<i>Lactococcus lactis,</i> an Efficient Cell Factory for Recombinant Protein Production and Secretion

Abstract

The use of Gram-positive bacteria for heterologous protein production proves to be a useful choice due to easy protein secretion and purification. The lactic acid bacterium Lactococcus lactis emerges as an attractive alternative to the Gram-positive model Bacillus subtilis. Here, we review recent work on the expression and secretion systems available for heterologous protein secretion in L. lactis, including promoters, signal peptides and mutant host strains known to overcome some bottlenecks of the process. Among the tools developed in our laboratory, inactivation of HtrA, the unique housekeeping protease at the cell surface, or complementation of the Sec machinery with B. subtilis SecDF accessory protein each result in the increase in heterologous protein yield. Furthermore, our lactococcal expression/secretion system, using both P_ZnzitR, an expression cassette tightly controlled by environmental zinc, and a consensus signal peptide, SP_Exp4, allows efficient production and secretion of the staphylococcal nuclease, as evidenced by protein yields (protein amount/biomass) comparable to those obtained using NICE or P170 expression systems under similar laboratory conditions. Finally, the toolbox we are developing should contribute to enlarge the use of L. lactis as a protein cell factory.

Molecular characterization and structural instability of the industrially important composite metabolic plasmid pLP712

“…Lactococcus lactis, a fermentative lactic acid bacterium, is one of the most widely used bacterial species in industrial food fermentations, and has more recently become the focus of diverse and novel biotechnology applications (Hugenholtz, 2008;Morello et al, 2008). Originally plantassociated, dairy L. lactis strains evolved through a process of reductive evolution (Kelly et al, 2010).…”

Heterologous expression of pneumococcal virulence factor PspC on the surface of Lactococcus lactis confers adhesive properties

“…The non-pathogenic Lactococcus lactis has been shown to be an optimal organism to express and decipher the function of prokaryotic and eukaryotic proteins (Kunji et al, 2003(Kunji et al, , 2005Monné et al, 2005;Morello et al, 2008 …”

“…The non-pathogenic Lactococcus lactis has been shown to be an optimal organism to express and decipher the function of prokaryotic and eukaryotic proteins (Kunji et al, 2003(Kunji et al, , 2005Monné et al, 2005;Morello et al, 2008). L. lactis was further reported to be more advantageous an expression host than Escherichia coli (Mierau & Kleerebezem, 2005;Zhou et al, 2006) and, with regard to pneumococcal PspC, the use of lactococci is preferred as PspC is again decorated on a Gram-positive cell surface.…”

“…Hence, the effects or influences of other pneumococcal proteins on, for example, adherence or induced host immune responses cannot be fully excluded. Therefore, we intended to study the effects of PspC under conditions in which none of the other pneumococcal virulence factors or adhesins may influence the course of infection.The non-pathogenic Lactococcus lactis has been shown to be an optimal organism to express and decipher the function of prokaryotic and eukaryotic proteins (Kunji et al, 2003(Kunji et al, , 2005Monné et al, 2005;Morello et al, 2008 …”

Respiration, a strategy to avoid oxidative stress in Lactococcus lactis, is regulated by the heme status

“…The "safe" and even "beneficial" status of LAB GRAS is attested to by their widespread presence in foods, allowing researchers to develop new applications of LAB GRAS in the area of biotechnology, e.g. production of recombinant proteins 2,23,26,27) .…”