic acid bacteria for the production of industrially important cpmpounds. Comput. Struct. Biotechnol. 2012, 3, e201210003. [CrossRef]
130. Kleerebezem, M.; Hugenholtz, J. Metabolic pathway engineering in lactic acid bacteria. Curr. Opin. Biotechnol. 2003, 14, 232–237. [CrossRef]
131. Castro-Aguirre, E.; Iniguez-Franco, F.; Samsudin, H.; Fang, X.; Auras, R. Poly(lactic acid)-mass production, processing, industrial applications, and end of life. Adv. Drug Deliv. Rev. 2016, 107, 333–366. [CrossRef]
132. Mack, D.R. D(-)-lactic acid-producing probiotics, D(-)-lactic acidosis and infants. Can. J. Gastroenterol. 2004, 18, 671–675. [CrossRef]
133. Yu, L.; Pei, X.; Lei, T.; Wang, Y.; Feng, Y. Genome shuffling enhanced L-lactic acid production by improving glucose tolerance of Lactobacillus rhamnosus. J. Biotechnol. 2008, 134, 154–159. [CrossRef]
134. Yi, X.; Zhang, P.; Sun, J.; Tu, Y.; Gao, Q.; Zhang, J.; Bao, J. Engineering wild-type robust Pediococcus acidilactici strain for high titer L-and D-lactic acid production from corn stover feedstock. J. Biotechnol. 2016, 217, 112–121. [CrossRef] [PubMed]
135. Okano, K.; Hama, S.; Kihara, M.; Noda, H.; Tanaka, T.; Kondo, A. Production of optically pure D-lactic acid from brown rice using metabolically engineered Lactobacillus plantarum. Appl. Microbiol. Biotechnol. 2017, 101, 1869–1875. [CrossRef] [PubMed]
136. Okano, K.; Zhang, Q.; Shinkawa, S.; Yoshida, S.; Tanaka, T.; Fukuda, H.; Kondo, A. Efficient production of optically pure D-lactic acid from raw corn starch by using a genetically modified L-lactate dehydrogenase gene-deficient and alpha-amylase-secreting Lactobacillus plantarum strain. Appl. Environ. Microbiol. 2009, 75, 462–467. [CrossRef] [PubMed]
137. Kuo, Y.C.; Yuan, S.F.; Wang, C.A.; Huang, Y.J.; Guo, G.L.; Hwang, W.S. Production of optically pure L-lactic acid from lignocellulosic hydrolysate by using a newly isolated and D-lactate dehydrogenase gene-deficient Lactobacillus paracasei strain. Bioresour. Technol. 2015, 198, 651–657. [CrossRef]
138. Kyla-Nikkila, K.; Hujanen, M.; Leisola, M.; Palva, A. Metabolic engineering of Lactobacillus helveticus CNRZ32 for production of pure L-(+)-lactic acid. Appl. Environ. Microbiol. 2000, 66, 3835–3841. [CrossRef]
139. Liu, J.; Dantoft, S.H.; Würtz, A.; Jensen, P.R.; Solem, C. A novel cell factory for efficient production of ethanol from dairy waste. Biotechnol. Biofuels 2016, 9, 33. [CrossRef]
140. Florou-Paneri, P.; Christaki, E.; Bonos, E. Lactic Acid Bacteria as Source of Functional Ingredients; IntechOpen: Rijeka, Croatia, 2012; pp. 589–614.
