Purification and genetic characterization of gassericin E, a novel co-culture inducible bacteriocin from Lactobacillus gasseri EV1461 isolated from the vagina of a healthy woman

Abstract

BackgroundLactobacillus gasseri is one of the dominant Lactobacillus species in the vaginal ecosystem. Some strains of this species have a high potential for being used as probiotics in order to maintain vaginal homeostasis, since they may confer colonization resistance against pathogens in the vagina by direct inhibition through production of antimicrobial compounds, as bacteriocins. In this work we have studied bacteriocin production of gassericin E (GasE), a novel bacteriocin produced by L. gasseri EV1461, a strain isolated from the vagina of a healthy woman, and whose production was shown to be promoted by the presence of certain specific bacteria in co-culture. Biochemical and genetic characterization of this novel bacteriocin are addressed.ResultsWe found that the inhibitory spectrum of L. gasseri EV1461 was broad, being directed to species both related and non-related to the producing strain. Interestingly, L. gasseri EV1461 inhibited the grown of pathogens usually associated with bacterial vaginosis (BV). The antimicrobial activity was due to the production of a novel bacteriocin, gassericin E (GasE). Production of this bacteriocin in broth medium only was achieved at high cell densities. At low cell densities, bacteriocin production ceased and only was restored after the addition of a supernatant from a previous bacteriocin-producing EV1461 culture (autoinduction), or through co-cultivation with several other Gram-positive strains (inducing bacteria). DNA sequence of the GasE locus revealed the presence of two putative operons which could be involved in biosynthesis and immunity of this bacteriocin (gaeAXI), and in regulation, transport and processing (gaePKRTC). The gaePKR encodes a putative three-component regulatory system, involving an autoinducer peptide (GaeP), a histidine protein kinase (GaeK) and a response regulator (GaeR), while the gaeTC encodes for an ABC transporter (GaeT) and their accessory protein (GaeC), involved in transport and processing of the bacteriocin. The gaeAXI, encodes for the bacteriocin gassericin E (GasE), a putative peptide bacteriocin (GaeX), and their immunity protein (GaeI).ConclusionsThe origin of the strain (vagina of healthy woman) and its ability to produce bacteriocins with inhibitory activity against vaginal pathogens may be an advantage for using L. gasseri EV1461 as a probiotic strain to fight and/or prevent bacterial infections as bacterial vaginosis (BV), since it could be better adapted to live and compete into the vaginal environment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0663-1) contains supplementary material, which is available to authorized users.

Lactobacillus paracasei HD1.7 used as a starter modulates the bacterial community and metabolome profile during fermentation of Chinese cabbage

“…This might also because Lactobacillus could produce antimicrobial substances which inhibited the growth of other Gram‐negative bacteria (Maldonado‐Barragán et al . ). In fact, L. paracasei HD1.7 itself is a bacteriocin producer (Ge et al .…”

Antimicrobial Compounds Produced by Vaginal Lactobacillus crispatus Are Able to Strongly Inhibit Candida albicans Growth, Hyphal Formation and Regulate Virulence-related Gene Expressions

“…It suggests that other antimicrobial compounds might play roles in the growth inhibition effects of CFS on C. albicans . The antimicrobial compounds, such as bacteriocin-like substances and biosurfactants, have been suggested to contribute to the antagonistic effects of probiotic Lactobacillus strains against a variety of vaginal pathogens (Madhu and Prapulla, 2014; Maldonado-Barragán et al, 2016). …”

Homologous expression and characterization of gassericin T and gassericin S, a novel class IIb bacteriocin produced byLactobacillus gasseriLA327

“…In contrast, an active peptide of GaeE (one amino acid variants of GatA, W22L), a component peptide of gassericin E produced by Lb. gasseri EV1461 20 , supports that GatA has the antibacterial activity in alone. Moreover, in this study, a putative immunity protein, GasI, would promote the production of GasAX, while each GasA and GasX production was not affected by gasI expression (Table 3).…”

“…gasseri K7, have been reported as class IIb bacteriocins of Lb. gasseri 19–20 . However, there have never been any reports for success of complete purification of class IIb bacteriocins produced by Lb.…”