Co-culture-inducible bacteriocin production in lactic acid bacteria

Abstract

It is common knowledge that microorganisms have capabilities, like the production of antimicrobial compounds, which do not normally appear in ideal laboratory conditions. Common antimicrobial discovery techniques require the isolation of monocultures and their individual screening against target microorganisms. One strategy to achieve expression of otherwise hidden antimicrobials is induction by co-cultures. In the area of bacteriocin-producing lactic acid bacteria, there has been some research focusing into the characteristics of co-culture-inducible bacteriocin production and particularly the molecular mechanism(s) of such interactions. No clear relationship has been seen between bacteriocin-inducing and bacteriocin-producing microorganisms. The three-component regulatory system seems to be playing a central role in the induction, but inducing compounds have not been identified or characterized. However, the presence of the universal messenger molecule autoinducer-2 has been associated in some cases with the co-culture-inducible bacteriocin phenotype and it may play the role in the additional regulation of the three-component regulatory system. Understanding the mechanisms of induction would facilitate the development of strategies for screening and development of co-culture bacteriocin-producing systems and novel products as well as the perseverance of such systems in food and down to the intestinal tract, possibly conferring a probiotic effect on the host.

Structural and compositional mismatch between captive and wild Atlantic salmon (Salmo salar) parrs’ gut microbiota highlights the relevance of integrating molecular ecology for management and conservation methods

“…Specific bacteria composing the gut microbiota are involved in nutrients degradation (Tremaroli & Bäckhed, ), activation of immune cells such as lymphoblasts (Gaboriau‐Routhiau et al., ), intestinal epithelium cell renewal (Rawls et al., ), and angiogenesis of the intestinal tract (Stappenbeck et al., ). In teleosts, epithelium and gut microorganisms actively prevent opportunistic pathogens growth by both acting as a physical barrier (Balcazar et al., ; Chabrillon et al., ) and promoting antimicrobial molecules synthesis (e.g., bacteriocin, enterocin) (Chanos & Mygind, ; Satish Kumar et al., ), thereby making the gut microbiota a major factor in the development and maturation of the digestive tract immune system (Fredborg, Theil, Jensen, & Purup, ; Rawls et al., ). It has also been observed that gene regulation and hormone secretion of the host are affected by metabolites from bacterial activity acting as signal molecules (Tremaroli & Bäckhed, ).…”

Competition amongGardnerellasubgroups from the human vaginal microbiome

“…Cell-free supernatant (CFS) is the first place to look for any such secreted small molecules that could affect the growth of other bacterial species or strains. Gardnerella isolates have been shown to inhibit the growth of some vaginal lactobacilli in a contact-independent manner [37, 38], and both inhibitory and stimulatory effects of Gardnerella CFS on the growth of a range of vaginal microbiota have been documented [39]. These previous reports, however, have involved relatively few isolates and no information regarding the Gardnerella species involved was provided.…”

“…In the present study, we detected no effect on the amount or mode of growth of Gardnerella isolates when they were exposed to the CFS from other isolates grown in isolation (Figs S1-S14). Since effector molecules are often only secreted when their producers are in contact with other bacterial species [39, 40], we also tested whether CFS from co-culture combinations (where competition had been observed in co-culture assays) affected the growth of Gardnerella strains. We found no effect of co-culture CFS on growth, which further supports the conclusion that there is no contest or direct interference competition between Gardnerella subgroups (Fig 4).…”

The Importance of Bacterial Culture to Food Microbiology in the Age of Genomics

“…The same phenotype may result from multiple mechanisms with differing genotypes (Wilson, 2014). The phenotype may also be dependent upon interactions with other organisms (Sanchez-Vizuete et al, 2015; Chanos and Mygind, 2016). Genetically homogenous cells may be phenotypically heterogeneous, as observed in persister cells and biofilms (Grote et al, 2015; Van Acker and Coenye, 2016; Verstraeten et al, 2016).…”