141. Linares, D.M.; Gómez, C.; Renes, E.; Fresno, J.M.; Tornadijo, M.E.; Ross, R.P.; Stanton, C. Lactic acid bacteria and Bifidobacteria with potential to design natural biofunctional health-promoting dairy foods. Front. Microbiol. 2017, 8, 846. [CrossRef]
142. Zhang, J.; Caiyin, Q.; Feng, W.; Zhao, X.; Qiao, B.; Zhao, G.; Qiao, J. Enhance nisin yield via improving acid-tolerant capability of Lactococcus lactis F44. Sci. Rep. 2016, 6, 27973. [CrossRef]
143. Fu, Y.; Mu, D.; Qiao, W.; Zhu, D.; Wang, X.; Liu, F.; Xu, H.; Saris, P.; Kuipers, O.P.; Qiao, M. Co-expression of nisin Z and leucocin C as a basis for effective protection against Listeria monocytogenes in pasteurized milk. Front. Microbiol. 2018, 9, 547. [CrossRef]
144. Burgess, C.; O’Connell-Motherway, M.; Sybesma, W.; Hugenholtz, J.; van Sinderen, D. Riboflavin production in Lactococcus lactis: Potential for in situ production of vitamin-enriched foods. Appl. Environ. Microbiol. 2004, 70, 5769–5777. [CrossRef]
145. LeBlanc, J.G.; Burgess, C.; Sesma, F.; de Giori, G.S.; van Sinderen, D. Ingestion of milk fermented by genetically modified Lactococcus lactis improves the riboflavin status of deficient rats. J. Dairy Sci. 2005, 88, 3435–3442. [CrossRef]
146. Wegkamp, A.; van Oorschot, W.; de Vos, W.M.; Smid, E.J. Characterization of the role of para-aminobenzoic acid biosynthesis in folate production by Lactococcus lactis. Appl. Environ. Microbiol. 2007, 73, 2673–2681. [CrossRef] [PubMed]
147. Wegkamp, A.; Starrenburg, M.; de Vos, W.M.; Hugenholtz, J.; Sybesma, W. Transformation of folate-consuming Lactobacillus gasseri into a folate producer. Appl. Environ. Microbiol. 2004, 70, 3146–3148. [CrossRef] [PubMed]
148. Santos, F.; Wegkamp, A.; de Vos, W.M.; Smid, E.J.; Hugenholtz, J. High-level folate production in fermented foods by the B12 producer Lactobacillus reuteri JCM1112. Appl. Environ. Microbiol. 2008, 74, 3291–3294. [CrossRef]
149. De Boeck, R.; Sarmiento-Rubiano, L.A.; Nadal, I.; Monedero, V.; Perez-Martinez, G.; Yebra, M.J. Sorbitol production from lactose by engineered Lactobacillus casei deficient in sorbitol transport system and mannitol-1-phosphate dehydrogenase. Appl. Microbiol. Biotechnol. 2010, 85, 1915–1922. [CrossRef]
150. Ladero, V.; Ramos, A.; Wiersma, A.; Goffin, P.; Schanck, A.; Kleerebezem, M.; Hugenholtz, J.; Smid, E.J.; Hols, P. High-level production of the low-calorie sugar sorbitol by Lactobacillus plantarum through metabolic engineering. Appl. Environ. Microbiol. 2007, 73, 1864–1872. [CrossRef]
151. Gaspar, P.; Neves, A.R.; Gasson, M.J.; Shearman, C.A.; Santos, H. High yields of 2,3-butanediol and mannitol in Lactococcus lactis through engineering of NAD(+) cofactor recycling. Appl. Environ. Microbiol. 2011, 77, 6826–6835. [CrossRef]
152. Gaspar, P.; Carvalho, A.L.; Vinga, S.; Santos, H.; Neves, A.R. From physiology to systems metabolic engineering for the production of biochemicals by lactic acid bacteria. Biotechnol. Adv. 2013, 31, 764–788. [CrossRef]
153. Mazzoli, R.; Bosco, F.; Mizrahi, I.; Bayer, E.A.; Pessione, E. Towards lactic acid bacteria-based biorefineries. Biotechnol. Adv. 2014, 32, 1216–1236. [CrossRef]
154. ′-untranslated leader sequence of slpA from Lactobacillus acidophilus. Appl. Microbiol. Biotechnol. 2006, 73, 366–373. [CrossRef]
155. Narita, J.; Nakahara, S.; Fukuda, H.; Kondo, A. Efficient production of L-(+)-lactic acid from raw starch by Streptococcus bovis 148. J. Biosci. Bioeng. 2004, 97, 423–425. [CrossRef]
156. Okano, K.; Kimura, S.; Narita, J.; Fukuda, H.; Kondo, A. Improvement in lactic acid production from starch using α-amylase-secreting Lactococcus lactis cells adapted to maltose or starch. Appl. Microbiol. Biotechnol. 2007, 75, 1007–1013. [CrossRef]
157. Okano, K.; Zhang, Q.; Yoshida, S.; Tanaka, T.; Ogino, C.; Fukuda, H.; Kondo, A. d-lactic acid production from cellooligosaccharides and β-glucan using l-LDH gene-deficient and endoglucanase-secreting Lactobacillus plantarum. Appl. Microbiol. Biotechnol. 2010, 85, 643–650. [CrossRef]
158. Moraïs, S.; Shterzer, N.; Grinberg, I.R.; Mathiesen, G.; Eijsink, V.G.H.; Axelsson, L.; Lamed, R.; Bayer, E.A.; Mizrahi, I. Establishment of a simple Lactobacillus plantarum cell consortium for cellulase-xylanase synergistic interactions. Appl. Environ. Microbiol. 2013, 79, 5242–5249. [CrossRef]
159. Cho, J.S.; Choi, Y.J.; Chung, D.K. Expression of Clostridium thermocellum endoglucanase gene in Lactobacillus gasseri and Lactobacillus johnsonii and characterization of the genetically modified probiotic Lactobacilli. Curr. Microbiol. 2000, 40, 257–263. [CrossRef]
160. Raha, A.R.; Chang, L.Y.; Sipat, A.; Yusoff, K.; Haryanti, T. Expression of a thermostable xylanase gene from Bacillus coagulans ST-6 in Lactococcus lactis. Lett. Appl. Microbiol. 2006, 42, 210–214. [CrossRef]
161. Ozkose, E.; Akyol, I.; Kar, B.; Comlekcioglu, U.; Ekinci, M.S. Expression of fungal cellulase gene in Lactococcus lactis to construct novel recombinant silage inoculants. Folia Microbiol. 2009, 54, 335–342. [CrossRef]
162. Nguyen, T.H.; Splechtna, B.; Yamabhai, M.; Haltrich, D.; Peterbauer, C. Cloning and expression of the beta-galactosidase genes from Lactobacillus reuteri in Escherichia coli. J. Biotechnol. 2007, 129, 581–591. [CrossRef]
163. Nguyen, T.T.; Nguyen, H.A.; Arreola, S.L.; Mlynek, G.; Djinovic-Carugo, K.; Mathiesen, G.; Nguyen, T.H.; Haltrich, D. Homodimeric beta-galactosidase from Lactobacillus delbrueckii subsp. bulgaricus DSM 20081: Expression in Lactobacillus plantarum and biochemical characterization. J. Agric. Food Chem. 2012, 60, 1713–1721.
164. Halbmayr, E.; Mathiesen, G.; Nguyen, T.H.; Maischberger, T.; Peterbauer, C.K.; Eijsink, V.G.; Haltrich, D. High-level expression of recombinant beta-galactosidases in Lactobacillus plantarum and Lactobacillus sakei using a sakacin P-based expression system. J. Agric. Food Chem. 2008, 56, 4710–4719. [CrossRef]
165. Nguyen, H.M.; Mathiesen, G.; Stelzer, E.M.; Pham, M.L.; Kuczkowska, K.; Mackenzie, A.; Agger, J.W.; Eijsink, V.G.; Yamabhai, M.; Peterbauer, C.K.; et al. Display of a beta-mannanase and a chitosanase on the cell surface of Lactobacillus plantarum towards the development of whole-cell biocatalysts. Microb. Cell Fact. 2016, 15, 169. [CrossRef] [PubMed]
166. Yang, P.; Li, Y.; Wang, Y.; Meng, K.; Luo, H.; Yuan, T.; Bai, Y.; Zhan, Z.; Yao, B. A novel beta-mannanase with high specific activity from Bacillus circulans CGMCC1554: Gene cloning, expression and enzymatic characterization. Appl. Biochem. Biotechnol. 2009, 159, 85–94. [CrossRef] [PubMed]
167. Sak-Ubol, S.; Namvijitr, P.; Pechsrichuang, P.; Haltrich, D.; Nguyen, T.H.; Mathiesen, G.; Eijsink, V.G.; Yamabhai, M. Secretory production of a beta-mannanase and a chitosanase using a Lactobacillus plantarum expression system. Microb. Cell Fact. 2016, 15, 81. [CrossRef]
168. Chien, L.-J.; Lee, C.-K. Hyaluronic acid production by recombinant Lactococcus lactis. Appl. Microbiol. Biotechnol. 2007, 77, 339–346. [CrossRef]
169. Prasad, S.B.; Jayaraman, G.; Ramachandran, K.B. Hyaluronic acid production is enhanced by the additional co-expression of UDP-glucose pyrophosphorylase in Lactococcus lactis. Appl. Microbiol. Biotechnol. 2010, 86, 273–283. [CrossRef]
170. Thakur, K.; Tomar, S.K.; De, S. Lactic acid bacteria as a cell factory for riboflavin production. Microb. Biotechnol. 2016, 9, 441–451. [CrossRef]
171. Eric, J. Use of Natural selection and evolution to develop new starter cultures for fermented foods. Annu. Rev. Food Sci. Technol. 2018, 9, 411–428.
172. Carvalho, R.D.; do Carmo, F.L.R.; de Oliveira Junior, A.; Langella, P.; Chatel, J.-M.; Bermúdez-Humarán, L.G.; Azevedo, V.; de Azevedo, M.S. Use of wild type or recombinant lactic acid bacteria as an alternative treatment for gastrointestinal inflammatory diseases: A focus on inflammatory bowel diseases and mucositis. Front. Microbiol. 2017, 8, 800. [CrossRef]
173. de Moreno de LeBlanc, A.; Del Carmen, S.; Chatel, J.-M.; Miyoshi, A.; Azevedo, V.; Langella, P.; Bermudez-Humaran, L.G.; LeBlanc, J.G. Current review of genetically modified lactic acid bacteria for the prevention and treatment of colitis using murine models. Gastroent. Res. Pract. 2015, 2015, 146972. [CrossRef]
174. Plavec, T.V.; Berlec, A. Engineering of lactic acid bacteria for delivery of therapeutic proteins and peptides. Appl. Microbiol. Biotechnol. 2019, 103, 2053–2066. [CrossRef]
175. Food and Drug Administration. Enforcement Policy Regarding Investigational New Drug Requirements for Use of Fecal Microbiota for Transplantation to Treat Clostridium difficile Infection Not Responsive to Standard Therapies. Center for Biologics Evaluation and Research. 2013. Available online: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/enforcement-policy-regarding-investigational-new-drug-requirements-use-fecal-microbiota (accessed on 18 November 2019).
176. Bron, P.A.; Kleerebezem, M. Lactic acid bacteria for delivery of endogenous or engineered therapeutic molecules. Front. Microbiol. 2018, 9, 1821. [CrossRef]
177. Research and Markets. Microbiome Therapeutics and Diagnostics Market (2nd Edition), 2017–2030. Available online: https://www.researchandmarkets.com/reports/4377904/microbiome-therapeutics-and-diagnostics-market (accessed on 19 November 2019).
178. Custers, R. The regulatory status of gene-edited agricultural products in the EU and beyond. Emerg. Top. Life Sci. 2017, 1, 20170019.
179. Callaway, E. CRISPR plants now subject to tough GM laws in European Union. Nature 2018, 560, 16. [CrossRef]
180. Shew, A.M.; Nalley, L.L.; Snell, H.A.; Nayga, R.M.; Dixon, B.L. CRISPR versus GMOs: Public acceptance and valuation. Glob. Food Secur. 2018, 19, 71–80. [CrossRef]
181. Wang, T.; Zhang, H.; Zhu, H. CRISPR technology is revolutionizing the improvement of tomato and other fruit crops. Hortic. Res. 2019, 6, 77. [CrossRef]